Vehicle power supply system

• US 20060097577A1
• Filed: 02/17/2004
• Published: 05/11/2006
• Est. Priority Date: 02/17/2003
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Senda, Takashi, Tanaka, Katsunori, Kato, Akira, Kamiya, Masaru
• Granted Patent: US 7,336,002 B2
• Time in Patent Office: Days
• US Class Current: 307/10.1
• 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: F02N 11/0866 comprising several power sources, e.g. battery and capacitor or two batteries
• CPC Class Codes: F02N 2200/063 Battery voltage
• CPC Class Codes: F02N 2250/02 Battery voltage drop at start, e.g. drops causing ECU reset
• CPC Class Codes: H02J 2310/46 for ICE-powered road vehicles
• CPC Class Codes: H02J 7/1423 with multiple batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A main power source (2) is, for example, an ordinary Pb battery and generates a voltage of 12-13 V. At the time of starting an engine, the main power source (2) supplies power to a starter (8a). The main power source (2) is given a higher priority than an auxiliary power source (3) to supply power to ordinary loads (8b). The auxiliary power source (3) is a high performance battery (e.g., Li ion battery), which has superior charge acceptance capability and better state detectability over the main power source (2). Furthermore, the auxiliary power source (3) has an internal resistance per unit capacity, which is smaller than that of the main power source (2), and generates a voltage of 9-12 V. A generator (1) is directly connected to the auxiliary power source (3). The auxiliary power source (3) stores regenerative power, which is generated by the generator (1) at the time of deceleration of a vehicle, and is used as a redundant power source for the main power source (2). The main power source (2) and the auxiliary power source (3) are connected to each other through a supply circuit (5), which has a DC/DC converter (4), and a second supply circuit 7, which has a switch (6).

Claims

1. A vehicle power supply system comprising:

a generator, which is mounted on a vehicle;

a main power source, to which an ordinary load, such as a lamp or an audio device, is connected;

an auxiliary power source, which is connected to the generator, wherein the auxiliary power source recovers regenerative electric power, which is generated by the generator using kinetic energy, such as kinetic energy of deceleration, or thermal energy, such as thermal energy of exhaust heat, and the auxiliary power source stores electric power that is generated by the generator;

a first supply circuit, which connects the auxiliary power source to the main power source and the ordinary load through a DC/DC converter;

a second supply circuit, which is in parallel with the first supply circuit and which connects the auxiliary power source to the main power source and the ordinary load through a switch; and

a control means for controlling operation of the DC/DC converter and operation of the switch, wherein the control means is enabled to select one of;

a first control state, in which the DC/DC converter is driven, and the switch is opened; and

a second control state, in which the DC/DC converter is stopped, and the switch is closed.

3. The vehicle power supply system according to claim 1, wherein the control means is also enabled to select a third control state, in which the DC/DC converter is driven, and the switch is closed.

4. The vehicle power supply system according to claim 1, wherein the main power source has a greater nominal voltage or nominal capacity over the auxiliary power source.

5. The vehicle power supply system according to claim 1, wherein the main power source has a smaller nominal voltage or nominal capacity over the auxiliary power source.

6. The vehicle power supply system according to claim 1, wherein the main power source and the auxiliary power source have a common operational range, in which a working voltage of the main power source generally coincides with a working voltage of the auxiliary power source.

7. The vehicle power supply system according to claim 1, wherein the main power source has superior low-temperature discharge characteristics over the auxiliary power source.

8. The vehicle power supply system according to claim 1, wherein the auxiliary power source has superior charge acceptance capability and better state detectability over the main power source.

9. The vehicle power supply system according to claim 1, wherein:

the main power source is one of a lead battery, a Li ion battery and a Ni hydrogen battery; and

the auxiliary power source is one of a lead battery, a Li ion battery, a Ni hydrogen battery and an electrical double-layer capacitor.

10. The vehicle power supply system according to claim 1, wherein at time of supplying power from the auxiliary power source to the main power source and the ordinary load, the control means selects the second control state when the voltage of the auxiliary power source has fallen to or below an allowable rated voltage of the ordinary load.

11. The vehicle power supply system according to claim 1, wherein when a level of power supplied from the auxiliary power source to the main power source and the ordinary load, or a level of power supplied from the main power source to the auxiliary power source and the ordinary load, is called as a power supply level, the control means selects one of the first control state and the second control state in accordance with the power supply level.

12. The vehicle power supply system according to claim 11, wherein:

the control means selects the first control state when the power supply level is equal to or below a predetermined value; and

the control means selects the second control state when the power supply level is above the predetermined value.

13. The vehicle power supply system according to claim 1, wherein the control means selects one of the first control state and the second control state in accordance with a voltage difference between the main power source and the auxiliary power source.

14. The vehicle power supply system according to claim 13, wherein:

the control means selects the second control state when the voltage difference between the main power source and the auxiliary power source is equal to or below a predetermined value; and

the control means selects the first control state when the voltage difference between the main power source and the auxiliary power source is above the predetermined value.

15. The vehicle power supply system according to claim 1, wherein when a level of power supplied from the auxiliary power source to the main power source and the ordinary load, or a level of power supplied from the main power source to the auxiliary power source and the ordinary load, is called as a power supply level, the control means selects one of the first control state and the second control state in accordance with the voltage difference between the main power source and the auxiliary power source and the power supply level.

16. The vehicle power supply system according to claim 15, wherein:

the control means first selects the first control state when the voltage of the auxiliary power source is higher than that of the main power source and also the power level supplied from the auxiliary power source to the main power source and the ordinary load is greater than a predetermined value; and

the control means then shifts from the first control state to the second control state after the voltage of the auxiliary power source falls to or below the allowable rated voltage of the ordinary load.

17. The vehicle power supply system according to claim 1, further comprising:

a third supply circuit, which supplies electric power from the auxiliary power source to an important load, which is involved in a basic running operation or a safety operation of the vehicle; and

a fourth supply circuit, which supplies electric power from the main power source to the important load, wherein each of the third supply circuit and the fourth supply circuit has a diode, which limits a reverse flow of an electric current therethrough.

18. The vehicle power supply system according to claim 1, further comprising:

a third supply circuit, which supplies electric power from the auxiliary power source to an important load, which is involved in a basic running operation or a safety operation of the vehicle; and

a fourth supply circuit, which supplies electric power from the main power source to the important load, wherein the third supply circuit has a diode, which limits a reverse flow of an electric current therethrough, in a case where the main power source has a higher nominal voltage or nominal capacity over the auxiliary power source.

19. The vehicle power supply system according to claim 1, further comprising:

a third supply circuit, which supplies electric power from the auxiliary power source to an important load, which is involved in a basic running operation or a safety operation of the vehicle; and

a fourth supply circuit, which supplies electric power from the main power source to the important load, wherein the fourth supply circuit has a diode, which limits a reverse flow of an electric current therethrough, in a case the main power source has a lower nominal voltage or nominal capacity over the auxiliary power source.

20. The vehicle power supply system according to claim 17, wherein the control means opens the switch when one of the main power source and the auxiliary power source fails in a state where the second control state is selected by the control means.

21. The vehicle power supply system according to claim 20, wherein the control means opens the switch when short-circuiting occurs between a cathode and an anode of one of the main power source and the auxiliary power source.

22. The vehicle power supply system according to claim 20, wherein the control means opens the switch when performance of the main power source falls.

23. The vehicle power supply system according to claim 20, wherein the control means opens the switch when performance of the auxiliary power source falls.

24. The vehicle power supply system according to claim 20, wherein the control means stops the DC/DC converter when one of the main power source and the auxiliary power source fails in a state where the first control state is selected by the control means.

25. The vehicle power supply system according to claim 3, wherein the control means switches from the second control state to the third control state when a temperature of the switch is increased beyond a predetermined value in a state where the second control state is selected by the control means.

26. The vehicle power supply system according to claim 1, wherein the ordinary load, which is connected to the main power source, includes an electrical load, which requires a dark current after stopping of the engine.

27. The vehicle power supply system according to claim 1, wherein at time of shifting from the first control state to the second control state or at time of shifting from the second control state to the first control state, the control means increases an output voltage of the DC/DC converter to a higher one of a voltage of the main power source and a voltage of the auxiliary power source or decreases the output voltage of the DC/DC converter to a lower one of the voltage of the main power source and the voltage of the auxiliary power source, and then the control means shifts from the first control state to the second control state or shifts from the second control state to the first control state.

28. The vehicle power supply system according to claim 1, wherein:

the control means senses a working sate, such as a temperature or a voltage, of the DC/DC converter in a state where the first control state is selected by the control means; and

the control means shifts from the first control sate to the second control state when the sensed working state of the DC/DC converter exceeds a predefined value.

29. The vehicle power supply system according to claim 1, wherein the control means controls an output voltage of the DC/DC converter such that the output voltage of the DC/DC converter generally coincides with an output voltage of the generator when the first control state is selected by the control means.

30. The vehicle power supply system according to claim 1, wherein the control means controls an output voltage of the generator such that the output voltage of the generator generally coincides with an output voltage of the DC/DC converter when the first control state is selected by the control means.

31. The vehicle power supply system according to claim 1, wherein the control means senses a charge acceptance capability of the main power source based on an output state of the DC/DC converter when the first control state is selected by the control means.

32. The vehicle power supply system according to claim 1, wherein:

the control means senses a voltage of the auxiliary power source and an output voltage of the DC/DC converter based on a running state of the vehicle; and

the control means controls an output of the generator based on a sensed result of the voltage of the auxiliary power source and of the output voltage of the DC/DC converter.

33. The vehicle power supply system according to claim 1, wherein the auxiliary power source supplies electric power to an electrical load, which does not require a dark current.

34. The vehicle power supply system according to claim 33, wherein the electrical load, which does not require the dark current, is one of:

an electrical load, such as an ECU that does not have an internal memory; and

an electrical load, such as an ECU that always uses an initial constant of an internal memory.

35. The vehicle power supply system according to claim 1, further comprising a dark current blocking means for blocking the dark current, wherein the auxiliary power source supplies electric power to an electrical load, which enables blocking of dark current.

36. The vehicle power supply system according to claim 1, wherein an auxiliary power source switch is connected in series with the auxiliary power source.

37. The vehicle power supply system according to claim 36, wherein the auxiliary power source switch is disposed between the generator and the auxiliary power source in such a manner that the auxiliary power source switch is positioned on a generator side of an input side connection of the DC/DC converter.

38. The vehicle power supply system according to claim 1, wherein the DC/DC converter includes a series regulator.

39. The vehicle power supply system according to claim 1, wherein in a case where a fully charged state of the auxiliary power source is sensed at time of performing regenerative power generation of the generator, the generator carries out the regenerative power generation at a voltage that is lower than a voltage of the auxiliary power source measured in the fully charged state of the auxiliary power source and supplies electric power to the ordinary load in one of the first control state and the second control state.

40. The vehicle power supply system according to claim 3, wherein in a case where a fully charged state of the auxiliary power source is sensed at time of performing regenerative power generation of the generator, the generator carries out the regenerative power generation at a voltage that is lower than a voltage of the auxiliary power source measured in the fully charged state of the auxiliary power source and supplies electric power to the ordinary load in one of the first control state, the second control state and the third control state.

41. The vehicle power supply system according to claim 1, wherein the main power source is maintained in a fully charged state in the first control state.

2. A vehicle power supply system comprising:

a generator, which is driven by an engine to generate electric power;

a main power source, to which an ordinary load, such as a lamp or an audio device, is connected;

an auxiliary power source, which is connected to the generator, wherein the auxiliary power source recovers regenerative electric power, which is generated by the generator at time of deceleration of a vehicle, and the auxiliary power source stores electric power that is generated by the generator through driving of the generator by the engine;

a first supply circuit, which connects the auxiliary power source to the main power source and the ordinary load through a DC/DC converter;

a second supply circuit, which is in parallel with the first supply circuit and which connects the auxiliary power source to the main power source and the ordinary load through a switch; and

a control means for controlling operation of the DC/DC converter and operation of the switch, wherein the control means is enabled to select one of;

a first control state, in which the DC/DC converter is driven, and the switch is opened; and

a second control state, in which the DC/DC converter is stopped, and the switch is closed.

42. A vehicle power supply system comprising:

a generating means for generating regenerative energy at time of decelerating a vehicle;

a high-performance main power storage means for directly storing the regenerative energy, which is generated by the generating means, and for supplying electric power to an electrical load, which is mounted on the vehicle;

an auxiliary power storage means for receiving and storing the electric power supplied from the main power storage means, wherein the auxiliary power storage means has superior discharge characteristics at a low temperature over the main power storage means; and

a starting device power source switching means for selecting one or both of the main power storage means and the auxiliary power storage means as a power source based on an engine starting temperature to supply electric power to a starting device for starting an engine at time of starting the engine, wherein an engine temperature or an engine temperature related temperature, which is measured at the time of starting the engine, is called as the engine starting temperature.

43. The vehicle power supply system according to claim 42, wherein:

a temperature range below a predetermined temperature T1 is called as an extremely low temperature range;

a temperature range between the predetermined temperature T1 and a predetermined temperature T2 (T1<

T2) is called as a low temperature range;

a temperature range between the predetermined temperature T2 and a predetermined temperature T3 (T2<

T3) is called as a normal temperature range;

a temperature range above the predetermined temperature T3 is called as a high temperature range;

the starting device power source switching means selects the main power storage means when the engine starting temperature is in the normal temperature range; and

the starting device power source switching means switches to use both the main power storage means and the auxiliary power storage means when the engine starting temperature is in one of the extremely low temperature range and the high temperature range.

44. The vehicle power supply system according to claim 42, wherein the auxiliary power storage means supplies electric power to the starting device at the time of starting the engine when the engine starting temperature is in the low temperature range.

45. The vehicle power supply system according to claim 43, wherein:

the auxiliary power storage means supplies electric power to the electrical load, which requires a guaranteed voltage, when the main power storage means supplies electric power to the starting device at the time of starting the engine; and

the main power storage means supplies electric power to the electrical load, which requires the guaranteed voltage, when the auxiliary power storage means supplies electric power to the starting device at the time of starting the engine.

50. The vehicle power supply system according to claim 42, further comprising a charging circuit, which supplies electric power from the main power storage means to the auxiliary power storage means, wherein:

the charging circuit includes a DC/DC converter; and

the auxiliary power storage means is charged with a micro current, which is supplied from the main power storage means to the auxiliary power storage means through the DC/DC converter.

51. The vehicle power supply system according to claim 42, further comprising a charging circuit, which supplies electric power from the main power storage means to the auxiliary power storage means, wherein:

the charging circuit includes a relay switch; and

the auxiliary power storage means is charged with electric power supplied from the main power storage means when the relay switch is turned on.

52. The vehicle power supply system according to claim 50, wherein when a voltage difference between the main power storage means and the auxiliary power storage means is smaller than a predetermined value, the DC/DC converter is operated, so that the auxiliary power storage means is charged with electric power supplied from the main power storage means.

53. The vehicle power supply system according to claim 50, wherein the auxiliary power storage means is charged with electric power supplied from the main power storage means when the generating means stops its power generating operation.

54. The vehicle power supply system according to claim 42, further comprising:

a current sensing means that is provided in a conductor portion, which supplies electric power from the main power storage means to the starting device and the electrical load;

a current sensing means that is provided in a conductor portion, which supplies electric power from the main power storage means to the auxiliary power storage means; and

a voltage sensing means for sensing a voltage of the main power storage means, wherein a measured value of each current sensing means and a measured value of the voltage sensing means are compared with a measured value of the charge state of the main power storage means obtained through the state sensing means, so that a power consumption level and a charge level of the auxiliary power storage means are sensed with relatively high accuracy.

55. The vehicle power supply system according to claim 42, wherein when the charge state of the main power storage means deviates from a predetermined state, the main power storage means is switched to the auxiliary power storage means to supply electric power to the electrical load, which requires the guaranteed voltage.

56. The vehicle power supply system according to claim 42, wherein supply of a dark current is performed from the main power storage means after the engine is stopped through operation of a key by a driver.

71. The vehicle power supply system according to claim 51, wherein when a voltage difference between the main power storage means and the auxiliary power storage means is smaller than a predetermined value, the relay switch is turned on, so that the auxiliary power storage means is charged with electric power supplied from the main power storage means.

46. A vehicle power supply system comprising:

a generating means for generating regenerative energy at time of decelerating a vehicle;

a high-performance main power storage means for directly storing the regenerative energy, which is generated by the generating means, and for supplying electric power to an electrical load, which is mounted on the vehicle;

an auxiliary power storage means for receiving and storing the electric power supplied from the main power storage means, so that the auxiliary power storage means is charged, wherein the auxiliary power storage means has superior discharge characteristics at a low temperature over the main power storage means;

an automatic engine stopping/starting control device, which automatically controls stopping and restarting of an engine; and

a starting device power source switching means for selecting one of the auxiliary power storage means and the main power storage means as a power source to supply electric power to a starting device for starting the engine, wherein the starting device power source switching means selects the auxiliary power storage means at time of starting the engine first time and selects the main power storage means at time of restarting the engine through use of the automatic engine stopping/starting control device.

47. The vehicle power supply system according to claim 46, wherein:

the main power storage means provides electric power to the electrical load, which requires a guaranteed voltage, at the time of starting the engine first time; and

the auxiliary power storage means provides electric power to the electrical load, which requires the guaranteed voltage, at the time of restarting the engine through use of the automatic engine stopping/starting control device.

48. The vehicle power supply system according to claim 46, wherein the main power storage means provides electric power to the electrical load while the engine is automatically stopped.

49. The vehicle power supply system according to claim 48, further comprising a state sensing means for sensing a charge state of the main power storage means, wherein when it is determined that the main power storage means alone is not enough to supply start-up electric power to the starting device based on a sensed result of the state sensing means, the start-up electric power is supplied to the starting device from the auxiliary power storage means alone or from both the auxiliary power storage means and the main power storage means.

57. A vehicle power supply system comprising:

a generator, which is driven by an engine to generate electric power;

a first battery, which is charged with electric power generated by the generator;

a second battery, which has an output voltage lower than that of the first battery, wherein the second battery supplies electric power to a starter at time of starting the engine;

a charging circuit, which supplies electric power from one of the generator and the first battery to the second battery; and

an assist circuit, which provides power assistance from the first battery to the starter in addition to power supply from the second battery to the starter.

58. The vehicle power supply system according to claim 57, wherein the power assistance from the first battery is executed at a predetermined timing after initiation of the power supply from the second battery to the starter.

59. The vehicle power supply system according to claim 58, wherein the predetermined timing, at which the power assistance from the first battery is executed, is determined based on elapsed time since the time of starting the engine or based on transition of a voltage value of the second battery.

60. The vehicle power supply system according to claim 57, an internal resistance per unit capacity of the first battery is smaller than that of the second battery.

61. The vehicle power supply system according to claim 58, wherein the power assistance from the first battery is stopped when the voltage of the first battery is lower than a predetermined value.

62. The vehicle power supply system according to claim 57, wherein the second battery has superior low-temperature discharge characteristics over the first battery.

63. The vehicle power supply system according to claim 57, wherein:

the charging circuit includes an ON-OFF means for turning on and turning off supply of the electric power to the second battery at a certain time ratio; and

the assist circuit includes one of a relay and a semiconductor switch.

64. The vehicle power supply system according to claim 63, wherein the ON-OFF means, which is provided in the charging circuit, is an electronic switching device that uses a semiconductor.

65. The vehicle power supply system according to claim 63, wherein the ON-OFF means, which is provided in the charging circuit, is a DC/DC converter.

66. The vehicle power supply system according to claim 65, wherein the DC/DC converter is provided in the generator.

67. The vehicle power supply system according to claim 57, further comprising a distributor, which is connected to the first battery and the second battery to control an output voltage of the first battery and an output voltage of the second battery, wherein supply of electric power to an important load, which is involved in a basic running operation or a safety operation of a vehicle, is carried out through the distributor.

68. The vehicle power supply system according to claim 57, wherein the first battery stores regenerative energy, which is generated by the generator at time of decelerating a vehicle.

69. The vehicle power supply system according to claim 57, wherein the second battery provides dark current to an electrical load after the engine is stopped through operation of a key by a driver.

70. The vehicle power supply system according to claim 57, wherein the vehicle power supply system is applied to a vehicle that has an automatic engine stopping/starting control device, which automatically controls stopping and restarting of the engine.