Battery system monitoring apparatus

Patent metadata

Field	Value
Publication number	US-9340122-B2
Application number	US-201114122463-A
Country	US
Kind code	B2
Filing date	Aug 18, 2011
Priority date	May 31, 2011
Publication date	May 17, 2016
Grant date	May 17, 2016

Abstract

A battery system monitoring apparatus that monitors a battery system is provided having a cell group having a plurality of unit cells connected in series, including: a first control device that controls the cell group; and a plurality of voltage detection lines that connect positive electrodes and negative electrodes of the unit cells to the first control device, for measuring inter-terminal voltages of the unit cells. The first control device includes a balancing switch connected between the voltage detection line connected to the positive electrode of each unit cell and the voltage detection line connected to the negative electrode thereof for conducting balancing discharge of the unit cell, for each of the unit cells. A first resistor is disposed in series with each of the voltage detection lines, a first capacitor is connected between the voltage detection line, and a GND which is a lowest-level potential of the cell group.

First claim

The invention claimed is:

1. A battery system monitoring apparatus for a battery system having a cell group having a plurality of unit cells connected in series, the battery system monitoring apparatus comprising:
a first control device that is disposed in correspondence with the cell group;
a plurality of voltage detection lines that are disposed to connect a positive electrode and a negative electrode of each unit cell of the unit cells to the first control device, and input an inter-terminal voltage of each unit cell of the unit cells to the first control device;
a first resistor disposed in series with each of the voltage detection lines;
a first capacitor connected to each of the voltage detection lines; and
a balancing discharge circuit disposed in correspondence with each unit cell of the unit cells and discharging said each unit cell when said each unit cell is discharged,
wherein the first capacitor is connected between the voltage detection lines in a position between the first resistor and the first control device, and the first capacitor is connected to a part which is a lowest-level potential of the cell group on a side opposite to a side connected to the voltage detection line,
wherein the balancing discharge circuit includes a balancing switch turned on or off when the unit cell is discharged, and a second resistor connected in series with the balancing switch, and
wherein the balancing discharge circuit is connected to the voltage detection line connected to the positive electrode of the unit cell and the voltage detection line connected to the negative electrode of the unit cell in a position on a side of the cell group with respect to the first resistor.

2. The battery system monitoring apparatus according to claim 1 ,
wherein the first control device includes:
a selection unit that selects the positive electrode and the negative electrode of one unit cell of the plurality of unit cells to be measured for an inter-terminal voltage, and outputs a potential of each of the positive electrode and the negative electrode of the one unit cell;
a voltage measurement unit that measures the inter-terminal voltage of the one unit cell according to the potential of each of the positive electrode and the negative electrode of the one unit cell, which is output from the selection unit;
a voltage comparison unit that compares the inter-terminal voltage of the one unit cell, which is measured by the voltage measurement unit, with a given voltage threshold value;
a first storage unit that stores a comparison result of the voltage comparison unit therein;
a determination unit that determines a disconnection of the voltage detection line based on the comparison result stored in the first storage unit; and
a second storage unit that stores a determination result of the determination unit therein.

3. The battery system monitoring apparatus according to claim 2 ,
wherein the determination unit determines whether the voltage detection line connected to the one unit cell is disconnected or not based on the inter-terminal voltage of the one unit cell, which is detected when the first balancing switch corresponding to the one unit cell, and a second balancing switch corresponding to a unit cell connected adjacent to and in series with the one unit cell are turned on or off, and
wherein the determination result of the disconnection of the voltage detection line connected to the one unit cell is stored in the second storage unit.

4. The battery system monitoring apparatus according to claim 3 ,
wherein the first control device sequentially measures the inter-terminal voltages with respect to all of the unit cells in the cell group,
wherein the determination unit determines whether the disconnection is present in all of the voltage detection lines that connect the cell group to the first control device or not based on a measurement result of the inter-terminal voltages of all of the unit cells, and
wherein the determination results of the disconnection of all of the voltage detection lines are stored in the second storage unit.

5. The battery system monitoring apparatus according to claim 1 ,
wherein the first control device further includes:
a balancing current detection unit that is disposed in correspondence to each of the unit cells and detects whether a balancing current flowing into the balancing discharge circuit corresponding to the unit cell is present or not when the balancing switch corresponding to the unit cell is turned on,
a first storage unit that stores a detection result detected by the balancing current detection unit,
a determination unit that determines a disconnection of the voltage detection line based on the detection result stored in the first storage unit, and
a second storage unit that stores a determination result of the determination unit therein,
wherein the determination unit determines whether the voltage detection line connected to one unit cell of the plurality of unit cells is disconnected or not on the basis of the presence or absence of the balancing current flowing into the balancing discharge circuit corresponding to the one unit cell when the first balancing switch corresponding to the one unit cell is turned on, and the second balancing switch corresponding to a unit cell connected adjacent to and in series with the one unit cell is turned off, and
wherein a determination result of the disconnection of the voltage detection line connected to the one unit cell is stored in the second storage unit.

6. The battery system monitoring apparatus according to claim 5 ,
wherein the first control device sequentially detects whether the balancing current is present in correspondence with all of the unit cells in the cell group or not,
wherein the determination unit determines whether the disconnection is present in all of the voltage detection lines that connect the cell group to the first control device or not based on detection results of whether the balancing current is present in correspondence with all of the unit cells or not, and
wherein all of the determination results are stored in the second storage unit.

7. The battery system monitoring apparatus according to claim 5 ,
wherein the balancing current detection unit includes: a reference voltage source;
a comparator that compares the inter-terminal voltage of the balancing switch corresponding to the unit cell with a reference voltage output from the reference voltage source to detect whether the balancing current flowing into the balancing discharge circuit corresponding to the unit cell is present or not; and
an input switching unit that reverses inputs of the reference voltage and a terminal voltage of the balancing switch to the comparator and inputs the reference voltage and the terminal voltage of the balancing switch to the comparator,
wherein an output value of the comparator is switched to the same output value as that when the voltage detection line connected with the balancing switch corresponding to the unit cell is disconnected when input of the reference voltage and the inter-terminal voltage of the balancing switch to the comparator is reversed by the input switching unit, and
wherein the determination result of the determination unit based on the output value of the comparator when input of the reference voltage and the inter-terminal voltage of the balancing switch to the comparator is reversed by the input switching unit is stored in the second storage unit.

8. The battery system monitoring apparatus according to claim 1 , further comprising
an short-circuiting switch that is disposed in correspondence with each unit cell of said each unit cells and short-circuits the voltage detection lines connected to the unit cell,

Assignees

• Yamauchi Tatsumi
• Machida Akihiro
• Kudo Akihiko
• Emori Akihiko
• Kikuchi Mutsumi
• Hitachi Automotive Systems Ltd

Inventors

• Yamauchi Tatsumi
• Machida Akihiro
• Kudo Akihiko
• Emori Akihiko
• Kikuchi Mutsumi

Classifications

• B60L58/24

  for controlling the temperature of batteries · CPC title

• H02J2105/37

  exchanging power with electric vehicles [EV] or with hybrid electric vehicles [HEV] · CPC title

• H02J7/80

  including monitoring or indicating arrangements · CPC title

• H02J7/54

  Passive balancing, e.g. using resistors or parallel MOSFETs · CPC title

• G01R31/3835

  involving only voltage measurements · CPC title