STATE OF CHARGE OPTIMIZING DEVICE AND ASSEMBLED BATTERY SYSTEM INCLUDING SAME

• US 20090085520A1
• Filed: 09/25/2008
• Published: 04/02/2009
• Est. Priority Date: 09/27/2007
• Status: Active Grant

• Current Assignee: Panasonic Energy (Shanghai) Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: MURAO, Hiroya
• Granted Patent: US 8,143,852 B2
• Time in Patent Office: Days
• US Class Current: 320/134
• CPC Class Codes: H02J 7/0014 Circuits for equalisation of charge between batteries
• 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 state of charge optimizing device according to the present invention optimizes a state of charge of each of a plurality of cells which are connected in series to form an assembled battery, and conducts the optimization by discharging or charging a part or all of the plurality of cells so that the differences between the amount of charge after the optimization and the amount of charge in a predetermined state of charge become uniform.

Claims

1. A state of charge optimizing device for optimizing a state of charge of each cell of a plurality of cells which are connected in series to form an assembled battery, wherein the device sets an optimization target value in accordance with a full charging capacity for each cell of a part or all of the plurality of cells, and conducts optimization by conducting discharging or charging in accordance with the set optimization target value.

2. The state of charge optimizing device according to claim 1, wherein the optimization target value is an amount of charge, or a value corresponding thereto, such that the difference between the amount of charge after optimization and the amount of charge in a predetermined state of charge is uniform among the plurality of cells.

3. The state of charge optimizing device according to claim 2, wherein the predetermined state of charge is set so that both a discharge characteristic and a charge characteristic of the assembled battery are favorable and well balanced.

4. The state of charge optimizing device according to claim 2, comprising:

a charging and discharging unit capable of charging and/or discharging each cell;

an amount of charge difference calculating unit calculating the difference between the current amount of charge and the amount of charge in the predetermined state of charge for at least one of the plurality of cells;

an optimization target value setting unit setting an optimization target value in accordance with the amount of charge difference calculated by the amount of charge difference calculating unit for each cell of a part or all of the plurality of cells; and

an optimizing processing unit making the charging and discharging unit conduct charging or discharging in accordance with the set optimization target value for each cell of a part or all of the plurality of cells when the optimization target value is set.

5. The state of charge optimizing device according to claim 4, wherein the optimization target value setting unit sets the optimization target value for each of the cells other than a reference cell which is the at least one cell of the plurality of cells, the optimization target value setting unit comprising:

a first processing unit adding the amount of charge difference of the reference cell calculated by the amount of charge difference calculating unit to the amount of charge in the predetermined state of charge for each of the cells other than the reference cell; and

a second processing unit setting the optimization target value to the amount of charge calculated by the first processing unit or a value corresponding thereto for each of the cells other than the reference cell.

6. The state of charge optimizing device according to claim 5, wherein the value corresponding to the amount of charge is a state of charge or a cell voltage, and the second processing unit of the optimization target value setting unit converts the amount of charge calculated by the first processing unit into a state of charge or a cell voltage and then sets the state of charge or the cell voltage obtained from the conversion as the optimization target value.

7. The state of charge optimizing device according to claim 5, wherein the amount of charge difference calculating unit calculates the amount of charge difference by subtracting the amount of charge in the predetermined state of charge from the current amount of charge for each of the cells that form the assembled battery, and the optimization target value setting unit specifies a cell with the smallest amount of charge difference calculated by the amount of charge difference calculating unit as the reference cell from the plurality of cells that form the assembled battery.

8. The state of charge optimizing device according to claim 4, wherein the amount of charge difference calculating unit calculates the difference between the current amount of charge and the amount of charge in the predetermined state of charge for each of the cells that form the assembled battery, the state of charge optimizing device comprising:

an identifying unit identifying a maximum value and a minimum value from the amount of charge difference calculated by the amount of charge difference calculating unit;

a calculating unit calculating the difference between the maximum value and the minimum value identified by the identifying unit; and

a determination unit determining whether or not a value calculated by the calculating unit is above a predetermined threshold,

the optimization target value setting unit setting the optimization target value when the calculated value is determined to be above the predetermined threshold by the determination unit.

9. An assembled battery system comprising an assembled battery that includes a plurality of cells connected in series, and the state of charge optimizing device according to claim 1.