Patent Publication Number: US-2006005738-A1

Title: Railroad vehicle with energy regeneration

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
      The invention of the present application is a continuation-in-part of U.S. patent application Ser. No. 10/435,261, filed May 9, 2003, entitled Multimode Hybrid Energy Railway Vehicle System and Method, which is a continuation-in-part of U.S. patent application Ser. No. 10/032,714, filed on Dec. 26, 2001, entitled Locomotive Energy Tender, now U.S. Pat. No. 6,612,245 (issued Sep. 2, 2003), which claims priority based on U.S. Provisional Application Ser. No. 60/278,975, filed on Mar. 27, 2001, the entire disclosures of which are incorporated herein by reference.  
      The following commonly owned, co-pending applications are related to the present application and are incorporated herein by reference: 
      U.S. patent application Ser. No. 10/033,172, filed on Dec. 26, 2001, and entitled “HYBRID ENERGY POWER MANAGEMENT SYSTEM AND METHOD”;     U.S. patent application Ser. No. 10/033,347, filed on Dec. 26, 2001, and entitled “HYBRID ENERGY LOCOMOTIVE ELECTRICAL POWER STORAGE SYSTEM”;     U.S. patent application Ser. No. 10/033,191, filed on Dec. 26, 2001, and entitled “HYBRID ENERGY LOCOMOTIVE SYSTEM AND METHOD”; and     U.S. patent application Ser. No. 10/032,7 14, filed on Dec. 26, 2001, and entitled “LOCOMOTIVE ENERGY TENDER”.   

    
    
     FIELD OF THE INVENTION  
      The invention relates generally to vehicles for use in connection with railways. In particular, the invention relates to a railroad vehicle operable from stored electrical energy, such as stored electrical energy being produced by a charging generator and/or by dynamic braking energy generated by electric traction motors during braking, the railroad vehicle being operable in a plurality of operating modes. The railroad vehicles are primarily load-carrying for carrying freight and that have power regeneration capability. Railway systems that comprise such railroad vehicles also are disclosed.  
     BACKGROUND OF THE INVENTION  
       FIG. 1A  is a block diagram of an exemplary prior art locomotive  100 . In particular,  FIG. 1A  generally reflects a typical prior art diesel-electric locomotive such as, for example, the AC6000 or the AC4400, both or which are available from General Electric Transportation Systems. As illustrated in  FIG. 1A , the locomotive  100  includes a diesel engine  102  driving an alternator/rectifier  104 . As is generally understood in the art, the alternator/rectifier  104  provides DC electric power to an inverter  106  that converts the AC electric power to a form suitable for use by a traction motor  108  mounted on a truck below the main engine housing. One common locomotive configuration includes one inverter/traction motor pair per axle. Such a configuration results in three inverters per truck, and six inverters and traction motors per locomotive.  FIG. 1A  illustrates a single inverter  106  for convenience.  
      Strictly speaking, an inverter converts DC power to AC power. A rectifier converts AC power to DC power. The term converter is also sometimes used to refer to inverters and rectifiers. The electrical power supplied in this manner may be referred to as prime mover power (or primary electric power) and the alternator/rectifier  104  may be referred to as a source of prime mover power. In a typical AC diesel-electric locomotive application, the AC electric power from the alternator is first rectified (converted to DC). The rectified AC is thereafter inverted (e.g., using power electronics such as IGBTs or thyristors operating as pulse width modulators) to provide a suitable form of AC power for the respective traction motor  108 .  
      As is understood in the art, traction motors  108  provide the tractive power to move locomotive  100  and any other vehicles, such as load vehicles, attached to locomotive  100 . Such traction motors  108  may be AC or DC electric motors. When using DC traction motors, the output of the alternator is typically rectified to provide appropriate DC power. When using AC traction motors, the alternator output is typically rectified to DC and thereafter inverted to three-phase AC before being supplied to traction motors  108 .  
      The traction motors  108  also provide a braking force for controlling speed or for slowing locomotive  100 . This is commonly referred to as dynamic braking, and is generally understood in the art. Simply stated, when a traction motor is not needed to provide motivating force, it can be reconfigured (via power switching devices) so that the motor operates as a generator. So configured, the traction motor generates electric energy which has the effect of slowing the locomotive. In prior art locomotives, such as the locomotive illustrated in  FIG. 1A , the energy generated in the dynamic braking mode is typically transferred to resistance grids  110  mounted on the locomotive housing. Thus, the dynamic braking energy is converted to heat and dissipated from the system. In other words, electric energy generated in the dynamic braking mode is typically wasted.  
      It should be noted that, in a typical prior art DC locomotive, the dynamic braking grids are connected to the traction motors. In a typical prior art AC locomotive, however, the dynamic braking grids are connected to the DC traction bus because each traction motor is normally connected to the bus by way of an associated inverter (see  FIG. 1B ).  FIG. 1A  generally illustrates an AC locomotive with a plurality of traction motors; a single inverter is depicted for convenience.  
       FIG. 1B  is an electrical schematic of a typical prior art AC locomotive. It is generally known in the art to employ at least two power supply systems in such locomotives. A first system comprises the prime mover power system that provides power to the traction motors. A second system provides power for so-called auxiliary electrical systems (or simply auxiliaries). In  FIG. 1B , the diesel engine (see  FIG. 1A ) drives the prime mover power source  104  (e.g., an alternator and rectifier), as well as any auxiliary alternators (not illustrated) used to power various auxiliary electrical subsystems such as, for example, lighting, air conditioning/heating, blower drives, radiator fan drives, control battery chargers, field exciters, and the like. The auxiliary power system may also receive power from a separate axle driven generator. Auxiliary power may also be derived from the traction alternator of prime mover power source  104 .  
      The output of prime mover power source  104  is connected to a DC bus  122  that supplies DC power to the traction motor subsystems  124 A- 124 F. The DC bus  122  may also be referred to as a traction bus because it carries the power used by the traction motor subsystems. As explained above, a typical prior art diesel-electric locomotive includes four or six traction motors. In  FIG. 1B , each traction motor subsystem comprises an inverter (e.g., inverter  106 A) and a corresponding traction motor (e.g., traction motor  108 A).  
      During braking, the power generated by the traction motors is dissipated through a dynamic braking grid subsystem  110 . As illustrated in  FIG. 1A , a typical prior art dynamic braking grid includes a plurality of contactors (e.g., DB 1 -DB 5 ) for switching a plurality of power resistive elements between the positive and negative rails of the DC bus  122 . Each vertical grouping of resistors may be referred to as a string. One or more power grid cooling blowers (e.g., BL 1  and BL 2 ) are normally used to remove heat generated in a string due to dynamic braking.  
      As indicated above, prior art locomotives typically waste the energy generated from dynamic braking. Attempts to make productive use of such energy have been unsatisfactory. For example, systems that attempt to recover the heat energy for later use to drive steam turbines require the ability to heat and store large amounts of water. Such systems are not suited for recovering energy to propel the locomotive itself. Another system attempted to use energy generated by a traction motor in connection with an electrolysis cell to generate hydrogen gas for use as a supplemental fuel source. Among the disadvantages of such a system are the safe storage of the hydrogen gas and the need to carry water for the electrolysis process. Still other prior art systems fail to recapture the dynamic braking energy at all, but rather selectively engage a special generator that operates when the associated vehicle travels downhill. One of the reasons such a system is unsatisfactory is because it fails to recapture existing braking energy.  
      Prior art hybrid energy railway vehicles typically operate from stored electric energy that is generated by a turbine engine and generator. Such hybrid energy railway vehicles rely on a turbine engine and generator as the sole source of stored electric energy on which to drive the traction motor of the hybrid energy railway vehicle. Such prior art hybrid energy railway vehicles fail to recapture dynamic braking energy generated by the traction motor of the hybrid energy railway vehicle and is required to turn on and off the turbine engine and generator as required by the level of charge of the hybrid energy railway vehicle storage system.  
      Therefore, there is a need for a number of types of multipurpose hybrid energy railway vehicles that can be used to capture and store the electrical energy, including electrical energy generated in the dynamic braking mode. There is further a need for such hybrid energy railway vehicles that selectively regenerate the stored energy for later use. There is a need for hybrid energy railway vehicles that are equipped with a resistive grid for dissipating energy. There is also a need for hybrid energy railway vehicles configured to enable the on-board electric energy storage system to be charged from an external electric energy system. There is another need for such railway vehicles to operate in a plurality of system and functional modes of operation. For example, the hybrid energy railway vehicle could operate in a standalone operation or in a consist in combination with one or more locomotives. Some embodiments of a hybrid vehicle could operate in anyone of several functional modes of operating modes including operating as a railway switcher, roadmate, pusher or electrical energy tender. Other embodiments of a hybrid energy railway vehicle could operate to carry freight, and may operate alternatively in a coasting mode, a dynamic braking mode, and a motoring mode. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1A  is a block diagram of a prior art diesel-electric locomotive.  
       FIG. 1B  is an electrical schematic of a prior art AC diesel-electric locomotive.  
       FIG. 2  is a block diagram of one embodiment of a hybrid energy locomotive system having a separate energy tender vehicle.  
       FIG. 3  is a block diagram of one embodiment of a hybrid energy locomotive system having a second engine for charging an energy storage system, including an energy storage system associated with an energy tender vehicle.  
       FIG. 4  is a block diagram illustrating one preferred embodiment of an energy storage and generation system suitable for use in connection with a hybrid energy locomotive system.  
       FIG. 5  is a block diagram illustrating an energy storage and generation system suitable for use in a hybrid energy locomotive system, including an energy management system for controlling the storage and regeneration of energy.  
       FIGS. 6A-6D  are timing diagrams that illustrate one embodiment of an energy management system for controlling the storage and regeneration of energy, including dynamic braking energy.  
       FIGS. 7A-7D  are timing diagrams that illustrate another embodiment energy management system for controlling the storage and regeneration of energy, including dynamic braking energy.  
       FIGS. 8A-8E  are timing diagrams that illustrate another embodiment energy management system for controlling the storage and regeneration of energy, including dynamic braking energy.  
       FIGS. 9A-9G  are electrical schematics illustrating several embodiments of an electrical system suitable for use in connection with a hybrid energy off-highway vehicle, such as a diesel-electric locomotive.  
       FIGS. 10A-10C  are electrical schematics illustrating additional embodiments of an electrical system suitable for use in connection with a hybrid energy off-highway vehicle, such as a diesel-electric locomotive.  
       FIG. 11  is an electrical schematic that illustrates one preferred way of connecting electrical storage elements.  
       FIG. 12  is a flow chart that illustrates one method of operating a hybrid energy locomotive system.  
       FIG. 13  is a block diagram of one embodiment of a multipurpose hybrid energy railway vehicle.  
       FIG. 14  is a block diagram of another embodiment of a multipurpose hybrid energy railway vehicle.  
       FIG. 15  is a block diagram of one embodiment of a railroad vehicle for carrying freight and having power regeneration capacity.  
       FIG. 16  is a block diagram of another embodiment of a railroad vehicle for carrying freight and having power regeneration capacity.  
       FIG. 17  is a block diagram of a portion of a train that exemplifies a system of the present invention, where that system comprises a plurality of railroad vehicles such as are diagrammed in  FIGS. 15 and 16 .  
       FIG. 18  is a block diagram of a railroad vehicle for carrying freight and having power regeneration capacity in which are depicted a number of components that may be included in various embodiments of such railroad vehicles. 
    
    
      Corresponding reference characters and designations generally indicate corresponding parts throughout the drawings.  
     DETAILED DESCRIPTION OF THE INVENTION  
      The art of hybrid locomotive energy systems has advanced through the inventions described in previously filed applications in this chain of patent applications. These focused on locomotives and tender cars that advantageously include the capacity to generate electrical power from a dynamic braking operating mode, to store such power, and to use such power at a later time during a motoring operating mode. Systems in such previously filed applications generally referred to components of a single hybrid energy railroad vehicle. The present application focuses on a class of multipurpose regenerative energy railway vehicles that is for carrying freight as one of its primary functions, and that also, through the components described herein, has power generation capability. Such railroad vehicles comprise a drive unit, such as a traction motor, operable in three movement-type operating modes: coasting; dynamic braking; and motoring. In some embodiments of such railroad vehicles, a power generation unit also is provided. As described herein, the use of this class of multipurpose regenerative energy railway vehicles provides substantial benefits for operation of railroad trains and for operation of individual railroad vehicles. As used herein, the term “train” is taken to mean several connected rail vehicles, which may include railroad vehicles of the present invention, that are capable of being moved together along a guideway, such as rail tracks, to transport freight (and/or passengers) from a first point to a second point along a planned route. Where there are a number of points for coupling or uncoupling rail vehicles along a planned route, a single train may vary in its exact composition as some rail vehicles are added to or taken away from the train at sequential points. While a train generally includes one or more locomotives to provide power for locomotion along rail tracks, trains comprising embodiments of the present invention may power along a section of rail tracks without a locomotive.  
      The systems claimed for the present invention pertain to trains, and may include groupings of load units in a yard, and rail between yards and other points of origination and destination for freight-carrying railroad vehicles. More generally, in that the railroad vehicles disclosed and claimed herein carry freight, they are a subtype of the broader class of vehicles known in the art as railroad cars (also referred to in the art as rolling stock). Further for the purposes of the present disclosure, railroad cars for carrying freight also are referred to as “load units.” This term includes the subtype disclosed and claimed herein, namely, a railroad vehicle carrying freight and having power generation capability.  
      Among those benefits for a train that includes such freight carrying-type railroad vehicles, described in greater detail herein, are the following: increased overall fuel efficiency; reduced total emissions; self-powering of auxiliary systems (i.e., non-motoring) on a particular railroad vehicle; additional adhesion capacity, by the combined motoring or dynamic braking of a number of such vehicles; reduction of the needed number or total power of locomotives for a particular train; improved train handling through lower drawbar forces and improved propulsion and braking; and reduction of tunnel temperature through use of motoring mode for such railroad vehicles in tunnels. Another advantage of use of such railroad vehicles in trains going through tunnels relates to the reduction or elimination of derating (or, alternatively, the adverse effect of derating) that may otherwise occur when the front locomotives&#39; traction motors operate at elevated temperature. For example, three front locomotives may be operating in a tunnel at such temperature as to cause the traction motors to derate, i.e., to operate at a lower-than-initially-set power. When railroad vehicles of the present invention are positioned at more rearward positions in a train, these are not exposed to such elevated temperature as intermediate cars take up such heat. Thus, these railroad vehicles would 1) not be as subject to duration, and could assist in powering the train, and 2) by so assisting, these railroad vehicles would lower the power requirements by the front locomotives and thus lessen the chance of their duration under conditions of similar demand for speed. Among those benefits for operation of individual freight carrying-type railroad vehicles, described in greater detail herein, are the following: self-powering of auxiliary systems (i.e., non-motoring) on a particular railroad vehicle, such as supplying power to a GPS system and for transmitting the location information to a centralized or local railroad information system, or supplying power to refrigerate or otherwise control the storage conditions of freight needing climate control; self-powering of braking systems, such as to apply braking when the individual railroad vehicle is stationary; self-powering of motoring mode of the individual railroad vehicle during coupling to and uncoupling from a train (and including moving from one track to another track, to switch from one train to another); and self-powering of motoring mode of the individual railroad vehicle at origination and at destination sites.  
       FIG. 2  is a block diagram of one embodiment of a hybrid energy locomotive system  200 . In this embodiment, the hybrid energy locomotive system preferably includes an energy tender vehicle  202  for capturing and regenerating at least a portion of the dynamic braking electric energy generated when the locomotive traction motors operate in a dynamic braking mode. The energy tender vehicle  202  is constructed and arranged to be coupled to the locomotive in a train configuration, and includes an energy capture and storage system  204  (also referred to in various embodiments as an electrical energy storage system, an energy storage medium or an energy storage). It should be understood that it is common to use two or more locomotives in a train configuration and that  FIG. 2  illustrates a single locomotive for convenience.  
      In one embodiment, the energy capture and storage system  204  selectively receives electrical power generated during the dynamic braking mode of operation and stores it for later regeneration and use. In the alternative or in addition to receiving and storing dynamic braking power, energy capture and storage system  204  can also be constructed and arranged to receive and store power from other sources. For example, excess prime mover power from engine  102  can be transferred and stored. Similarly, when two or more locomotives are operating in a train, excess power from one of the locomotives can be transferred and stored in energy capture and storage system  204 . Also, a separate power generator (e.g., diesel generator) can be used to supply a charging voltage (e.g., a constant charging voltage) to energy capture and storage system  204 . Still another source of charging is an optional off-train charging source  220 . For example, energy capture and storage system  204  can be charged by external sources such as a battery charger in a train yard or at a wayside station. Additional examples of external energy system  220  include a locomotive, a second hybrid energy railway vehicle, an electric grid or distribution line, a third rail, or an electrical overhead line.  
      The energy capture and storage system  204  preferably includes at least one of the following storage subsystems for storing the electrical energy generated during the dynamic braking mode: a battery subsystem, a flywheel subsystem, or an ultracapacitor subsystem. Other storage subsystems are possible. These storage subsystems may be used separately or in combination. When used in combination, these storage subsystems can provide synergistic benefits not realized with the use of a single energy storage subsystem. A flywheel subsystem, for example, typically stores energy relatively fast but may be relatively limited in its total energy storage capacity. A battery subsystem, on the other hand, often stores energy relatively slowly but can be constructed to provide a relatively large total storage capacity. Hence, a flywheel subsystem may be combined with a battery subsystem wherein the flywheel subsystem captures the dynamic braking energy that cannot be timely captured by the battery subsystem. The energy thus stored in the flywheel subsystem may be thereafter used to charge the battery. Accordingly, the overall capture and storage capabilities are preferably extended beyond the limits of either a flywheel subsystem or a battery subsystem operating alone. Such synergies can be extended to combinations of other storage subsystems, such as a battery and ultracapacitor in combination where the ultracapacitor supplies the peak demand needs.  
      It should be noted at this point that, when a flywheel subsystem is used, a plurality of flywheels is preferably arranged to limit or eliminate the gyroscopic effect each flywheel might otherwise have on the locomotive and load vehicles. For example, the plurality of flywheels may be arranged on a six-axis basis to greatly reduce or eliminate gyroscopic effects. It should be understood, however, that reference herein to a flywheel embraces a single flywheel or a plurality of flywheels.  
      Referring still to  FIG. 2 , energy capture and storage system  204  not only captures and stores electric energy generated in the dynamic braking mode of the locomotive, it also supplies the stored energy to assist the locomotive effort (i.e., to supplement and/or replace prime mover power). For example, energy tender vehicle  202  optionally includes a plurality of energy tender traction motors  208  mounted on the trucks supporting energy tender vehicle  202 . The electrical power stored in energy capture and storage system  204  may be selectively supplied (i.e., via lines  210 ) to the energy tender traction motors  208 . Thus, during times of increased demand, energy tender traction motors  208  augment the tractive power provided by locomotive traction motors  108 . As another example, during times when it is not possible to store more energy from dynamic braking (e.g., energy capture and storage system  204  is charged to capacity), efficiency considerations may suggest that energy tender traction motors  208  also augment locomotive traction motors  108 .  
      It should be appreciated that when energy capture and storage system  204  drives energy tender traction motors  208 , additional circuitry will likely be required. For example, if energy capture and storage system  204  comprises a battery storing and providing a DC voltage, one or more inverter drives may be used to convert the DC voltage to a form suitable for use by the energy tender traction motors  208 . Such drives are preferably operationally similar to those associated with the main locomotive.  
      Rather than (or in addition to) using the electrical power stored in energy capture and storage system  204  for powering separate energy tender traction motors  208 , such stored energy may also be used to augment the electrical power supplied to locomotive traction motors  108  (e.g., via line  212 ).  
      Other configurations are also possible. For example, the locomotive itself may be constructed and arranged (e.g., either during manufacturing or as part of a retrofit program) to capture, store, and regenerate excess electrical energy, such as dynamic braking energy or excess motor power. In another embodiment, a locomotive may be replaced with an autonomous tender vehicle. In still another embodiment, similar to the embodiment illustrated in  FIG. 2 , the separate energy tender vehicle is used solely for energy capture, storage, and regeneration—the tender does not include the optional traction motors  208 . In yet another embodiment, a separate tender vehicle is replaced with energy capture and storage subsystems located on some or all of the load units attached to the locomotive. Such load units may optionally include separate traction motors. In each of the foregoing embodiments, the energy capture and storage subsystem can include one or more of the subsystems elsewhere described herein. This includes, where appropriate, inclusion of such described subsystems for use on the multipurpose regenerative energy railway vehicles that are for carrying freight as one of their primary functions (i.e., ‘load units,’) that additionally comprise energy capture and storage subsystems, and optionally also comprise separate traction motors), such as are depicted in  FIGS. 15-18  and further described herein. As noted above, a “load unit” is a type of railroad car that is for carrying freight.  
      When a separate energy tender vehicle (e.g., energy tender vehicle  202 ) is used, the tender vehicle  202  and the locomotive are preferably coupled electrically (e.g., via line  212 ) such that dynamic braking energy from the locomotive traction motors and/or from optional energy tender traction motors  208  is stored in energy storage means on board the tender. During motoring operations, the stored energy is selectively used to propel locomotive traction motors  108  and/or optional traction motors  208  of tender vehicle  202 . Similarly, when the locomotive engine produces more power than required for motoring, the excess prime mover power can be stored in energy capture and storage  202  for later use. This is exemplary, and is not meant to be limiting of embodiments of the present invention, which may include, for example, providing electrical energy to, and receiving electrical energy from, a source external to the train.  
      If energy tender vehicle  202  is not electrically coupled to the locomotive (other than for standard control signals), traction motors  208  on the tender vehicle can also be used in an autonomous fashion to provide dynamic braking energy to be stored in energy capture and storage system  204  for later use. One advantage of such a configuration is that tender vehicle  202  can be coupled to a wide variety of locomotives in almost any train. Examples of embodiments of an autonomous tender vehicle such as a multipurpose hybrid energy railway vehicle are illustrated in  FIGS. 13 and 14  and are described below.  
      It should be appreciated that when energy tender traction motors  208  operate in a dynamic braking mode, various reasons may counsel against storing the dynamic braking energy in energy capture and storage system  204  (e.g., the storage may be full). Thus, it is preferable that dynamic braking energy is selectively dissipated by grids (not shown) associated with energy tender vehicle  202 , or transferred to locomotive grids  110  (e.g., via line  212 ).  
      The embodiment of  FIG. 2  will be further described in terms of one possible operational example. It is to be understood that this operational example does not limit the invention. The locomotive system  200  is configured in a consist including a locomotive (e.g., locomotive  100  of  FIG. 1 ), an energy tender vehicle  202 , and at least one load vehicle. The locomotive may be, for example, an AC diesel-electric locomotive. Tractive power for the locomotive is supplied by a plurality of locomotive traction motors  108 . In one preferred embodiment, the locomotive has six axles, each axle includes a separate locomotive traction motor  108 , and each traction motor  108  is an AC traction motor  108 . The locomotive includes a diesel engine  102  that drives an electrical power system. More particularly, the diesel engine  102  drives an alternator/rectifier  104  that comprises a source of prime mover electrical power (sometimes referred to as traction power or primary power). In this particular embodiment, the prime mover electrical power is DC power that is converted to AC power for use by the traction motors  108 . More specifically, one or more inverters (e.g., inverter  106 ) receive the prime mover electrical power and selectively supply AC power to the plurality of locomotive traction motors  108  to propel the locomotive. Thus, locomotive traction motors  108  propel the locomotive in response to the prime mover electrical power.  
      Each of the plurality of locomotive traction motors  108  is preferably operable in at least two operating modes, a motoring mode and a dynamic braking mode. In the motoring mode, the locomotive traction motors  108  receive electrical power (e.g., prime mover electrical power via inverters) to propel the locomotive. As described elsewhere herein, when operating in the dynamic braking mode, the traction motors  108  generate electricity. In the embodiment of  FIG. 2 , energy tender vehicle  202  is constructed and arranged to selectively capture and store a portion of the electricity generated by the traction motors  108  during dynamic braking operations. This is accomplished by energy capture and storage system  204 . The captured and stored electricity is selectively used to provide a secondary source of electric power. This secondary source of electric power may be used to selectively supplement or replace the prime mover electrical power (e.g., to help drive one or more locomotive traction motors  108 ) and/or to drive one or more energy tender traction motors  208 . In the latter case, energy tender traction motors  208  and locomotive traction motors  108  cooperate to propel the consist.  
      Advantageously, energy capture and storage system  204  can store dynamic braking energy without any electrical power transfer connection with the primary locomotive. In other words, energy capture and storage system  204  can be charged without a connection such as line  212 . This is accomplished by operating the locomotive engine  102  to provide motoring power to locomotive traction motors  108  while operating tender vehicle  202  in a dynamic braking mode. For example, the locomotive engine  102  may be operated at a relatively high notch setting while tender vehicle traction motors  208  are configured for dynamic braking. Energy from the dynamic braking process can be used to charge energy capture and storage system  204 . Thereafter, the stored energy can be used to power energy tender traction motors  208  to provide additional motoring power to the train. As further discussed below, in other embodiments, a second engine  302  may be one embodiment of a charging source that is located on a second vehicle  301  (See  FIG. 3  and discussion below) or on a hybrid energy railway vehicle  1302  as a hybrid energy railway vehicle charging electric energy source  1304 . In such arrangements, energy capture and storage system  204  can be charged by means of the second charging engine  302  or hybrid energy railway vehicle charging source  1304 . In yet another embodiment, energy capture and storage system  204  may be charged from an external electric energy system  220 . One of the advantages of such a configurations are that tender vehicle  202  can be placed anyway in the train. For example, in one wireless embodiment, tender vehicle  202  provides its own local power (e.g., for controls or lighting) and communicates via a radio link with other vehicles in the train, as necessary. An air brake connection would likely also be connected to tender vehicle  202 . Of course, minimal wiring such as standard lighting wiring and control wiring could be optionally routed to tender vehicle  202 , if so desired.  
      It is known in the art that diesel-electric locomotives are often loud and the vibrations associated with the engine make the environment uncomfortable for train operators. Accordingly, in one embodiment, tender vehicle  202  is modified to include an operator compartment such that the train engineer can operate the train from the relative comfort of the tender, rather than from the locomotive.  FIG. 2  reflects this schematically at the aft end of tender  202  with reference character  230 . Additionally, in the embodiment where the tender vehicle  202  operates in an autonomous mode, a train operator can operate the tender vehicle  202  as an autonomous hybrid energy railway vehicle  1302  or switcher and can control the operation of other railway vehicles.  
       FIG. 3  is a block diagram of another embodiment of a hybrid energy locomotive system  300 . This embodiment includes a second engine vehicle  301  for charging the energy tender vehicle  202 . The second engine vehicle  301  comprises a diesel engine  302  that is preferably smaller than the main locomotive engine  102 , but which otherwise operates according to similar principles. For example, second engine vehicle  301  comprises an alternator/rectifier  304  (driven by the second engine  302 ), one or more inverters  306 , and a plurality of braking grids  310 . In one embodiment, second engine  302  runs at a constant speed to provide a constant charging source (e.g., 200-400 hp) for energy tender vehicle  202 . Thus, when a hybrid energy locomotive system is configured as shown in  FIG. 3 , energy capture and storage system  204  preferably receives charging energy from one or both of the primary locomotive (e.g., dynamic braking energy), and second engine vehicle  301  (e.g., direct charging) via line  312 . It should be understood that, although second engine vehicle  301  is shown as a separate vehicle, it could also be included, for example, as an integral part of energy tender vehicle  202  or a load vehicle. As discussed above and further discussed below in regard to  FIGS. 13 and 14 , the hybrid energy tender vehicle may operate in an autonomous operating mode as a hybrid energy railway vehicle  1302  where the hybrid energy railway vehicle  1302  is equipped with a charging electric energy source  1304  or a second engine  302  for charging energy capture and storage system  204 . Also, dynamic braking generators (e.g., via traction motors  308 ) could be optionally included with second engine  301  thereby providing an additional source of power for storage in energy capture and storage system  204 .  
      Additionally, and relevant to the apparatus and system claims provided herein, a multipurpose regenerative energy railroad vehicle that is for carrying freight as one of its primary functions may have such subsystems while comprising a substantial volume of its total space adapted and designed for carrying freight of one type or another. For example, the maximum possible volume for carrying freight on a flatbed-type rail car is the volume defined by the area of the flat bed times the maximum allowed height of freight on that flat bed. For a tanker car, this maximum possible volume is the volume within the tank, and for an open-top wagon, such as for coal and other bulk materials, the maximum possible volume for carrying freight is the volume within the walls of the wagon. It is appreciated that the total space adapted and designed for carrying freight of one type or another is independent of the volume or weight of the actual load in that volume at any one time, as the actual load may occupy a much smaller volume than the total volume for freight.  
       FIG. 15  depicts one embodiment of a railroad vehicle  1500  comprising a structure  1510  for supporting freight to be carried on the vehicle, specifically within the confines of a defined containment area  1512  supported by the structure  1510 , a plurality of wheels  1520  rotatably attached to the structure  1510  for engaging railroad rail (depicted as  1590 ), a traction motor  1530  coupled to at least one of wheels  1520 , designated in  FIG. 15  as driving wheel  1520 D, an electrical energy storage system  1550 , a controller  1570 , and a communication link  1580 . The traction motor  1530  may operate in a motoring mode for transmitting mechanical energy to the driving wheel  1520 D, a dynamic braking mode for braking the driving wheel  1520 D, and a coasting mode during which neither motoring nor dynamic braking occur. The traction motor  1530  uses electrical energy when operating in the motoring mode and generates dynamic braking electrical energy when operating in the dynamic braking mode. In the embodiment depicted in  FIG. 15 , the electrical energy storage system  1550  is disposed within structure  1510  above driving wheel  1520 D, and is separated from defined containment area  1512  by a barrier wall  1514 . The electrical energy storage system  1550  is in electrical communication with the traction motor  1530 , and is adapted to store dynamic braking electrical energy when the traction motor  1530  is operated in the dynamic braking mode and is adapted to discharge electrical energy to the traction motor  1530  when the traction motor is operated in the motoring mode. The controller  1570  is in communication with the traction motor  1530  and with the electrical energy storage system  1550  and is responsive to a control command to selectively operate the traction motor in the motoring mode, the coasting mode, and the dynamic braking mode. Generally, a controller as used herein may also be referred to as a “control system” (other than an “external control system”) or as an “energy management system.” A control command is obtained from the communication link  1580 , and may be sent from an external control source (shown as  1595 ). Such external control source  1595  may be selected from a centralized control source (not shown) and a hand-held control source (not shown, such as an “operator control unit” that is used to control locomotives), the latter being utilizable when one or a small number of railroad vehicles  1500  are separated from a train and are being moved, for instance, at a point of origination or at a destination, without the use of a locomotive. Whatever the type of external control source, such external control source is adapted to transmit a signal indicative of the control command to the controller to selectively operate the traction motor  1530  in the motoring mode, the coasting mode, and the dynamic braking mode. Also, it is appreciated that the signals indicative of the control command may provide for varying levels of operation in the coasting mode, and in the dynamic braking mode, so that a desired level of powering or braking, respectively, results. Further, it is appreciated that these modes are distinct from the operating modes of an air brake system (i.e., a non-braking or a braking mode (at varying levels)). In various embodiments, the external control source integrates and coordinates the control commands to controller in the presently described railroad vehicles, and also to the air brake system.  
       FIG. 16  depicts a second, alternative arrangement of elements in another embodiment of a railroad vehicle.  FIG. 16  depicts a railroad vehicle  1600  comprising a structure  1610  for supporting freight to be carried on the vehicle, specifically within the confines of a defined containment area  1612  supported by the structure  1610 , a plurality of wheels  1620  rotatably attached to the structure  1610  for engaging railroad rail (depicted as  1690 ), two traction motors  1630  respectively coupled to driving wheels  1620 D, an electrical energy storage system  1650  disposed between driving wheels  1620 D and beneath structure  1610 , a controller  1670 , and a communication link  1680 . The traction motor  1630  may operate in a motoring mode for transmitting mechanical energy to the driving wheel  1620 D, a dynamic braking mode for braking the driving wheel  1620 D, and a coasting mode during which neither motoring nor dynamic braking occur. The traction motor  1630  uses electrical energy when operating in the motoring mode and generates dynamic braking electrical energy when operating in the dynamic braking mode. In the embodiment depicted in  FIG. 16 , the electrical energy storage system  1650  is in electrical communication with the traction motor  1630 . The electrical energy storage system  1650  is adapted to store dynamic braking electrical energy when the traction motor  1630  is operated in the dynamic braking mode and is adapted to discharge electrical energy to the traction motor  1630  when the traction motor is operated in the motoring mode. The controller  1670  is in communication with the traction motor  1630  and with the electrical energy storage system  1650  and is responsive to a control command to selectively operate the traction motor in the motoring mode, the coasting mode, and the dynamic braking mode. A control command is obtained from the communication link  1680 , and may be sent from an external control source (shown as  1695 ). Such external control source  1695  may be selected from a centralized control source (not shown) and a hand-held control source (not shown, such as an “operator control unit” that is used to control locomotives), the latter being utilizable when one or a small number of railroad vehicles  1600  are separated from a train and are being moved, for instance, at a point of origination or at a destination, without the use of a locomotive. Whatever the type of external control source, such external control source is adapted to transmit a signal indicative of the control command to the controller to selectively operate the traction motor  1630  in the motoring mode, the coasting mode, and the dynamic braking mode.  
      It is appreciated that resistance grids are not a required component of the energy-regenerating railroad vehicles such as those depicted in  FIGS. 15 and 16 . Since the railroad vehicle embodiments in  FIGS. 15 and 16  as used in various systems embodiments are not primarily responsible for braking, the operating modes may be alternatively set so as to maintain a desired level of energy stored in electrical energy storage system, and the respective traction motors on such vehicles may be set in the coasting mode rather than dynamic braking mode when the train needs to be slowed down. That is, in such situations the locomotives, and tender vehicles if such are part of the train, would be responsible for the braking rather than certain railroad vehicles that have a full charge in their respective electrical energy storage system and are not equipped with resistance grids. In other embodiments, resistive grids may be present in energy-regenerating railroad vehicles, and these vehicles may assume a greater role in overall braking of a train.  
      It also is appreciated that in a train comprising, for example, 100 railroad vehicles such as those depicted in  FIGS. 15 and 16 , and locomotives (conventional and/or those described herein), the 100 railroad vehicles most often will comprise electrical energy storage systems that are in different states of charge.  FIG. 17  schematically depicts two sections  1705  and  1706  of a train  1700 , comprising locomotives  1710 , a control source  1715  located in one of locomotives  1710 , railroad vehicles  1720 A-K, and conventional load-carrying rail cars  1730 A-G. Along a given distance of travel, the respective electrical energy storage system of railroad vehicles  1720 A-F may be at or below about a 50 percent charge, while the respective electrical energy storage system of railroad vehicles  1720 G-K may be at or above about a 90 percent charge. In such circumstance railroad vehicles  1720 A-F would be selected to operate in dynamic braking mode when overall slowing of the train  1700  is required along the given distance of travel. This assumes that none of the railroad vehicles  1720 G-K are equipped with resistive grids for dissipation of electrical energy generated while in the dynamic braking mode.  
      Such a train  1700  is one embodiment of a self-powered railroad system having power regeneration capacity in the form of at least one railroad vehicle as described herein, A self-powered railroad system may additionally comprise supplemental control sources, such as those that may be located at various locations for various purposes. It is further appreciated that along a relatively long distance of travel for a train embodying such railroad system, considering the respective destinations of the 100 railroad vehicles, the self-powering requirements at such destinations, and the slopes of travel and braking requirements, various algorithms are developed and are utilized to optimize the control programs of the control source that sends control commands to the respective 100 railroad vehicles. These control programs provide control commands to the railroad vehicles to reach desired objectives, such as overall operational efficiency, charge of a respective railroad vehicle&#39;s electrical energy storage system upon delivery to its destination.  
      Table 1 provides an hypothetical example of operating modes of respective railroad vehicles that have regenerative braking and electrical energy storage systems, such as those depicted in  FIGS. 15 and 16 , as they would be found in one embodiment of a self-powered railroad system. The travel over a distance is divided into zones during which the slopes of the rail tracks are either sufficient for dynamic braking of at least a number of the railroad vehicles while maintaining a desired overall train velocity, or are of a slope along which additional propulsion may be provided by the railroad vehicles to supplement the propulsive forces of the locomotive(s). The slope indicated for each zone is an average, and it is assumed that there are variations along the track, including curves and differences in slope, some of which necessitate changes in command signals and operating modes of one or more of the railroad vehicles identified in Table 1.  
               TABLE 1                          Example of respective operating modes based on initial status, destination charge requirement, and slope of track.                                                 Identification   Current   Miles   Minimum %   Miles 0-20   Miles   Miles   Miles   % charge       number of specific   Charge, %   to   charge required   Slope = 0   21-50,   51-90,   91-100,   at 100 th         railroad vehicles:   of maximum   destination   at destination   degrees   Slope = +4°   Slope = −2°   Slope = 0°   mile                                                         RV-001   10   50   80   charge   coast   Drop   N/A   N/A                       to 80%       off       RV-002   10   100   50   coast   coast   charge   coast   52       RV-003   20   100   50   coast   coast   charge   coast   53       RV-004   20   150   80   coast   charge   charge   coast   70       RV-005   30   100   20   coast   coast   charge   motor   20       RV-006   30   200   10   coast   motor   charge   motor   5       RV-007   50   200   10   coast   motor   charge   motor   5       RV-008   50   500   40   coast   motor   charge   motor   5       RV-009   50   500   80   coast   motor   charge   motor   5       RV-010   50   100   80   coast   coast   charge   charge   80       RV-011   80   100   80   coast   coast   charge   motor   85       RV-012   80   100   80   coast   coast   coast   coast   80                  
 
      Railroad Vehicle RV-001 is to be delivered at mile 50 of this section of track, so is charged along the flat 0-20 mile span by operating its respective traction motor in dynamic braking mode, and supplying the electrical energy thereby generated to its electrical energy storage system. When the electrical energy storage system is at the required 80 percent charge, this information is provided to the control source (external of RV-001) and a control command is sent to RV-001&#39;s controller that switches the operating mode from dynamic braking (indicated by “charge” in Table 1) to coasting mode. This coasting mode continues until RV-001 is separated from the train at its destination. Having an 80% charge at that point provides sufficient power supply to operate the traction motor in motoring mode to enable RV-001 to move to a desired docking location at the destination, and to move from that docking location back to the main rail line after its unloading and/or reloading operations are complete. Such movements may be effectuated by an origination/destination-type external control source at a point of origination or at a destination, eliminating the need for a locomotive for such movements.  
      The relative degree of dynamic braking for the various railroad vehicles may be adjusted for the train and also may take into account the various requirements of the particular railroad vehicles. For example, RV-002 and RV-003 have 10% and 20% charges, respectively, at mile  0  of this span, and have a minimum requirement of 50% charge at their common destination at 100 miles. Therefore RV-002 will received control commands that set somewhat greater dynamic braking than the dynamic braking that will be occurring in RV-003, since the latter need not be charged as much as RV-002 by mile 100. This may be achieved by degree of dynamic braking and/or duration of dynamic braking. In this regard, it is noted that in Table 1 “charge” for a particular span of miles is taken to mean that charging occurs during that span. However, once a desired charge level is attained, a control command may be provided to change operating mode to coast during that span. Variations such as those described above may result in periodic changes in operating mode, such as around a curve or down a short, steep slope. Also, the final charge levels of 52% and 53%, respectively for RV-002 and RV-003, are shown to indicate that a particular railroad vehicle may be charged above its required charge-at-destination such as when the overall train requires additional dynamic braking, or, alternatively, due to expected or unforeseen variances in performance along the span.  
      It is further appreciated that along a span of track some railroad vehicles may be motoring, some may be coasting, and some may be in the dynamic braking mode. To demonstrate this, RV-004 is shown as charging (dynamic braking mode) along miles 21-50, during a relatively steep slope, whereas the other railroad vehicles are either in the motoring or the coasting mode. Similarly, RV-010 is set to charge during the last ten mile span, even though this is not along a downward slope over which dynamic braking may be more efficient. Accordingly, dynamic braking may be applied as needed to attain a desired or required charge for a particular railroad vehicle, even if this increases the load on the locomotive(s) of the train and/or other railroad vehicles that are operating in motoring mode.  
      Also, while not shown specifically in Table 1, the control commands to the various railroad vehicles along a long train may take into account the fact that some railroad vehicles may be along an upward slope while others are on the other side of a peak in the rail tracks and are along a downward slope. In such circumstance there may be a transitioning of the operating mode near or at the peak for respective railroad vehicles as they are crossing the peak from one slope to the other. For example, when advancing up to a peak, railroad vehicles may be in a motoring mode, and at or near the peak may transition to a coasting mode. (Also, farther down the slope, they may be transitioned to a dynamic braking mode.) There may be informational signals provided from sensors in the particular railroad vehicles (such as grade detectors, or elevation detectors), or the position may be determined by other means, such as GPS, and such grade or elevation or positional information, when received by the control source, would elicit a control command that would result in the change of operating mode for that particular railroad vehicle. Generally, this and other status data indicative of an operation of the railroad vehicle may be communicated to an external control source by a communications link of one or more railroad vehicles.  
      In the example of Table 1, the control source for all the railroad vehicles of the train is located in the locomotive that is connected, directly or indirectly, to the railroad vehicles. However, this is not meant to be limiting. In various embodiments of the present system, an external control source may be located in a railyard tower control, which may send control signals to any of the railroad vehicles as described herein, or to locomotives, etc. An external control source also may be in an off-board remote control device (i.e., external to the railroad vehicle and not located in the locomotive or elsewhere in a train). Such device would be well-suited for use at points of origination and destination for railroad vehicles as described herein, to send control signals to power such vehicles to or from a train to enable coupling and decoupling without the need of a locomotive. Also, a control source may comprise a wayside wireless communication transmitter linked to a dispatch center. Systems of the present invention, as claimed herein, may comprise any of the above types of control sources, in their respective locations. Control signals may be sent by any suitable communications link, such as wire, wireless, or any other form of conveying control signals from a control source to a controlled device. Such off-board control devices are distinct from on-train control systems, such as housed in a locomotive that controls railroad vehicles that are part of a train powered by that locomotive.  
      Thus, in addition to the exemplary embodiment of a self-powered railroad system disclosed above, a self-powered railroad system is appreciated to include one or more of the following combinations: 
          1. An hand-held off-board remote control device, comprising an external control source, and at least one railroad vehicle that is primarily load-carrying for carrying freight and that has power regeneration capability, wherein the off-board remote control device is adapted to control the at least one railroad vehicle for coupling and uncoupling from a train, and for moving along rails between the train and a destination (i.e., a loading dock).     2. A stationary off-board remote control device, comprising an external control source, and at least one railroad vehicle that is primarily load-carrying for carrying freight and that has power regeneration capability, wherein the off-board remote control device is adapted to control the at least one railroad vehicle for coupling and uncoupling from a train, and for moving along rails between the train and a destination (i.e., a loading dock). One example of a stationary off-board remote control device is a centralized device in a dispatch center in a rail yard.     3. Either #1 or #2, additionally comprising load cars that do not have power regeneration capacity and that are coupled to and transported under power from the noted at least one railroad vehicle. 
 
 Embodiments of such self-powered railroad system are comprised of one or more railroad vehicles as described herein. 
       

      Additionally, the algorithms and control programs may take into consideration the lowering of drawbar forces by distributing propulsion among selected railroad vehicles to supplement the propulsive forces from the locomotives. In conventional trains, a locomotive supplies the drawbar force for all cars behind it. For a long train, this force may be substantial, and consideration of the same may necessitate modification of operations, such as slower acceleration and deceleration. However, when a number of railroad vehicles of the present invention, such as those depicted in  FIGS. 15 and 16 , are distributed along the train, and are in the motoring mode, the maximum drawbar force from the locomotive is lowered. This may result in improved handling, greater efficiency, and less wear.  
      Further with regard to assisting with adhesion issues, such as on inclines when the tracks are wet, a train with a portion of the freight-bearing cars as railroad vehicles of the present invention may greatly alter the adhesion requirements to achieve a desired train speed. Currently when a train goes up a grade, the amount of tractive effort produced by the locomotive is limited by the weight of the locomotive and the rail conditions. Since load-bearing railroad vehicles of the present invention are also able to produce tractive effort, and typically the combined total weight of such railroad vehicles is much heavier than the locomotives, the adhesion issues are much improved with their use. This is true especially for driving over poor rail conditions like snow, or oil contamination of the tracks. For example, a train weighing 24,000,000 pounds requiring 390,000 pounds of tractive effort may be pulled by three locomotives, each weighing 420,000 pounds. In such example each of the locomotives and the track need to have an adhesion coefficient of about 31 percent. However, if all wheels are powered (i.e., if all cars are railroad vehicles with traction motors for all wheels), then the adhesion requirement drops to about two percent Trains having a smaller percentage of total cars as railroad vehicles, and/or the railroad vehicles having less than all wheels powered, would result in an intermediate value for adhesion coefficient. Also, generally, the amount of available adhesion increases as more and more wheels traverse the rail. Therefore, rails over which such trains routinely travel have less need for adhesion-enhancing equipment like sanders.  
      Further, when a train is comprised of a sufficient number (or percentage) of total load cars that are railroad vehicles that comprise a traction motor, an electrical energy storage system, a controller and a communication link, that train may operate as a train system of the present invention without the inclusion of a locomotive. Specific railroad vehicles of such train system may selectively keep all electric energy for internal usage, or may provide a portion of the electric energy to other railroad vehicles through appropriate electrical conduits. Additionally, a number or portion of such railroad vehicles of such non-locomotive train may additionally comprise a charging electric energy source as described herein.  
      Thus, with regard to the use of railroad vehicles as disclosed herein, as they are employed in trains systems as described herein, such railroad vehicles may contribute to: improvement in overall fuel efficiency; reduction of emissions; a lower requirement for the total number of locomotives in a particular train (with some train system embodiments not requiring locomotives); lowering of adhesion needed to power the train over a particular incline during adverse conditions (and less need for sanders and rail cleaners that otherwise are used to maintain a specified level of adhesion); reduction of drawbar force; less need for pusher vehicles; improved tunnel performance (due in part to lower emissions and heat generation while in a tunnel); improved braking performance; and less track wear.  
      With regard to other benefits more related to the performance of individual railroad vehicles as disclosed herein, such railroad vehicles may contribute to: less delay and effort in moving specific railroad vehicles between a train and a point of origin or destination (due to self-powering, independent movement capability); ability to apply and hold brakes at a standing point (i.e., at 0 m.p.h.); and supply of electrical power to auxiliary applications including security alarms, location systems (i.e. GPS); heating and refrigeration; door operation; safety alarms in a rail yard; safety alarms at a grade crossing; train breakage indicators; and small tools (such as may be used near the railroad vehicle, such as in a rail yard).  
      In some embodiments of the railroad vehicles, the electrical energy generated by the traction motor of a particular railroad vehicle unit may be sufficient to power braking systems for that railroad vehicle. That is, the power may be utilized to drive an electric brake line that would replace the air brake line typical of current train brake systems. This would require the provision of sufficient energy storage so as to have sufficient power reserves during a range of normal operating conditions. This may also involve a number or percentage of the railroad vehicles additionally comprising a charging electric energy source to provide additional electric energy, as needed, to assure electrical energy to power the braking systems for that railroad vehicle, and optionally for other, adjacent railroad vehicles. An electric brake train may use wires connected between the locomotives and the load-bearing railroad vehicles, or these connections could be made via a wireless control and monitoring system. An electric brake train can transmit the brake information faster than communications of a currently used airbrake system on a similarly sized train. Also, with such electric brake system the total amount of braking can be increased. Such system also may be used to prevent wheel slide. Also, in some alternative embodiments, the power provided by the present railroad vehicle systems may be used to power onboard compressors for faster charging of an airbrake system.  
      Embodiments of railroad vehicles comprising a primary space for carrying freight may have components in addition to those described above for the embodiments of  FIGS. 15 and 16 . For example,  FIG. 18  depicts a railroad vehicle  1802  that comprises a number of additional components, some or all of which may be provided in particular embodiments of the present invention.  
      Railroad vehicle  1802  depicted in  FIG. 18  includes a charging electric energy source  1804  that provides charging electric energy  1806  to energy capture and storage system  204 . Such charging electric energy source  1804  may be comprised of a diesel engine, a gasoline engine, a natural gas engine, a fuel cell, a gas turbine, an electric generator, an alternator and/or an inverter. Charging electric energy source  1804  may provide a steady charging source to energy capture and storage system  204  independent of the charge level energy capture and storage system  204  or may cycle on or off or at various operating levels based on the charge level or charging requirements of the energy capture and storage system  204 . In various embodiments, the charging electric energy source  1804  may occupy a sufficiently small space to allow for substantial freight storage capacity. When a train is comprised of a sufficient number (or percentage) of total load cars that are railroad vehicles that comprise a charging electric energy source, such as  1804 , that train may operate as a train system of the present invention without the inclusion of a locomotive. This provides a distributed ‘onboard’ power generation without the need for a locomotive. Specific railroad vehicles of such train system may selectively keep all electric energy for internal usage, or may provide a portion of the electric energy to other railroad vehicles, or may communicate with an ‘offboard’ external energy system such as an offboard electric grid (stationary and beside the rail tracks), an electric third rail, an electrical overhead line, or a stationary offboard external energy storage system (such as for charging the onboard energy capture and storage system.  
      In embodiments where the charging electric energy source  1804  operates independently of the charge level of the energy capture and storage system  204 , all or a portion of the charging electric energy  1806  not required by energy capture and storage system  204  may be transferred to another vehicle via the external energy transfer interface  1816  including a locomotive or to another railroad vehicle  1802 . Such external energy transfer interface  1816  may be adapted to be detachably connected to any external energy system  220  including a locomotive, a second railroad vehicle  1802 , an electric grid, an electric third rail, an electrical overhead line, or an external energy storage system.  
      The hybrid energy railway vehicle  1802  may supply the stored electric energy as stored in energy capture and storage system  204  to the railroad vehicle traction motors  208  via a line  1808  to the traction bus  210 . The railroad vehicle traction motors  208  operate in response to the provided stored electric energy passed along line  1808  and then traction bus  210  to propel the railroad vehicle  1802  on a plurality of railroad vehicle wheels  1809 . In other embodiments, the hybrid energy railway vehicle  1802  may also be equipped with a converter  1826  that is electrically coupled to energy capture and storage system  204 . The converter  1826  selectively transfers stored electric energy from energy capture and storage system  204  and supplies the transferred stored electric energy to the traction motors  208 .  
      As discussed above, the railroad vehicle traction motor  208  also operates in a dynamic braking mode of operation to generate dynamic braking electric energy. The dynamic braking electric energy is provided to energy capture and storage system  204  where it is stored (shown as line  1808 ) as stored electric energy. Such stored dynamic braking electric energy may be provided to the railroad vehicle traction motor  208  during the motoring mode of the traction motor  208 .  
      Also, as discussed above, such as for the embodiments of  FIGS. 15 and 16 , the railroad vehicle traction motor  208  may operate in a coasting mode. Also, in various embodiments, energy capture and storage system  204  may be configured with a removable energy storage unit  1828 . Such storage unit  1828  may be removed from hybrid energy railway vehicle  1802  and replaced by a replacement storage unit  1828 . In one embodiment, storage unit  1828  is configured to be electrically charged by an external charging system (not shown). In one embodiment and method of operation, the storage units  1828  are removed from the hybrid energy railway vehicle  1802  when their charge is depleted. The storage unit  1828  is transferred to a site remote from the hybrid energy railway vehicle  1802 . An external charging system recharges the energy storage unit  1828 . One such external charging system could be another hybrid energy railway vehicle  1802  which had previously charged the energy storage unit  1828 . After being externally charged, the storage unit  1828  is re-installed on the hybrid energy railway vehicle  1802 . The hybrid energy railway vehicle  1802 , energy capture and storage system  204  and storage unit  1828  are configured to provide for an efficient removal and re-installation of the storage unit  1828  from the hybrid energy railway vehicle  1802 .  
      The railroad vehicle  1802  may also be configured with a resistive grid  310  that is electrically coupled by any electrical coupling including the traction system bus  210  as shown in  FIG. 18  as electrical connection line  1812 . A circuit may be electrically connected between the resistive grid  310  and the traction system bus  210  and may be controlled by a controller  1818 , the energy capture and storage system  204  or other means including an energy management system (not shown in  FIG. 18 ). In various embodiments during certain time periods, the circuit  1814  may selectively supply dynamic braking electric energy to the resistive grid  310  where the resistive grid  310  dissipates the supplied dynamic braking electric energy. This may occur, for instance, when one or more railroad vehicles  1802  are included in a train that routinely travels over steep terrain in which braking capacity supplemental to those of the locomotives (and hybrid tenders and railroad vehicles lacking resistive grids) is desired. In another embodiment, the circuit  1814  may selectively supply charging energy to the resistive grid. As discussed above, the charging electric energy source  1804  may operate to provide more charging electric energy  1806  than required by energy capture and storage system  204 . In such a case, the charging electric energy source  1804  may continue to operate with the circuit  1814  supplying any excess charging electric energy to the resistive grid  310 . In yet another embodiment, the electric energy capture and storage system  204  may be electrically connected to the resistive grid  310 . In such an embodiment, the circuit  1814  may selectively supply stored electric power to the resistive grid  310 . The supplying of stored electric power to the resistive grid  310  may be desired when an anticipated requirement for storage capacity for storing dynamic braking energy may exceed the current charging capacity of the energy capture and storage system  204 .  
      In another embodiment similar to that discussed above with regard to  FIGS. 2 and 3 , the railroad vehicle  1802  is electrically coupled to a locomotive  1810  via electrical coupling  212  or external energy transfer interface  1816 . In such an embodiment, the locomotive  1810  has a prime mover electrical generation system (such as shown in  FIG. 2  as  102 ,  104 , and  106 ) and a traction motor (not shown) having a dynamic braking mode of operation. The locomotive  1810  provides energy capture and storage system  204  of the railroad vehicle  1802  with locomotive prime mover electrical energy and/or locomotive dynamic braking electric energy. Such provided locomotive prime mover or dynamic braking electric energy is stored by energy capture and storage system  204  and provided as stored electric energy. In the alternative, energy capture and storage system  204  of the railroad vehicle  1802  provides the stored electric energy to the locomotive  1810  via the electrical coupling  212 . In such an arrangement, a traction motor of the locomotive  1810  is operable in response to the supplied stored electric energy to propel the locomotive  1810 . One or more railroad vehicles, such as those depicted in  FIGS. 15, 16  and  18 , may be electrically coupled to a locomotive such as locomotive  1810 .  
      The railroad vehicle  1802  may also be configured with a controller  1818 . The controller  1818  controls one of more operations of the railroad vehicle  1802  or components of the railroad vehicle  1802 . Such controlled operations may be distributed to the various components or operations of the railroad vehicle  1802  via control lines  1820 . As shown in  FIG. 18 , controller  1818  may control the traction motor  208 , energy capture and storage system  204 , the charging electric energy source  1804 , the resistive grids  310 , and the external energy transfer interface  1816 .  
      In one embodiment, the controller  1818  comprises a computer readable medium  1832  having computer executable instructions for controlling the operation of the railroad vehicle  1802 . As discussed in greater detail elsewhere herein, the computer executable instructions may define a plurality of railroad vehicle  1802  operating modes, so that the technical effect of the computer readable medium is the control of operating modes and therefore control of the operation of the railroad vehicle  1802  such as by defining a plurality of operating modes. Operating modes may be movement-type (e.g., motoring, coasting, dynamic braking) or functional-type, discussed below. Each of the operating modes defines a profile or set of operational parameters. The controller  1818  may be configured with one or more processors  1830  and the computer readable medium  1832 . The processor  1830  of the controller  1818  controls an operation of the railroad vehicle  1802  and accordingly has the technical effect of controlling one or more operational characteristics of the railroad vehicle  1802  consistent with or as a finction of the set of operational parameters associated with a selected or defined operating mode. The controller  1818  or components thereof may be located on the railroad vehicle  1802  or may in whole or part be located remote from the railroad vehicle  1802 . For example, the computer readable medium  1832  containing the computer executable instructions may be located at a remote data center or railway operations center (see  1824 ). A processor  1830  located on the railroad vehicle  1802  queries the remote data center and the computer executable instructions are communicated to the processor  1830  from the remote computer readable medium  1832  as required to operate the railroad vehicle  1802  in a desired mode of operation.  
      Railroad vehicle  1802  may be operable in a plurality of functional-type operating modes. In one embodiment, each operating mode is customized to optimize the operation of the railroad vehicle  1802  for a particular type of functional operation. The modes of functional operation may be defined and controlled by the controller  1818  as described above. For example, in one embodiment the railroad vehicle  1802  may have a plurality of discreet functional operating modes including a railway switcher mode, a railway roadmate mode, a railway pusher mode, or a railway energy tender mode.  
      Each functional-type operating mode, and each movement-type operating mode, defines one or more operating profiles. Each operating profile defines one or more operating characteristics, parameters or configurations of the railroad vehicle  1802 . Operating parameters vary by operating profile or operating mode and include one or more of the following: storing in the energy capture and storage system  204 ; energy capture and storage system  204  configuration; generating and capturing of dynamic braking energy; dissipating of dynamic braking energy, charging energy, or stored energy by the resistive grid  310 ; operating the charging electric energy source  1804 ; operating a generator to generate charging electric energy in response to the operation of the charging source  1804 ; transferring of stored, charging, or dynamic braking electric energy to an external electric energy system  220 ; receiving external electric energy from an external electric energy system  220  or another vehicle such as a locomotive  1810 , another railroad vehicle  1802  or an energy tender  202 ; supplying of stored energy to another vehicle; operating the tender motor  208  in the motoring mode or dynamic braking mode; receiving a control command from an external control source  1824 ; and transmitting control commands to remote vehicles.  
      Further as to components that may be in communication with the external control source  1824 , in some embodiments a communication link  1822  is in communication with the contoller  1818 . The communication link  1822  may be any communication facility including a wired link to another railway vehicle such as a locomotive, a wireless communication facility, or a remote control link. In accordance with the depiction in FIG.  18 , the communication link  1822  receives a control command from the external control source  1824  and provides the received control command to the controller  1818 . The controller  1818  operates in response to the external control command and controls an operation of the railroad vehicle  1802  responsive to the external control command. As one example of such an arrangement, a railway operator with a remote control device or remote railway control system operated by an operator located in a remote location may operate an external control device or system  1824 . The external control source  1824  would provide external control commands to the communication link  1822  and the connected controller  1818  to control the movement of the hybrid energy railway vehicle  1802  in a railway yard or terminal.  
      As to the three fundamental movement-type operating mode of a railroad vehicle—coasting, dynamic braking, and motoring, each of these similarly defines one or more operating profiles, which defines one or more operating characteristics, parameters or configurations of the railroad vehicle  1802 , and of the railroad vehicles  1500  and  1600 . Thus, generally, a coasting mode, in which neither power is provided to the driven wheel(s) nor electrical energy is generated through dynamic braking, may include one or more of the following operations: sending a signal to a traction motor, responsive to a control command, to operate in a coasting mode; and operating the traction motor in the coasting mode. More particularly, for an asynchronous (induction) type AC motor, a coasting mode may be initiated by sending a control signal to the current-providing electric switches to stop firing. For DC traction motors, a coasting mode may be initiated by turning off the motor, such as by opening contacts or by operating an electric switch.  
      A dynamic braking mode may include one or more of the following: sending a signal to a traction motor, responsive to a control command, to operate in a dynamic braking mode; operating the traction motor in the dynamic braking mode; transferring electrical energy to the energy capture and storage system; storing electrical energy in the energy capture and storage system; and monitoring and adjusting the level of dynamic braking (which may include operating from control commands from an external control source or from a controller, such as a feedback-type control system, on the particular railroad vehicle). A motoring mode may include one or more of the following: sending a signal to a traction motor, responsive to a control command, to operate in a motoring mode; operating the traction motor in the motoring mode; transferring electrical energy from the energy capture and storage system to the traction motor; and monitoring and adjusting the level of motoring (which may include operating from control commands from an external control source or from a controller, such as a feedback-type control system, on the particular railroad vehicle).  
      Also, generally as to terminology as used herein and as used in the art, some references consider that dynamic braking refers to having a circuit in which kinetic energy from a braking action by a traction motor is dissipated in a braking resistor. Such references distinguish this from regenerative braking in which the traction motor acts as a generator and develops an induced voltage, which may then be sent to an electrical energy storage system. It is noted that in the present disclosure the term “dynamic braking” is meant to include not only braking in which the kinetic energy of traction motor braking is ultimately dissipated in a braking resistor, but also braking in which electricity is generated and stored in an electrical energy storage system. The usage of the term is made clear by the context. One example of such references is Power Electronics—circuits, devices and applications, 2 nd  edition, 1993 Muhammad H. Rashid, Prentice Hall, N.J., pages 493-501. This text is incorporated by reference herein specifically for its teachings of DC and AC drives, from pages 493-590.  
      As is known in the art, and as may be applied to various embodiments of railroad vehicles, such as railroad vehicles  1500 ,  1600  and  1802  (in all variations of the latter), a traction motor may drive one wheel, or may drive more than one wheel. Also, such railroad vehicles may have a number of percentages and ranges defining a total possible freight volume x, such as established by a defined containment area, in relation to a maximum possible volume y obtainable for freight if no components related to propulsion and energy storage were present. For example, consider a hypothetical railroad vehicle adapted to carry grain in a defined containment area, and comprising to the front of such area a space z for an energy capture and storage system, a controller, and a communication link. Assuming a traction motor by the wheels occupies space that would not otherwise be occupied by grain (i.e., if there were no traction motor present, such as in a conventional rail car for grain), then x=y−z. As a further specific example, if a particular rail car structure would otherwise provide for 20,000 cubic feet of grain storage with no space allotted for an energy capture and storage system, a controller, and a communication link, and if such rail car structure were adapted to provide for a lesser space, 18,000 cubic feet, for grain storage in order to provide a 2,000 cubic feet space for such components, then the total possible freight volume x is 18,000 cubic feet, the maximum volume y is 20,000 cubic feet, and the space z is 2,000 cubic feet. In such specific example the total possible freight volume x is 90 percent of the maximum possible volume y.  
      More generally, in view of this example and these definitions, embodiments of a railroad vehicle may have a total possible freight volume that is at least 50 percent and up to about 99 percent of the maximum possible volume for a respective type of load car. That is, the space for the energy capture and storage system, the controller and the communication link does not occupy more than 50 percent of the total possible freight volume. (This calculation does not include space, such as between wheel sets on a box car, that may be used, for example, for an energy capture and storage system.) Such embodiments include certain embodiments that have a space, up to about 30 percent of the maximum possible volume, occupied by an energy capture and storage system, a controller, and a communication link. In other of such embodiments, a railroad vehicle may have a total possible freight volume that is at least 70 percent of the maximum possible volume, and up to about 85 percent of the maximum possible volume. A railroad vehicle comprising a total possible freight volume that is at least 50 percent of the maximum possible volume is considered to have a substantial volume of its total space for carrying freight of one type or another.  
      The railroad vehicles additionally may be comprised of arrangements and combinations of components discussed below, such as are described for multipurpose hybrid energy railway vehicles that do not comprise a substantial volume of its total space for carrying freight. Also, it is appreciated that the term “system” may variously be applied to a combination of components of a single vehicle, or to a different, broader system that may include multiple rail cars and one or more locomotives.  
       FIG. 13  is an embodiment of a multipurpose hybrid energy railway vehicle  1302  configured to operate in an autonomous operating mode, e.g., autonomous from a locomotive. The embodiment of  FIG. 13  includes a charging electric energy source  1304  that provides charging electric energy  1306  to energy capture and storage system  204 . Such charging electric energy source  1304  may be comprised of a diesel engine, a gasoline engine, a natural gas engine, a fuel cell, a gas turbine, an electric generator, an alternator and/or an inverter. Charging electric energy source  1304  may provide a steady charging source to energy capture and storage system  204  independent of the charge level energy capture and storage system  204  or may cycle on or off or at various operating levels based on the charge level or charging requirements of the energy capture and storage system  204 .  
      In the embodiment where the charging electric energy source  1304  operates independent of the charge level of the energy capture and storage system  204 , all or a portion of the charging electric energy  1306  not required by energy capture and storage system  204  may be transferred to another vehicle via the external energy transfer interface  1316  including a locomotive or to another hybrid energy railway vehicle  1302 . Such external energy transfer interface  1316  may be adapted to be detachably connected to any external energy system  220  including a locomotive, a second hybrid energy railway vehicle  1302 , an electric grid, an electric third rail, an electrical overhead line, or an external energy storage system.  
      The hybrid energy railway vehicle  1302  supplies the stored electric energy  1308  as stored in energy capture and storage system  204  to the hybrid energy railway vehicle traction motors  208  via traction bus  210 . The hybrid energy railway vehicle traction motors  208  operate in response to the provided stored electric energy (shown by line  1308 ) to propel the hybrid energy railway vehicle  1302  on the plurality of hybrid energy railway vehicle wheels (as shown).  
      As discussed above, the hybrid energy railway vehicle traction motor  208  also operates in a dynamic braking mode of operation to generate dynamic braking electric energy. The dynamic braking electric energy is provide to energy capture and storage system  204  where it is stored (shown as line  1308 ) as stored electric energy. Such stored dynamic braking electric energy is provided to the hybrid energy railway vehicle traction motor  208  as stored electric energy during the motoring mode of the traction motor  208 .  
      The hybrid energy railway vehicle  1302  may also be configured with a resistive grid  310  that is electrically coupled by any electrical coupling including the traction system bus  210  as shown in  FIG. 13  as electrical connection line  1312 . A circuit may be electrically connected between the resistive grid  310  and the traction system bus  210  and may be controlled by a control system  1318 , the energy capture and storage system  204  or other means including energy management system  502 . The circuit  1314  selectively supplies dynamic braking electric energy to the resistive grid  310  where the resistive grid  310  dissipates the supplied dynamic braking electric energy. In another embodiment, the circuit  1314  may selectively supply charging energy to the resistive grid. As discussed above, the charging electric energy source  1304  may operate to provide more charging electric energy  1306  than required by energy capture and storage system  204 . In such a case, the charging electric energy source  1304  may continue to operate with the circuit  1314  supplying any excess charging electric energy to the resistive grid  310 . In yet another embodiment, the electric energy capture and storage system  204  may be electrically connected to the resistive grid  310 . In such an embodiment, the circuit  1314  may selectively supply stored electric power to the resistive grid  310 . The supplying of stored electric power to the resistive grid  310  may be desired when an anticipated requirement for storage capacity for storing dynamic braking energy may exceed the current charging capacity of the energy capture and storage system  204 .  
      In another embodiment similar to that discussed above with regard to  FIGS. 2 and 3 , the hybrid energy railway vehicle  1302  is electrically coupled to a locomotive  1310  via electrical coupling  212  or external energy transfer interface  1316 . In such an embodiment, the locomotive  1310  has a prime mover electrical generation system (such as shown in  FIG. 2  as  102 ,  104 , and  106 ) and a traction motor (not shown) having a dynamic braking mode of operation. The locomotive  1310  provides energy capture and storage system  204  of the hybrid energy railway vehicle  1302  with locomotive prime mover electrical energy and/or locomotive dynamic braking electric energy. Such provided locomotive prime mover or dynamic braking electric energy is stored by energy capture and storage system  204  and provided as stored electric energy. In the alternative, energy capture and storage system  204  of the hybrid energy railway vehicle  1302  provides the stored electric energy to the locomotive  1310  via the electrical coupling  212 . In such an arrangement, a traction motor of the locomotive  1310  is operable in response to the supplied stored electric energy to propel the locomotive  1310 .  
      The hybrid energy railway vehicle  1302  may also be configured with a control system  1318 . The control system  1318  controls one of more operations of the hybrid energy railway vehicle  1302  or components of the hybrid energy railway vehicle  1302 . Such controlled operations may be distributed to the various components or operations of the hybrid energy railway vehicle  1302  via control lines  1320 . As shown in  FIG. 13 , control system  1318  may control the traction motor  208 , energy capture and storage system  204 , the charging electric energy source  1304 , the resistive grids  310 , and the external energy transfer interface  1316 .  
      In one embodiment, the control system  1318  comprises a computer readable medium  1332  having computer executable instructions for controlling the operation of the hybrid energy railway vehicle  1302 . As discussed in greater detail below, the computer executable instructions may define a plurality of hybrid energy railway vehicle  1302  operating modes. Each of the operating modes defines a profile or set of operational parameters. The control system  1318  may be configured with one or more processors  1330  and the computer readable medium  1332 . The processor  1330  of the control system  1318  controls an operation of the hybrid energy railway vehicle  1302  by controlling one or more operational characteristics of the hybrid energy railway vehicle  1302  consistent with or as a function of the set of operational parameters associated with a selected or defined operating mode. The control system  1318  or components thereof may be located on the hybrid energy railway vehicle  1302  or may in whole or part be located remote from the hybrid energy railway vehicle  1302 . For example, the computer readable medium  1332  containing the computer executable instructions may be located at a remote data center or railway operations center (see  1324 ). A processor  1330  located on the hybrid energy railway vehicle  1302  queries the remote data center and the computer executable instructions are communicated to the processor  1330  from the remote computer readable medium  1332  as required to operate the hybrid energy railway vehicle  1302  in a desired mode of operation.  
      As discussed above, hybrid energy railway vehicle  1302  may be operable in a plurality of operating modes. In one embodiment, each operating mode is customized to optimize the operation of the hybrid energy railway vehicle  1302  for a particular type of operation. The modes of operation may be defined and controlled by the control system  1318  as described above. For example, in one embodiment the hybrid energy railway vehicle  1302  may have a plurality of discreet operating modes including a railway switcher mode, a railway roadmate mode, a railway pusher mode, or a railway energy tender mode.  
      Each mode of operation defines one or more operating profiles. Each operating profile defines one or more operating characteristics, parameters or configurations of the hybrid energy railway vehicle  1302 . Operating parameters vary by operating profile or operating mode and include one or more of the following: storing in the energy capture and storage system  204 ; energy capture and storage system  204  configuration; generating and capturing of dynamic braking energy; dissipating of dynamic braking energy, charging energy, or stored energy by the resistive grid  310 ; operating the charging electric energy source  1304 ; operating a generator to generate charging electric energy in response to the operation of the charging source  1304 ; transferring of stored, charging, or dynamic braking electric energy to an external electric energy system  220 ; receiving external electric energy from an external electric energy system  220  or another vehicle such as a locomotive  1310 , another hybrid energy railway vehicle  1302  or an energy tender  202 ; supplying of stored energy to another vehicle; operating the tender motor  208  in the motoring mode or dynamic braking mode; receiving a control command from an external control system  1324 ; and transmitting control commands to remote vehicles.  
      A hybrid energy railway vehicle  1302  operating in a switcher mode is used in a railway operation for moving railway vehicles such as rolling stock or idle locomotives around a railway yard or terminal in order to configure a train comprised of one or more locomotives and one or more rolling stock railway vehicles. A switcher is often used for moving and collecting railway vehicles over a relatively short distance and is not required for long-haul trips.  
      When operating in the switcher mode, the hybrid energy railway vehicle  1302  is required to stand idle for long periods of time or long periods of idling while rolling stock and locomotives are coupled to other railway vehicles. In such as mode, the hybrid energy railway vehicle  1302  is required to provide immediate high tractive power and to maintain full power during its short interval of operation. Such a configuration requires that the switcher mode operate the hybrid energy railway vehicle  1302  by providing stored electric energy at a relatively low energy, but a high power level. During idle periods, the switcher mode operates at a low operating power level but a high energy storage level to sustain the low power demand and the low power charging levels. When operating in the switcher mode, the hybrid energy railway vehicle  1302  charges the energy capture and storage system  204  from an onboard charging energy source  1304  or from an external energy system  220 . Excess charging energy may be dissipated in the resistive grid  310  or may be discharged to an external energy system  220 . The resistive grid  310 , however, are not be configured to dissipate high energy levels which are often associated with a locomotive resistive grid as only small amounts of dynamic braking energy will be required to be dissipated by the resistive grid  310 .  
      In one embodiment of the operating the hybrid energy railway vehicle  1302  in the switcher mode, the switch mode defines a particular set of the operational parameters as described above. As an example, the energy capture and storage system  204  may be configured to provide the high power electrical energy level to the traction motor  208  for short periods of time to motor the hybrid energy railway vehicle  1302  around the rail yard. The energy capture and storage system  204  is configured to receive charging electrical energy at a low level and steady basis from the energy charging source  1304 . Additionally, the energy capture and storage system  204  may be configured to receive charging electrical energy from an external energy system  220 . In contrast to other operating modes, the switcher mode is not configured to receive or supply high energy levels to an external electrical energy system  220 . Additionally, as the switcher mode is used around the railway yard, the system is not configured to receive a high levels of dynamic braking energy from the traction motor  208 .  
      A hybrid energy railway vehicle  1302  operating in a pusher mode provides additional tractive effort and power to the consist in a train. The pusher mode may be used to assist a consist propelling a train traveling uphill where the additional tractive effort is only required for a small segment of the total track traversed by the train. The pusher mode may also operate as a braker, whereby the pusher assists a train traveling downhill by providing additional braking effort. A hybrid energy railway vehicle  1302  operating in the pusher mode typically involves attaching the hybrid energy railway vehicle  1302  to the train at the bottom of a hill. The pusher provides tractive effort during the climb up the hill discharging the stored electric energy from the energy capture and storage system  204  to propel the traction motor  208 . At the top of the hill, the pusher is disconnected from the train that continues motoring on the track. The pusher mode hybrid energy railway vehicle  1302  is attached to a different train traveling in the opposite direction to provide additional dynamic braking going down the hill. During the dynamic braking, dynamic braking energy is generated by the traction motor  208  and is stored in the energy capture and storage system  204 . The dynamic braking energy replenishes some of all of the stored energy utilized during the earlier climb up the hill. This cycle of discharging and charging the energy capture and storage system  204  is repeated in each operation of the hybrid energy railway vehicle  1302  operating in the pusher mode of operation.  
      In one embodiment of operating the hybrid energy railway vehicle  1302  in the pusher mode, the energy capture and storage system  204  is configured to deliver high energy levels to the traction motor  208  over an extended period of time traveling up the hill. The energy capture and storage system  204  is also configured to store high levels of dynamic braking energy generated by the traction motor  208  during extended periods of dynamic braking during decent down the hill. Furthermore, resistive grids and the cooling system (not shown) for the resistive grids is configured to dissipate excess dynamic braking energy not required for storage by the energy capture and storage system  204 . In the pusher operating mode, the energy capture and storage system  204  is configured to cycle continuous between delivering high amounts of stored energy to the traction motor  208  and receiving high amounts of dynamic braking energy from the traction motor  208  or from another vehicle such as an electrically coupled locomotive. Additionally, resistive grid  310  dissipates high levels of dynamic braking energy. In this mode of operation, charging the energy capture and storage system  204  from a electrical energy source  1304  or from an external electric energy system  220  may be provided but may not be necessary.  
      A hybrid energy railway vehicle  1302  operating in a energy tender mode operates as an electric energy storage vehicle and does not provide additional tractive effort or dynamic braking effort to a consist or train. In such a configuration, the hybrid energy railway vehicle  1302  is mechanically and electrically coupled to a locomotive  1310  or to another hybrid energy railway vehicle  1302  that supplies external electric energy to the energy tender. The hybrid energy railway vehicle  1302  receives and stores the external electric energy provided by the locomotive  1310 . The locomotive  1310  provides external electric energy generated by its prime mover power source, typically a diesel engine and generator, or dynamic braking energy generated by a traction motor of the other vehicle during dynamic braking.  
      When the hybrid energy railway vehicle  1302  is operating in the energy tender mode, the electrical energy configuration of the hybrid energy railway vehicle  1302  is a function of the electric energy and operating characteristics of the supplying vehicle, the locomotive  1310  or another hybrid energy railway vehicle  1302 . For example, in one embodiment of a locomotive  1310 , the locomotive prime mover produces 4,400 HP of electric energy and the locomotive traction system is capable of utilizing up to 6,000 HP of electric energy. As such, 1,600 HP of electric energy may be provided from stored electric energy of the hybrid energy railway vehicle  1302  to the locomotive traction system to provide supplemental electrical energy to derive additional locomotive tractive effort. The high horsepower requirement of the locomotive traction system and therefore the high level of supplied stored electric energy may be required for only a few minutes or may be required for a few hours. However, for the majority of operating time of the locomotive  1310  and the hybrid energy railway vehicle  1302  operating in the energy tender mode, the power production and usage levels are considerably less these high levels. As such, the energy tender mode configures the hybrid energy railway vehicle  1302  to provide high levels of electric energy to the locomotive for short periods of time.  
      During dynamic braking, the traction motors of a locomotive can produce 5,200 to 7,800 HP of electric energy during dynamic braking. Some or all of the locomotive dynamic braking electric energy may be provided to the energy capture and storage system  204  of the hybrid energy railway vehicle  1302  for storage. As the production of dynamic braking energy at these levels may also only be available for short periods of time, the energy capture and storage system  204  and the hybrid energy railway vehicle  1302  is configured to receive and store these high levels of electric energy and provide high power output at the same time.  
      In one embodiment of the energy tender mode, the energy capture and storage system  204  is configured to receive large amounts of electrical energy from an electrically connected locomotive  1310  during periods of locomotive dynamic braking. The energy capture and storage system  204  is configured to provide an optimal level of stored electric energy to supplement the primary electric energy driving the traction motor of the locomotive  1310 . In the energy tender mode, the hybrid energy railway vehicle  1302  is not configured to generate its own charging electric energy or its own dynamic braking electrical energy. Additionally, all stored electric energy would be provided to the locomotive  1310  and none of the stored electric energy is supplied to the traction motor  208  of the hybrid energy railway vehicle  1302 . As an option, a portion of the electrical energy received by the hybrid energy railway vehicle  1302  from the locomotive  1310  is dissipated by the resistive grid  310  of the hybrid energy railway vehicle  1302  thereby supplementing the dissipating capacity of the resistive grid of the locomotive  1310 . This provides increased braking capacity to the locomotive  1310 .  
      A hybrid energy railway vehicle  1302  operating in a roadmate mode operates in an autonomous manner from other railway vehicles and locomotive  1310  to provide additional tractive effort and dynamic braking to control the movement of the train. The hybrid energy railway vehicle  1302  operating in the roadmate mode is mated with or controlled by a “lead” locomotive  1310  in a consist configuration and may optionally be electrically coupled to a locomotive  1310 .  
      In the roadmate mode, the hybrid energy railway vehicle  1302  works in conjunction with a locomotive  1310  to provide a high power demand often for a sustained period of operation. In this configuration, the hybrid energy railway vehicle  1302  generates and stores charging electric power from the charging source  1304  and stores dynamic braking electric energy during dynamic braking of traction motors  208  of the hybrid energy railway vehicle  1302 . As an option, external electric energy from an electrically coupled locomotive  1310  generated by the locomotive prime mover energy power source or from the locomotive traction motors during dynamic braking may be provided to the hybrid energy railway vehicle  1302  operating in the roadmate mode. As such, in the roadmate configuration, the energy capture and storage system  204  of the hybrid energy railway vehicle  1302  could be 10,000 HP or higher since the typical locomotive alone produces 5,200 to 7,800 HP during dynamic braking. The hybrid energy railway vehicle  1302  operating in the roadmate mode is required to provide high horsepower production or storage of electric energy that may last for several minutes or as long as a few hours.  
      In one embodiment of the hybrid energy railway vehicle  1302  operating in the roadmate mode, the energy storage and capture system  204  may be configured to supply stored energy to operate the traction motor  208  at high energy levels for short periods of time and to operate the traction motor  208  at a lower sustained energy level for long periods. In such an embodiment, the energy capture and storage system  204  would receive a continuous low level of charging electric energy from the electric energy source  1304  and higher levels of dynamic braking energy from the traction motor  208 . In contrast to the hybrid energy railway vehicle  1302  operating in a pusher mode as addressed above, the roadmate mode does not require an energy capture and storage system  204  configuration that is regularly cycled between receiving high levels of electric energy and supplying high levels of stored energy since in the roadmate mode anticipates regular long periods of supplying low energy levels due to extended periods of speed maintaining and idling.  
      Other modes of operation, operating mode profiles and operational parameters are anticipated by this invention.  
      In operation, a multipurpose hybrid energy railway vehicle  1302  may be configured with the control system  1318  with computer readable medium  1332  containing the computer executable instructions. The computer executable instructions define a plurality of operating modes, each operating mode defining one or more operating characteristics as described above. In practice, the operating characteristics for each operating mode is defined based on defined operating criteria and/or as a function of an optimization characteristic. An operator, the control system, or a remote control command specifies or selects a particular one of the plurality of operating modes. The control system  1318  executes the instructions for the particular operating mode and thereby configures the hybrid energy railway vehicle  1302 . A particular operating mode is chosen or selected each time the configuration or operation of the hybrid energy railway vehicle  1302  needs to be changed to meet the requirements and/or to optimize the operation for the intended use of the vehicle. By providing for the optimization of a plurality of operating modes of a single hybrid energy railway vehicle  1302 , railroad operators can decrease costs by reducing capital investment in multiple vehicles, each of which in the prior art are designed for only a single use. Additionally, the utilization of the multipurpose vehicle will be substantially greater than a prior art single use vehicle since the multipurpose vehicle will have fewer long periods of non-operation.  
      The hybrid energy railway vehicle  1302  may be equipped with an operator compartment for use by an operator of the hybrid energy railway vehicle  1302 . In such as case, the control system  1318  is operable from within the operator compartment such that an operator of the hybrid energy railway vehicle  1302  located in the operator compartment controls an operation of the hybrid energy railway vehicle  1302 . For example, when the hybrid energy railway vehicle  1302  operates in a railway operation as a switcher, the control system  1318  is used to control the movement of the hybrid energy railway vehicle  1302  to move one or more railway cars in and around a railway yard or terminal.  
      The hybrid energy railway vehicle  1302  may also be configured with a communication link  1322  that is in communication with the control system  1318 . The communication link  1322  may be any communication facility including a wired link to another railway vehicle such as a locomotive, a wireless communication facility, or a remote control link. The communication link  1322  receives an external control command from an external control system  1324  and provides the received external control command to the control system  1318 . The control system  1318  operates in response to the external control command and controls an operation of the hybrid energy railway vehicle  1302  responsive to the external control command. As one example of such an arrangement, a railway operator with a remote control device or remote railway control system operated by an operator located in a remote location may operate an external control device or system  1324 . The external control system  1324  would provide external control commands to the communication link  1322  and the connected control system  1318  to control the movement of the hybrid energy railway vehicle  1302  in a railway yard or terminal.  
      In another aspect, the control system  1318  of the hybrid energy railway vehicle  1302  may be configured to control one or more operations of one or move other railway vehicles. For instance, an operator riding in an operator compartment  230  of the hybrid energy railway vehicle  1302  may control an operation of one or two locomotives or another hybrid energy railway vehicle  1302  which is coupled to the hybrid energy railway vehicle  1302  such as in a consist configuration. In such case, the control system  1318  originates one or more control commands or signals that would be communicated over communication link  1322  to the other railway vehicle. By utilizing either a wired trainline communication facility or a wireless or radio communication facility, the control system  1318  of the hybrid energy railway vehicle  1302  can control a locomotive or another hybrid energy railway vehicle  1302  that is operating in consist or train configuration in conjunction with the hybrid energy railway vehicle  1302 .  
      As noted above and as depicted in  FIG. 13 , an external energy transfer interface  1316  may be electrically connected to the energy capture and storage system  204 . An external electrical energy system  220  provides external electrical energy to the external energy transfer interface  1316 , which is stored in the energy capture and storage system  204 . Such received external electric energy may also be used to power the hybrid energy railway vehicle traction motors  208 . Alternatively, stored electric energy may be provided by the energy capture and storage system  204  via the external energy transfer interface  1316  to provide the stored electric energy to the external electrical energy system  220 . The external electrical energy system  220  may be any electrical system external to the hybrid energy railway vehicle  1302  including an electric grid, electric distribution lines, an electrified third rail, an electrical overhead line, or another vehicle configured to receive stored electric energy. Alternatively, the external energy transfer interface  1316  may be electrically coupled to the traction motor  208  or to traction bus  210  such that dynamic braking energy generated by the hybrid energy railway vehicle traction motor  208  is transferred to an external electric energy system  220 . In another embodiment, as discussed above, the external energy transfer interface  1316  provides some or all of the charging electric energy  1306  to the external electric energy system  220 .  
      The hybrid energy railway vehicle  1302  may also be equipped with a converter  1326  that is electrically coupled to energy capture and storage system  204 . The converter  1326  selectively transfers stored electric energy from energy capture and storage system  204  and supplies the transferred stored electric energy to the traction motors  208 .  
      Energy capture and storage system  204  may be configured with a removable energy storage unit  1328 . Such storage unit  1328  may be removed from hybrid energy railway vehicle  1302  and replaced by a replacement storage unit  1328 . In one embodiment, storage unit  1328  is configured to be electrically charged by an external charging system (not shown). In one embodiment and method of operation, the storage units  1328  are removed from the hybrid energy railway vehicle  1302  when their charge is depleted. The storage unit  1328  is transferred to a site remote from the hybrid energy railway vehicle  1302 . An external charging system recharges the energy storage unit  1328 . One such external charging system could be another hybrid energy railway vehicle  1302  which had previously charged the energy storage unit  1328 . After being externally charged, the storage unit  1328  is re-installed on the hybrid energy railway vehicle  1302 . The hybrid energy railway vehicle  1302 , energy capture and storage system  204  and storage unit  1328  are configured to provide for an efficient removal and re-installation of the storage unit  1328  from the hybrid energy railway vehicle  1302 .  
      In another embodiment and method of operation, hybrid energy railway vehicle  1302  is equipped with storage units  1328  which have been depleted, e.g., no stored energy. The hybrid energy railway vehicle  1302  operates in an operating mode, such as an energy tender mode, whereby the hybrid energy railway vehicle  1302  generates dynamic braking energy from hybrid energy railway vehicle traction motor  208  and stores the dynamic braking energy in the energy capture and storage system  204 . After charging the energy storage unit  1328 , the energy storage unit  1328  is removed from the hybrid energy railway vehicle  1302 . The removed energy storage unit  1328  is installed on another hybrid energy railway vehicle  1302 , a hybrid electric locomotive (not shown), or is discharged into an external energy storage system or external energy electric system  220 .  
      In another embodiment of the invention, a hybrid energy railway vehicle  1302  is configured with a charging electric energy source  1304 , an energy capture and storage system  204 , a converter  1326 , a traction system  208 , a resistive grid  310 , and a resistive grid circuit  1314 . The energy capture and storage system  204  receives charging electric energy from the charging electric energy source  1304 . The converter  1326  is electrically coupled to the energy capture and storage system  204  such that the energy capture and storage system  204  selectively transfers stored electric energy to converter  1326 . The converter  1326  provides energy tender drive energy to the traction motor  208  to propel the hybrid energy railway vehicle  1302 . The resistive grid circuit  1314  selectively supplies charging electric energy to the resistive grid  310  where it is dissipated as heat. For example, the charging electric energy source  1304  may be configured to operate on a continuous basis independent of the required level of charging energy required by the energy capture and storage system  204 . In operation, the circuit  1314  may operate to selectively supply charging energy to the resistive grid  310  in response to an operating parameter, a result of a command from the control system  1330 , input from the energy capture and storage system  204 , or a control signal from the control system  1318 . As such, the charging electric energy source  1304  continues to operate even though the energy capture and storage system  204  does not have an immediate need for the charging energy, as the excess charging energy is dissipated.  
       FIG. 14  is another embodiment of a multipurpose hybrid energy railway vehicle  1402  configured to operate in an autonomous mode. The embodiment of  FIG. 14  is configured to store dynamic braking energy generated by the hybrid energy railway vehicle traction motor  208  and does not include a hybrid energy railway vehicle charging electric energy source  1304 . In this embodiment, traction motor  208  provides dynamic braking electric energy during a dynamic braking mode of operation (shown as line  1408 ) to a converter  1406 . The converter  1406  provides to the energy capture and storage system  204 , dynamic braking electric energy to be stored (via line  1404 ). Energy capture and storage system  204  receives the dynamic braking energy and selectively stores the dynamic braking energy. Energy capture and storage system  204  provides stored electric energy via line  1404  to the converter  1406  as required by the converter  1406  to provide energy tender drive power to the traction motor  208 . The converter  1406  provides stored electric energy (via line  1408 ) to the traction system bus  210  and thereby to the traction motor  208  to propel the hybrid energy railway vehicle  1402 .  
      In one embodiment as shown in  FIG. 14 , the converter  1406  provides some or all of the stored energy received by the converter from the energy capture and storage system  204  and/or the dynamic braking energy received from the traction motor  208  to the resistive grid  310 . The electrical energy supplied to the resistive grid  310  is dissipated as heat energy. As indicated, line  1410  electrically connects the converter  1406  to the electric circuit  1312  that is connected either directly to the resistive grid  310  or to resistive grid circuit  1314 . In an alternative embodiment, energy to be dissipated by the resistive grid  310  is supplied to the traction bus via line  1408  and is provided to the resistive grid  310  via line  1312  or via resistive grid circuit  1314 .  
      In operation, a hybrid energy railway vehicle  1302  consistent with the many aspects of the invention may be operated by a number of methods. One embodiment of a method of operating a hybrid energy railway vehicle system includes supplying charging electrical energy with an electrical energy source  1304 . A traction motor  208  operates in a dynamic braking mode to generate dynamic braking electrical energy. The charging electrical energy and dynamic braking electrical energy is stored in an energy capture and storage system  204  to produce stored electrical energy. Stored electrical energy is supplied to the traction motor  208  that operates in a motoring mode in response to the supplied stored electrical energy for driving on or more wheels of the hybrid energy railway vehicle  1302 .  
      In another embodiment of the method, the method includes operating a traction motor  208  in a dynamic braking mode to generate dynamic braking electrical energy. The generated dynamic braking electrical energy is stored in an energy capture and storage system  204  to produce stored electrical energy. Stored electrical energy is supplied to the traction motor that operates in a motoring mode in response to the supplied stored electrical energy for driving one or more wheels of the hybrid energy railway vehicle  1302 .  
      In yet another embodiment of a method of operating a hybrid energy railway vehicle system  1302 , the method includes receiving external electrical energy from an external electrical energy system  220 . The received external electrical energy is stored in an energy capture and storage system  204  to produce stored electrical energy. Stored electrical energy is supplied to a traction motor  208  that operates in a motoring mode in response to the supplied stored electrical energy for driving on or more wheels of the hybrid energy railway vehicle  1302 .  
      In another embodiment, a method of operating a hybrid energy railway vehicle system  1302  includes operating a traction motor  208  in a dynamic braking mode to generate dynamic braking electrical energy. The dynamic braking electrical energy is stored in an energy capture and storage system  204  to produce stored electrical energy. Stored electrical energy is supplied to an external electrical energy system  220 .  
      In still another embodiment, a method of operating a hybrid energy railway vehicle system  1302  includes defining a plurality of operating modes, each of the plurality of operating modes defining a set of operational parameters. A value for each of the operational parameters in the set of operational parameters is specified as a finction of an optimization characteristic. An operation of the hybrid energy railway vehicle  1302  is controlled as a finction of a particular set of operational parameters defined by a particular operating mode responsive to a desired use of the hybrid energy railway vehicle  1302 .  
      As optional variations on the above methods, charging electrical energy or dynamic braking electrical energy may be supplied to a resistive grid  310 . Such an embodiment may be desirable when excess dynamic braking energy is generated or where it is desirable to discharge the energy capture and storage system  204  prior to a new use or in anticipation of a future need to store dynamic braking energy that may be in excess of that capable of being dissipated by the resistive grid  310  during dynamic braking. In another optional embodiment, stored electrical energy may be provided to an external electrical energy system  220  or external electrical energy may be provided by the external electrical energy system  220  that is then stored in the energy capture and storage system  204 . As one example, where the external electrical energy system  220  is a locomotive  1310 , the supplied stored electrical energy could be utilizes by the locomotive  1310  to drive a traction motor of the locomotive  1310 .  
      Referring now to  FIG. 4 ,  FIG. 4  is a system-level block diagram that illustrates aspects of one preferred energy storage and generation system. In particular,  FIG. 4  illustrates an energy storage and generation system  400  suitable for use with a hybrid energy locomotive system, such as hybrid energy locomotive system  200  or system  300  ( FIGS. 2 and 3 ). Such an energy storage and generation system  400  could be implemented, for example, as part of a separate energy tender vehicle (e.g.,  FIGS. 2 and 3 ) and/or incorporated into a locomotive.  
      As illustrated in  FIG. 4 , a diesel engine  102  drives a prime mover power source  104  (e.g., an alternator/rectifier converter). The prime mover power source  104  preferably supplies DC power to an inverter  106  that provides three-phase AC power to a locomotive traction motor  108 . It should be understood, however, that the system  400  illustrated in  FIG. 4  can be modified to operate with DC traction motors as well. Preferably, there is a plurality of traction motors (e.g., one per axle), and each axle is coupled to a plurality of locomotive wheels. In other words, each locomotive traction motor preferably includes a rotatable shaft coupled to the associated axle for providing tractive power to the wheels. Thus, each locomotive traction motor  108  provides the necessary motoring force to an associated plurality of locomotive wheels  109  to cause the locomotive to move.  
      When traction motors  108  are operated in a dynamic braking mode, at least a portion of the generated electrical power is routed to an energy storage medium such as energy capture and storage system  204 . To the extent that energy capture and storage system  204  is unable to receive and/or store all of the dynamic braking energy, the excess energy is preferably routed to braking grids  110  for dissipation as heat energy. Also, during periods when engine  102  is being operated such that it provides more energy than needed to drive traction motors  108 , the excess capacity (also referred to as excess prime mover electric power) may be optionally stored in energy capture and storage system  204 . Accordingly, energy capture and storage system  204  can be charged at times other than when traction motors  108  are operating in the dynamic braking mode. This aspect of the system is illustrated in  FIG. 4  by a dashed line  402 .  
      The energy capture and storage system  204  of  FIG. 4  is preferably constructed and arranged to selectively augment the power provided to traction motors  108  or, optionally, to power separate traction motors associated with a separate energy tender vehicle (see  FIG. 2  above) or a load vehicle. Such power may be referred to as secondary electric power and is derived from the electrical energy stored in energy storage  204 . Thus, the system  400  illustrated in  FIG. 4  is suitable for use in connection with a locomotive having an on-board energy storage medium and/or with a separate energy tender vehicle.  
       FIG. 5  is a block diagram that illustrates aspects of one preferred embodiment of an energy storage and generation system  500  suitable for use with a hybrid energy locomotive system. The system  500  includes an energy management system  502  for controlling the storage and regeneration of energy. It should be understood, however, that the energy management system  502  illustrated in  FIG. 5  is also suitable for use with other large, off-highway vehicles that travel along a relatively well-defined course. Such vehicles include, for example, large excavators, excavation dump trucks, and the like. By way of further example, such large excavation dump trucks may employ motorized wheels such as the GEB23.TM. AC motorized wheel employing the GE150AC.TM. drive system (both of which are trademarked products available from the assignee of the present invention). Therefore, although  FIG. 5  is generally described with respect to a locomotive system, the energy management system  500  illustrated therein is not to be considered as limited to locomotive applications.  
      Referring still to the exemplary embodiment illustrated in  FIG. 5 , system  500  preferably operates in the same general manner as system  400  of  FIG. 4 ; the energy management system  502  provides additional intelligent control functions.  FIG. 5  also illustrates an optional energy source  504  that is preferably controlled by the energy management system  502 . The optional energy source  504  may be a second engine (e.g., the charging engine illustrated in  FIG. 3 , charging electric energy source  1304  as illustrated in  FIGS. 13 and 14 , another hybrid energy railway vehicle  1302 , or another locomotive in the consist) or a completely separate power source (e.g., a wayside power source such as battery charger, a third rail, or an overhead line) for charging energy storage  204 . In one embodiment, such a separate charger includes an electrical power station for charging an energy storage medium associated with a separate energy tender vehicle (e.g., vehicle  202  of  FIG. 2 ) while stationary, or a system for charging the energy storage medium while the tender vehicle is in motion. In one preferred embodiment, optional energy source  504  is connected to a traction bus (not illustrated in  FIG. 5 ) that also carries primary electric power from prime mover power source  104 .  
      As illustrated, the energy management system  502  preferably includes an energy management processor  506 , a database  508 , and a position identification system  510 , such as, for example, a global positioning satellite system receiver (GPS)  510 . The energy management processor  506  determines present and anticipated train position information via the position identification system  510 . In one embodiment, energy management processor  506  uses this position information to locate data in the database  508  regarding present and/or anticipated track topographic and profile conditions, sometimes referred to as track situation information. Such track situation information may include, for example, track grade, track elevation (e.g., height above mean sea level), track curve data, tunnel information, speed limit information, and the like. It is to be understood that such database information could be provided by a variety of sources including: an onboard database associated with processor  510 , a communication system (e.g., a wireless communication system) providing the information from a central source, manual operator input(s), via one or more wayside signaling devices, a combination of such sources, and the like. Finally, other vehicle information such as, the size and weight of the vehicle, a power capacity associated with the prime mover, efficiency ratings, present and anticipated speed, present and anticipated electrical load, and so on may also be included in a database (or supplied in real or near real time) and used by energy management processor  506 .  
      It should be appreciated that, in an alternative embodiment, energy management system  502  could be configured to determine power storage and transfer requirements associated with energy storage  204  in a static fashion. For example, energy management processor  506  could be preprogrammed with any of the above information, or could use look-up tables based on past operating experience (e.g., when the vehicle reaches a certain point, it is nearly always necessary to store additional energy to meet an upcoming demand).  
      The energy management processor  506  preferably uses the present and/or upcoming track situation information, along with vehicle status information, to determine power storage and power transfer requirements. Energy management processor  506  also determines possible energy storage opportunities based on the present and future track situation information. For example, based on the track profile information, energy management processor  506  may determine that it is more efficient to completely use all of the stored energy, even though present demand is low, because a dynamic braking region is coming up (or because the train is behind schedule and is attempting to make up time). In this way, the energy management system  502  improves efficiency by accounting for the stored energy before the next charging region is encountered. As another example, energy management processor  506  may determine not to use stored energy, despite present demand, if a heavier demand is expected in the future. Advantageously, energy management system  502  may also be configured to interface with engine controls. Also, as illustrated in  FIG. 5 , energy storage  204  may be configured to provide an intelligent control interface  512  with energy management system  502 .  
      In operation, energy management processor  506  determines a power storage requirement and a power transfer requirement. Energy storage  204  stores electrical energy in response to the power storage requirement. Energy storage  204  provides secondary electric power (e.g., to a traction bus connected to inverters  106  to assist in motoring) in response to the power transfer requirement. The secondary electric power is derived from the electrical energy stored in energy storage  204 .  
      As explained above, energy management processor  506  preferably determines the power storage requirement based, in part, on a situation parameter indicative of a present and/or anticipated track topographic characteristic. Energy management processor  506  may also determine the power storage requirement as a function of an amount of primary electric power available from the prime mover power source  104 . Similarly, energy management processor  506  may determine the power storage requirement as a function of a present or anticipated amount of primary electric power required to propel the locomotive system.  
      Also, in determining the energy storage requirement, energy management processor  506  preferably considers various parameters related to energy storage  204 . For example, energy storage  204  will have a storage capacity that is indicative of the amount of power that can be stored therein and/or the amount of power that can be transferred to energy storage  204  at any given time. Another similar parameter relates to the amount of secondary electric power that energy storage  204  has available for transfer at a particular time.  
      As explained above, system  500  preferably includes a plurality of sources for charging energy storage  204 . These sources include dynamic braking power, excess prime mover electric power, and external charging electric power. Preferably, energy management processor  506  determines which of these sources should charge energy storage  204 . In one embodiment, present or anticipated dynamic braking energy is used to charge energy storage  204 , if such dynamic braking energy is available. If dynamic braking energy is not available, either excess prime mover electric power or external charging electric power is used to charge energy storage  204 .  
      In the embodiment of  FIG. 5 , energy management processor  506  preferably determines the power transfer requirement as a function of a demand for power. In other words, energy storage  204  preferably does not supply secondary electric power unless traction motors  108  are operating in a power consumption mode (e.g., a motoring mode, as opposed to a dynamic braking mode). In one form, energy management processor  506  permits energy storage  204  to supply secondary electric power to inverters  106  until either (a) the demand for power terminates or (b) energy storage  204  is completely depleted. In another form, however, energy management processor  506  considers anticipated power demands and controls the supply of secondary electric power from energy storage  204  such that sufficient reserve power remains in energy storage  204  to augment prime mover power source during peak demand periods. This may be referred to as a “look-ahead” energy management scheme.  
      In the look-ahead energy management scheme, energy management processor  506  preferably considers various present and/or anticipated track situation parameters, such as those discussed above. In addition, energy management processor may also consider the amount of power stored in energy storage  204 , anticipated charging opportunities, and any limitations on the ability to transfer secondary electric power from energy storage  204  to inverters  106 .  
      FIGS.  6 A-D,  7 A-D, and  8 A-E illustrate, in graphic form, aspects of three different embodiments of energy management systems, suitable for use with a hybrid energy vehicle, that could be implemented in a system such as system  500  of  FIG. 5 . It should be appreciated that these figures are provided for exemplary purposes and that, with the benefit of the present disclosure, other variations are possible. It should also be appreciated that the values illustrated in these figures are included to facilitate a detailed description and should not be considered in a limiting sense. It should be further understood that, although the examples illustrated in these figures relate to locomotives and trains, the energy management system and methods identified herein may be practiced with a variety of large, off-highway vehicles that traverse a known course and which are generally capable of storing the electric energy generated during the operation of such vehicles. Such off-highway vehicles include vehicles using DC and AC traction motor drives and having dynamic braking/retarding capabilities.  
      There are four similar charts in each group of figures (FIGS.  6 A-D, FIGS.  7 A-D, and FIGS.  8 A-D). The first chart in each group (e.g.,  FIGS. 6A, 7A , and  8 A) illustrates the required power for both motoring and braking. Thus, the first chart graphically depicts the amount of power required by the vehicle. Positive values on the vertical axis represent motoring power (horsepower); negative values represent dynamic braking power. It should be understood that motoring power could originate with the prime mover (e.g., diesel engine in a locomotive), or from stored energy (e.g., in an energy storage medium in a separate energy tender vehicle or in a locomotive), or from a combination of the prime mover and stored energy. Dynamic braking power could be dissipated or stored in the energy storage medium.  
      The horizontal axis in all charts reflects time in minutes. The time bases for each chart in a given figure group are intended to be the same. It should be understood, however, that other reference bases are possible.  
      The second chart in each group of figures (e.g.,  FIGS. 6B, 7B , and  8 B) reflects theoretical power storage and consumption. Positive values reflect the amount of power that, if power were available in the energy storage medium, could be drawn to assist in motoring. Negative values reflect the amount of power that, if storage space remains in the energy storage medium, could be stored in the medium. The amount of power that could be stored or drawn is partially a function of the converter and storage capabilities of a given vehicle configuration. For example, the energy storage medium will have some maximum/finite capacity. Further, the speed at which the storage medium is able to accept or supply energy is also limited (e.g., batteries typically charge slower than flywheel devices). Other variables also affect energy storage. These variables include, for example, ambient temperature, the size and length of any interconnect cabling, current and voltage limits on DC-to-DC converters used for battery charging, power ratings for an inverter for a flywheel drive, the charging and discharging rates of a battery, or a motor/shaft limit for a flywheel drive. The second chart assumes that the maximum amount of power that could be transferred to or from the energy storage medium at a given time is 500 h.p. Again, it should be understood that this 500 h.p. limit is included for exemplary purposes. Hence, the positive and negative limits in any given system could vary as a function of ambient conditions, the state and type of the energy storage medium, the type and limits of energy conversion equipment used, and the like.  
      The third chart in each figure group (e.g.,  FIGS. 6C, 7C , and  8 C) depicts a power transfer associated with the energy storage medium. In particular, the third chart illustrates the actual power being transferred to and from the energy storage medium versus time. The third chart reflects limitations due to the power available for storage, and limitations due to the present state of charge/storage of the energy storage medium (e.g., the speed of the flywheel, the voltage in an ultracapacitor, the charge in the battery, and the like).  
      The fourth chart in each figure group (e.g.,  FIGS. 6D, 7D , and  8 D) depicts actual energy stored. In particular, the fourth chart illustrates the energy stored in the energy storage medium at any particular instant in time.  
      Referring first to FIGS.  6 A-D, these figures reflect an energy management system that stores energy at the maximum rate possible during dynamic braking until the energy storage medium is completely full. In this embodiment, all energy transfers to the storage medium occur during dynamic braking. In other words, in the embodiment reflected in FIGS.  6 A-D, no energy is transferred to the energy storage medium from excess prime mover power available during motoring, or from other energy sources. Similarly, energy is discharged, up to the maximum rate, whenever there is a motor demand (limited to and not exceeding the actual demand) until the energy storage medium is completely discharged/empty. FIGS.  6 A-D assume that the energy storage medium is completely discharged/empty at time  0 .  
      Referring now specifically to  FIG. 6A , as mentioned above, the exemplary curve identified therein illustrates the power required (utilized) for motoring and dynamic braking. Positive units of power reflect when motoring power is being applied to the wheels of the vehicle (e.g., one or more traction motors are driving locomotive wheels). Negative units of power reflect power generated by dynamic braking.  
       FIG. 6B  is an exemplary curve that reflects power transfer limits. Positive values reflect the amount of stored energy that would be used to assist in the motoring effort, if such energy were available. Negative units reflect the amount of dynamic braking energy that could be stored in the energy storage medium if the medium were able to accept the full charge available. In the example of  FIG. 6B , the energy available for storage at any given time is illustrated as being limited to 500 units (e.g., horsepower). As explained above, a variety of factors limit the amount of power that can be captured and transferred. Thus, from about 0 to 30 minutes, the locomotive requires less than 500 h.p. If stored energy were available, it could be used to provide all of the motoring power. From about 30 minutes to about 65 or 70 minutes, the locomotive requires more than 500 h.p. Thus, if stored energy were available, it could supply some (e.g., 500 h.p.) but not all of the motoring power. From about 70 minutes to about 75 minutes or so, the locomotive is in a dynamic braking mode and generates less than 500 h.p. of dynamic braking energy. Thus, up to 500 h.p. of energy could be transferred to the energy storage medium, if the medium retained sufficient capacity to store the energy. At about 75 minutes, the dynamic braking process generates in excess of 500 h.p. Because of power transfer limits, only up to 500 h.p. could be transferred to the energy storage medium (again, assuming that storage capacity remains); the excess power would be dissipated in the braking grids. It should be understood that  FIG. 6B  does not reflect the actual amount of energy transferred to or from the energy storage medium. That information is depicted in  FIG. 6C .  
       FIG. 6C  reflects the power transfer to/from the energy storage medium at any given instant of time. The example shown therein assumes that the energy storage medium is completely empty at time 0. Therefore, the system cannot transfer any power from the storage at this time. During a first time period A (from approximately 0-70 minutes), the vehicle is motoring (see  FIG. 6A ) and no power is transferred to or from the energy storage. At the end of the first time period A, and for almost 30 minutes thereafter, the vehicle enters a dynamic braking phase (see  FIG. 6A ). During this time, power from the dynamic braking process is available for storage (see  FIG. 6B ).  
      During a second time period B (from approximately 70-80 minutes), dynamic braking energy is transferred to the energy storage medium at the maximum rate (e.g., 500 units) until the storage is full. During this time there is no motoring demand to deplete the stored energy. Thereafter, during a third time period C (from approximately 80-105 minutes) the storage is full. Consequently, even though the vehicle remains in the dynamic braking mode or is coasting (see  FIG. 6A ), no energy is transferred to or from the energy storage medium during time period C.  
      During a fourth time period D (from approximately 105-120 minutes), the vehicle resumes motoring. Because energy is available in the energy storage medium, energy is drawn from the storage and used to assist the motoring process. Hence, the curve illustrates that energy is being drawn from the energy storage medium during the fourth time period D.  
      At approximately 120 minutes, the motoring phase ceases and, shortly thereafter, another dynamic braking phase begins. This dynamic braking phase reflects the start of a fifth time period E that lasts from approximately 125-145 minutes. As can be appreciated by viewing the curve during the fifth time period E, when the dynamic braking phase ends, the energy storage medium is not completely charged.  
      Shortly before the 150-minute point, a sixth time period F begins which lasts from approximately 150-170 minutes. During this time period and thereafter (see  FIG. 6A ), the vehicle is motoring. From approximately 150-170 minutes, energy is transferred from the energy storage medium to assist in the motoring process. At approximately 170 minutes, however, the energy storage is completely depleted. Accordingly, from approximately 170-200 minutes (the end of the sample window), no energy is transferred to or from the energy storage medium.  
       FIG. 6D  illustrates the energy stored in the energy storage medium of the exemplary embodiment reflected in FIGS.  6 A-D. Recall that in the present example, the energy storage medium is assumed to be completely empty/discharged at time 0. Recall also that the present example assumes an energy management system that only stores energy from dynamic braking. From approximately 0-70 minutes, the vehicle is motoring and no energy is transferred to or from the energy storage medium. From approximately 70-80 minutes or so, energy from dynamic braking is transferred to the energy storage medium until it is completely full. At approximately 105 minutes, the vehicle begins another motoring phase and energy is drawn from the energy storage medium until about 120 minutes. At about 125 minutes, energy from dynamic braking is again transferred to the energy storage medium during another dynamic braking phase. At about 145 minutes or so, the dynamic braking phase ends and storage ceases. At about 150 minutes, energy is drawn from the energy storage medium to assist in motoring until all of the energy has been depleted at approximately 170 minutes.  
      FIGS.  7 A-D correspond to an energy management system that includes a “look ahead” or anticipated needs capability. Such a system is unlike the system reflected in FIGS.  6 A-D, which simply stores dynamic braking energy when it can, and uses stored energy to assist motoring whenever such stored energy is available. The energy management system reflected by the exemplary curves of FIGS.  7 A-D anticipates when the prime mover cannot produce the full required demand, or when it may be less efficient for the prime mover to produce the full required demand. As discussed elsewhere herein, the energy management system can make such determinations based on, for example, known present position, present energy needs, anticipated future track topography, anticipated future energy needs, present energy storage capacity, anticipated energy storage opportunities, and like considerations. The energy management system depicted in FIGS.  7 A-D, therefore, preferably prevents the energy storage medium from becoming depleted below a determined minimum level required to meet future demands.  
      By way of further example, the system reflected in FIGS.  7 A-D is premised on a locomotive having an engine that has a “prime mover limit” of 4000 h.p. Such a limit could exist for various factors. For example, the maximum rated output could be 4000 h.p. or operating efficiency considerations may counsel against operating the engine above 4000 h.p. It should be understood, however, that the system and figures are intended to reflect an exemplary embodiment only, and are presented herein to facilitate a detailed explanation of aspects of an energy management system suitable for use with off-highway hybrid energy vehicles such as, for example, the locomotive system illustrated in  FIG. 2 .  
      Referring now to  FIG. 7A , the exemplary curve illustrated therein depicts power required for motoring (positive) and braking (negative). At approximately 180 minutes, the motoring demand exceeds 4000 h.p. Thus, the total demand at that time exceeds the 4000 h.p. operating constraint for the engine. The “look ahead” energy management system reflected in FIGS.  7 A-D, however, anticipates this upcoming need and ensures that sufficient secondary power is available from the energy storage medium to fulfill the energy needs.  
      One way for the energy management system to accomplish this is to look ahead (periodically or continuously) to the upcoming track/course profile (e.g., incline/decline, length of incline/decline, and the like) for a given time period (also referred to as a look ahead window). In the example illustrated in FIGS.  7 A-D, the energy management system looks ahead 200 minutes and then computes energy needs/requirements backwards. The system determines that, for a brief period beginning at 180 minutes, the engine would require more energy than the preferred limit.  
       FIG. 7B  is similar to  FIG. 6B .  FIG. 7B , however, also illustrates the fact that the energy storage medium is empty at time 0 and, therefore, there can be no power transfer from the energy storage medium unless and until it is charged.  FIG. 7B  also reflects a look ahead capability.  
      Comparing FIGS.  6 A-D with FIGS.  7 A-D, it is apparent how the systems respectively depicted therein differ. Although the required power is the same in both examples (see  FIGS. 6A and 7A ), the system reflected in FIGS.  7 A-D prevents complete discharge of the energy storage medium prior to the anticipated need at 180 minutes. Thus, as can be seen in  FIGS. 7C and 7D , prior to the 180 minute point, the system briefly stops transferring stored energy to assist in motoring, even though additional stored energy remains available. The additional energy is thereafter transferred, beginning at about 180 minutes, to assist the prime mover when the energy demand exceeds 4000 h.p. Hence, the system effectively reserves some of the stored energy to meet upcoming demands that exceed the desired limit of the prime mover.  
      It should be understood and appreciated that the energy available in the energy storage medium could be used to supplement driving traction motors associated with the prime mover, or could also be used to drive separate traction motors (e.g., on a tender or load vehicle). With the benefit of the present disclosure, an energy management system accommodating a variety of configurations is possible.  
      FIGS.  8 A-E reflect pertinent aspects of another embodiment of an energy management system suitable for use in connection with off-highway hybrid energy vehicles. The system reflected in FIGS.  8 A-E includes a capability to store energy from both dynamic braking and from the prime mover (or another charging engine such as that illustrated in  FIG. 3 ). For example, a given engine may operate most efficiently at a given power setting (e.g., 4000 h.p.). Thus, it may be more efficient to operate the engine at 4000 h.p. at certain times, even when actual motoring demand falls below that level. In such cases, the excess energy can be transferred to an energy storage medium.  
      Thus, comparing FIGS.  8 A-D with FIGS.  6 A-D and  7 A-D, the differences between the systems respectively depicted therein become apparent. Referring specifically to  FIGS. 8A and 8D , from about 0-70 minutes, the motoring requirements ( FIG. 8A ) are less than the exemplary optimal 4000 h.p. setting. If desirable, the engine could be run at 4000 h.p. during this time and the energy storage medium could be charged. As illustrated, however, the energy management system determines that, based on the upcoming track profile and anticipated dynamic braking period(s); an upcoming dynamic braking process will be able to fully charge the energy storage medium. In other words, it is not necessary to operate the engine at 4000 h.p. and store the excess energy in the energy storage medium during this time because an upcoming dynamic braking phase will supply enough energy to fully charge the storage medium. It should be understood that the system could also be designed in other ways. For example, in another configuration the system always seeks to charge the storage medium whenever excess energy could be made available.  
      At approximately 180 minutes, power demands will exceed 4000 h.p. Thus, shortly before that time (while motoring demand is less than 4000 h.p.), the engine can be operated at 4000 h.p. with the excess energy used to charge the energy storage medium to ensure sufficient energy is available to meet the demand at 180 minutes. Thus, unlike the systems reflected in  FIGS. 6D and 7D , the system reflected in  FIG. 8D  provides that, for a brief period prior to 180 minutes, energy is transferred to the energy storage medium from the prime mover, even though the vehicle is motoring (not braking).  
       FIG. 8E  illustrates one way that the energy management system can implement the look ahead capability to control energy storage and transfer in anticipation of future demands.  FIG. 8E  assumes a system having a 200 minute look ahead window. Such a look-ahead window is chosen to facilitate an explanation of the system and should not be viewed in a limiting sense. Beginning at the end of the window (200 minutes), the system determines the power/energy demands at any given point in time. If the determined demand exceeds the prime mover&#39;s capacity or limit, the system continues back and determines opportunities when energy can be stored, in advance of the determined excess demand period, and ensures that sufficient energy is stored during such opportunities.  
      Although FIGS.  6 A-D,  7 A-D, and  8 A-E have been separately described, it should be understood that the systems reflected therein could be embodied in a single energy management system. Further, the look-ahead energy storage and transfer capability described above could be accomplished dynamically or in advance. For example, in one form, an energy management processor (see  FIG. 5 ) is programmed to compare the vehicle&#39;s present position with upcoming track/course characteristics in real or near real time. Based on such dynamic determinations, the processor then determines how to best manage the energy capture and storage capabilities associated with the vehicle in a manner similar to that described above with respect to FIGS.  7 A-D and  8 A-E. In another form, such determinations are made in advance. For example, an off-vehicle planning computer may be used to plan a route and determine energy storage and transfer opportunities based on a database of known course information and projected conditions such as, for example, vehicle speed, weather conditions, and the like. Such pre-planned data would thereafter be used by the energy management system to manage the energy capture and storage process. Look ahead planning could also be done based on a route segment or an entire route.  
      It should further be understood that the energy management system and methods described herein may be put into practice with a variety of vehicle configurations. For example, such systems and methods could be practiced with a locomotive having a separate energy tender vehicle housing the energy capture and storage medium. As another example, the energy management systems and methods herein described could be employed with a locomotive having a separate energy tender vehicle that employs its own traction motors. In another example, the energy management systems and methods described herein may be employed as part of an off-highway vehicle, such as a locomotive, in which the energy storage medium is included as part of the vehicle itself. Other possible embodiments and combinations should be appreciated from the present disclosure and need not be recited in additional detail herein.  
       FIGS. 9A-9G  are electrical schematics illustrating several different embodiments of an electrical system suitable for use in connection with a hybrid energy locomotive. In particular, the exemplary embodiments illustrated in these figures relate to a hybrid energy diesel-electric locomotive system. It should be understood that the embodiments illustrated in  FIGS. 9A-9G  could be incorporated in a plurality of configurations, including those already discussed herein (e.g., a locomotive with a separate energy tender vehicle, a locomotive with a self-contained hybrid energy system, an autonomous tender vehicle, and the like).  
       FIG. 9A  illustrates an electrical schematic of a locomotive electrical system having a energy capture and storage medium suitable for use in connection with aspects of the systems and methods disclosed herein. The particular energy storage element illustrated in  FIG. 9A  comprises a battery storage  902 . The battery storage  902  is preferably connected directly across the traction bus (DC bus  122 ). In this exemplary embodiment, an auxiliary power drive  904  is also connected directly across DC bus  122 . The power for the auxiliaries is derived from DC bus  122 , rather than a separate bus.  
      It should be appreciated that more than one type of energy storage element may be employed in addition to battery storage  902 . For example, an optional flywheel storage element  906  can also be connected in parallel with battery storage  902 . The flywheel storage  906  shown in  FIG. 9A  is preferably powered by an AC motor or generator connected to DC bus  122  via an inverter or converter. Other storage elements such as, for example, capacitor storage devices (including ultracapacitors) and additional battery storages (not shown) can also be connected across the DC bus and controlled using choppers and/or converters and the like. It should be understood that although battery storage  902  is schematically illustrated as a single battery, multiple batteries or battery banks may likewise be employed.  
      In operation, the energy storage elements (e.g., battery storage  902  and/or any optional energy storage elements such as flywheel  906 ) are charged directly during dynamic braking operations. Recall that, during dynamic braking, one or more of the traction motor subsystems (e.g.,  124 A- 124 F) operate as generators and supply dynamic braking electric power that is carried on DC bus  122 . Thus, all or a portion of the dynamic braking electric power carried on DC bus  122  may be stored in the energy storage element because the power available on the bus exceeds demand. When the engine is motoring, the battery (and any other optional storage element) is permitted to discharge and provide energy to DC bus  122  that can be used to assist in driving the traction motors. This energy provided by the storage element may be referred to as secondary electric power. Advantageously, because the auxiliaries are also driven by the same bus in this configuration the ability to take power directly from DC bus  122  (or put power back into bus  122 ) is provided. This helps to minimize the number of power conversion stages and associated inefficiencies due to conversion losses. It also reduces costs and complexities.  
      It should be appreciated that the braking grids may still be used to dissipate all or a portion of the dynamic braking electric power generated during dynamic braking operations. For example, an energy management system is preferably used in connection with the system illustrated in  FIG. 9A . Such an energy management system is configured to control one or more of the following functions: energy storage; stored energy usage; and energy dissipation using the braking grids. It should further be appreciated that the battery storage (and/or any other optional storage element) may optionally be configured to store excess prime mover electric power that is available on the traction bus.  
      Those skilled in the art should appreciate that certain circumstances preclude the operation of a diesel engine when the locomotive and/or train need to be moved. For example, the engine may not be operable. As another example, various rules and concerns may prevent the operation of the engine inside buildings, yards, maintenance facilities, or tunnels. In such situations, the train is moved using stored battery power. Advantageously, various hybrid energy locomotive configurations disclosed herein permit the use of stored power for battery jog operations directly. For example, the battery storage  902  of  FIG. 9A  can be used for battery jog operations. Further, the prior concept of battery jog operations suggests a relatively short time period over a short distance. The various configurations disclosed herein permit jog operations for much longer time periods and over much longer distances.  
       FIG. 9B  illustrates a variation of the system of  FIG. 9A . A primary difference between  FIGS. 9A and 9B  is that the system shown in  FIG. 9B  includes chopper circuits DBC 1  and DBC 2  connected in series with the braking grids. The chopper circuits DBC  1  and DBC 2  allow fine control of power dissipation through the grids that, therefore, provides greater control over the storage elements such as, for example, battery storage  902 . In one embodiment, chopper circuits DBC 1  and DBC 2  are controlled by an energy management system (see  FIG. 5 ). It should also be appreciated that chopper circuits DBC 1  and DBC 2 , as well as any optional storage devices added to the circuit (e.g., flywheel storage  906 ), could also be used to control transient power.  
      In the configuration of  FIG. 9A , the dynamic braking contactors (e.g., DB 1 , DB 2 ) normally only control the dynamic braking grids in discrete increments. Thus, the power flowing into the grids is also in discrete increments (assuming a fixed DC voltage). For example, if each discrete increment is 1000 h.p. the battery storage capability is 2000 h.p. and the braking energy returned is 2500 h.p. the battery cannot accept all of the braking energy. As such, one string of grids is used to dissipate 1000 h.p. leaving 1500 h.p. for storage in the battery. By adding choppers DBC 1 , DBC 2 , the power dissipated in each grid string can be more closely controlled, thereby storing more energy in the battery and improving efficiency. In the foregoing example, choppers DBC 1  and DBC 2  can be operated at complementary 50% duty cycles so that only 500 h.p. of the braking energy is dissipated in the grids and 2000 h.p. is stored in the battery.  
       FIG. 9C  is an electrical schematic of a locomotive electrical system illustrating still another configuration for implementing an energy storage medium. In contrast to the systems illustrated in  FIGS. 9A and 9B . The battery storage  902  of  FIG. 9C  is connected to DC bus  122  by way of a DC-to-DC converter  910 . Such a configuration accommodates a greater degree of variation between DC bus  122  voltage and the voltage rating of battery storage  902 . Multiple batteries and/or DC storage elements (e.g., capacitors) could be connected in a similar manner. Likewise, chopper control, such as that illustrated in  FIG. 9B  could be implemented as part of the configuration of  FIG. 9C . It should be further understood that the DC-to-DC converter  910  may be controlled via an energy management processor (see  FIG. 5 ) as part of an energy management system and process that controls the storage and regeneration of energy in the energy storage medium.  
      In operation, the electric power carried on DC bus  122  is provided at a first power level (e.g., a first voltage level). The DC-to-DC converter  910  is electrically coupled to DC bus  122 . The DC-to-DC converter  910  receives the electric power at the first power level and converts it to a second power level (e.g., a second voltage level). In this way, the electric power stored in battery storage  902  is supplied at the second power level. It should be appreciated that the voltage level on DC bus  122  and the voltage supplied to battery storage  902  via DC-to-DC converter  910  may also be at the same power level. The provision of DC-to-DC converter  910 , however, accommodates variations between these respective power levels.  
       FIG. 9D  is an electrical schematic of a locomotive electrical system that is similar to the system shown in  FIG. 9C . One difference between these systems is that the auxiliary power subsystem  904  reflected in  FIG. 9D  is connected to DC bus  122  via a pair of DC-to-DC converters  912  and  914 . Such a configuration provides the advantage of allowing the use of existing, lower voltage auxiliary drives and/or motor drives having low insulation. On the other hand, in this configuration, the auxiliary power traverses two power conversion stages. It should be understood that although  FIG. 9D  illustrates the auxiliaries as consuming power all of the time-not regenerating-bi-directional DC-to-DC converters can also be used in configurations in which it is desirable to have the auxiliaries regenerate power (see, for example,  FIG. 9G ). These DC-to-DC converters  912  and  914  are preferably controlled via an energy management system that controls the storage and regeneration of energy in the energy storage medium.  
       FIG. 9E  illustrates, in electrical schematic form, still another configuration of an energy storage medium. Unlike the examples illustrated in  FIGS. 9A-9D , however, the configuration of  FIG. 9E  includes a separate DC battery bus  922 . The separate battery bus  922  is electrically isolated from main DC bus  122  (the traction bus) by a DC-to-DC converter  920  (also referred to as a two-stage converter). Accordingly, the power flow between the traction bus (DC bus  122 ), the energy storage elements, and the auxiliaries preferably passes through the bi-directional DC-to-DC converter  920 . In the configuration of  FIG. 9E , any additional storage elements (e.g., flywheels, capacitors, and the like) are preferably connected across the DC battery bus  922 , rather than across the main DC bus  122 . The DC-to-DC converter  920  may be controlled via an energy management system that controls the storage and regeneration of energy in the energy storage medium.  
       FIG. 9F  reflects a variation of the configuration of  FIG. 9E . In the configuration of  FIG. 9F , any variable voltage storage elements (e.g., capacitors, flywheels, and the like) that are used in addition to battery storage  902  are connected directly across main DC bus  122  (the traction bus). However, battery storage  902  remains connected across the isolated DC battery bus  922 . Advantageously, in this configuration DC-to-DC converter  920  matches the voltage level of battery storage  902  but avoids two conversions of large amounts of power for the variable voltage storage elements. Like the other configurations, the configuration of  FIG. 9F  may be implemented in connection with an energy management system that oversees and controls the storage and regeneration of energy in the energy storage medium.  
       FIG. 9G  reflects a variation of the configuration of  FIG. 9F  in which only the auxiliaries are connected to a separate auxiliary bus  930  through two-stage converter  920 . Accordingly, electric power carried on DC bus  122  is provided at a first power level and power carried on the auxiliary bus  930  is provided at a second power level. The first and second power levels may or may not be the same.  
       FIGS. 10A-10C  are electrical schematics that illustrate additional embodiments, including embodiments particularly suited for modifying existing AC diesel-electric locomotives to operate in accordance with aspects of the present disclosure. It should be understood, however, that the configurations illustrated and described with respect to  FIGS. 10A-10C  are not limited to retrofitting existing diesel-electric locomotives.  
       FIG. 10A  illustrates a variation of the embodiment illustrated in  FIG. 9C . The embodiment of  FIG. 10A  uses only battery storage devices and does not include a non-battery storage, such as optional flywheel storage  906 . In particular,  FIG. 10A  illustrates an embodiment having a converter  1006  (e.g., a DC-to-DC converter) connected across DC bus  122 . A battery storage element  1002  is connected to the converter  1006 . Additional converters and battery storage elements may be added to this configuration in parallel. For example, another converter  1008  may be connected across DC bus  122  to charge another battery storage element  1004 . One of the advantages of the configuration of  FIG. 10A  is that it facilitates the use of multiple batteries (or battery banks) having different voltages and/or charging rates.  
      In certain embodiments, power transfer between energy storage devices is facilitated. The configuration of  FIG. 10A , for instance, allows for energy transfer between batteries  1002  and  1004  via the DC bus  122 . For example, if, during motoring operations, the engine (prime mover) supplies 2000 h.p. of power to the DC traction bus, the traction motors consume 2000 h.p., and battery  1002  supplies 100 h.p. to the traction bus (via converter  1006 ), the excess 100 h.p. is effectively transferred from battery  1002  to battery  1004  (less any normal losses).  
      The configuration illustrated in  FIG. 10B  is similar to that of  FIG. 10A , except that it uses a plurality of converters (e.g., converters  1006 ,  1008 ) connected to the DC bus  122  to supply a common battery  1020  (or a common battery bank). One of the advantages of the configuration of  FIG. 10B  is that it allows the use of relatively smaller converters. This may be particularly advantageous when retrofitting an existing locomotive that already has one converter. A similar advantage of this configuration is that it allows the use of higher capacity batteries. Still another advantage of the configuration of  FIG. 10B  is that it permits certain phase shifting operations, thereby reducing the ripple current in the battery and allowing the use of smaller inductors (not shown). For example, if converters  1006  and  1008  are operated at 1000 Hz, 50% duty cycles, and the duty cycles are selected such that converter  1006  is on while converter  1008  is off, the converter effect is as if a single converter is operating at 2000 Hz, which allows the use of smaller inductors.  
       FIG. 10C  an electrical schematic illustrating another embodiment that is particularly well suited for retrofitting an existing diesel-electric locomotive to operate as a hybrid energy locomotive. The configuration of  FIG. 10C  uses a double set of converters  1006 ,  1030  and one or more batteries  1020  (of the same or different voltage levels). An advantage of the system depicted in  FIG. 10C  is that the battery  1020  can be at a higher voltage level than the DC bus  122 . For example, if the converters  1006 ,  1008  illustrated in  FIGS. 10A and 10B  are typical two quadrant converters, they will also have freewheeling diodes associated therewith (not illustrated). If the voltage of battery  1002 ,  1004  ( FIG. 10A ), or  1020  ( FIG. 10B ) exceeds the DC bus voltage, the battery will discharge through the freewheeling diode. A double converter, such as that illustrated in  FIG. 10C , avoids this situation. One advantage of this capability is that the voltage level on the DC bus can be modulated to control power to the dynamic braking grids independently.  
       FIG. 11  is an electrical schematic that illustrates one preferred way of connecting electrical storage elements. In particular,  FIG. 11  illustrates an electrical schematic of a system that may be used for retrofitting a prior art diesel-electric locomotive to operate as a hybrid energy locomotive, or for installing a hybrid energy system as part of the original equipment during the manufacturing process. The embodiment illustrated assumes an AC diesel-electric locomotive with six axles. Each axle is driven by an individual traction motor subsystem. One such AC locomotive is the AC4400, available from the assignee of the present invention.  
      Typically, the converter/motor system has extra capability (e.g., power capacity) available in the majority of operating conditions. Such extra capability may be due to lower actual ambient conditions, as compared with the design criteria. For example, some locomotives are designed to operate in ambient temperatures of up to 60 degrees Celsius, which is well above typical operating conditions. Considerations other than thermal conditions may also result in extra capacity during significant operating periods. In a typical diesel-electric locomotive, for instance, the use of all of the traction motors may only be required for low speed and when the locomotive operates in an adhesion limited situation (poor rail conditions). In such case, the weight on the driven axles determines the pulling power/tractive effort. Hence, all axles/motors need to be driven to obtain maximum tractive effort. This can be especially true if the train is heavily loaded during poor rail conditions (snowy or slippery). Such conditions are normally present for only a fraction of the locomotive operating time. During the majority of the operating time, all of the traction motors/inverters are not fully utilized to supply tractive effort. Thus, for example, when retrofitting an existing prior art locomotive, or manufacturing a new locomotive, it is possible to take advantage of this partial underutilization of the traction motors/inverters.  
      By way of a specific example, the embodiment of  FIG. 11  is configured such that one of the six traction motor subsystems is connected to the energy storage element  1102 , through a transfer switch  1104  and a plurality of windings  1110 . More particularly, the traction motor subsystem  1124 F includes an inverter  106 F and a traction motor  1108 F. Such a configuration is suited for retrofitting a single axle of an existing prior art diesel-electric locomotive. It should be understood that retrofitting a typical prior art diesel-electric locomotive requires the addition of power conversion equipment and associated cooling devices. The space available for installing the retrofit equipment, however, is generally limited. Therefore, one of the advantages of the “single-axle” configuration of  FIG. 11  is that it tends to minimize impacts and makes retrofitting a more viable option. Similar advantages, however, may also be enjoyed when the hybrid energy system is installed as original equipment during manufacturing.  
      The transfer switch  1104  preferably comprises a three-phase set of contactors or a set of motorized contacts (e.g., bus bars) that connect inverter  106 F to traction motor  1108 F when all of the axles are needed, and connects inverter  1106 F to inductors  1110  and battery  1102  when battery charging or discharging is desired. Thus, transfer switch  1104  has a first connection state and a second connection state. In the first connection state, transfer switch  1104  connects inverter  106 F to traction motor  1108 F. In the second connection state, transfer switch connects inverter  106 F to battery  1102 .  
      Transfer switch  1104  is preferably controlled by a switch controller  1120 . In one form, the switch controller  1120  is a manual operator-controlled switch that places transfer switch  1104  into the first or the second connection state. In another form, the switch controller reflects control logic that controls the connection state of transfer switch  1104  in accordance with a preferred operating scheme. Table II (below) is indicative of one such preferred operating scheme. Other schemes are possible.  
      Although  FIG. 11  illustrates a three-phase connection between battery  1102  and transfer switch  1104 , it is not necessary that all three phases be used. For example, if the power requirement is relatively low, only one or two phases may be used. Similarly, three separate batteries could be independently connected (one to each phase), or one large battery could be connected to two phases, with a relatively smaller battery connected to the third phase. Further, power transfer between multiple batteries having different voltage potentials and/or capacities is also possible.  
      The configuration of  FIG. 11  is especially advantageous in the context of retrofitting existing locomotives because transfer switch  1104  is believed to be much less expensive than adding additional inverters and/or DC-to-DC converters. Such advantage, however, is not limited to the retrofit context. Also, it should be understood that the configuration of  FIG. 11  is not limited to a single inverter per transfer switch configuration.  
       FIG. 11  further illustrates an optional charging source  1130  that may be electrically connected to DC traction bus  122 . The charging source  1130  may be, for example, another charging engine (see  FIG. 3 ) or an external charger, such as that discussed in connection with  FIG. 5 .  
      The general operation of the configuration of  FIG. 11  will be described by reference to the connection states of transfer switch  1104 . When transfer switch  1104  is in the first switch state, the sixth axle is selectively used to provide additional motoring or braking power. In this switch state, battery  1102  is effectively disconnected and, therefore, neither charges nor discharges.  
      When the sixth axle is not needed, switch controller  1120  preferably places transfer switch  1104  in the second connection state-battery  1102  is connected to inverter  106 F. If, at this time, the other traction motors (e.g., traction motor  108 A) are operating in a dynamic braking mode, electrical energy is generated and carried on DC traction bus  122 , as described in greater detail elsewhere herein. Inverter  106 F transfers a portion of this dynamic braking electrical energy to battery  1102  for storage. If, on the other hand, the other traction motors are operating in a motoring mode, inverter  106 F preferably transfers any electrical energy stored in battery  1102  onto DC traction bus  122  to supplement the primary electric power supplied by prime mover power source  104 . Such electrical energy transferred from battery  1102  to DC traction bus  122  may be referred to as secondary electric power. In one preferred embodiment, inverter  106 F comprises a chopper circuit (not shown) for controlling the provision of secondary electric power to DC traction bus  122  from battery  1102 .  
      It should be understood, however, that battery  1102  can also be charged when the other traction motors are not operating in a dynamic braking mode. For example, the battery can be charged when transfer switch  1104  is in the second connection state (battery  1102  is connected to inverter  106 F) and the other traction motors are motoring or idling if the amount of power drawn by the other traction motors is less than the amount of primary electric power carried on DC traction bus  122 .  
      Advantageously, battery  1102  can also be charged using charging electric power from optional energy source  1130 . As illustrated in  FIG. 11 , optional energy source  1130  is preferably connected such that it provides charging electric power to be carried on DC traction bus  122 . When optional energy source  1130  is connected and providing charging electric power, switch controller  1120  preferably places transfer switch  1104  in the second connection state. In this configuration, inverter  106 F transfers a portion of the electric power carried on DC traction bus  122  to battery  1102  for storage. As such, battery  1102  may be charged from optional energy source  1130 .  
      In summary, in the embodiment of  FIG. 11 , when transfer switch is in the second connection state, battery  1102  may be charged from dynamic braking energy, from excess locomotive energy (e.g., when the other traction motors draw less power than the amount of primary electric power carried on DC traction bus  122 ), and/or from charging electric power from optional charging source  1130 . When transfer switch  1104  is in the second connection state and the other traction motors draw more power than the amount of primary electric power carried on DC traction bus  122 , inverter  1106  transfers secondary electric power from battery  1102  to DC traction bus  122  to supplement the primary electric power. When transfer switch  1104  is in the first connection state, battery  1102  is disconnected and traction motor  1108 F is operable to assist in motoring and/or dynamic braking. Table II summarizes one set of operating modes of the embodiment of  FIG. 11 .  
                   TABLE II                       Five Axles   Six Axles                  Low Speed and Low Tractive   Battery Fully Charged &amp; Dynamic       Effort Settings   Braking       High Speed Motoring   No Battery Charging &amp; Motoring Battery           Discharged &amp; Motoring Very High           Speed Dynamic Braking                  
 
      While  FIG. 11  illustrates an energy storage device in the form of a battery, other energy storage devices, such as flywheel systems or ultracapacitors, may also be employed instead of or in addition to battery  1102 . Further, it should be understood that the configuration of  FIG. 11  may be scaled. In other words, the configuration can be applied to more than one axle.  
       FIG. 12  is a flow chart that illustrates one method of operating a hybrid energy locomotive system. The particular method illustrated relates to a system including a locomotive vehicle and an energy tender vehicle. The locomotive includes a diesel-electric prime mover power source that supplies primary electric power to a plurality of traction motor systems associated with the locomotive. As explained elsewhere herein, the traction motor systems operate the locomotive in a motoring mode in response to the primary electric power. In this particular example, the energy tender also includes a plurality of traction motor systems (see  FIG. 2 ). The energy tender traction motor systems are operable in both a motoring mode and a dynamic braking mode. The energy tender vehicle also includes an energy storage system for capturing at least a portion of the electrical energy generated when the energy tender traction motors operate in the dynamic braking mode.  
      At blocks  1202  and  1204 , primary electric power is supplied to one or more of the locomotive traction motor systems, thereby causing the locomotive to operate in a motoring mode. When the locomotive traction motor systems operate in the motoring mode, it is possible to operate one or more of the energy tender traction motor systems in a dynamic braking mode, as shown by block  1206 . Of course, the energy tender traction motor systems can be operated in the dynamic braking mode at other times such as, for example, when the locomotive traction motor systems operate in the dynamic braking mode. As shown at blocks  1208  and  1210 , when one or more of the energy tender traction motor systems operate in the dynamic braking mode, electrical energy is generated. Some of the dynamic braking energy is preferably stored in the energy storage system for later use. For example, such stored power may be converted and supplied as secondary electric power for use by the energy tender traction motor systems to assist in motoring, as shown by block  1212 .  
      Advantageously, the method of  FIG. 12  permits locating the energy tender vehicle anywhere in the train because the energy tender vehicle can capture dynamic braking energy from its own traction motor systems. In other words, the energy capture system need not be electrically connected to the locomotive in order to store energy for later use.  
      Although the foregoing descriptions have often referred to AC diesel-electric locomotive systems to describe several pertinent aspects of the disclosure, the present invention should not be interpreted as being limited to such locomotive systems. For example, aspects of the present disclosure may be employed with “all electric” locomotives powered by electric “third rails” or overhead power systems. Further, aspects of the hybrid energy locomotive systems and methods described herein can be used with diesel-electric locomotives using a DC generator rather than an AC alternator and combinations thereof. Also, the hybrid energy locomotive systems and methods described herein are not limited to use with AC traction motors. As explained elsewhere herein, the energy management system disclosed herein may be used in connection with non-locomotive off-highway vehicles such as, for example, large excavators.  
      As can now be appreciated, the hybrid energy systems and methods herein described provide substantial advantages over the prior art. Such advantages include improved fuel efficiency, increased fuel range, and reduced emissions such as transient smoke. Other advantages include improved speed by the provision of an on-demand source of power for a horsepower burst. Such a system also provides improved tunnel performance such as, for example, improved immunity to oxygen and/or temperature derations in tunnels. Also among the advantages are reduced noise and vibration conditions, which may be particularly beneficial to personnel who work on the train. Significantly, the hybrid energy locomotive system herein described may also be adapted for use with existing locomotive systems.  
      When introducing elements of the present invention or preferred embodiments thereof, the articles “a”, “an”, “the”, and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including”, and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.  
      In view of the above, it will be seen that several objects of the invention are achieved and other advantageous results attained.  
      As various changes could be made in the above exemplary constructions and methods without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. It is further to be understood that the steps described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated. It is also to be understood that additional or alternative steps may be employed with the present invention.