Electric system for electric vehicle

• US 6,066,928 A
• Filed: 12/15/1998
• Issued: 05/23/2000
• Est. Priority Date: 12/15/1997
• Status: Expired due to Term

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Inventors: Ito, Junichi, Kinoshita, Shigenori, Fujita, Koetsu
• Primary Examiner(s): Sircus, Brian
• Application Number:
  US09/212,499
• Time in Patent Office: 525 Days
• Field of Search: 318/139, 318/254, 318/439, 318/138, 318/798-817, 180/65.1, 180/65.3, 180/65.4, 180/65.8
• US Class Current: 318/139
• CPC Class Codes: B60L 50/40 using propulsion power supplied by capacitors
• CPC Class Codes: B60L 58/10 for monitoring or controlling batteries
• CPC Class Codes: B60L 7/10 Dynamic electric regenerative braking B60L7/22 takes precedence
• CPC Class Codes: H02P 2209/01 Motors with neutral point connected to the power supply
• 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

Abstract

An electric system for an electric vehicle includes a voltage type inverter that receives dc input voltage from a dc input circuit, and generates variable ac voltage of a variable frequency, and an ac motor including a plurality of windings each of which has one end connected to an ac output terminal of the voltage type inverter, the other ends of the windings being connected together to provide a neutral point of motor windings. A variable-voltage energy storage element is connected between the neutral point and a connecting point provided in the dc input circuit, and an on-vehicle dc power supply is connected to the opposite ends of the energy storage element or input terminals of the dc input circuit. The inverter performs switching operations in a zero-voltage vector mode, to operate as a chopper, so that power is transferred between the variable-voltage energy storage element, and the dc input side of the inverter.

Claims

1. An electric system for an electric vehicle, comprising:

a dc input circuit;

a voltage type inverter that is connected to said dc input circuit to receive input voltage from said dc input circuit, and generate variable ac voltage of a variable frequency;

an ac motor including a plurality of windings each of which has one end connected to an ac output terminal of said voltage type inverter, the other ends of said windings being connected together to provide a neutral point of motor windings;

a variable-voltage energy storage element connected between said neutral point and a connecting point provided in said dc input circuit; and

an on-vehicle dc power supply connected to opposite ends of said variable-voltage energy storage element.

3. An electric system for an electric vehicle according to claims 1, wherein said variable-voltage storage element is connected to one of output terminals of said dc input circuit as said connecting point provided in said dc input circuit.

4. An electric system for an electric vehicle according to claim 1, wherein said variable-voltage storage element is connected to a middle point of output terminals of said dc input circuit as said connecting point provided in said dc input circuit.

5. An electric system for an electric vehicle according to claim 1, wherein said dc input circuit comprises a semiconductor switch arm comprising a series circuit of two semiconductor switching devices each of which is connected in parallel with a diode in a reverse direction, and wherein said variable-voltage energy storage element is connected to a middle point of said semiconductor switch arm as said connecting point provided in said dc input circuit.

9. An electric system for an electric vehicle according to claim 1, wherein said inverter operates as a chopper in a zero-voltage vector mode, so that power is transferred between said variable-voltage energy storage element and said dc input circuit.

11. An electric system for an electric vehicle according to claim 5, wherein said semiconductor switching arm is turned on and off to perform a chopper operation while said inverter is operating in a zero-voltage vector mode, so that power is transferred between said variable-voltage energy storage element and said dc input circuit.

13. An electric system for an electric vehicle according to claim 4, wherein the middle point of the output terminals of said dc input circuit is provided by a connecting point of a plurality of input capacitors that are connected in series.

15. An electric system for an electric vehicle according to claim 1, wherein said variable-voltage energy storage element comprises one of an electric double layer capacitor and an electrochemical capacitor.

17. An electric system for an electric vehicle according to claim 1, further comprising a capacitor for absorbing high-frequency current, said capacitor being connected in parallel with said variable-voltage energy storage element.

19. An electric system for an electric vehicle according to claim 1, wherein a voltage of the variable-voltage energy storage element or the dc voltage applied to said voltage type inverter is controlled to be constant, or variable depending upon operating conditions of said ac motor.

21. An electric system for an electric vehicle according to claim 1, wherein said ac motor is an electric motor for driving the vehicle.

23. An electric system for an electric vehicle according to claim 1, wherein said ac motor is an electric motor for driving accessories of the vehicle.

25. An electric system for an electric vehicle according to claim 3, wherein said dc input circuit comprises a capacitor connected between the output terminals of said dc input circuit as an input capacitor of said voltage type inverter.

27. An electric system of an electric vehicle according to claim 1, wherein said on-vehicle dc power supply comprises a chemical battery.

29. An electric system for an electric vehicle according to claim 1, wherein said on-vehicle dc power supply comprises an engine generator.

31. An electric system for an electric vehicle according to claim 1, wherein said on-vehicle dc power supply comprises a fuel battery.

33. An electric system of an electric vehicle according to claim 3, wherein the dc voltage Vi applied to said voltage type inverter, a voltage Vc of said variable-voltage energy storage element, and a terminal voltage (between lines) Vm of said ac motor have relationships as represented by

35. An electric system for an electric vehicle according to claim 4, wherein the dc voltage Vi applied to said voltage type inverter, a voltage Vc of said variable-voltage energy storage element, and a terminal voltage (between lines) Vm of said ac motor have relationships as represented by

37. An electric system for an electric vehicle according to claim 5, wherein the dc voltage Vi applied to said voltage type inverter, a voltage Vc of said variable-voltage energy storage element, and a terminal voltage (between lines) Vm of said ac motor have relationships as represented by

39. An electric system for an electric vehicle according to claim 5, wherein the dc voltage Vi applied to said voltage type inverter Vi, a voltage Vc of said variable-voltage energy storage element, and a terminal voltage (between lines) Vm of said ac motor have relationships as represented by

2. An electric system for an electric vehicle, comprising:

a dc input circuit including input terminals;

a voltage type inverter that is connected to said dc input circuit to receive dc input voltage from said dc input circuit, and generate variable ac voltage of a variable frequency;

an ac motor including a plurality of windings each of which has one end connected to an ac output terminal of said voltage type inverter, the other ends of said windings being connected together to provide a neutral point of the motor windings;

a variable-voltage energy storage element connected between said neutral point and a connecting point provided in said dc input circuit; and

an on-vehicle dc power supply connected to said input terminals of said dc input circuit.

6. An electric system for an electric vehicle according to claim 2, wherein said variable-voltage storage element is connected to one of output terminals of said dc input circuit as said connecting point provided in said dc input circuit.

7. An electric system for an electric vehicle according to claim 2, wherein said variable-voltage storage element is connected to a middle point of output terminals of said dc input circuit as said connecting point provided in said dc input circuit.

8. An electric system for an electric vehicle according to claim 2, wherein said dc input circuit comprises a semiconductor switch arm comprising a series circuit of two semiconductor switching devices each of which is connected in parallel with a diode in a reverse direction, and wherein said variable-voltage energy storage element is connected to a middle point of said semiconductor switch arm as said connecting point provided in said dc input circuit.

10. An electric system for an electric vehicle according to claim 2, wherein said inverter operates as a chopper in a zero-voltage vector mode, so that power is transferred between said variable-voltage energy storage element and said dc input circuit.

12. An electric system for an electric vehicle according to claim 8, wherein said semiconductor switching arm is turned on and off to perform a chopper operation while said inverter is operating in a zero-voltage vector mode, so that power is transferred between said variable-voltage energy storage element and said dc input circuit.

14. An electric system for an electric vehicle according to claim 7, wherein the middle point of the output terminals of said dc input circuit is provided by a connecting point of a plurality of input capacitors that are connected in series.

16. An electric system for an electric vehicle according to claim 2, wherein said variable-voltage energy storage element comprises one of an electric double layer capacitor and an electrochemical capacitor.

18. An electric system for an electric vehicle according to claim 2, further comprising a capacitor for absorbing high-frequency current, said capacitor being connected in parallel with said variable-voltage energy storage element.

20. An electric system for an electric vehicle according to claim 2, wherein a voltage of the variable-voltage energy storage element or the dc voltage applied to said voltage type inverter is controlled to be constant, or variable depending upon operating conditions of said ac motor.

22. An electric system for an electric vehicle according to claim 2, wherein said ac motor is an electric motor for driving the vehicle.

24. An electric system for an electric vehicle according to claim 2, wherein said ac motor is an electric motor for driving accessories of the vehicle.

26. An electric system for an electric vehicle according to claim 6, wherein said dc input circuit comprises a capacitor connected between the output terminals of said dc input circuit as an input capacitor of said voltage type inverter.

28. An electric system of an electric vehicle according to claim 2, wherein said on-vehicle dc power supply comprises a chemical battery.

30. An electric system for an electric vehicle according to claim 2, wherein said on-vehicle dc power supply comprises an engine generator.

32. An electric system for an electric vehicle according to claim 2, wherein said on-vehicle dc power supply comprises a fuel battery.

34. An electric system of an electric vehicle according to claim 6, wherein the dc voltage Vi applied to said voltage type inverter, a voltage Vc of said variable-voltage energy storage element, and a terminal voltage (between lines) Vm of said ac motor have relationships as represented by

36. An electric system for an electric vehicle according to claim 7, wherein the dc voltage Vi applied to said voltage type inverter, a voltage Vc of said variable-voltage energy storage element, and a terminal voltage (between lines) Vm of said ac motor have relationships as represented by

38. An electric system for an electric vehicle according to claim 8, wherein the dc voltage Vi applied to said voltage type inverter, a voltage Vc of said variable-voltage energy storage element, and a terminal voltage (between lines) Vm of said ac motor have relationships as represented by

40. An electric system for an electric vehicle according to claim 8, wherein the dc voltage Vi applied to said voltage type inverter Vi, a voltage Vc of said variable-voltage energy storage element, and a terminal voltage (between lines) Vm of said ac motor have relationships as represented by