Cell balance adjusting circuit, abnormal cell voltage detecting circuit, method of adjusting cell balance, and method of detecting abnormal cell voltage

• US 6,459,236 B2
• Filed: 12/20/2000
• Issued: 10/01/2002
• Est. Priority Date: 12/20/1999
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Kawashima, Shingo
• Primary Examiner(s): Tso, Edward H.
• Assistant Examiner(s): TIBBITS, PIA FLORENCE
• Application Number:
  US09/739,892
• Publication Number:
  US 20020017895A1
• Time in Patent Office: 650 Days
• Field of Search: 320/118
• US Class Current: 320/118
• CPC Class Codes: H02J 7/0019 using switched or multiplexed charge circuits
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A cell balance adjusting circuit includes a series connection of basic cells; and a voltage holder connected through a switching circuit to individual terminals of the basic cells, wherein the switching circuit shows a switching operation to provide a parallel connection between an intermediate point between adjacent two of the basic cells and the voltage holder, and the switching circuit shows a unidirectional sequential scanning of the switching operation to all of the basic cells, and the switching circuit repeats the unidirectional sequential scanning.

Claims

1. A cell balance adjusting circuit comprising:

a series connection of basic cells;

a switching circuit connected to all the terminals of the basic cells; and

a voltage holder connected, via the switching circuit, to the series connection of basic cells,

the switching circuit comprising a first set of switches and a second set of switches,

the first set of switches connecting a first terminal of the voltage holder with a first side terminal of each basic cell, and

the second set of switches connecting a second terminal of the voltage holder with a second side terminal of each basic cell,

wherein the first and second set of switches are operable to place a current basic cell in a parallel connection with the voltage holder by repeatedly proceeding from a first cell of the series connection of basic cells to a final cell of the series connection of basic cells.

2. The cell balance adjusting circuit of claim 1, further comprising:

a switch control circuit connected to each of the switches for controlling individual switching operations of the switches so that elements of the first and second set of switches individually place each basic cell of the series connection of basic cells in parallel connection with the voltage holder by repeatedly proceeding from the first cell to the final cell.

3. The cell balance adjusting circuit of claim 2, further comprising:

a voltage judging circuit;

the first voltage holder switch connecting the first terminal of the voltage holder with a first side of the voltage judging circuit; and

the second voltage holder switch connecting the first terminal of the voltage holder with a second side of the voltage judging circuit,

the voltage judging circuit being connected repeatedly proceeding from a first cell of the series connection of basic cells to a final cell of the series connection of basic cells, via the first and second voltage holder switches, with the voltage holder after the switch control circuit connects and releases each of basic cells in parallel connection with the voltage holder,

the voltage judging circuit detecting a voltage of the voltage holder after a previous one of the basic cells has been disconnected from the voltage holder and before a next one of the basic cells is connected to the voltage holder.

4. The cell balance adjusting circuit of claim 3, wherein the first and second voltage holder switches have a higher withstand voltage than the switching circuit.

5. The cell balance adjusting circuit of claim 1, wherein each switch comprises a switching transistor.

6. The cell balance adjusting circuit of claim 1, wherein each switch comprises a mechanical switch.

7. The cell balance adjusting circuit of claim 1, wherein the voltage holder comprises a capacitor.

8. The cell balance adjusting circuit of claim 1, wherein the voltage holder comprises a secondary battery cell having the same structure as the basic cells.

9. A method of adjusting a cell balance of series-connected basic cells connected to a voltage holder through a switching circuit connected to all the terminals of the basic cells, comprising the step of:

repeatedly sequentially proceeding from a first cell of the series-connected basic cells to a final cell of the series-connected basic cells to individually place each basic cell in a parallel connection with the voltage holder.

10. The method of claim 9, wherein each basic cell is placed in parallel connection with the voltage holder with the switching circuit comprising a first set of switches and a second set of switches,

the first set of switches connecting a first terminal of the voltage holder with a first side terminal of each basic cell, and

the second set of switches connecting a second terminal of the voltage holder with a second side terminal of each basic cell,

the first and second set of switches being operated to individually place each basic cell in parallel connection with the voltage holder.

11. The method of claim 10, wherein the step of individually placing each basic cell in parallel connection with the voltage holder is executed using a switch control circuit connected to each of the switches for controlling individual switching operations of the switches so that elements of the first and second set of switches individually place each basic cell of the series connection of basic cells in parallel connection with the voltage holder by repeatedly proceeding from the first cell to the final cell.

12. The method of claim 10, wherein the step of individually placing each basic cell in parallel connection with the voltage holder is executed using a switching transistor as one of the switches.

13. The method of claim 10, wherein the step of individually placing each basic cell in parallel connection with the voltage holder is executed using a mechanical switch as one of the switches.

14. The method of claim 9, wherein the step of individually placing each basic cell in parallel connection with the voltage holder is executed using a capacitor within the voltage holder.

15. The method of claim 9, wherein the step of individually placing each basic cell in parallel connection with the voltage holder is executed using a secondary battery cell having the same structure as the basic cells as part of the voltage holder.

16. The method of claim 9, wherein the step of individually placing each basic cell in parallel connection with the voltage holder includes the further step of placing a voltage judging circuit in connection with the voltage holder after each basic cell connects with and releases from the parallel connection with the voltage holder,

wherein the voltage judging circuit detects a voltage of the voltage holder.

17. The method of claim 16, wherein the step of placing a voltage judging circuit in connection with the voltage holder is accomplished via operation of a connection circuit connecting the voltage judging circuit in parallel with the voltage holder.

18. The method of claim 17, wherein the step of placing a voltage judging circuit in connection with the voltage holder is accomplished using the connection circuit with a higher withstand voltage than the switching circuit.