Abstract:
An electric vehicle utilizes an internal combustion engine to drive the vehicle&#39;s main electric drive system in the regeneration mode and to charge the battery when the vehicle is stopped. The electric vehicle&#39;s main drive controller and motor are used as the generator to recharge the battery when the vehicle is stopped via a clutch mechanism allowing the motor to act as a generator while the vehicle is at rest. As the vehicle proceeds throughout the drive cycle, the vehicle is powered by the electric motor from the battery. The battery is recharged to a specified state of charge when the vehicle is parked. The internal combustion engine only operates to charge the battery, and the electric motor is used to propel the vehicle.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/933,350, filed on Jan. 30, 2014, and herein incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    This invention relates to a method and a system for the operation and charging of the batteries of an electric vehicle (EV). 
         [0003]    Present day hybrid or extended range electric vehicles may employ an internal combustion engine to provide power to propel the vehicle when the battery pack is depleted or at a low state of charge (SOC) while the vehicle is in motion. Current hybrid electric drive systems utilize an internal combustion coupled to a generator to charge the main drive battery when the vehicle is in motion. The electric motor may be used to generate power to propel the vehicle or alternately used to augment the internal combustion engine as it propels the vehicle. 
         [0004]    However, the battery packs required on many such electric vehicles are not optimized for efficiency and the driving parameters of the vehicle. Battery pack size, generator capacity and the size of the internal combustion engine are not optimized for efficient and reliable operation over the vehicle&#39;s drive cycles. In many cases, the internal combustion engine and/or the battery packs are over-sized for efficient operation and add extraneous weight to the vehicle. 
       SUMMARY OF THE INVENTION 
       [0005]    A method and system according to embodiments of this invention provide for an extended range option for electric vehicles utilizing an internal combustion engine to drive the vehicle&#39;s main electric drive system in the regeneration mode and to charge the main battery when the vehicle is stopped. This invention in various embodiments utilizes the electric vehicle&#39;s main drive controller and motor as the generator to recharge the main battery module when the vehicle is stopped via a clutch mechanism allowing the motor to act as a generator while the vehicle is at rest. A system to charge the main battery via the standard J1772 infrastructure or alternatively an induction charging infrastructure for an initial charge may be accomplished at the beginning of the drive cycle. As the vehicle proceeds throughout the drive cycle, the vehicle is powered by the electric motor from the main battery. As the vehicle is stopped and in park, the main battery is recharged to a computed SOC from the main drive motor and controller acting as a generator powered by the internal combustion engine, so as to allow the vehicle to complete its daily drive cycle while not allowing the battery to go below a desired SOC. 
         [0006]    It is common for delivery vehicles to be at rest more than in motion. The internal combustion engine provides the needed heat or cooling to keep the cabin at a comfortable temperature during cold or warm weather while the vehicle is stopped. The internal combustion engine may not run the whole time the vehicle is stopped. It only needs to run long enough to make up for the difference in energy that would have been needed if all the energy was coming from a battery large enough to complete the drive or for cabin climate control. 
         [0007]    One advantage of this invention is that the high voltage battery module can be much smaller, lighter, and never be fully discharged to prolong the life of the battery as well as reduce overall cost of the vehicle, as only one electric motor is required to propel the vehicle and charge the battery for the duration of its intended drive cycle, as opposed to conventional hybrid vehicles. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
           [0009]      FIG. 1  is a schematic diagram of one embodiment of an electric vehicle according to this invention in one state of operation; 
           [0010]      FIG. 2  is a schematic diagram similar to  FIG. 1  with the electric vehicle in a second state of operation; and 
           [0011]      FIG. 3  is a schematic diagram similar to  FIG. 1  with the electric vehicle in a third state of operation. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0012]    Given the description above in general terms, reference will now be made to the accompanying drawings, not necessarily drawn to scale. 
         [0013]    The onboard charging of an electric vehicle&#39;s main battery module utilizes the same propulsion equipment provided to power the vehicle in its normal propulsion mode. The electric propulsion equipment is alternately coupled and decoupled to an onboard internal combustion engine which is used to charge the battery when the vehicle is stopped and in park mode and the drive shaft system when the vehicle is in the propulsion mode. The battery module may be alternately charged from commercially available J1772 compliant infrastructure or induction charging equipment from any number of suppliers to provide an initial charge. It may alternately be used to charge in an abnormal situation. Various embodiments of the invention are intended to provide an alternative to existing series or parallel hybrid systems in that this invention is less complex and less costly. The battery module size may be modified to accommodate the particular drive cycle. Alternately, the amount of time the internal combustion engine runs when the vehicle is in the stopped mode may be modified to accommodate the desired drive cycle. In addition when the vehicle is in the normal propulsion mode, regenerative energy is also channeled to the main battery pack to extend range and to allow the vehicle to stop with less wear on the conventional braking system. 
         [0014]    The embodiments of this invention are purposely designed for the intended drive cycles of the vehicle. The battery module, the internal combustion engine, the main drive motor and the internal charger are optimized for efficiency and cost for the intended drive cycle. The vehicle is always powered by the electric motor assembly while the vehicle is in motion. The internal combustion engine is only used in the stopped/parked state to charge the battery to the desired SOC required to meet the prescribed drive cycle. Battery module size, generator capacity and other components can be scaled to accommodate varying drive cycles. 
         [0015]    A system configuration of an electric vehicle (EV)  10  suitable for embodiments of this invention is shown in  FIG. 1 . This EV  10  is a rear-wheel-drive vehicle; that is, a right rear wheel and a left rear wheel are ground engaging, driving wheels  12 , and each of the front wheels  14  are driven wheels. The electric vehicle  10  schematically shown in  FIGS. 1-3  in one embodiment may be a delivery truck or vehicle, but one of ordinary skill in the art will appreciate that this invention may be utilized not only in a delivery truck, but in many other electric vehicle platforms. 
         [0016]    The vehicle  10  is a rear wheel drive vehicle such that right and left rear wheels  12  are mounted on a rear axle  16 . The rear axle  16  includes a differential  18  which is coupled to a drive shaft  20  of the vehicle  10 . The drive shaft  20  extends from a main motor  22  which may be mounted between a pair of vehicle chassis spaced rails (not shown). The drive shaft  20  includes a clutch assembly  24  downstream from the main motor  22  as well as a park pawl and sprocket assembly  26  between the main motor  22  and the rear axle  16 . 
         [0017]    The vehicle  10  also includes the pair of front wheels  14  mounted on a front axle  28 . In the current embodiment shown in  FIGS. 1-3 , the rear wheels  12  are the drive wheels and the front wheels  14  are the driven wheels. The vehicle  10  may also include an internal combustion engine  30  which is shown in  FIGS. 1-3  mounted near the front axle  28 ; however, the engine  30  is not coupled to drive the front wheels  14 . The output from the engine  30  may be coupled to a regenerative drive  32  and an optional gear reduction assembly  34 . A drive shaft  36  extends from the engine  30  through a clutch assembly  38  and directly into the main motor generator  22 . A motor controller  40  is likewise coupled to the main motor  22  as well as a charger  42 , power electronics module  44  and a battery module  46 . The vehicle  10  may also include an electric power steering pump  48 , a fuel tank  50  for the internal combustion engine  30 , an exhaust  52  to vent the byproducts of the combustion from the engine  30 , an auxiliary hydraulic heating system  54  for the cabin and other areas of the vehicle  10  and a hydro-boost brake system  56  coupled to the wheels  12 ,  14  for controlling the speed and stopping of the vehicle  10 . 
         [0018]    The battery module  46  shown in  FIG. 1  is a driving power supply source coupled to electric motor  22 . Current discharged from the battery module  46  is supplied to the motor  22  via an inverter as part of the power electronics  44 . The inverter is an electric power converter and converts the discharged power (DC) from the battery  46  to a power type (three phase alternating current in this figure) suitable for the motor  22  under the control of the motor controller  40 . The motor controller  40  controls the inverter according to reference torque output from a vehicle controller  58  so that the corresponding motor  22  outputs the real torque corresponding to the reference torque. 
         [0019]    The vehicle controller  58  is a control unit for functions such as the output torque control of the motor  22 , state monitoring and control of the respective onboard components, the transmission of vehicle conditions to a crew, and the like. The vehicle controller  58  can be realized by modifying the software of a conventional electronic control unit. Output from various kinds of sensors provided on various parts of the vehicle  10  is input into the vehicle controller  58  and is utilized for controlling the motor output and monitoring the vehicle conditions. 
         [0020]      FIGS. 1-3  show the overall concept of the invention in its various operating modes. 
         [0021]    State  1  is shown in  FIG. 1  when the vehicle  10  is stopped for an extended period of time and connected to a standard battery charging station  60  such as J1772, CHAdeMO, Induction charging, etc. The electric energy flows from the external charging source  60  such as an EVSE, via the charger  42 , power switching logic of the power electronics  44  and into the battery module  46 . Clutches  24 ,  38  are disengaged or open such that no energy flows into or from the main electric drive motor  22  or the internal combustion engine  30 . 
         [0022]      FIG. 1  shows one embodiment of the invention where one of three states of operation of the vehicle  10  is described along with a summary of power flow through the major system components. State  1  of the vehicle  10  is a normal state where the vehicle  10  is parked and connected to a standard J1772 Level 2 charging infrastructure  60  such as a Clipper Creek 100CS level 2 EVSE or alternately to a Momentum Dynamics induction charging station or equivalent. In this state, energy from the grid is directed thru the EVSE  60 , alternately an induction charging system via an onboard charger  42  such as the EDN model 348 7KW units, thru the power electronics  44 , including the appropriate power switching and logic technology, and into the high voltage battery  46 . The high voltage battery module  46  may be comprised of any number of manufacture&#39;s high power cells for a combined voltage of 600 volts DC, but not greater than 700 volts DC, in various embodiments. In the present embodiment of the invention, the battery  46  has a capacity of 45 kWh usable energy. It is understood that the battery  46  may be of varying size dependent of the intended use of the vehicle  10 . The high voltage battery  46  is monitored and controlled via an integrated battery management system (BMS) such as one supplied by the cell manufacturer or an independent supplier such as the Orion BMS manufactured by EWERT Energy Systems. In state  1 , the onboard internal combustion engine  30 , in this embodiment a PSI 2.4 L multi fuel engine, is in the off position and decoupled from any other component in the drive system. Additionally in state  1  the electric motor/generator  22 , in this embodiment a TM4 1850 series with a CO200HV-A1 controller, is also in the off position and decoupled from drive system. 
         [0023]    State  2  is shown in  FIG. 2  when the vehicle  10  is in the parked mode, such as when the driver is parked and absent from the vehicle  10  making package delivery to a business or residence, or stopped for lunch. In this state, clutch  38  is engaged or closed and clutch  24  is disengaged or open such that the energy flow is from the internal combustion engine  30  via clutch  38 , which turns the electric motor  22  causing the regenerative drive in the generator mode to provide energy back into the main battery  46  in proportion to a predetermined amount necessary to provide the required state of charge (SOC) for the particular route. At the initiation of state  2  when clutch  38  is closed and clutch  24  is open, briefly power flows from the main battery  46  thru the motor controller  40  to the motor  22  to start the internal combustion engine  30 . As soon as the internal combustion engine  30  starts, the motor controller  40  switches to the generator mode to direct power flow to the battery  46  as described above. 
         [0024]    State  2  of the vehicle  10  is a normal state of operation where the vehicle is stopped and in park mode. The vehicle  10  is not connected to the grid, but is capable of being charged via the onboard internal combustion engine  30  and onboard electric propulsion drive system. In state  2 , if the appropriate algorithm requires the battery  46  to accept energy, the internal combustion engine  30  is turned on, clutch  38  is closed and clutch  24  is open. The vehicle  10  does not move. Rotation of the internal combustion engine  30  coupled to the electric motor  22  and the electric motor  22  being in the generator mode causes energy from the electric motor  22  in the generator mode to supply energy to the battery  46  in an amount determined by specific control algorithms required by the drive cycle being executed at that specific time. It is understood that the amount of energy replaced in the battery  46  is in addition to the amount provided by the vehicle&#39;s regenerative capability while the vehicle  10  is in motion. 
         [0025]    State  3  is shown in  FIG. 3  when the vehicle  10  is in motion during its normal drive cycle. In this case clutch  38  is open and clutch  24  is closed, directing energy flow from the battery  46 , power electronics  44 , motor controller  40  and motor  22  to the differential  18 , axle  16  and finally to the rear wheels  12 . 
         [0026]    State  3  of the vehicle  10  is the normal mode of the vehicle  10  where it is free to move. In this state the internal combustion engine  30  is in the off mode, clutch  38  is open and clutch  24  is closed. Energy from the battery  46  flows thru the power electronics  44  and logic in the normal fashion that is common to electric vehicles, that is, energy from the battery  46  is routed thru the power electronics  44  under supervisory control to the electric drive system with the motor  22  in the normal motor mode to provide torque thru the differential  18  to the wheels  12  causing motion of the vehicle  10 . The electric motor assembly  22  may operate in a drive mode (state  3 ) or in a generator mode (state  2 ). 
         [0027]    In various embodiments of this invention, the battery module  46  may be, but not limited to, a  45  kWh usable energy system contained in saddle packs each along and contained within a steel frame on either side of the chassis frame rails. The main electric drive motor  22  and its associated speed reducer and clutches  24 ,  38  may be positioned internal to the chassis frame rails. The internal combustion engine  30  used in the parked generator mode of state  2  along with its associated cooling radiator, fuel system  50 , and the like may be in their normal place in the forward end of the chassis rails. The regenerative motor controller  40 , associated power switching components  44 , battery charging components  42 , DC/DC converter, may be in an acceptable space within the frame rails. The fuel tank  50  and associated fuel supply system necessary for the internal combustion engine  30 , along with the required ABS brake module  56 , and associated internal combustion engine control unit, may be in a normal space within the frame rails. 
         [0028]    One embodiment of the invention includes a small internal combustion engine  30  such at a 0.97 L or 2.4 L derated 25HP engine from Power Systems International (PSI) as the prime mover in the stationary generator mode (state  2 ) coupled thru an isolation clutch  38  such as, but not limited to an MMC EM clutch from Ogura products. The PSI 0.97 L or 2.4 L engine (or equivalent) may utilize fuels such as gasoline, propane, natural gas or bi-fuel. Alternative embodiments of the invention may include higher torque/lower speed internal combustion engines  30 . 
         [0029]    Cabin heating may be provided by the internal combustion engine  30  while the vehicle  10  is stopped and may be supplemented by directed infrared heating elements installed high in the cabin to provide additional heat as required while the vehicle  10  is in motion. Additionally, cabin heating may be accomplished via a fossil fuel heater in conjunction with a scavenge heat system from the electronic components, internal combustion engine  30  and heated reservoir. 
         [0030]    One embodiment of the invention may include a battery module  46  with 45 kWh usable energy and it&#39;s associated Battery Management System (BMS). The battery  46  may be charged externally via any number of level 2 EVSE systems from any number of suppliers and an on board charger  42  such as, but not limited to, model CMP 348 7KW series from the EDN Group. 
         [0031]    One embodiment of the invention includes a TM4 1850 series dual shaft motor  22  as the main drive motor and an associated regenerative drive controller  40  such as model CO200HV-A1. It is understood that alternate regenerative drive systems may be employed depending on the size and use of the vehicle  10 . 12-volt electrical power may be derived, but is not limited to, as coming from the main 45 kWh battery pack via an EDN model DHF 362 series DC/DC converter. 
         [0032]    One embodiment of the invention may include the components of the invention installed in a Workhorse W88 or other suitable chassis. It is understood that any of any number of chassis configurations may be used. In one embodiment of the invention, the 45 kWh usable high-power battery pack is contained within an independent steel frame that spans the chassis frame rails. A 2.4 L PSI multi fuel 25HP internal combustion engine  30  may be mounted in the forward end of the chassis as is customary for vehicles driven by an internal combustion engine. In addition, the electric drive/generator motor may also be located in the forward end of the chassis along with its associated clutches, parking brake, and cooling equipment. In addition, the motor controller  40  and onboard charging equipment  42  may also be located in the forward portion of the chassis. Fuel tank  50  and other ABS braking modules  56  and the like may be mounted in their customary place along the chassis as is common practice in the industry. 
         [0033]    An optional auxiliary hydronic heating system  54  for use in cold climates, along with the electric power steering  48  and hydro-boost brake system  56 , fuel tank  50  for the internal combustion engine  30  and internal combustion engine exhaust  52  may be included in the vehicle  10 . It is understood that the internal combustion engine exhaust may exit from either the driver or passenger side of the vehicle  10 . 
         [0034]    In various embodiments, the internal combustion engine  30 , main electric drive motor  22 , associated clutches  24 ,  38  and regenerative drive unit are configured on a carrier frame for easy alignment and insertion and removal from the chassis of the vehicle  10 . In this embodiment of the invention, the parking pawl and sprocket  26  may be integrated into the rear clutch assembly  24  as to form a homogenous unit. Integral to the forward clutch  38  may be a flex plate installed to dampen vibrations from the internal combustion engine  30 . 
         [0035]    From the above disclosure of the general principles of this invention and the preceding detailed description of at least one embodiment, those skilled in the art will readily comprehend the various modifications to which this invention is susceptible. Therefore, we desire to be limited only by the scope of the following claims and equivalents thereof.