Power Storage System

• US 20090015199A1
• Filed: 04/11/2006
• Published: 01/15/2009
• Est. Priority Date: 04/11/2006
• Status: Active Grant

• Current Assignee: Nexgen Control Systems LLC
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Kitanaka, Hidetoshi
• Granted Patent: US 7,772,806 B2
• Time in Patent Office: Days
• US Class Current: 320/118
• CPC Class Codes: B60L 2200/26 Rail vehicles
• CPC Class Codes: B60L 2210/10 DC to DC converters
• CPC Class Codes: B60L 2240/525 Temperature of converter or components thereof
• CPC Class Codes: B60L 2260/165 of converters
• CPC Class Codes: B60L 58/20 having different nominal voltages
• CPC Class Codes: H02H 3/32 involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors
• CPC Class Codes: H02H 3/33 using summation current transformers H02H3/347 takes precedence
• CPC Class Codes: H02H 7/1213 for DC-DC converters
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00306 Overdischarge protection
• CPC Class Codes: H02J 7/00309 Overheat or overtemperature protection
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

A power storage system capable of surely carrying out activation, operation, and stopping that are crucial and necessary in the use of the power storage system and appropriately addressing various kinds of abnormalities is provided. The power storage system regulates DC power from a DC power supply into prescribed voltage and current using a DC-DC converter unit for storage in a power storage unit. The power storage system includes a primary side current detecting unit, a primary side voltage detecting unit, a primary side switch unit, and a primary side filter unit on the DC power supply side (primary side) of the DC-DC converter, and a secondary side filter unit, a secondary side switch unit, a secondary side voltage detecting unit, and a secondary side current detecting unit on the power storage unit side (secondary side) of the DC-DC converter, and the on/off states of at least the primary side switch unit, the DC-DC converter unit, and the secondary side switch unit are controlled by a system control unit provided with an externally applied operation command and signals obtained from elements such as the primary side current detecting unit and the primary side voltage detecting unit.

Claims

1. A power storage system comprising:

a DC-DC converter unit regulating DC power from a DC power supply into prescribed voltage and current; and

a power storage unit storing DC power regulated by the DC-DC converter unit,

wherein the power storage system, on the DC power supply side (the primary side) of the DC-DC converter unit, includes;

a primary side current detecting unit for detecting a current of a main circuit;

a primary side voltage detecting unit for detecting a voltage of the main circuit;

a primary side switch unit for opening and closing the main circuit; and

a primary side filter unit for reducing harmonics of the main circuit,

the power storage system, on the power storage unit side (the secondary side) of the DC-DC converter unit, includes;

a secondary side filter unit for reducing harmonics of the main circuit;

a secondary side switch unit for opening and closing the main circuit;

a secondary side voltage detecting unit for detecting a voltage of the main circuit; and

a secondary side current detecting unit for detecting a current of the main circuit, and

the power storage system includes a system control unit for controlling on/off states of at least the primary side switch unit, the secondary side switch unit and the DC-DC converter unit, inputted operational commands from outside of the power storage system and signals from the primary side current detecting unit, the primary side voltage detecting unit, the primary side switch unit, the primary side filter unit, the DC-DC converter unit, the secondary side filter unit, the secondary side switch unit, the secondary side voltage detecting unit, the secondary side current detecting unit and the power storage unit.

2. The power storage system according to claim 1, wherein the primary side filter unit includes a reactor connected in series with the main circuit and a primary side capacitor connected between the positive and negative sides of the main circuit,

the secondary side filter unit includes a reactor connected in series with the main circuit and a secondary side capacitor connected between the positive and negative sides of the main circuit, and

the power storage system further comprises a discharge circuit unit for discharging the primary side capacitor and the secondary side capacitor separately or simultaneously in response to a command from the system control unit.

3. The power storage system according to claim 2, wherein the primary side current detecting unit, the primary side voltage detecting unit, the primary side switch unit and the primary side filter unit are arranged in series,

the power storage system further comprises a breaking unit having current breaking means between the DC power supply and the primary side current detecting unit.

4. The power storage system according to claim 3, wherein the secondary side filter unit, the secondary side switch unit, the secondary side voltage detecting unit and the secondary side current detecting unit are arranged in series,

the power storage system further comprises a protective unit having current breaking means between the secondary side current detecting unit and the power storage unit.

5. The power storage system according to claim 3, wherein the breaking unit includes a switch having a main contact and an auxiliary contact mechanically coupled thereto the main contact.

6. The power storage system according to claim 1, wherein the primary side switch unit has means for opening and closing the positive side of the main circuit.

7. The power storage system according to claim 6, wherein the primary side switch unit includes a switch having a main contact and an auxiliary contact mechanically coupled thereto the main contact.

8. The power storage system according to claim 7, wherein the primary side switch unit includes a circuit having the switch and a charging resistor connected to the switch.

9. The power storage system according to claim 1, wherein the primary side current detecting unit has means for detecting the difference between current flows through a positive side line and current flows through a negative side line.

10. The power storage system according to claim 2, wherein each of the primary side filter unit and the secondary side filter unit has a noise filter.

11. The power storage system according to claim 1, wherein the DC-DC converter unit includes a bidirectional buck-boost converter circuit.

12. The power storage system according to claim 1, wherein the DC-DC converter unit includes a bidirectional buck converter circuit.

13. The power storage system according to claim 1, wherein the secondary side switch unit has means for opening and closing only the positive side or both the positive side and the negative side of the main circuit.

14. The power storage system according to claim 13, wherein the secondary side switch unit includes a switch having a main contact and an auxiliary contact mechanically coupled thereto the main contact.

15. The power storage system according to claim 14, wherein the secondary side switch unit includes a circuit having the switch and a charging resistor connected to the switch.

16. The power storage system according to claim 1, wherein the secondary side current detecting unit has means for detecting the difference between current flows through a positive side line and current flows through a negative side line.

17. The power storage system according to claim 4, wherein the protective unit includes means for detecting the state of the current breaking means.

18. The power storage system according to claim 1, wherein the power storage unit includes a plurality of cells connected in series-parallel and a status signal from a monitor device for detecting the state of the plurality of cells is inputted to the system control unit.

19. The power storage system according to claim 5, wherein the system control unit determines that the breaking unit turns on normally by receiving an auxiliary contact signal from the breaking unit after the system control unit outputs a closing command to the breaking unit.

20. The power storage system according to claim 7, wherein the system control unit determines that the primary side switch unit turns on normally by receiving an auxiliary contact signal from the primary side switch unit after the system control unit outputs a closing command to the primary side switch unit.

21. The power storage system according to claim 2, wherein the system control unit recognizes the completion of the charging of the primary side capacitor when a prescribed period elapses after difference between a value detected by the primary side voltage detecting unit and a voltage of the primary side capacitor becomes a prescribed value or less.

22. The power storage system according to claim 11, wherein the secondary side capacitor built in the secondary side filter unit is charged by the output of the bidirectional buck-boost converter circuit when the power storage system is activated with DC power from the DC power supply.

23. The power storage system according to claim 12, wherein the primary side capacitor built in the primary side filter unit is charged by the power of the power storage unit when the power storage system is activated with DC power from the power storage unit.

24. The system according to claim 2, wherein the system control unit recognizes the completion of the charging of the secondary side capacitor when a prescribed period elapses after difference between a value detected by the secondary side voltage detecting unit and a voltage of the secondary side capacitor becomes a prescribed value or less.

25. The power storage system according to claim 14, wherein the system control unit determines that the secondary side switch unit turns on normally by receiving an auxiliary contact signal from the secondary side switch unit after the system control unit outputs a closing command to the secondary side switch unit.

26. The power storage system according to claim 1, wherein the system control unit controls the current of the DC-DC converter unit to be zero after determining that the primary side switch unit and the secondary side switch unit turn on normally.

27. The power storage system according to claim 1, wherein in order to stop the power storage system, the system control unit controls the DC-DC converter unit so that the current of the DC-DC converter unit is gradually reduced at a prescribed rate to be zero and wherein switching elements built in the DC-DC converter unit are turned off after the current become zero.

28. The power storage system according to claim 1, wherein the system control unit turns off the primary side switch unit and the secondary side switch unit after switching elements built in the DC-DC converter unit are turned off.

29. The power storage system according to claim 4, wherein the system control unit detects abnormalities based on signals from the breaking unit, the primary side current detecting unit, the primary side voltage detecting unit, the primary side switch unit, the primary side filter unit, the DC-DC converter unit, the secondary side filter unit, the secondary side switch unit, the secondary side switch unit, the secondary side voltage detecting unit, the secondary side current detecting unit, the protective unit and the power storage unit and

the system control unit, according to the content of the abnormality, controls at least one of the breaking unit, the primary side switch unit, the DC-DC converter unit, the discharge circuit unit and the secondary side switch unit.

30. The power storage system according to claim 29, wherein when the content of the abnormality indicates that the primary side current detecting unit detects the difference between current flows through a positive side line and current flows through a negative side line is a prescribed value or more, or when the secondary side current detecting unit detects the difference between current flows through a positive side line and current flows through a negative side line is a prescribed value or more, the system control unit turns off at least the primary side switch unit, the secondary side switch unit and the DC-DC converter unit and turn on the discharge circuit unit connected to the primary side switch unit and the secondary side switch unit.

31. The power storage system according to claim 29, wherein when the abnormality exists in any of the breaking unit, the primary side switch unit and the secondary side switch unit, the system control unit turns off at least the primary side switch unit, the secondary side switch unit and the DC-DC converter unit and turn on the discharge circuit unit.

32. The power storage system according to claim 29, wherein when the content of the abnormality indicates that a charging abnormality in the primary side capacitor or the secondary side capacitor, the system control unit turns off at least the primary side switch unit, the secondary side switch unit and the DC-DC converter unit and turn on the discharge circuit unit.

33. The power storage system according to claim 29, wherein when the content of the abnormality indicates that over voltage occurs on the primary side capacitor or the secondary side capacitor, the system control unit turns off at least the primary side switch unit, the secondary side switch unit and the DC-DC converter unit and turn on the discharge circuit unit.

34. The power storage system according to claim 29, wherein when the content of the abnormality indicates that over current flows through the DC-DC converter unit, the system control unit turns off the DC-DC converter unit.

35. The power storage system according to claim 29, wherein when the content of the abnormality indicates that temperature of the DC-DC converter unit is abnormal, the system control unit turns off the DC-DC converter unit.

36. The power storage system according to claim 29, wherein when the abnormality occurs on a switching element in the DC-DC converter unit, the system control unit turns off at least the primary side switch unit, the secondary side switch unit and the DC-DC converter unit and turn on the discharge circuit unit.

37. The power storage system according to claim 29, wherein when the content of the abnormality indicates that self opening of the breaking unit, the system control unit turns off at least the primary side switch unit, the secondary side switch unit and the DC-DC converter unit and turn on the discharge circuit unit.

38. The power storage system according to claim 29, wherein when the content of the abnormality indicates that self opening of the protective unit, the system control unit turns off at least the primary side switch unit, the secondary side switch unit and the DC-DC converter unit and turn on the discharge circuit unit.

39. The power storage system according to claim 29, wherein when the abnormality occurs on the power storage unit, the system control unit turns off at least the primary side switch unit, the secondary side switch unit and the DC-DC converter unit and turn on the discharge circuit unit.

40. The power storage system according to claim 29, wherein when the system control unit detects an abnormality, the system control unit stores the content of the abnormality and notifies an external device of the abnormality.

41. The power storage system according to claim 29, wherein the system control unit divides the abnormalities, based on their contents, into a plurality of categories, the abnormalities are divided at least into those that allow automatic reactivation to be carried out after stopping caused by the abnormality detection and those that allow reactivation to be carried out only after manual resetting operation is performed.