EQUALIZATION DEVICE, EQUALIZATION PROCESSING PROGRAM, BATTERY SYSTEM, ELECTRIC VEHICLE AND EQUALIZATION PROCESSING METHOD

• US 20110127963A1
• Filed: 11/30/2010
• Published: 06/02/2011
• Est. Priority Date: 11/30/2009
• Status: Active Grant

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: FURUKAWA, Kimihiko, YAMAUCHI, Yutaka, MURAO, Hiroya
• Granted Patent: US 8,497,661 B2
• Time in Patent Office: Days
• US Class Current: 320/118
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 58/19 Switching between serial connection and parallel connection of battery modules
• CPC Class Codes: B60L 58/22 Balancing the charge of battery modules
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A battery ECU acquires open circuit voltages of a plurality of battery cells that are divided into a plurality of groups A, B, C using a plurality of detecting units, and calculates SOCs of the battery cells based on the open circuit voltages. Then, the battery ECU selects the group to which the battery cell having the largest SOC among the SOCs of the plurality of battery cells belongs, and selects the battery cell to be discharged in the selected group. A series circuit composed of a resistor and a switching element is connected in parallel with each battery cell. The battery ECU turns on the switching element corresponding to the selected battery cell. At this time, the battery cell is connected to the resistor, thus being discharged.

Claims

1. An equalization device arranged to perform equalization processing of charge states of a plurality of battery cells that are connected in series, wherein

said plurality of battery cells are divided into a plurality of groups,

said equalization device comprising:

a detector arranged to detect the charge states of said plurality of battery cells;

a selector arranged to select any of said plurality of groups based on the charge states detected by said detector; and

an equalization processing unit arranged to perform the equalization processing by selectively causing the battery cells that belong to the group selected by said selector to discharge.

2. The equalization device according to claim 1, wherein

said selector selects the group to which the battery cell having a highest charge state among the charge states of the plurality of battery cells detected by said detector belongs.

3. The equalization device according to claim 1, wherein

said detector includes a plurality of detecting units corresponding to said plurality of groups, respectively, and

each of said plurality of detecting units is configured to detect the charge states of the battery cells that belong to the corresponding group.

4. The equalization device according to claim 1, wherein

said plurality of battery cells are divided into said plurality of groups such that each two of the battery cells that are connected adjacent to each other belong to different groups.

5. The equalization device according to claim 1, wherein

said plurality of groups include a first group to an M-th group, M is a natural number of not less than two, said plurality of battery cells include a first battery cell to an N-th battery cell sequentially arranged from one end to the other end of series connection, and N is a natural number of not less than 2M, and

said plurality of battery cells are divided into said plurality of groups such that when a remainder resulting from dividing i by M is k, an arbitrary i-th battery cell belongs to a “

k+1-th”

group.

6. The equalization device according to claim 1, wherein said charge state is any of a rate of charge, a remaining capacity, a voltage, a depth of discharge, a current integrated value and a difference of an amount of stored charges.

8. A battery system comprising:

a plurality of battery cells that are connected in series; and

the equalization device according to claim 1.

9. An electric vehicle comprising:

a plurality of battery cells that are connected in series and divided into a plurality of groups;

the equalization device according to claim 1;

a motor driven by electric power supplied from said plurality of battery cells; and

a drive wheel rotated by a torque generated by said motor.

7. An equalization processing program that is executable by a computer for performing equalization processing of charge states of a plurality of battery cells that are connected in series and divided into a plurality of groups, causing said computer to execute the processes of:

acquiring the charge states of said plurality of battery cells;

selecting any of said plurality of groups based on the acquired charge states; and

performing the equalization processing by selectively causing the battery cells that belong to the selected group to discharge.

10. An equalization processing method for performing equalization processing of charge states of a plurality of battery cells that are connected in series and divided into a plurality of groups, comprising the steps of:

acquiring the charge states of said plurality of battery cells;

selecting any of said plurality of groups based on the acquired charge states; and

performing the equalization processing by selectively causing the battery cells that belong to the selected group to discharge.