JP2001327091A - Abnormality detector of battery set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect abnormality of a plurality of battery cells connected in series accurately, without making the circuitry or software complicated. SOLUTION: A plurality of battery cells B connected in series are connected, respectively in parallel with cell voltage detection elements 50. Each cell voltage detection element 50 has voltage-current characteristics supplying a current which depends on the output voltage of a corresponding battery cell B. Sum of currents flowing through all cell voltage detection elements 50 is detected by an element current detecting means 60. The detected sum of currents is fed to a comparison decision means 90 which makes a decision for each battery cell B whether an abnormality is generated, by comparing the sum of currents with a reference value for detecting abnormality of the battery cell B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality detecting device used for generating an abnormality in a battery pack formed by connecting a plurality of battery cells in series.

[0002]

2. Description of the Related Art Electric vehicles such as HEV, PEV, FCEV and the like have attracted attention as low-pollution vehicles for solving environmental problems and energy problems. A high-voltage battery mounted on an electric vehicle serves as a power source for a motor and has a function of storing power generated by regeneration.

[0003] Such a high-voltage battery for an electric vehicle is used as a so-called assembled battery in which a plurality of battery cells are connected in series in order to obtain a high voltage. The assembled battery is required to detect the output voltage of each battery cell with high accuracy, for example, to monitor the state of charge of each battery cell. However, a large number of battery cells are used in the assembled battery, and there is a problem that the circuit configuration is significantly complicated in order to independently detect the output voltages of all the battery cells.

[0004] For this purpose, it has been practiced to measure the voltage of each block by treating a large number of battery cells connected in series as blocks of an appropriate number of battery cells.

FIG. 5 is a circuit diagram showing an example of a conventional abnormality detecting device used for detecting overcharge and overdischarge in a battery pack. The assembled battery 1 configured by connecting a large number of battery cells B in series is connected to a motor generator 3 via an inverter 2 to form a main circuit. Each battery cell B constituting the assembled battery 1 is grouped into n blocks each constituted by an appropriate number of battery cells B.

[0006] In the ECU 4, the output voltages of a large number of battery cells B constituting the battery pack 1 are input to n comparators C1 to Cn as voltage sensors, respectively. , N blocks of output voltage V
1 to Vn are respectively detected. Each of the comparators C1 to Cn
Output voltages V1 to Vn detected by ECU 4
Is provided to the comparison determination means 5 provided therein.

The comparing and judging means 5 compares each of the input output voltages V1 to Vn of each block with each of predetermined judgment reference values in order to detect overcharge and overdischarge. Over-charge and over-discharge are detected. Each determination reference value set by the comparison determination means 5 is not constant, and a main circuit current value detected by a current detector 6 provided in a main circuit supplied with current from the battery pack 1 to the inverter 2, and It is changed based on the temperature data of the battery pack 1 detected by the temperature sensor 7.

[0008]

In the conventional abnormality detecting device having such a configuration, the output voltage of each of a large number of battery cells B constituting the battery pack 1 is determined in units of blocks constituted by a plurality of battery cells. Is detected. In this case, the detected voltage of each block is measured as the total voltage value of the battery cells B constituting the block. Therefore, the respective voltages of the battery cells B cannot be detected, and the detection accuracy of the battery cells B is poor. As a result, overcharge and overdischarge of each battery cell B cannot be accurately detected. There is.

[0009] Overcharging of each battery cell B has a significant adverse effect on its life. In addition, due to overcharging, abnormal heat generation occurs in the battery cells B, which adversely affects the surrounding battery cells B. Overdischarging of the battery cell B also has a significant adverse effect on battery life. If overcharge and overdischarge in each of the battery cells B cannot be detected with high accuracy, these adverse effects significantly reduce the controllability of the motor generator. Properties will be significantly reduced.

[0010] By measuring the output voltage of each battery cell B, overdischarge and overcharge can be accurately detected. For this purpose, the circuit configuration and the software for executing the ECU control program are required. Is significantly complicated.

The present invention solves such a conventional problem, and an object of the present invention is to detect an abnormality with high accuracy without complicating a circuit configuration, software for executing a control program, and the like. It is an object of the present invention to provide a battery pack abnormality detecting device capable of performing the above-described steps.

[0012]

An abnormality detecting apparatus for a battery pack according to the present invention is an abnormality detecting apparatus for a battery pack comprising a plurality of battery cells connected in series, and comprises an output of each battery cell in the battery pack. So that the current corresponding to the voltage flows
A plurality of cell voltage detection elements connected in parallel to each battery cell, element current detection means for detecting the sum of the current values flowing through all of these cell voltage detection elements, and the cell current detection means, respectively. Comparing means for comparing the sum of the current values with a reference value for determining that an abnormality has occurred in any of the battery cells.

The comparing and judging means compares the sum of the current values detected by the element current detecting means with a judging reference value for detecting overcharging of each battery cell, and determines whether each battery cell is overcharged. To detect.

The comparing and judging means compares the sum of the current values detected by the element current detecting means with a judging reference value for detecting the overdischarging of each battery cell, and judges the overdischarging of each battery cell. To detect.

The comparing and judging means changes the judging reference value based on the temperature of each battery cell and the current history output from the battery pack.

Each of the cell voltage detecting elements causes a current to flow in a predetermined direction when the output voltage of each battery cell exceeds the first threshold voltage, and reverses when the output voltage falls below a second threshold voltage lower than the first threshold voltage. Current flows in the direction.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of a battery pack abnormality detecting apparatus according to the present invention. This abnormality detection device is used for detecting overcharge and overdischarge of the battery pack 10 mounted on an HEV (hybrid electric vehicle).

The battery pack 10 is configured by connecting a plurality of battery cells B in series, and the voltage of the battery pack 10 is supplied to a motor generator 30 via an inverter 20. The inverter 20 is controlled by a second ECU 100 controlled by a first ECU (electronic control unit) 40, and the second ECU 100
Inverter 2 based on the battery information received from CU 40
0 to bring the motor generator 30 into a predetermined operating state.

The abnormality detecting device of the present invention is used for detecting overcharge and overdischarge of the battery pack 10, and each cell voltage detecting element provided corresponding to one battery cell B constituting the battery pack 10. 50. Each cell voltage detecting element 50 is connected in parallel to each battery cell B, and the voltage of each battery cell B is detected based on the detection result of each cell voltage detecting element 50.

Each cell voltage detecting element 50 is constituted by a Zener diode or the like having a voltage-current characteristic in which a current according to the output voltage of the corresponding battery cell B flows. In this embodiment, in particular, FIG. It is configured to have the voltage-current characteristics as shown. That is, when the output voltage V of the battery cell B connected in parallel is equal to or higher than the first threshold voltage V1, the cell voltage detection element 50 outputs a positive current corresponding to the output voltage V of the battery cell B. When the output voltage V of the battery cell B falls below a second threshold voltage V0 smaller than the first threshold voltage V1, a voltage −in which a current flows in a direction opposite to the output voltage V of the battery cell B, − It has current characteristics.

FIG. 3A is a circuit diagram showing a specific configuration of the cell voltage detecting element 50. This cell voltage detecting element 5
0 is a Schottky diode 51 and a transistor 52
The Schottky diode 51 is in a non-conducting state even when a slight positive voltage is applied. However, when the polarity of the applied voltage is switched, a small voltage (second threshold voltage) is applied. The voltage is switched to the conductive state by V0, and a current flows in a direction corresponding to the negative polarity.

The base of the transistor 52 is connected to the connection point of the resistors 53 and 54 in the series circuit of the resistors 53 and 54 connected in parallel with the Schottky diode 51, and the voltage of the base is set to a predetermined positive polarity. (First threshold voltage) V1, the path of the current ID parallel to the Schottky diode 51 becomes conductive, and the current ID flows in the positive polarity direction. The cell voltage detection element 50 having such a configuration has a voltage-current characteristic having two-stage threshold voltages V0 and V1 as shown in FIG. 3B. Then, by adding polarity adjustment, gain adjustment, and the like to such voltage-current characteristics, the voltage-current characteristics having the two-step threshold shown in FIG. 2 are realized.

The abnormality detecting device shown in FIG. 1 is provided with one element current detector 60. Element current detector 60
Is constituted by a current transformer that detects the sum of the current values flowing through the respective cell voltage detection elements 50. The current transformer is set in a floating state at a portion where each line through which the current ID flows through each cell voltage detection element 50 is set in a floating state, and the sum of the current values flowing through each cell voltage detection element 50 is calculated. , As a current signal.

The sum of the current values detected as current signals by the element current detector 60 is calculated by the converter 61.
The signal is changed to a voltage signal,
Input to 0.

The current supplied from the battery pack 10 to the inverter 20 is detected by a main circuit current detector 70. The main circuit current detector 70
The main circuit current supplied from the battery pack 10 to the inverter 20 is detected and provided to the comparison determination means 90 in the ECU 40.

Further, the comparison / determination means 90 includes the assembled battery 1
The output of each cell temperature sensor 80 for detecting the temperature of each battery cell B at 0 is provided.

The comparing and judging means 90 includes a first comparator 91 for detecting overcharge, a second comparator 92 for detecting overdischarge, a first judgment reference value for overcharge and an overdischarge. And a determination level calculation unit 93 that generates a second determination reference value for.

The determination level calculating section 93 determines the first determination reference value and the first determination reference value based on the temperature of each battery cell B detected by each cell temperature sensor 80 and the history of the current flowing from the battery pack 10 to the inverter 20. 2 are generated.

The judgment level calculation section 93 generates first and second judgment reference values based on the graphs shown in FIGS. 4A and 4B, respectively.

FIG. 4A shows the influence of the main circuit current and the cell temperature on the cell voltage regarded as overcharged in the past 100 msec. FIG. 4 (b)
The graph shows the influence of the main circuit current and the cell temperature on the cell voltage considered as overdischarge during the past 100 msec. In FIGS. 4A and 4B, the discharge of the main circuit current is represented as (+).

The output voltage of the battery cell B to be regarded as overcharged is not affected by the main circuit current and the temperature of the battery cell B when the main circuit current during the past 100 msec is 50 A or more. It is constant at 63V, but the past 100
If the main circuit current during msec is less than 50A,
Under the influence of the main circuit current and the temperature of the battery cell B, the voltage drops to a minimum of about 1.4V. Similarly, when the main circuit current during the past 100 msec is 50 A or more, the output voltage of the battery cell B to be regarded as overdischarge is about 1 V without being affected by the main circuit current and the temperature of the battery cell B. It is constant, but when the main circuit current during the past 100 msec is smaller than 50 A, the voltage rises to about 1.2 V at the maximum under the influence of the main circuit current and the temperature of the battery cell B.

As described above, the judgment level calculation section 93
Based on the graphs shown in (a) and (b), a first determination reference value and a second determination reference value are created and generated from the main circuit current detector 70 and each cell temperature sensor 80 output signal, respectively. The first criterion value and the second criterion value obtained from the first comparator 91 and the second comparator 92, respectively.
Give to each.

The first criterion value input to the first comparator 91 is that the voltage detected by the element current detector 60 is such that one of the battery cells B of the battery pack 10 is overcharged. Is set in accordance with the voltage caused by the current rise due to the current. The second determination reference value input to the second comparator 92 is such that the voltage detected by the element current detector 60 is 10 is set in accordance with a voltage generated by a current drop due to overdischarge of any one of the battery cells B.

The first comparator 91 compares the sum of the current values detected by the element current detector 60 with the first judgment reference value input from the judgment level calculation unit 93, and determines the sum of the current values. An overcharge detection signal is output when the value exceeds the first determination reference value. Further, the second comparator 92 is connected to the element current detector 6
The sum of the current values detected at 0 is determined by the determination level calculation unit 9.
The second comparator outputs a signal of overdischarge detection when the sum of the current values is smaller than the second determination reference value.

In the battery pack abnormality detecting device having such a configuration, overcharge and overdischarge of each battery cell B of the battery pack 10 are detected as follows.

When the output voltage of each battery cell B in the battery pack 10 is between the first threshold voltage V1 and the second threshold voltage V0, current flows to any of the cell voltage detecting elements 50. Absent. As a result, the sum of the current values detected by the element current detector 60 becomes zero. Therefore, the first comparator 9
No signal is output from either the first or second comparator 92.

On the other hand, when any of the battery cells B of the battery pack 10 is overcharged, only the output voltage of the battery cell B increases. When this voltage rise becomes larger than the first threshold voltage V1 set in the cell voltage detection element 50, the cell voltage detection element 50 corresponding to the battery cell B
Current flows to the element current detector 60.
Is detected by As a result, when the level of the input signal from the element current detector 60 to the first comparator 91 and the second comparator 92 increases and becomes larger than the first determination reference value in the first comparator 91, the battery pack 10 It is determined that one of the battery cells B has overcharged, and the first comparator 91 outputs an overcharge detection signal.

On the other hand, when any of the battery cells B in the battery pack 10 is overdischarged, only the output voltage of the battery cell B decreases. This voltage drop causes the second threshold voltage V
When it becomes smaller than 0, a current flows in the cell voltage detecting element 50 corresponding to the battery cell B in a direction opposite to the current direction at the time of overcharge. As a result, the current value detected by the element current detector 60 decreases. As a result, the voltage level of the signal input from the element current detector 60 to the second comparator 92 decreases and becomes lower than the second determination reference value input to the second comparator 92, and the battery pack 1
When it is determined that overdischarge has occurred in any of the battery cells B within 0, the first comparator 91 outputs an overdischarge detection signal.

In this way, the ECU 40 detects that one of the battery cells B in the battery pack 10 has been overcharged or overdischarged. Moreover, based on the current rise due to overcharge and the current drop due to overdischarge with respect to the sum of the current values flowing through all the cell voltage detection elements 50,
Since the overcharge and the overdischarge are respectively detected, even when a plurality of battery cells B in the battery pack 10 are simultaneously overcharged or overdischarged, the battery cell B is overcharged or overdischarged. Can be respectively detected.

As described above, in the battery pack abnormality detecting device of this embodiment, overcharging and overdischarging of the battery cell B can be performed without individually detecting each output voltage of each battery cell B in the battery pack 10. , Can be detected for each battery cell B.
Moreover, the sum of the current values corresponding to the output voltages of all the battery cells B is used as the output of the element current detector 60 as the first EC
E is output to the comparison determination means 90 in U40,
There is no risk that the number of wires connected to the CU 40 will increase, and there is no risk that software for executing the control in the ECU 40 will be complicated.

Further, the comparison / judgment means 90 uses the judgment level calculation section 93 to determine the temperature of the battery cells B connected in series and the current history of the main circuit current flowing from the battery cells B to the inverter 20. Since the first criterion value and the second criterion value are respectively set, overcharge and overdischarge of each battery cell B can be detected with high accuracy. The method of determining the overcharge and overdischarge determination levels is not limited to the method based on the graph shown in FIG. 4, but is determined based on the current history according to the characteristics of the battery.

Each of the voltage detecting elements 50 is a battery cell B
When the output voltage becomes equal to or higher than the first threshold voltage V1, the current flows in a predetermined direction, and when the output voltage becomes equal to or lower than the second threshold voltage V0 smaller than the first threshold voltage V1, the current flows in the reverse direction. With this configuration, both overcharge and overdischarge can be accurately detected.

[0044]

As described above, the abnormality detecting apparatus for a battery pack according to the present invention includes a plurality of battery cells connected in series as described above.
Combining a cell voltage detection element through which a current corresponding to the output voltage of the battery cell flows, comparing the sum of the current values flowing through all of the cell voltage detection elements with a determination reference value for battery cell abnormality detection, Since it is configured to perform abnormality detection, the abnormality of each of a plurality of battery cells constituting the assembled battery can be detected with high accuracy without complicating the circuit configuration and software for executing the control. be able to.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an example of an embodiment of a battery pack abnormality detection device according to the present invention.

FIG. 2 is a characteristic diagram of a cell voltage detecting element used in the abnormality detecting device.

FIG. 3A is a circuit diagram showing a specific configuration of the cell voltage detection element, and FIG. 3B is a characteristic diagram of the cell voltage detection element.

4A is a graph showing the influence of the current history of the main current circuit and the cell temperature on the cell voltage to be considered as overcharge, and FIG. 4B is a graph showing the main current circuit on the cell voltage to be considered as overdischarge. 6 is a graph showing the influence of the current history and the cell temperature of the present invention.

FIG. 5 is a configuration diagram showing an example of a conventional battery pack abnormality detection device.

[Explanation of symbols]

 Reference Signs List 10 battery pack 20 inverter 30 motor generator 40 ECU 50 cell voltage detection element 60 element current detector (element current detection means) 70 main circuit current detector 80 cell temperature sensor 90 comparison and judgment means 91 first comparator 92 second comparator 93 Judgment level calculation unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02J 7/00 H02J 7/00 S 302 302D 7/04 7/04 L 7/34 7/34 C (72 ) Inventor Maki Ichiro 555 Sakaijuku, Kosai-shi, Shizuoka Prefecture F-term in Panasonic Eve Energy Co., Ltd. 5G003 AA07 BA03 CA01 CA11 CA20 CB01 CC02 CC04 DA13 FA04 5H030 AA06 AS08 BB01 BB21 DD20 FF21 FF41 FF42

Claims (5)

[Claims] 1. An abnormality detection device for a battery pack comprising a plurality of battery cells connected in series, wherein a current corresponding to an output voltage of each battery cell in the battery pack flows through each battery cell. A plurality of cell voltage detection elements connected in parallel, an element current detection means for detecting the sum of the current values flowing through all of these cell voltage detection elements, and a sum of the current values detected by the element current detection means And a comparison determining means for comparing with a determination reference value for determining that an abnormality has occurred in any one of the battery cells. 2. The comparing and judging means compares the total of the current values detected by the element current detecting means with a judging reference value for detecting overcharging of each battery cell, and judges whether each battery cell has an overcharge. 2. The abnormality detection device for an assembled battery according to claim 1, wherein the abnormality is detected. 3. The comparing and judging means compares the sum of the current values detected by the element current detecting means with a judgment reference value for detecting overdischarge of each battery cell, The abnormality detecting device for an assembled battery according to claim 1, wherein the abnormality is detected. 4. The battery pack abnormality detecting device according to claim 2, wherein the comparison determination unit changes the determination reference value based on a temperature of each battery cell and a current history output from the battery pack. . 5. The cell voltage detecting element according to claim 1, wherein a current flows in a predetermined direction when an output voltage of each battery cell is equal to or higher than a first threshold voltage, and is equal to or lower than a second threshold voltage lower than the first threshold voltage. 2. The abnormality detection device for an assembled battery according to claim 1, wherein a current flows in a reverse direction.