Apparatus for regulating state of charge of cells of battery set

• US 5,998,969 A
• Filed: 05/12/1998
• Issued: 12/07/1999
• Est. Priority Date: 05/12/1997
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Origuchi, Masato, Tsuji, Tadashi
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): LUK, LAWRENCE W
• Application Number:
  US09/076,106
• Time in Patent Office: 574 Days
• Field of Search: 320/132, 320/149, 320/116, 320/118, 320/119, 320/130
• US Class Current: 320/132
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits

Abstract

There is disclosed an apparatus for precisely regulating, with a simple structure, a state of charge of each of cells constituting a battery set. In the apparatus, a detection circuit, a plurality of discharge circuit connected to corresponding one of the cells, respectively, and a control circuit are provided. The detection circuit detects open-circuit voltage of each of the plurality of cells, the plurality of discharge circuit discharges a charging electricity charged in the cells, and the control circuit controls to uniform the state of charge of each of the cells, utilizing the discharge circuit respectively corresponding to each of the cells, based on the open-circuit voltage of each of the cells detected by the detection circuit.

Claims

1. An apparatus for regulating a state of charge of each of cells of a battery set wherein the cells are serially connected to each other, comprising:

an open-circuit voltage detection circuit detecting an open-circuit voltage of each of said cells;

a plurality of discharge circuits respectively connected to each of said cells;

a plurality of discharge circuits respectively connected to each of said cells so as to discharge an electric charge charged in a corresponding one of said cells; and

a control circuit which unifies a state of charge of each of said cells, utilizing a corresponding one of said plurality of discharge circuits, based on said open-circuit voltage of each of said cells detected by said detection circuit.

2. An apparatus for regulating a state of charge of each of cells of battery set according to claim 1, wherein said control circuit controls to unify the state of charge of each of said cells when said battery set is discharged, when said battery set is charged, or when said battery set is in a cessation state.

3. An apparatus for regulating a state of charge of each of cells of battery set wherein the cells are serially connected to each other, comprising:

a detection circuit detecting an open-circuit voltage of each of said cells;

a plurality of discharge circuits respectively connected to each of said cells;

a plurality of discharge circuits respectively connected to each of said cells so as to discharge an electric charge charged in a corresponding one of said cells; and

a control circuit which unifies a state of charge of each of said cells, utilizing a corresponding one of said plurality of discharge circuits, based on said open-circuit voltage of each of said cells detected by said detection circuit; and

wherein said control circuit obtains a frequency distribution of said open-circuit voltage of each of said cells detected by said detection circuiting, and quantifies said frequency distribution so as to conduct a statistical processing, thereby calculating a discharge capacity in order to unify said state of charge of each of said cells.

4. An apparatus for regulating a state of charge of each of cells of a battery set according to claim 3, wherein said control circuit regards said frequency distribution as a normal distribution, sets a regulation target voltage and discharges each of said cells using said discharge circuit such that a terminal voltage of each of said cells becomes equal to said regulation target voltage, and wherein said regulation target voltage is set based on an average value of said open-circuit voltages of said cells detected by said detection circuit, and based on a standard deviation of said open-circuit voltages.

5. An apparatus for regulating a state of charge of each o cells of a battery set according to claim 4, wherein said discharge circuit is a serial circuit comprising a resistor and a switch, and wherein said control circuit intermittently closes said switch of said discharge circuit to discharge of each of said cells.

6. An apparatus for regulating a state of charge of each cells of a battery set according to claim 3, wherein said control circuit comprises a first calculation circuit which obtains a predetermined statistical value by quantifying said frequency distribution so as to conduct a statistical processing, and a second calculation circuit which calculates a necessary amount of discharge for each of said cells based on said predetermined statistical value obtained by said first calculation circuit, and wherein said detection circuit, said discharge circuit and said second calculation circuit are integrally formed with said battery set and said first calculation circuit is disposed outside said battery set so as to be substantially insulated from said detection circuit, said discharge circuit and said second calculation circuit.

7. An apparatus for regulating a state of charge of each of cells of battery set wherein the cells are serially connected to each other, comprising:

a detection circuit detecting an open-circuit voltage of each of said cells;

a plurality of discharge circuits respectively connected to each of said cells;

a plurality of discharge circuits respectively connected to each of said cells so as to discharge an electric charge charged in a corresponding one of said cells; and

a control circuit which unifies a state of charge of each of said cells, utilizing a corresponding one of said plurality of discharge circuits, based on said open-circuit voltage of each of said cells detected by said detection circuit; and

wherein a threshold value for judging an abnormality is set based on said open-circuit voltage of each of said cells detected by said detection circuit, and wherein any of said cells having open-circuit voltage exceeding said threshold value is deleted from an object to be regulated.