Patent Publication Number: US-2009237038-A1

Title: Double alternator and electrical system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation-in-Part (CIP) of patent application Ser. No. 11/935,452, filed on Nov. 6, 2007, which is now pending and entitled “Double Alternator and Electrical System for a Vehicle.” The Ser. No. 11/935,452 application is a continuation application of patent application Ser. No. 11/734,003, filed on Apr. 11, 2007, which has issued as U.S. Pat. No. 7,291,933 entitled “Double Alternator and Electrical System for a Vehicle.” This CIP application claims the benefit of priority of both the Ser. No. 11/935,452 and Ser. No. 11/734,003 applications. The published version of the Ser. No. 11/935,452 application, namely Pub. No. US2008/0252081A1 published on Oct. 16, 2008, and and the U.S. Pat. No. 7,291,933 patent issued on Nov. 6, 2007, are each incorporated herein by this reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention generally relates to the field of electrical current supply systems and more particularly, a double alternator and associated electrical systems. 
     Motor vehicles have in the past been provided with auxiliary alternators for providing back up power to a vehicle battery. In many cases, these auxiliary systems have also included an auxiliary battery. Providing a separate alternator and battery, however, adds a significant amount of weight to the vehicle, especially if the vehicle is an aircraft, and increases the cost of the vehicle, owing to the unnecessary duplication of alternator parts and mounting hardware. Many prior art systems also suffer the disadvantage that the current produced by one alternator cannot be cross fed to power a single battery. 
     Accordingly, there remains a need for a double alternator electrical system that is lightweight, reliable, inexpensive to manufacture, simple and cost effective. Also, there is a need for a double alternator that is capable of being mounted on a motor using existing hardware in the same location as a conventional alternator. There is a need for a double alternator for use with a vehicle, and for non-vehicular use. The double alternator should be versatile inasmuch as it is capable of use in single and dual battery vehicle electrical systems and in systems that provide cross feed capability between dual electrical power circuits. In the dual battery system, the double alternator system should be capable of replacing existing production of motor-charging engines. For example, the double alternator system should be capable of replacing a 90 amp alternator and 500 amp single battery system to provide two 250 amp batteries and, in effect, two 45 amp alternators using the same space required by the existing system, and capable of control via voltage regulators, whether internal, external, or one of each. Finally, the double alternator should improve safety and minimize maintenance of the vehicle charging electrical system. 
     BRIEF SUMMARY OF THE INVENTION 
     Therefore it is an object of the invention to provide a lightweight double alternator for a vehicle. 
     It is another object of the invention to provide a reliable double alternator electrical system for a vehicle. 
     It is another object of the invention to provide a double alternator system that is simple, inexpensive to manufacture, and thus cost effective. 
     It is another object of the invention to provide a double alternator system that is versatile inasmuch as it is capable of use in single and dual battery vehicle electrical systems. 
     It is another object of the invention to provide cross feed capability between dual electrical power circuits. 
     These and other objects of the present invention are achieved in the preferred embodiments disclosed below by providing an electrical system for a vehicle having a motor. The system includes a housing including an adapter housing disposed between opposing front and rear housing sections and a drive assembly. The drive assembly includes a shaft journalled in the front and rear housing sections and a pulley fixed radially about the shaft for being driven by the vehicle motor. A pair of stators, each including an output winding, provide a multi-phase AC voltage by virtue of a pair of rotors each fixed radially about the shaft for rotation therewith producing a magnetic field to induce the multi-phase AC voltage across the output windings of the stators. Two sets of slip rings, each encircle the shaft and are electrically connected to one of the windings of one of the pair of rotors and insulated from the other slip rings and the shaft, and a pair of multi-phase full wave rectifiers, each electrically connected to one of the stators, receive the three-phase AC voltage produced across the winding of one of the stators and convert the AC voltage to DC voltage. Each of two sets of brushes are electrically connected to one of the slip rings to receive field current from a voltage regulator, and a pair of voltage regulators for control DC voltage output. 
     According to another preferred embodiment of the invention the electrical system includes a storage battery comprising a main system terminal and a ground terminal connected to a system ground, the main terminal connected to both the of the rectifiers for receiving the DC voltage and providing electrical power to the vehicle. 
     According to another preferred embodiment of the invention, the voltage regulators are connected to the field windings and sense an amount of current in the system to control an amount provided to the field windings. 
     According to another preferred embodiment of the invention, the system includes a pair of single pole switches, each one of the pair for selectively connecting the main terminal to one of the field windings. 
     According to another preferred embodiment of the invention, the system includes a pair of indicator lamps, each one of the pair connected between one of the pair of single pole switches and one of the field windings to indicate whether the field winding is receiving current from the main terminal. 
     According to another preferred embodiment of the invention, an electrical system includes a housing including an adapter housing disposed between opposing front and rear housing sections and a drive assembly that includes a shaft journalled in the front and rear housing sections and a pulley fixed radially about the shaft for being driven by the vehicle motor. A pair of rotors each include a field winding and are each fixed radially about the shaft for rotation therewith for providing current to produce a magnetic field to induce three-phase AC voltage, and a stator corresponding to each rotor each includes an output winding fixed around one of the rotors for producing the three-phase AC voltage. A set of brushes corresponds to each rotor and a pair three-phase full wave rectifiers are each electrically connected to one of the output windings for receiving the three-phase AC voltage produced across the windings of one of the stators and converting the AC voltage to DC voltage. A pair of voltage regulators each control DC voltage output from one of the rectifiers, and a first storage battery is connected to a system ground and a first electrical power subsystem to receive DC voltage from one of the pair of three-phase full wave rectifiers. A second storage battery connected to a system ground and a second electrical power subsystem to receive DC voltage from the other of the pair of three-phase full wave rectifiers and a cross feed switch selectively cross feeds DC voltage between the first and second subsystems. 
     According to another preferred embodiment of the invention, the electrical system includes a front bus bar connected to the first power subsystem. 
     According to another preferred embodiment of the invention, the electrical system includes a computer, ignition, and radio connected to the front bus bar. 
     According to another preferred embodiment of the invention, the electrical system includes a rear bus bar connected to the second power subsystem. 
     According to another preferred embodiment of the invention, the electrical system includes interior lights, headlights, seats and an air conditioner connected to the rear bus bar. 
     According to another preferred embodiment of the invention, the electrical system includes a cross feed contactor between the electrical power subsystems. 
     According to another preferred embodiment of the invention, the electrical system includes a double pole starter switch. 
     According to another preferred embodiment of the invention, the system includes a manual double pole master switch. 
     According to another preferred embodiment of the invention, both batteries are energized to start the vehicle motor. 
     According to another preferred embodiment of the invention, the system includes a starter for starting the vehicle motor. 
     According to another preferred embodiment of the invention, the system includes a housing enclosing a pair of rotor windings fixed to a shaft to rotate to produce magnetic fields inducing AC voltage across a stator winding corresponding to each rotor. A rectifier is electrically connected to a one of the pair of stators to convert AC voltage from the first of the pair to DC voltage for charging a storage battery, a rectifier electrically connected to the other of the pair of stators to convert AC voltage from the other stator winding to DC voltage for charging the storage battery. A controller is connected to both of the rotor windings for controlling an amount of voltage supplied to the rotor windings and hence the voltage supplied by the stators to charge the storage battery, and an electrical circuit supplies power to the vehicle connected to the battery. 
     According to another preferred embodiment of the invention, the voltage regulators employ shunts for measuring output voltage and or amperage from the rectifiers. 
     According to another preferred embodiment of the invention, the controller equalizes the field current provided to the rotor windings. 
     According to another preferred embodiment of the invention, the system includes independent annunciator lamps for indicating alternator operating statuses. 
     According to yet another embodiment of the invention, a double alternator system includes a housing, a shaft rotatably mounted in the housing, a first brushless winding assembly, and a second winding assembly. The first brushless winding assembly includes a first field winding fixed in the housing, a first output winding fixed in the housing, and a first rotor fixed to the shaft to rotate relative to the first field winding and first output winding to induce a first AC voltage in the first output winding upon an introduction of a first current in the first field winding and rotation of the shaft. A first rectifier within the housing is electrically connected to the first output winding to produce a first DC voltage upon induction of the first AC voltage. A first electrical output contact is electrically isolated from the housing and electrically connected to the first rectifier to convey the first DC voltage through the housing. The second winding assembly is positioned within the housing and about the shaft to induce a second AC voltage upon rotation of the shaft. A second rectifier within the housing is electrically connected to the second winding assembly to produce a second DC voltage upon induction of the second AC voltage. A second electrical output contact is electrically isolated from the housing and electrically connected to the second rectifier to convey the second DC voltage through the housing. 
     According to another embodiment of the invention, a power generation system includes a housing, a shaft rotatably mounted in the housing, a first brushless winding assembly disposed within the housing and about the shaft to generate a first AC voltage upon rotation of the shaft, a first rectifier electrically connected to the first brushless winding assembly to produce a first DC voltage upon generation of the first AC voltage, a second winding assembly disposed within the housing and about the shaft to generate a second AC voltage upon rotation of the shaft, a second rectifier electrically connected to the second winding assembly to produce a second DC voltage upon generation of the second AC voltage, a first electrical output contact disposed outside the housing and electrically connected to the first rectifier to receive the first DC voltage, and a second electrical output contact disposed outside the housing and electrically connected to the second rectifier to receive the second DC voltage. 
     According to yet another embodiment of the invention, a double alternator system includes a first brushless winding assembly to generate a first electrical voltage, a second winding assembly to generate a second electrical voltage, a rotatable shaft common to the first brushless winding assembly and second winding assembly to cause generation of the first electrical voltage and second electrical voltage upon rotation of the shaft, and a housing in which said winding assemblies are disposed and through which said first and second electrical voltages are carried to respective first and second electrical output contacts. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
       The subject matter that is regarded as the invention may be best understood by reference to the following description taken in conjunction with the accompanying drawing figures in which: 
         FIG. 1  is a double alternator according to an embodiment of the invention; 
         FIG. 2  is a schematic of an electrical system including the double alternator; 
         FIG. 3  is a schematic showing an alternative embodiment of the electrical system; 
         FIG. 4  is a circuit diagram of another alternative embodiment of the electrical system; 
         FIG. 5  is also a circuit diagram of an alternative embodiment of the system; 
         FIG. 6  is a circuit diagram of yet another alternative embodiment of the electrical system; 
         FIG. 7  is a schematic diagram of a controller for an electrical system including a double alternator; 
         FIG. 8  is a partially cross-sectioned view of yet another embodiment of a double alternator; and 
         FIG. 9  is an exploded perspective view of a output winding, field winding and rotor of the double alternator of  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     Referring to the drawings wherein identical reference numerals denote the same elements throughout the various views,  FIG. 1  is an embodiment of a double alternator  10  for a vehicle having a motor. A housing having an adapter housing  14  is disposed between front  12  and rear  16  housing sections and a drive assembly including a rotatable shaft  24  is journalled in bearings  22  and  26  fitted in the housing. A pulley  28  is fixed radially to the shaft  24  for receiving a belt driven by the vehicle motor (not shown). The double alternator  10  also includes a pair of rotors  30  and  32  each including field windings fixed radially to the shaft  24  for rotation within one of a pair of stators  40  and  42  having windings across which voltage is induced by rotor windings. Two sets of slip rings  46  and  48  encircle the shaft  24  with one of each of the set electrically connected to one of the rotor windings and insulated from the other slip rings and the shaft  24 . Each one of a pair of three-phase full wave rectifiers  50  and  52  is connected to one of the stators  40  or  42  and pair of voltage regulators control DC voltage output. One half of the double alternator  10  comprises the rotor  30 , stator  40 , slip rings  46 , brushes  47  and rectifier  50 , while the other half comprises the rotor  32 , stator  42 , slip rings  48 , brushes  49  and rectifier  52 . 
     In operation, from an ignition key or switch, voltage is sent to an overvoltage relay, if one is used, to a regulator. The regulator adds positive voltage to a field wire, positive voltage to the brush  49  and the positive slip ring  48  to rotor  32  winding. Voltage flows back out of rotor  32  to a negative slip ring to a negative brush to ground. This circuit field/rotor is turned on and off by the regulator. The regulator is monitoring the output volts. The rotor  32  spinning and with voltage creates a magnetic field. The stator windings  42  are energized by the magnetic fields of the rotor. The stator (normal three phase) produces voltage pulses out to rectifier (diodes). Output of rectifier goes to battery positive lead. Negative diodes are also necessary for DC current, in the invention. This is done by the halves separately and at the same time. 
       FIG. 2  is a diagram of an embodiment of a basic electrical system  80  for a vehicle including the double alternator  11  and  13 . The system  80  includes a storage battery  60  including a main system power terminal  81  and a ground terminal  82  for connection to a system ground. Each rotor is supplied with field current from the battery  60  through one of a pair of single pole switches  84  and  86  and a lamp  83  or  85  is connected between each switch  84  or  86  and the alternator  10  to indicate whether the half of the alternator  11  or  13  to which the lamp  83  or  85  is connected is receiving current. One of a pair of diodes  88  and  89  is connected between each alternator half  11  and  13  and the main power terminal  81  of the battery  60  and the voltage regulators  124  and  125  and rectifiers  50  and  52  are also represented in the figure. 
       FIG. 3  is another exemplary electrical system  100  for a vehicle including the double alternator having the two halves  11  and  13 . In the system represented by  FIG. 3 , the storage battery  60  is connected to a front busbar  90  where, for example, a vehicle computer, ignition system, and radio can be connected to receive current from the battery  60 , and another storage battery  62  is connected to a rear busbar  92  that provides current to interior lights, headlights and air conditioning systems of the vehicle. Output from each of the rectifiers of the double alternator charges one of the storage batteries  60  or  62 . In this embodiment of the double alternator electrical system, both batteries  60  and  62  are energized for starting the vehicle via the contactors  64 ,  66 ,  94  and  95  and a manual switch  96  is provided to connect a cross feed contactor  94  which cross feeds current between the busbars  90  and  92  so that the vehicle can continue to operate if one half of the double alternator  10  is not charging. The system also includes a starter  93 , a manual double pole master switch  98  and a double pole starter switch  91 . 
       FIG. 4  is a circuit diagram of another exemplary electrical system  120  including the double alternator and a single storage battery  60 . The diagram shows a pair of voltage regulators  124  and  125  each connected to control field current supplied to a respective half  11  and  13  of the double alternator from the battery  60 . Another switch  127  is provided to selectively bring the half  13  of the alternator  10  online to charge the battery  60  to supply current to a main power bus  128  of the vehicle in the event the half  11  fails to charge. A starter switch  99 , contactor  97 , and starter  93  are provided for starting the vehicle and an essential busbar  121  is provided for connecting essential operating electronics. The system  120  also includes an instrument panel ground busbar  123  and a battery busbar  129 . The battery  60  is connected to the system through a battery master switch  131  and contactor  133 . 
       FIG. 5  is a circuit diagram of another alternative embodiment  130  of the electrical system including the double alternator. A primary battery  60  is charged by one half  11  and an auxiliary battery  62  via an auxiliary power switch  132  by the other half  13  of the double alternator. An auxiliary voltage regulator  125  provides a back up system available to power the primary power system via a cross feed switch  137  that closes a cross feed contactor  138 . 
       FIG. 6  is a circuit diagram of yet another alternative embodiment  150  of the electrical system including the double alternator and a battery  60 . A voltage regulator  152  is provided to control the voltage output of the half  13  of the double alternator serving as an auxiliary alternator and a crow bar circuit  153  is included to prevent overvoltage from damaging the electrical system  150 . A voltage regulator  125  is provided for controlling the other half  11  of the alternator. 
       FIG. 7  is a schematic diagram of an embodiment of a controller  200  for the double alternator  10 . The controller  200  includes two voltage regulators  202  and  204  that each employ one of a pair of shunts  210  and  212  for measuring the voltage and or amperage output from the halves  11  and  13  of the alternator and adjusting the amount of field current supplied. An equalizer  220  is provided between the two field current outputs and one of a pair of independent annunciators  224  and  226  corresponds to each half  11  and  13  of the double alternator to indicate failures and thus the need to feed voltage from one of the alternator halves  11  or  13  to the other. 
       FIG. 8  is a partially cross-sectioned view of yet another embodiment of a double alternator  300  that includes first and second brushless winding assemblies  400  and  500  within a common housing  302 . A shaft  304  rotatably mounted in the housing and disposed along a longitudinal axis  301  has a longitudinal end  306  that extends from the housing. A pulley  308  or other mechanical coupling is applied to the longitudinal end of the shaft to rotate the shaft when electrical power is to be produced by the first and second brushless winding assemblies. The double alternator  300  may serve, for example, as the alternator for a fuel combustion engine such as the motor of a motorized vehicle or may be mounted to a stationary support structure for stationary use in an electrical power generation system. 
     The first brushless winding assembly  400  includes a first field winding  410 , a first output winding  420 , and a first rotor  430 . The first field winding  410  is coiled about a spool  412  having longitudinal ends  414  and  416  and an internal bore  418  ( FIG. 9 ) defined between the ends and around the longitudinal axis  301 . The spool  412  is attached to the housing  302  at its longitudinal end  414  and maintains the first field winding  410  in a fixed position relative to the housing as the shaft  304  is rotated 
     The first rotor  430  has a central core  432  ( FIG. 9 ) having an internal bore  434  that engages the shaft  304  ( FIG. 8 ). The rotor  430  also has an outer body  434  connected to the central core at a first end  436  of the body. The outer body  434  extends around the first field winding  410 , which is positioned within an annular volume  431  defined between the central core  432  and the outer body  434 . Outer fins  438  extend radially outward from the outer body  434  of the rotor. As the shaft  304  is rotated, all portions of the rotor  430  turn with the shaft while the first field winding  410  remains stationary relative to the housing. 
     The first output winding  420  is attached to the housing  302  radially outward from the first rotor  430  with respect to the longitudinal axis  301 . The first output winding permits rotation of the rotor while remaining stationary relative to the housing. As the first rotor  430  turns with the shaft  304 , the outer fins  438  of the rotor pass near to the output winding. 
     For electrical power production by the first brushless winding assembly, a first current is passed through the first field winding  410 , which generates a magnetic field within the internal bore  418  ( FIG. 9 ) of the spool  412 . The generated magnetic field causes magnetization within the central core  432  of the rotor  430 , and magnetic effects are conveyed by the rotor out to the outer body  434  and outer fins  438 . As the magnetically affected outer fins  438  turn within the first output winding  420  by rotation of the shaft  304 , an oscillating voltage is induced in the output winding. Such an oscillating voltage is known in the electrical arts as an alternating-current (AC) voltage. Thus, an electrical AC voltage in the output winding is induced and controlled by the first current passed through the first field winding  410  and by rotation of the rotor  430  without any electrically conducting brush contact abutting the rotor, the shaft, or any other rotating component. Therefore these descriptions refer to the winding assembly  400  as a brushless winding assembly. 
     The second brushless winding assembly  500  includes a second field winding  510 , a second output winding  520 , and a second rotor  530 . From a broad perspective, the second brushless winding assembly  500  and its components are functionally equivalent to the first brushless winding assembly  400  and its corresponding components and so a further detailed description need not be duplicated here. 
     A first rectifier  50  and a second rectifier  52  are within the housing  302  of  FIG. 8  and are schematically represented in  FIG. 2  as well. The first and second rectifiers  50  and  52  are electrically connected to the first and second output windings  420  and  520 , respectively. The first rectifier  50  receives the first AC voltage from the first output winding  420  and produces a first direct-current (DC) voltage. The second rectifier  52  receives the second AC voltage from the second output winding  520  and produces a second direct-current (DC) voltage. Like the first and second AC voltages, the first and second DC voltages may be the same or different in any given operational situation of the double alternator  300 . 
     The first and second DC voltages produced by the first and second rectifiers  50  and  52  are conveyed through the housing to first and second electrical output contacts  450  and  550  by respective conducting wires, strips, or connectors. The first and second electrical contacts are electrically connected to the first and second rectifiers  50  and  52 , respectively, to receive the first and second DC voltages and to make those voltages available to loads and devices electrically downstream of the double alternator  300 . The first and second electrical output contacts  450  and  550  are electrically isolated from the housing to prevent unwanted grounding and to minimize the likelihood of electrical shocks. Two first electrical output contacts  450  are shown in  FIG. 8  to represent that two output contacts are provided for the first brushless winding assembly  400  in order to convey the first DC voltage through the housing as an electrical potential difference between the two contacts. The second DC voltage is similarly expressed as an electrical potential difference between the two second electrical output contacts  550 . In another embodiment of a double alternator according to at least one embodiment of the invention, internal grounding is utilized and a single first electrical output contact  450  and a single second electrical output contact  550  are electrically isolated from the housing to convey the first DC voltage and the second DC voltage through the housing respectively. In that embodiment, the first and second DC voltages are each expressed as an electrical potential difference between its single electrical output contact  450  and the housing  302 . 
     First and second electrical input contacts  452  and  552  are also shown in  FIG. 8 . These contacts carry the first and second electrical currents that are passed through the first and second field windings  410  and  510 , respectively, to generate magnetic fields to cause magnetization of the rotors  430  and  530  and the induction of the first and second AC voltages in the first and second output windings upon rotation of the shaft  304 . Two first electrical input contacts  452  are shown to represent that current passed through the first field winding enters the double alternator  300  by one of the two contacts and exits by the other. Two second electrical input contacts  552  are similarly shown. The first and second electrical input contacts  452  and  552  are electrically isolated from the housing to prevent unwanted grounding and to minimize the likelihood of electrical shocks. 
     Although the second brushless winding assembly  500  and its components are functionally equivalent to the first brushless winding assembly  400  and its components from a broad perspective, it should be noted that, from a more specific perspective, various dimensions and other construction parameters may differ between the first and second brushless winding assemblies. For example, the number of turns in the first and second field windings  410  and  510  may be the same or may differ. Thus, within the scope of these descriptions, the first and second brushless winding assemblies may be identically constructed as depicted in  FIG. 8  or they may be of different sizes and configurations. 
     As the electrical response characteristics of the first and second brushless winding assemblies  400  and  500  are governed by their constructions, the first AC voltage induced in the first output winding  420  and the second AC voltage induced in the second output winding  520  may be the same or may be different at any given rotation rate of the shaft  304 . Likewise, the first and second DC voltages provided at the first and second electrical output contacts  450  and  550 , respectively, may be the same or may differ at any given rotation rate of the shaft  304  according to the design preferences prevailing in any particular double alternator constructed according to these descriptions. The electrical currents that result when such a double alternator  300  is placed into service will likely vary according to the devices placed downstream of the alternator. Thus, the electrical currents in terms of amperage flowing through the first electrical output contacts  450  may be the same or may differ from the electrical currents flowing through the second electrical output contacts  550 . 
     The first and second brushless winding assemblies  400  and  500  rely upon the same shaft  304  and their rotors  430  and  530  therefore rotate together with the shaft at the same rate. Nonetheless, their output voltages and currents can be varied independently according to the first and second currents provided to the first and second field windings  410  and  510  through the first and second electrical input contacts  452  and  552 . Such currents are provided and regulated by an external current source. For example, as represented in  FIG. 2 , the first and second voltage regulators  124  and  125  are electrically connected to the first and second halves  11  and  13  of a double alternator. This represents that the first and second voltage regulators  124  and  125  are electrically connected the first and second field windings  410  and  510  to provide the first and second currents which ultimately induce and control the electrical AC voltages in the output windings  420  and  520  when the first and second brushless winding assemblies  400  and  500  serve in lieu of the first and second halves  11  and  13  in the electrical system of  FIG. 2 . 
       FIG. 7  also shows voltage regulators  202  and  204  electrically connected to the first and second halves  11  and  13  of a double alternator similarly representing that the first and second voltage regulators  202  and  204  are electrically connected the first and second field windings  410  and  510  to provide the first and second currents when the first and second brushless winding assemblies  400  and  500  serve in lieu of the first and second halves  11  and  13  in the electrical system of  FIG. 2 . Indeed, in each of  FIGS. 2-7 , the first and second halves  11  and  13  of the double alternator  10  of  FIG. 1  may be replaced by the first and second brushless winding assemblies  400  and  500  of the double alternator  300  of  FIG. 8 . Thus, according to various electrical system embodiments described herein and illustrated in the drawings, certain embodiments of a double alternator according to these descriptions include first and second voltage regulators configured to maintain the first and second DC voltages produced by the first and second rectifiers  50  and  52  at first and second predetermined values, respectively. In one such embodiment, the first and second predetermined values are different, and in another embodiment, the first and second predetermined values are substantially the same. 
     The double alternator  10  illustrated in  FIG. 1  includes brushes for carrying electrical current to rotating components, while the double alternator  300  has brushless winding assemblies. In yet another embodiment of the invention, a double alternator includes one brushed winding assembly and one brushless winding assembly.  FIGS. 1 and 9  relate to this other embodiment in that the output winding  420 , the field winding  410  and the rotor  430  of  FIG. 9  together replace the stator  40  and the rotor  30  of  FIG. 1  in constructing this other embodiment. Thus, by such construction, the output winding  420  serves in a role similar to that of the stator  40 , while the field winding  410  and rotor  430  together supplant the rotor  30 . According to this other embodiment then, the stator  42  and the rotor  32  together serve as a brushed winding assembly while the output winding  420 , the field winding  410  and the rotor  430  together serve as a brushless winding assembly, and both the brushed winding assembly and brushless winding assembly rely upon the rotation of the shaft  24  for electrical power production. 
     A double alternator according to these descriptions can provide two alternator portions having the same or different phase outputs. For example, in one embodiment according to these descriptions, both alternator portions provide a three phase output. In another embodiment, one alternator portion provides a three phase output, and another alternator portion provides a four phase output. In yet another embodiment, at least one alternator portion provides a phase output of greater than four. A double alternator according to these descriptions can provide electrical outputs from the output windings in order to provide AC outputs. For example, in at least one embodiment, one alternator portion provides an AC output, and another alternator portion provides a DC output. The shaft  24  can be driven by a belt, a coupling, a gear, or by other means. According to these descriptions, the voltages input to and output from a double alternator are variable and may be the same or different for two alternator portions. For example, in at least one embodiment, a first alternator portion serves as a 6 volt alternator, and a second alternator portion serves as a 12 volt alternator. In another embodiment, at least one alternator portion serves as a 24 volt alternator. Similarly, the two alternator portions may provide the same or different amperages. For example, in at least one embodiment, a first alternator portion provides 30 amps and a second alternator portion provides 70 amps. 
     Embodiments of a double alternator and electrical systems having double alternators are described above. Various details of the invention may be changed without departing from its scope. Furthermore, the foregoing description of the preferred embodiments of the invention and best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation.