State-of-charge adjusting apparatus

• US 7,859,227 B2
• Filed: 07/18/2007
• Issued: 12/28/2010
• Est. Priority Date: 08/11/2006
• Status: Active Grant

• Current Assignee: Yazaki Corporation
• Original Assignee: Yazaki Corporation
• Inventors: Saigo, Tsutomu
• Primary Examiner(s): Tso; Edward
• Assistant Examiner(s): Fantu; Yalkew
• Application Number:
  US11/826,702
• Publication Number:
  US 20080036424A1
• Time in Patent Office: 1,259 Days
• Field of Search: 320/136
• US Class Current: 320/136
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 10/482 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/0025 Sequential battery discharge in systems with a plurality of batteries
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

The state-of-charge adjusting apparatus which enables to shorten a time to reach a capacity equalization is provided. A CPU extracts a block consisting of a plurality of unit cells connected continuously to each other, the plurality of the unit cells each having a voltage higher than a target voltage, and connects both ends of each block to a discharge resistance to make each block discharge. Thereafter, the CPU extracts a unit cell having a voltage higher than the target voltage and connects both ends of the extracted unit cell to the discharge resistance to make the extracted unit cell discharge until the voltage of the extracted unit cell reaches the target voltage.

Claims

1. A state-of-charge adjusting apparatus comprising:

a voltage detecting means for detecting each voltage of a plurality of unit cells, the plurality of the unit cells consisting of secondary batteries connected in series;

a discharge resistance connectable to at least one of the unit cells for discharging at least one of the unit cells; and

a capacity equalizing means for controlling discharge of the plurality of the unit cells through the discharge resistance on the basis of a voltage of each unit cell detected by the voltage detecting means so that the voltage values of the plurality of the unit cells become uniform,

wherein the capacity equalizing means includes;

(a) a block extracting means which extracts a block consisting of a plurality of unit cells connected continuously to each other, said plurality of the unit cells each having a voltage higher than a target voltage;

(b) a first equalizing discharge means which then connects both ends of said block extracted by the block extracting means to the discharge resistance so as to discharge said extracted block;

(c) a unit cell extracting means which extracts a unit cell having a voltage higher than the target voltage after action of the first equalizing discharge means is finished; and

(d) a second equalizing discharge means which then connects both ends of the unit cell extracted by the unit cell extracting means to the discharge resistance so as to discharge the extracted unit cell until the voltage of the extracted unit cell reaches the target voltage;

wherein the capacity equalizing means further includes a first discharge control means which makes the block extracting means and the first equalizing discharge means act repeatedly in sequence when the block extracting means extracts the block, until no blocks having a voltage higher than the target voltage are present and makes the first equalizing discharge means finish to act when the block extracting means does not extract the block any more, and then, following the absence of blocks having a voltage higher than the target voltage, makes the unit cell extracting means and the second equalizing discharge means act repeatedly in sequence when the unit cell extracting means extracts the unit cell, until no unit cells having a voltage higher than the target voltage are present, and makes the second equalizing discharge means finish to act when the unit cell extracting means does not extract the unit cell anymore.

2. The apparatus according to claim 1, wherein the first equalizing discharge means connects both ends of said each block to the discharge resistance so as to discharge said each block for a first predetermined time period.

3. The apparatus according to claim 1, wherein the block extracting means extracts a block per group, said groups being obtained by dividing the plurality of the unit cells into groups of unit cells, each group of unit cells having less unit cells than said plurality of unit cells.

4. The apparatus according to claim 1, wherein the second equalizing discharge means includes:

a discharge means which discharges the unit cell for a second predetermined time period; and

a second discharge control means which makes the discharge means repeat a discharge until a voltage of the unit cell reaches the target voltage, the voltage detecting means detecting said voltage of the unit cell whenever a discharge by the discharge means finishes.