MODULAR AUXILIARY POWER UNIT ASSEMBLY FOR AN ELECTRIC VEHICLE

• US 20100187031A1
• Filed: 01/29/2009
• Published: 07/29/2010
• Est. Priority Date: 01/29/2009
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Waszak, Michal-Wolfgang, King, Robert Dean, Vyas, Parag, Hemmelmann, Jan
• Granted Patent: US 8,376,070 B2
• Time in Patent Office: Days
• US Class Current: 180/65.265
• CPC Class Codes: B60K 6/46 Series type
• CPC Class Codes: B60L 2220/18 Reluctance machines
• CPC Class Codes: B60L 2270/142 acoustic
• CPC Class Codes: B60L 2270/145 Structure borne vibrations
• CPC Class Codes: B60L 50/10 using propulsion power supplied by engine-driven generators, e.g. generators driven by combustion engines
• CPC Class Codes: B60W 20/12 using control strategies taking into account route information estimation or calculation of non-directly measurable driving parameters B60W40/00
• CPC Class Codes: H02P 9/04 Control effected upon non-electric prime mover and dependent upon electric output value of the generator
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors

Abstract

A system and method for a propulsion system includes an electric motor and an energy storage unit configured to supply a primary power to the electric motor. The propulsion system also includes a plurality of auxiliary power units (APUs) configured to supply a secondary power to at least one of the electric motor and the energy storage unit. Each of the plurality of APUs includes a free-piston engine configured to generate a mechanical output, a linear generator configured to transform the mechanical output to an electrical power, and a controller. The controller receives a power command from the electric motor and/or the energy storage unit, determines an amount of secondary power needed to meet the power command, and selectively activates a number of the plurality of APUs to generate the needed amount of secondary power.

Claims

1. A propulsion system comprising:

an electric motor;

an energy storage unit configured to supply a primary power to the electric motor; and

a plurality of auxiliary power units (APUs) configured to supply a secondary power to at least one of the electric motor and the energy storage unit, each of the plurality of APUs comprising;

a free-piston engine configured to generate a mechanical output;

a linear generator configured to transform the mechanical output to an electrical power; and

a controller configured to;

receive a power command from the at least one of the electric motor and the energy storage unit;

determine an amount of secondary power needed to meet the power command; and

selectively activate a number of the plurality of APUs to generate the needed amount of secondary power.

2. The propulsion system of claim 1 further comprising one of a rectifier and a bidirectional convertor electrically connected to the linear generator.

3. The propulsion system of claim 1 further comprising a DC link electrically connecting the electric motor and the energy storage unit to distribute power therebetween;

and

wherein the secondary power supplied by the plurality of APUs is fed into the DC link to be distributed to at least one of the energy storage unit, the electric motor, and an auxiliary load.

4. The propulsion system of claim 1 wherein the free-piston engine comprises an internal combustion engine having a drive assembly.

5. The propulsion system of claim 4 wherein the drive assembly comprises:

a rod;

a first piston coupled to a first end of the rod; and

one of a returning spring and a second piston coupled to a second end of the rod.

6. The propulsion system of claim 1 wherein the controller is configured to individually operate each of the plurality of APUs in one of an on condition or an off condition based on the needed amount of secondary power.

7. The propulsion system of claim 6 wherein the controller is configured to operate each of the plurality of APUs in the on condition above a minimum efficiency threshold.

8. The propulsion system of claim 6 wherein the controller is configured to determine a transition strategy for altering an operating efficiency of each of the plurality of APUs in the on condition.

9. The propulsion system of claim 1 wherein each of the plurality of APUs is configured to generate a fraction of the secondary power.

10. The propulsion system of claim 1 wherein the controller is configured to receive one of an instantaneous power requirement of the electric motor and a recharging command for the energy storage device.

11. The propulsion system of claim 1 wherein each of the plurality of APUs further comprises at least one fuel injector configured to control firing of the free-piston engine;

and

wherein the controller is configured to regulate a firing sequence of the at least one fuel injector of each of the selectively activated plurality of APUs to selectively manage at least one of a noise and vibration output of the selectively activated plurality of APUs and an operating efficiency of the propulsion system.

12. A method for supplying auxiliary power to a vehicle comprising:

providing a vehicle propulsion system comprising an electric motor, an energy storage device, and a DC link electrically connecting the electric motor and the energy storage device;

electrically connecting each of a plurality of crankshaft-less engine and linear generator combinations to the DC link;

determining a band-limited power requirement of the vehicle propulsion system; and

selectively activating a number of the plurality of crankshaft-less engine and linear generator combinations to provide power to the DC link based on the vehicle propulsion system band-limited power requirement.

13. The method of claim 12 further comprising:

determining a charge requirement of the energy storage device; and

if the charge requirement is below a charge threshold, controlling the plurality of crankshaft-less engine and linear generator combinations to recharge the energy storage device.

14. The method of claim 12 further comprising individually operating each of the activated crankshaft-less engine and linear generator combinations above an efficiency threshold.

15. The method of claim 12 further comprising selectively operating a fuel-injection timing sequence for each of the activated crankshaft-less engine and linear generator combinations to minimize noise and vibration of each of the activated crankshaft-less engine and linear generator combinations.

16. The method of claim 12 further comprising selectively operating a fuel-injection timing sequence for each of the activated crankshaft-less engine and linear generator combinations to operate at a frequency other than a natural frequency of each of the activated crankshaft-less engine and linear generator combinations.

17. The method of claim 12 wherein determining the band-limited power requirement of the vehicle propulsion system comprises determining a band-limited, real-time power requirement of the electric motor.

18. The method of claim 12 wherein selectively activating a number of the plurality of crankshaft-less engine and linear generator combinations comprises individually controlling each of the activated crankshaftless engine and linear generator combinations to deliver an equal fraction of the band-limited power requirement.

19. An auxiliary power assembly comprising:

a plurality of auxiliary power units (APUs) configured to generate a secondary power, each of the plurality of APUs comprising a free-piston combustion engine (FPE) and a linear generator; and

a controller configured to;

sense a power requirement of at least one of an electric motor and an energy storage device;

determine an optimal operation strategy of the plurality of APUs based on the sensed power requirement; and

operate the plurality of APUs according to the optimal operation strategy to provide the secondary power to at least one of the electric motor and the energy storage device.

20. The auxiliary power assembly of claim 19 wherein the controller is configured to operate each of the plurality of APUs in one of an active and a non-active state.

21. The auxiliary power assembly of claim 20 wherein the controller is configured to operate less than all of the plurality of APUs in the active state to provide the secondary power according to the optimal operation strategy.

22. The auxiliary power assembly of claim 20 wherein the controller is configured to operate each of the APUs in the active state above a minimum efficiency threshold according to the optimal operation strategy.

23. The auxiliary power assembly of claim 19 wherein the controller is configured to operate the plurality of APUs according to the optimal operation strategy to provide at least one of a supplemental power to the electric motor, a supplemental power to an auxiliary load, and a recharging power to the energy storage device.

24. The auxiliary power assembly of claim 19 wherein the controller is configured to individually regulate a firing sequence of fuel injectors associated with each of the plurality of APUs to selectively transition the plurality of APUs between the active state and the non-active state.

25. The auxiliary power assembly of claim 24 wherein the firing sequence of fuel injectors optimizes an operating efficiency of the auxiliary power assembly.