Ultracapacitor power supply for an electric vehicle

• US 6,265,851 B1
• Filed: 06/12/2000
• Issued: 07/24/2001
• Est. Priority Date: 06/11/1999
• Status: Expired due to Term

• Current Assignee: Murata Machinery Limited (Muratec)
• Original Assignee: PRI Automation, Inc. (Azenta, Inc.)
• Inventors: Weiss, Mitchell, Brien, Richard M.
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): LUK, LAWRENCE W
• Application Number:
  US09/591,771
• Time in Patent Office: 407 Days
• Field of Search: 320/162, 320/137, 320/104, 320/103, 363/155, 363/131, 363/132
• US Class Current: 320/162
• CPC Class Codes: B60L 2200/26 Rail vehicles
• CPC Class Codes: B60L 50/40 using propulsion power supplied by capacitors
• CPC Class Codes: B60L 50/52 characterised by DC-motors
• CPC Class Codes: B60R 16/03 for supply of electrical power to vehicle subsystems or for circuit arrangements for charging batteries H02J7/00
• CPC Class Codes: H02J 2310/46 for ICE-powered road vehicles
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/40 using two or more transmitting or receiving devices H02J50/50 takes precedence
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H02J 7/0018 using separate charge circuits
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

An ultracapacitor power supply for an electric vehicle is provided which employs an ultracapacitor as the primary power source and a battery as a supplemental power source. This vehicle is particularly effective in power-rail system having gaps in the power-rail or in non-power rail systems having recharging stations positioned along the track The ultracapacitor recharges quickly upon vehicle passage over a live power rail or entry into a recharging station. Optimum performance is achieved when the capacitor is allowed to fully recharge. The battery need only provide power when the ultracapacitor has been discharged or during acceleration or other periods of peak power consumption, thereby reducing the number of battery recharges required during any given operational period.

Claims

1. A power supply for furnishing direct current (DC) power to an electrical vehicle, said power supply mounted on said electrical vehicle and comprising:

a primary ultracapacitor power source generating a primary output voltage and a primary output current used to power the electric vehicle, the primary ultracapacitor power source comprising an ultracapacitor assembly having a plurality of ultracapacitor cells, each of said plurality of ultracapacitor cells holding a charge;

a secondary power source generating a secondary output voltage and a secondary output current used to power the electric vehicle in the event that the charge held by the plurality of ultracapacitor cells in the primary ultracapacitor power source falls below a level necessary to power the electric vehicle;

a switching circuit connected to said primary and secondary power sources and selecting in response to a control signal either or both of said power sources to provide power to said engine;

a controller coupled to the primary power source, the secondary power source, and the switching circuit and the controller configured and arranged to monitor the primary voltage and the primary current and to provide the control signal in the event that the primary voltage and the primary current falls below a level necessary to power the electric vehicle for the switching circuit to connect the secondary power source; and

a recharging system coupled to the primary power source and the secondary power source and an external power supply for providing a charging current for the primary and secondary power sources.

2. The power supply of claim 1 wherein the recharging system comprises:

a charge current regulation circuit for maintaining a power supply charge current at an essentially constant rate during a recharging operation and comprising;

a current surge limiter coupled to said external power supply and coupled to said primary power source, said active current surge limiter to limit said charge current when said charge voltages are near to a full discharge and to furnish most of said charge current when said charge voltages are near to a full charge.

3. The power supply of claim 2, wherein the recharging system further comprises a DC-to-DC converter in parallel with said active current surge limiter to furnish most off said charge current when said charge voltages are near to said full discharge.

4. The power supply of claim 2 wherein said recharging station includes an input device sized and configured to mate to an output device of a recharging station generating said charge current.

5. The power supply of claim 1 wherein said current surge limiter is an active current surge limiter.

6. The power supply of claim 1, wherein each one of said plurality of cells of said ultracapacitor assembly includes a cell voltage equalizer comprising:

an over-voltage detection circuit for detecting a cell over-voltage exceeding a maximum allowable cell voltage.

7. The power supply of claim 1, wherein each one of said plurality of cells of said ultracapacitor assembly includes a discharge circuit to reduce said cell over-voltage to a level below said maximum allowable cell voltage.

8. The power supply of claim 1, wherein each one of said plurality of cells of said ultracapacitor assembly includes a reporting circuit to report said over-voltage to control circuitry of said vehicle.

9. The power supply of claim 1 further including a dc/dc converter coupled to said switching device and to said engine, said dc/dc converter to receive current from said switching device and to provide power to the engine.

10. The power supply of claim 1 wherein the secondary power source comprises a battery having one or more battery cells, each of said one or more battery cells holding a charge.

11. The power supply of claim 10 wherein the battery is a rechargeable battery.

12. The power supply of claim 1 wherein the secondary power source comprises a second ultracapacitor having one or more ultracapacitor cells, each of said one or more ultracapactor cells holding a charge.

13. A power supply for furnishing direct current (DC) power to an engine of an electric vehicle, said power supply mounted on said electric vehicle and comprising:

a primary ultracapacitor power source generating a primary output voltage and a primary output current used to power the motor of the electric vehicle, the primary ultracapacitor power source comprising an ultracapacitor assembly having a plurality of ultracapacitor cells, each of said plurality of ultracapacitor cells holding a charge having a voltage, said primary power source to provide power to said engine;

a recharging system coupled to the primary power source and an external power supply for providing a charging current for the primary power source.

14. The power supply of claim 13 further comprising

a secondary power source generating a secondary output voltage and a secondary output current;

a switching device connected to said primary and secondary power sources and selecting in response to a control signal either, or both, of said power sources to provide power to said engine;

a controller coupled to the primary power source, the secondary power source, and the switching device and providing the control signal for the switching device.

15. The power supply of claim 14 wherein said secondary power source comprises a rechargeable battery having one or more battery cells, each of said one or more battery cells holding a charge and having a voltage, said secondary power source being coupled to said recharging system to receive recharging current for said rechargeable battery.

16. The power supply of claim 14 wherein said recharging system comprises:

a charge current regulation circuit for maintaining a power supply charge current at an essentially constant rate during a recharging operation and comprising;

an active current surge limiter coupled to said external power supply and coupled to said primary power source, said active current surge limiter to limit said charge current when said charge voltages are near to a full discharge and to furnish most of said charge current when said charge voltages are near to a full charge.

17. The power supply of claim 16, wherein the recharging system further comprises a DC-to-DC converter in parallel with said active current surge limiter to furnish most off said charge current when said charge voltages are near to said full discharge.

18. The power supply of claim 13, wherein each one of said plurality of cells of said ultracapacitor assembly includes a cell voltage equalizer comprising:

an over-voltage detection circuit for detecting a cell over-voltage exceeding a maximum allowable cell voltage.

19. The power supply of claim 13, wherein each one of said plurality of cells of said ultracapacitor assembly includes a discharge circuit to reduce said cell over-voltage to a level below said maximum allowable cell voltage.

20. The power supply of claim 13, wherein each one of said plurality of cells of said ultracapacitor assembly includes a reporting circuit to report said over-voltage to control circuitry of said vehicle.

21. The power supply of claim 13 further including a dc/dc converter coupled to said switching device and to said engine, said dc/dc converter to receive current from said switching device and to provide power to the engine.