JP2000060011A - State detecting method of assembled battery and state detecting equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely enable detecting abnormality when dynamic range of a measuring system is reduced. SOLUTION: Two battery groups A1, A2 composed of the respective five battery cells 11 are divided by a central lead 12. Voltages of the respective battery groups A1, A2 are measured by a microcomputer 21. The time rate of change of the voltages are compared in the microcomputer 21. When unbalance exists, it is detected as an abnormality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a state detecting method and a state detecting apparatus for detecting an abnormality of an assembled battery formed by connecting a plurality of cells in series.

[0002]

2. Description of the Related Art For example, as a power battery for an electric vehicle, a required high voltage and a large capacity can be secured by combining a large number of battery modules each having a plurality of battery cells connected in series. Further, each battery module is provided with a module monitoring circuit, which is configured to quickly detect deterioration or failure of each battery cell.

In such a case, a signal line pair is conventionally derived from both ends of each battery cell, and the signal line group is connected to a monitoring circuit.

[0004]

However, this configuration requires a large number of signal lines in accordance with the number of cells, and thus has the disadvantage of increasing weight and cost. In addition, since a relatively large potential difference is generated between the two signal lines derived from both ends of the series circuit, there is a danger of a short circuit accident or fire due to insulation breakdown, and there is a problem that measures to prevent such a problem become large. . When the voltage of the battery cell is 1.2 V and the voltage of the battery module is 12 V, the dynamic range of the measurement system needs to be considerably large in order to detect the abnormality of one of the ten cells. Therefore, problems such as susceptibility to noise are caused.

[0005] Incidentally, as in the configuration disclosed in, for example, JP-A-5-258778, it has been considered that some of the optical fibers are used to reduce the weight, but this still requires a large number of optical fibers. Inevitably, the manufacturing cost is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a method and an apparatus for detecting a state of an assembled battery which can reliably measure an abnormality even if the dynamic range of a measurement system is reduced. To provide.

[0007]

According to the first aspect of the present invention, there is provided a method for detecting a state of an assembled battery in which a plurality of cells are connected in series. It is characterized in that the series voltage of the unit cell group of each group is detected and the state of the assembled battery is determined based on the comparison of the detected voltages.

The invention according to claim 2 is an apparatus for detecting a state of an assembled battery in which a plurality of cells are connected in series, wherein the cells in the assembled battery are divided into a plurality of groups, and It is characterized in that it comprises a voltage detecting means for detecting the series voltage of the unit cell group and an abnormality determining means for judging an abnormality of the assembled battery based on a comparison between the detected series voltages.

According to a third aspect of the present invention, in the state detecting device of the second aspect, the abnormality determining means determines an abnormality by detecting a temporal change of the series voltage for each of the unit cell groups of each group. It is characterized by having a configuration of

The invention according to claim 4 is the invention according to claim 2 or 3.
In the invention of the above, the assembled battery is composed of an even number of unit cells connected in series, and the voltage detection means is a unit cell of two groups divided at an intermediate point of a series circuit constituting the assembled battery. It is characterized in that each series voltage is detected.

[0011]

According to the first and second aspects of the present invention, if one or more of the cells belonging to a certain group are defective, the series voltage of the group including the single cell and the other voltage are reduced. When the series voltage is compared with the series voltage of the group of normal cell groups, the comparison result is different from the normal state, and an abnormality can be detected based on the result. In this method / apparatus, the voltage detecting means for monitoring the voltage only needs to detect the series voltage of the unit cells in the plurality of groups, and therefore, it is necessary to detect the entire series voltage of the assembled battery. In addition, the dynamic range of the measurement system can be reduced as compared with the related art.

Further, since the invention of claim 3 is configured to detect a temporal change in the series voltage for each of the unit cell groups, when the capacity of the battery cell decreases, the temporal change in the voltage at the time of charging / discharging may occur. Utilizing the increase, it is also possible to determine a decrease in capacity.

Further, according to the fourth aspect of the present invention, the battery group constituting the assembled battery is divided into two equal groups by bisecting from the center, so that the structure for comparison of each group is simplified and the detection is made easier. The effect of improving accuracy is obtained.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to, for example, a power battery system of an electric vehicle will be described below with reference to FIGS. The overall configuration is as shown in FIG. A plurality of battery modules 10 are connected in series to form a group battery for power. A voltage monitoring device 20 is incorporated in each battery module 10, and a signal from each voltage monitoring device 20 is provided to the management device 30. . As shown in FIG. 2, each battery module 10 is configured by connecting in series a total of ten battery cells 11 as nickel metal hydride rechargeable batteries, and a central lead is connected from an intermediate point of the series circuit. 12 have been derived. Thereby, the battery module 10 including the ten battery cells 11
Are divided by a central lead 12 into two battery group groups A1 and A2 each including five battery cells 11.

On the other hand, each voltage monitoring device 20 is provided with a microcomputer 21 such that analog signal input ports Ia1 and Ia2 of the input ports are supplied with voltage signals from the battery groups A1 and A2. Has become. Specifically, the positive electrode lead 13 and the negative electrode lead 14
And the voltage dividing resistors 22 and 23 are connected in series.
The common connection point of the two resistors 22 and 23 is connected to the input port Ia1, the voltage dividing resistors 24 and 25 are connected in series between the center lead 12 and the negative electrode lead 14, and both resistors 24 and 25 are connected.
Are connected to the input port Ia2. Therefore, the input port Ia1 receives a value obtained by dividing the entire series voltage of the battery module 10, and the input port Ia2 receives a value obtained by dividing the voltage of the battery group A2 composed of the half battery cells 11 on the negative electrode side. Therefore, each battery group group A1, A
2 are VA1 and VA2, the input port Ia1 has V
A1 + VA2 can be detected, and V is detected at input port Ia2.
A2 can be detected.

In this embodiment, the microcomputer 21 converts the voltage applied to each of the input ports Ia1 and Ia2 into a digital signal, and changes the series voltages VA1 and VA2 of the battery groups A1 and A2 with time based on the voltage. dV
A1 / t and dVA2 / t are calculated, and the microcomputer 21 and the voltage dividing resistor groups 22 to 25 function as voltage detecting means for detecting the series voltage of each battery group A1, A2. ing. Further, the microcomputer 21 has a function of calculating a difference between the temporal changes dVA1 / t and dVA2 / t of the series voltages of the battery groups A1 and A2, and comparing the difference with a reference voltage variation table stored in a memory. .

Then, the series voltages VA1, VA2 of each of the battery group groups A1, A2 (the temporal changes dVA1 / t, dVA2 /
Based on the comparison of t), the microcomputer 21 also functions as abnormality determination means as described below.

(1) When dVA1 / t and dVA2 / t are 0 and the difference between the series voltages VA1 and VA2 is 1 V or more, the output LED of the voltage monitoring device 20 is regarded as abnormal.
26 is turned on to give an alarm signal to the management device 30. d
When VA1 / t and dVA2 / t = 0, it means that no charge / discharge current is flowing. At that time, each series voltage VA1,
When the difference of VA2 is 1 V or more, the battery group A
This is because one of the battery cells 11 of A1 and A2 is considered to have caused an internal short circuit. In particular, this setting of 1 V is suitable when the unit cell is a Ni-MH battery.

(2) If dVA1 / t and dVA2 / t> 0 and the values are larger than a predetermined reference value, the output LED 26 of the voltage monitoring device 20 is also regarded as abnormal.
Is turned on to give an alarm signal to the management device 30. FIG.
As shown in (A), when both VA1 and VA2 rise, it means that the battery is being charged. However, the fact that one of the initial voltages is lower than a predetermined value as compared with the other and that the slope is large is not. This is because it is considered that the capacity of the battery group decreases and the internal impedance increases.
That is, | dVA1 / t−dVA2 / t |> C (C is a predetermined reference value), and it is determined that the battery is abnormal when the difference between the battery groups A1 and A2 becomes larger than a certain value. .

(3) When dVA1 / t and dVA2 / t <0, if the value is smaller than a predetermined reference value, the output LED 26 of the voltage monitoring device 20 is also regarded as abnormal.
Is turned on to give an alarm signal to the management device 30. FIG.
When both VA1 and VA2 fall as shown in (B),
Although the battery is being discharged, one of the initial voltages is higher than the other by a predetermined value or more and the slope is large, the capacity of the battery group decreases, and the internal impedance increases. It is thought that there is. That is, | dVA1 / t−dVA2 / t |> C (C is a predetermined reference value), and it is determined that the battery is abnormal when the difference between the battery groups A1 and A2 becomes larger than a certain value. . At the time of discharge, measurement is performed for several tens of seconds when a constant load current is flowing (the vehicle is traveling at a constant speed) for more accurate determination. Also,
More practically, when performing the above comparison, it is preferable to apply a mask with the magnitude of VA1 or VA2 to cancel the variation in the characteristics at the end of charge and the end of discharge.

As described above, according to the present embodiment, the voltage to be measured is the series voltage (standard 1) of the entire battery module 10.
2V), but a series voltage (5 V standard) of the unit cell groups A1 and A2 of each group divided into two, and it is sufficient that a voltage change of at least one of the battery cells 11 can be detected in the voltage. . Therefore, the dynamic range of the measurement system can be reduced as compared with the related art in which it is necessary to detect the entire series voltage of the battery pack, and as a result, the state of the battery pack is accurately detected with less influence of noise. be able to.

<Other Embodiments>

The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention. Various changes can be made without departing from the scope of the present invention.

(1) In the above embodiment, the ten battery cells 11 are divided into five cells. However, the ten battery cells 11 are not necessarily divided into the same number of battery groups, and are divided into three or more battery group groups. You may do so. In short, what is necessary is just to detect the series voltage of the unit cell group of each group divided into a plurality of groups and determine the state of the assembled battery based on the comparison of the detected voltages.

(2) In the above embodiment, an example in which the present invention is applied to an assembled battery of a nickel-metal hydride secondary battery for an electric vehicle is shown. However, the present invention is not limited to this, and other types of batteries may be used for other purposes. In other words, the present invention can be widely applied to an apparatus for detecting a state of an assembled battery in which a plurality of unit cells (not limited to a battery module but may be a battery cell) are connected in series.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an entire battery assembly system;

FIG. 2 is a circuit diagram showing a battery module and a voltage monitoring device.

FIG. 3 is a graph schematically showing a temporal change in voltage of a battery group.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Battery module (unit cell) 11 ... Battery cell A1, A2 ... Battery group group (group) 20 ... Voltage monitoring device

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G016 CA00 CA03 CB05 CB06 CB12 CB23 CB31 CB33 CC01 CC03 CC04 CC06 CC07 CC10 CC16 CC20 CC27 CC28 CD02 CD03 CE00 CE01 2G035 AA08 AB03 AC01 AC19 AD22 AD28 AD38 AD49 AD65 5G003 BA03 CA030 EA AA06 AS08 FF44 5H115 PA14 PG04 PI13 QN03 TI05 TR19 TU04 TW10 TZ07

Claims (4)

[Claims] 1. A method for detecting a state of an assembled battery in which a plurality of cells are connected in series, wherein the cells in the assembled battery are divided into a plurality of groups, and A method for detecting a state of an assembled battery, comprising detecting a series voltage and determining a state of the assembled battery based on a comparison of the detected voltages. 2. An apparatus for detecting a state of an assembled battery in which a plurality of cells are connected in series, wherein the cells in the assembled battery are divided into plural groups, and An assembled battery state detecting device comprising: voltage detecting means for detecting a series voltage; and abnormality determining means for determining an abnormality of the assembled battery based on a comparison between the detected series voltages. 3. The apparatus according to claim 2, wherein the abnormality determining means determines a failure by detecting a temporal change in the series voltage for each of the unit cell groups in each of the groups. Battery state detection device. 4. The assembled battery is composed of an even number of cells connected in series, and the voltage detecting means is composed of two groups of cells divided at an intermediate point of a series circuit constituting the assembled battery. The state detecting device for an assembled battery according to claim 2 or 3, wherein each of the series voltages is detected.