JP4069721B2 - Abnormality detection device for battery pack - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for detecting an abnormal state of a battery pack.
[0002]
[Prior art]
In a battery pack in which a plurality of single cells (hereinafter referred to as cells) are connected in series, when the cell voltage falls below the overdischarge threshold, it is determined that the cell is in an overdischarge state, and the cell voltage is A battery pack abnormality detection apparatus that determines that a cell is in an overcharged state when an overcharge threshold value is reached is known (see, for example, Patent Document 1).
[0003]
Prior art documents related to the invention of this application include the following.
[Patent Document 1]
JP 05-258778 A (page 2-3, FIG. 1)
[0004]
[Problems to be solved by the invention]
However, in the conventional battery pack abnormality detection device, the overdischarge threshold value and the overcharge threshold value are fixed values. Therefore, when the internal resistance of the cell increases, the cell voltage changes sharply, and the cell voltage If charging / discharging is prohibited after detecting an abnormal state exceeding the threshold, the control may not be in time.
[0005]
The present invention provides an assembled battery abnormality detection device that reliably detects an abnormality of an assembled battery at an early stage.
[0006]
[Means for Solving the Problems]
The present invention estimates the internal resistance of the assembled battery and estimates the internal resistance. The larger the value, the lower the overcharge threshold, and the larger the estimated internal resistance, the higher the overdischarge threshold. .
[0007]
【The invention's effect】
According to the present invention, the abnormality of the assembled battery can be reliably detected at an early stage.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment in which the present invention is applied to an assembled battery in which n cells (unit cells) are connected in series will be described. The present invention is not limited to an assembled battery in which a plurality of cells are connected in series, and can also be applied to an assembled battery in which a plurality of cell parallel circuits in which a plurality of cells are connected in parallel are connected in series. .
[0009]
Further, the present invention can be applied to all types of batteries in which the chemical reaction inside the battery becomes milder and the internal resistance of the battery increases as the temperature of the battery decreases.
[0010]
<< First Embodiment of the Invention >>
FIG. 1 shows the configuration of the first embodiment. In the assembled battery 1, n cells 11, 12, 13,..., 1n are connected in series. Both ends C0-C1, C1-C2, C2-C3,..., Cn-1-Cn of each cell 11-1n of the assembled battery 1 include current bypass circuits 21-2n, overcharge detection circuits 31-3n, and Overdischarge detection circuits 41 to 4n are connected in parallel.
[0011]
The current bypass circuits 21 to 2n are circuits that, when the voltage across the cell exceeds a predetermined voltage, bypass the charging current that has been flowing through the cell and stop charging the cell. Various circuits such as a circuit in which a resistor and a Zener diode are connected in series and a circuit in which a resistor and a transistor are connected in series can be used for the current bypass circuits 21 to 2n.
[0012]
FIG. 2 shows details of the overcharge detection circuits 31 to 3n and the overdischarge detection circuits 41 to 4n. These circuits are all common to the cells 11 to 1n. The overcharge detection circuits 31 to 3n include a comparator C1, an inverter IV1, a transistor (FET) Q1, and resistors R1 to R3. First, considering the case where the transistor Q1 is turned off while the threshold switching signal SIG is at a low level, the comparator C1 divides the control power supply voltage Vcc by the resistor R1 and the resistor (R2 + R3). The threshold voltage Vc1 is compared with the cell voltage Vc.
[Expression 1]
Vc1 = (R2 + R3) / (R1 + R2 + R3) · Vcc
When the cell voltage Vc exceeds the threshold value Vc1, the output of the comparator C1 becomes low level, is inverted to high level by the inverter IN1, and is output to the OR elements 51 to 5n as overcharge detection signals.
[0013]
Next, when the threshold value switching signal SIG changes to high level to turn on the transistor Q1, and both ends of the resistor R3 are short-circuited, the comparator C1 sets the control power supply voltage Vcc between the resistors R1 and R2. The divided threshold voltage Vc2 is compared with the cell voltage Vc.
[Expression 2]
Vc2 = R2 / (R1 + R2) · Vcc
When the cell voltage Vc exceeds the threshold value Vc2, the output of the comparator C1 becomes low level, is inverted to high level by the inverter IN1, and is output to the OR elements 51 to 5n as overcharge detection signals.
[0014]
As described above, the threshold for overcharge detection can be switched between Vc1 and Vc2 by the threshold switching signal SIG. When the threshold value switching signal SIG is at a low level, the overcharge detection threshold value Vc1 is selected, and when the threshold value switching signal SIG is at a high level, the overcharge detection threshold value Vc2 is selected. Here, as described above, the overcharge threshold value Vc2 is lower than the threshold value Vc1.
[Equation 3]
Vc2 <Vc1
Therefore, the high overcharge threshold value Vc1 is selected by the low level threshold value switching signal SIG, and the low overcharge threshold value Vc2 is selected by the high level threshold value switching signal SIG.
[0015]
The overdischarge detection circuits 41 to 4n include a comparator C2, an inverter IV2, a transistor (FET) Q2, and resistors R4 to R6. First, considering the case where the transistor Q2 is turned off while the threshold switching signal SIG is at a low level, the comparator C2 divides the control power supply voltage Vcc by the resistor (R4 + R5) and the resistor R6. The threshold voltage Vd1 is compared with the cell voltage Vc.
[Expression 4]
Vd1 = R6 / (R4 + R5 + R6) .Vcc
When the cell voltage Vc becomes lower than the threshold value Vd1, the output of the comparator C2 is inverted to a high level and is output to the OR elements 51 to 5n as an overdischarge detection signal.
[0016]
Next, when the threshold value switching signal SIG changes to high level, the output of the inverter IV2 becomes low level, the transistor Q2 is turned on, and both ends of the resistor R4 are short-circuited. The comparator C2 compares the threshold voltage Vd2 obtained by dividing the control power supply voltage Vcc by the resistors R5 and R6 with the cell voltage Vc.
[Equation 5]
Vd2 = R6 / (R5 + R6) · Vcc
When the cell voltage Vc becomes lower than the threshold value Vd2, the output of the comparator C2 is inverted to a high level and is output to the OR elements 51 to 5n as an overdischarge detection signal.
[0017]
Thus, the overdischarge detection threshold value can be switched between Vd1 and Vd2 by the threshold value switching signal SIG. When the threshold switching signal SIG is at a low level, the overdischarge detection threshold Vd1 is selected, and when the threshold switching signal SIG is at a high level, the overdischarge detection threshold Vd2 is selected. Here, as described above, the overdischarge threshold value Vd2 is higher than the threshold value Vd1.
[Formula 6]
Vd2> Vd1
Therefore, the low overdischarge threshold value Vc1 is selected by the low level threshold value switching signal SIG, and the high overdischarge threshold value Vc2 is selected by the high level threshold value switching signal SIG.
[0018]
Returning to FIG. 1 and continuing the description, the OR elements 51 to 5 n receive the overcharge detection signal or the overdischarge detection signal of any of the cells 11 to 1 n and output it to the OR element 6. The charge / discharge control circuit 7 stops charging the assembled battery 1 when the overcharge detection signal of any of the cells 11 to 1n is input from the OR element 6, and the overcharge detection of any of the cells 11 to 1n from the OR element 6. Discharge of the assembled battery 1 to which the discharge detection signal is input is stopped.
[0019]
The charge / discharge control circuit 7 switches the threshold values Vc1 and Vc2 of the overcharge detection circuits 31 to 3n and the threshold values Vd1 and Vd2 of the overdischarge detection circuits 41 to 4n by the threshold value switching signal SIG. The overcharge detection threshold value Vc1 and the overdischarge detection threshold value Vd1 are selected by the low level threshold value switching signal SIG, and the overcharge detection threshold value Vc2 and the overdischarge detection value are selected by the high level threshold value switching signal SIG. The threshold value Vd2 is selected.
[0020]
FIG. 3 shows voltage changes during charging when the internal resistance of the assembled battery is small, and voltage changes during charging when the internal resistance is large. In general, as the temperature of the battery decreases, the chemical reaction inside the battery becomes gradual, so that the internal resistance of the battery increases. When charging is performed in a state where the battery temperature is high, the battery voltage (cell voltage) Vc increases according to the characteristic curve with a small internal resistance shown in FIG. When the battery voltage Vc reaches the overcharge threshold Vc1, overcharge detection signals are output from the overcharge detection circuits 31 to 3n to the charge / discharge control circuit 7. The charge / discharge control circuit 7 executes the charge stop process immediately after receiving the overcharge detection signal.
[0021]
Here, there is a “control delay time” from when the battery voltage Vc reaches the overcharge threshold value Vc1 until when the charging is actually stopped. Therefore, as shown in FIG. 3, even after the battery voltage Vc reaches the overcharge threshold value Vc1, the battery voltage Vc continues to rise during the control delay time. However, when charging is performed in a state where the battery temperature is high, the battery voltage Vc gradually increases. Therefore, even if the battery voltage Vc continues to increase during the control delay time, the battery voltage before the charge stop control is executed. Vc does not reach the battery deterioration start voltage.
[0022]
On the other hand, when charging is performed in a state where the battery temperature is low, since the internal resistance of the battery is large, the change of the battery voltage Vc becomes steep, and the battery voltage Vc increases according to the characteristic curve of the large internal resistance shown in FIG. . When the battery voltage Vc reaches the overcharge threshold value Vc1, an overcharge detection signal is output from the overcharge detection circuits 31 to 3n to the charge / discharge control circuit 7, and the charge / discharge control circuit 7 immediately executes a charge stop process. However, when charging is performed in a state where the battery temperature is low, the battery voltage Vc rapidly increases. Therefore, the battery voltage Vc continues to increase during the control delay time, and the battery deteriorates before the charge stop control is executed. The starting voltage is reached. That is, the charge stop control is not in time, and the battery is deteriorated.
[0023]
Therefore, in the first embodiment, an increase in the internal resistance of the assembled battery 1 is estimated, and when the increase in the internal resistance is estimated, the overcharge threshold value Vc1 is switched to a low threshold value Vc2. As a result, even if the battery voltage Vc suddenly increases during charging due to an increase in internal resistance, overcharge detection is performed from the overcharge detection circuits 31 to 3n when the threshold value Vc2 lower than the overcharge threshold value Vc1 is exceeded. A signal is output, and the charge / discharge control circuit 7 performs charge stop control. As a result, even if the battery voltage Vc continues to rise during the control delay time, the battery voltage Vc does not reach the battery deterioration start voltage before the charge stop control is executed, and the battery deterioration due to overcharging is avoided. be able to.
[0024]
Here, the overcharge threshold value Vc2 when the internal resistance is increased includes the battery voltage Vc after the control delay time when the maximum internal resistance expected under normal use conditions of the battery pack 1 is generated. Set a value that does not exceed.
[0025]
FIG. 4 shows voltage changes during discharge when the internal resistance of the battery pack is small, and voltage changes during discharge when the internal resistance is large. As described above, generally, as the temperature of the battery decreases, the chemical reaction inside the battery becomes moderate, and the internal resistance of the battery increases. When discharging in a state where the battery temperature is high, the battery voltage (cell voltage) Vc decreases according to the characteristic curve with small internal resistance shown in FIG. When battery voltage Vc reaches overdischarge threshold Vd1, overdischarge detection signals are output from overdischarge detection circuits 41 to 4n to charge / discharge control circuit 7. The charge / discharge control circuit 7 executes the discharge stop process immediately after receiving the overdischarge detection signal.
[0026]
Here, there is a “control delay time” from when the battery voltage Vc reaches the overdischarge threshold Vd1 until when the discharge is actually stopped. Therefore, as shown in FIG. 4, even after the battery voltage Vc reaches the overdischarge threshold Vd1, the battery voltage Vc continues to decrease during the control delay time. However, when charging is performed in a state where the battery temperature is high, the battery voltage Vc gradually decreases. Therefore, even if the battery voltage Vc continues to decrease during the control delay time, the battery voltage before the discharge stop control is executed. Vc does not reach the battery deterioration start voltage.
[0027]
On the other hand, when discharging is performed in a state where the battery temperature is low, since the internal resistance of the battery is large, the change of the battery voltage Vc becomes steep, and the battery voltage Vc decreases according to the characteristic curve of the large internal resistance shown in FIG. . When the battery voltage Vc reaches the overdischarge threshold Vd1, overdischarge detection signals are output from the overdischarge detection circuits 41 to 4n to the charge / discharge control circuit 7, and the charge / discharge control circuit 7 immediately executes a discharge stop process. However, when discharging is performed in a state where the battery temperature is low, the battery voltage Vc rapidly decreases. Therefore, the battery voltage Vc continues to decrease during the control delay time, and the battery deteriorates before the discharge stop control is executed. The starting voltage is reached. That is, the discharge stop control is not in time, and the battery is deteriorated.
[0028]
Therefore, in the first embodiment, an increase in the internal resistance of the assembled battery 1 is estimated, and when the increase in the internal resistance is estimated, the overdischarge threshold value Vd1 is switched to the high threshold value Vd2. As a result, even if the battery voltage Vc suddenly drops during discharge due to an increase in internal resistance, overdischarge detection is performed from the overdischarge detection circuits 41 to 4n when it falls below a threshold value Vd2 higher than the overdischarge threshold value Vd1. A signal is output, and the discharge stop control is immediately executed by the charge / discharge control circuit 7. As a result, even if the battery voltage Vc continues to decrease during the control delay time, the battery voltage Vc does not fall below the battery deterioration start voltage before the discharge stop control is executed, and the battery deterioration due to overdischarge is avoided. be able to.
[0029]
Here, the overdischarge threshold value Vd2 when the internal resistance is increased is the battery deterioration start voltage after the control delay time when the maximum internal resistance expected under normal use conditions of the battery pack 1 is generated. Set a value not lower than.
[0030]
Next, a method for estimating the internal resistance of the assembled battery 1 according to the first embodiment will be described. When the overcharged state is detected in any of the cells 11 to 1n before the charge capacity of the assembled battery 1 reaches the target charge capacity during charging of the assembled battery 1, the cell of the overcharged state is detected. The change in voltage Vc is steeper than the voltage change in other cells, and the internal resistance of the cell is estimated to be larger than that in other cells. Therefore, in such a case, the threshold switching signal SIG is set to the high level to switch the high overcharge threshold Vc1 to the low threshold Vc2.
[0031]
As described above, in the first embodiment, when the assembled battery 1 is being charged, if the overcharged state is detected in any of the cells 11 to 1n before the charging capacity of the assembled battery 1 reaches the target charging capacity. The internal resistance of any cell of the assembled battery 1 is estimated to be large, and the overcharge threshold is changed from the high value Vc1 to the low value Vc2 by this estimation. As a result, the low overcharge threshold Vc2 is used in the next overcharge / discharge detection cycle, and in particular, the voltage Vc of the cell in which the overcharge state is detected in the previous detection cycle reaches the battery deterioration start voltage. It is possible to avoid the deterioration of the cell, and it is possible to reliably detect the abnormality of the assembled battery at an early stage.
[0032]
Moreover, when the overdischarge state is detected in any of the cells 11 to 1n before the discharge capacity of the assembled battery 1 reaches the target discharge capacity during the discharge of the assembled battery 1, the overdischarge state is detected. The change in the voltage Vc of the cell is steeper than the voltage change of the other cells, and the internal resistance of the cell is estimated to be larger than that of the other cells. Therefore, in such a case, the threshold value switching signal SIG is set to the high level to switch the low overdischarge threshold value Vd1 to the high threshold value Vd2.
[0033]
As described above, in the first embodiment, during the discharge of the assembled battery 1, when the overdischarge state is detected in any of the cells 11 to 1n before the discharge capacity of the assembled battery 1 reaches the target discharge capacity. The internal resistance of any cell of the assembled battery 1 is estimated to be large, and the overdischarge threshold is changed from the low value Vd1 to the high value Vd2 by this estimation. As a result, the high overdischarge threshold value Vd2 is used in the next overcharge / discharge detection cycle, and in particular, the voltage Vc of the cell in which the overdischarge state is detected in the previous detection cycle reaches the battery deterioration start voltage. It is possible to avoid the deterioration of the cell, and it is possible to reliably detect the abnormality of the assembled battery at an early stage.
[0034]
In the first embodiment described above, during charging / discharging of the assembled battery 1, before the charging / discharging capacity of the assembled battery 1 reaches the target charging / discharging capacity, any of the cells 11-1n is overcharged or overdischarged. In the example, it is estimated that the internal resistance of a cell in which an overcharged state or an overdischarged state is detected is larger than that of other cells. It is not limited to the form. For example, a method of sampling the current flowing through the assembled battery during charging and discharging and the cell voltage, performing a linear regression on the current and voltage of the sampling result on a two-dimensional plane, and estimating the internal resistance of the battery from the slope of this regression line, etc. Can be used.
[0035]
<< Second Embodiment of the Invention >>
In the first embodiment described above, the example in which the internal resistance of the assembled battery 1 is estimated by the charge / discharge control circuit 7 has been described, but the second embodiment in which a hardware device is used as the internal resistance estimation means will be described. .
[0036]
FIG. 5 shows the configuration of the second embodiment. In addition, the same code | symbol is attached | subjected to the apparatus similar to the structure of 1st Embodiment shown in FIG. 1, and it demonstrates centering around difference. The temperature sensor 8 detects the temperature of the assembled battery 1, and when the temperature of the assembled battery 1 drops below a preset threshold, a high level threshold switching signal SIG is detected with the overcharge detection circuits 31 to 3n and overdischarge detection. Output to circuits 41 to 4n.
[0037]
As described above, generally, as the temperature of the battery decreases, the chemical reaction inside the battery becomes milder, so that the internal resistance of the battery increases. Therefore, in the second embodiment, when the temperature of the assembled battery 1 falls below the threshold value, it is determined that the internal resistance of the assembled battery 1 has increased, and the threshold value switching signal SIG is switched to the high level. As a result, the overcharge threshold value is switched from the high value Vc1 to the low value Vc2, and the overdischarge threshold value is switched from the low value Vd1 to the high value Vd2.
[0038]
As described above, when the temperature of the assembled battery 1 falls below the threshold value, the overcharge threshold value is switched from the high value Vc1 to the low value Vc2, and the overdischarge threshold value is switched from the low value Vd1 to the high value Vd2. I made it. That is, in the second embodiment, the temperature of the assembled battery 1 is detected, the internal resistance of the assembled battery 1 is estimated based on the temperature detection value, and the overcharge threshold and overdischarge are performed according to the estimated internal resistance value. The threshold value was changed. As a result, the abnormality of the assembled battery 1 can be reliably detected at an early stage, and even if the internal resistance increases when the temperature of the assembled battery 1 decreases and the voltage change at the time of charge / discharge becomes steep, the cell voltage Vc is It is possible to avoid the deterioration of the cell due to reaching the deterioration start voltage.
[0039]
The battery temperature threshold value and the overcharge / discharge threshold values Vc2 and Vd2 include the battery voltage after the above-described control delay time at the lowest temperature expected under normal use conditions of the battery pack 1. A value at which Vc does not reach the battery deterioration start voltage is set.
[0040]
<< Third Embodiment of the Invention >>
A third embodiment in which another hardware device is used as the internal resistance estimation means will be described. FIG. 6 shows the configuration of the third embodiment. In addition, the same code | symbol is attached | subjected to the apparatus similar to the structure of 1st Embodiment shown in FIG. 1, and it demonstrates centering around difference. The charging / discharging time integration circuit 9 integrates the charging / discharging time of the assembled battery 1 and overcharges the high-level threshold switching signal SIG when the integrated value of the charging / discharging time of the assembled battery 1 reaches a preset threshold value. It outputs to the detection circuits 31 to 3n and the overdischarge detection circuits 41 to 4n.
[0041]
In general, as the battery deteriorates, the internal resistance increases and the voltage change becomes steep. Therefore, in the third embodiment, when the integrated value of the charge / discharge time of the assembled battery 1 reaches the threshold value, it is determined that the internal resistance of the assembled battery 1 has increased, and the threshold value switching signal SIG is set to the high level. Switch to. As a result, the overcharge threshold value is switched from the high value Vc1 to the low value Vc2, and the overdischarge threshold value is switched from the low value Vd1 to the high value Vd2.
[0042]
As described above, when the integrated value of the charge / discharge time of the assembled battery 1 reaches the threshold value, the overcharge threshold value is switched from the high value Vc1 to the low value Vc2, and the overdischarge threshold value is changed from the low value Vd1 to the high value. Switching to Vd2. That is, in the third embodiment, the charging / discharging time of the assembled battery 1 is integrated, the internal resistance of the assembled battery 1 is estimated based on this charging / discharging time integrated value, and the overcharge threshold is determined according to the estimated internal resistance value. The value and overdischarge threshold were changed. Thereby, the abnormality of the assembled battery 1 can be reliably detected at an early stage, and the assembled battery 1 is gradually deteriorated due to long-term use of the assembled battery 1 to increase the internal resistance. Even if it becomes steep, it can be avoided that the cell voltage Vc reaches the battery deterioration start voltage and the cell is deteriorated.
[0043]
It should be noted that the battery voltage Vc after the control delay time described above is used for the battery pack charge / discharge time integrated value threshold value and the overcharge / discharge threshold value Vc2, Vd2 when the battery is used under normal use conditions. Set a value that does not reach the start voltage.
[0044]
<< Fourth Embodiment of the Invention >>
A fourth embodiment in which another hardware device is used as the internal resistance estimation means will be described. FIG. 7 shows the configuration of the fourth embodiment. In addition, the same code | symbol is attached | subjected to the apparatus similar to the structure of 1st Embodiment shown in FIG. 1, and it demonstrates centering around difference. The timer circuit 10 counts the operating time from the time when the battery pack 1 is turned on, and when the operating time reaches a predetermined time set in advance, a high-level threshold switching signal SIG is sent to the overcharge detection circuits 31 to 3n. It outputs to the discharge detection circuits 41-4n.
[0045]
In general, the temperature of a battery is low at the time of power-on, that is, at the start of operation, and the temperature rises as the operation time increases. That is, immediately after the power is turned on, the temperature is low, so the internal resistance is high, and the voltage change becomes steep. Therefore, in the fourth embodiment, it is determined that the internal resistance of the assembled battery 1 is high during a predetermined operation time from the time of power-on, and the threshold value switching signal SIG is set to a high level during that period. As a result, the overcharge threshold value is switched from the high value Vc1 to the low value Vc2 and the overdischarge threshold value is switched from the low value Vd1 to the high value Vd2 during a predetermined operation time from the time when the power is turned on.
[0046]
As described above, during the predetermined operation time from the time when the battery pack 1 is turned on, the overcharge threshold value is switched from the high value Vc1 to the low value Vc2, and the overdischarge threshold value is changed from the low value Vd1 to the high value Vd2. Switched to. That is, in the fourth embodiment, the operation time from the time when the battery pack 1 is turned on is counted, and the internal resistance of the battery pack 1 is estimated based on the operation time after the battery pack 1 is turned on. The overcharge threshold and overdischarge threshold were changed according to the estimated value. As a result, the abnormality of the assembled battery 1 can be reliably detected at an early stage, and even if the internal resistance of the assembled battery 1 immediately after power-on is high and the voltage change becomes steep, the cell voltage Vc becomes the battery deterioration start voltage. And cell degradation can be avoided.
[0047]
The predetermined operating time and overcharge / discharge threshold values Vc2 and Vd2 are values at which the battery voltage Vc after the control delay time described above does not reach the battery deterioration start voltage when used under normal use conditions. Set.
[0048]
The correspondence between the constituent elements of the claims and the constituent elements of the embodiment is as follows. That is, the overcharge detection circuits 31 to 3n are overcharge detection means, the overdischarge detection circuits 41 to 4n are overdischarge detection means, the overcharge detection circuits 31 to 3n and the overdischarge detection circuits 41 to 4n are overcharge detection. The charging / discharging control circuit 7, the temperature sensor 8, the charging / discharging time integrating circuit 9, and the timer circuit 10 constitute an internal resistance estimating means and a threshold changing means, respectively. In addition, as long as the characteristic function of this invention is not impaired, each component is not limited to the said structure.
[0049]
In the above-described embodiment, when the overcharge detection signal or the overdischarge detection signal is output before the target charge / discharge capacity is reached during the charge / discharge of the assembled battery, the inside of any cell of the assembled battery An example of estimating that the resistance has increased, or an example of estimating the internal resistance of the assembled battery based on the temperature of the assembled battery, the accumulated charge / discharge time, and the operation time from the time of power-on was shown. The method for estimating the internal resistance is not limited to the method of the above-described embodiment.
[0050]
In the above-described embodiment, an example in which the overcharge threshold value and the overdischarge threshold value are changed in two stages according to the estimated internal resistance value is shown. The number of threshold change stages is not limited to two, and may be three or more. Or you may change an overcharge threshold value and an overdischarge threshold value continuously according to an internal resistance estimated value.
[0051]
In the above-described embodiment, an example in which the overcharge threshold value and the overdischarge threshold value are simultaneously changed according to the estimated internal resistance value of the assembled battery 1 has been described. Thereby, the signal line which sends threshold switching signal SIG can be unified, and a device can be simplified. Of course, the overcharge threshold value and the overdischarge threshold value may not be changed at the same time, and a threshold value switching signal line may be provided separately for switching at different timings.
[0052]
Furthermore, in the second to fourth embodiments described above, examples in which the hardware devices of the temperature sensor 8, the charge / discharge time integration circuit 9, and the timer circuit 10 are used as the internal resistance estimation means of the assembled battery 1 are shown. By configuring the internal resistance estimation means with such a hardware device, the overcharge detection circuits 31 to 3n and the overdischarge detection circuits 41 to 4n are also hardware devices. The apparatus can be configured, and the apparatus can be simplified without using a microcomputer or an A / D converter.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a first exemplary embodiment.
FIG. 2 is a diagram showing details of an overcharge detection circuit and an overdischarge detection circuit.
FIG. 3 is a diagram illustrating a voltage change during charging when the internal resistance of the assembled battery is small and a voltage change during charging when the internal resistance is large.
FIG. 4 is a diagram showing a voltage change during discharging when the internal resistance of the assembled battery is small and a voltage change during discharging when the internal resistance is large.
FIG. 5 is a diagram showing a configuration of a second exemplary embodiment.
FIG. 6 is a diagram showing a configuration of a third exemplary embodiment.
FIG. 7 is a diagram showing a configuration of a fourth exemplary embodiment.
[Explanation of symbols]
1 battery pack
6,51-5n OR element
7 Charge / discharge control circuit
8 Temperature sensor
9 Charge / discharge time integration circuit
10 Timer circuit
11, 12, 13, ... 1n cell (single cell)
31-3n Overcharge detection circuit
41 to 4n overdischarge detection circuit

Claims (8)

Abnormal battery pack that detects the overcharge status of battery packs that are connected in series with multiple single cells (hereinafter referred to as cells), or battery packs that are connected in parallel with multiple cell parallel circuits with multiple cells connected in parallel A detection device,
Overcharge detection means for outputting an overcharge detection signal when a voltage across the cell or the cell parallel circuit exceeds an overcharge threshold;
Internal resistance estimating means for estimating the internal resistance of the assembled battery;
An overcharge threshold value changing means for lowering the overcharge threshold value as the estimated internal resistance value of the assembled battery becomes larger . Abnormality of a battery pack that detects an overdischarge status of a battery pack in which a plurality of single cells (hereinafter referred to as cells) are connected in series, or a battery pack in which a plurality of cells connected in parallel are connected in series. A detection device,
Overdischarge detection means for outputting an overdischarge detection signal when a voltage across the cell or the cell parallel circuit falls below an overdischarge threshold;
Internal resistance estimating means for estimating the internal resistance of the assembled battery;
An assembled battery abnormality detection device comprising: overdischarge threshold value changing means for increasing the overdischarge threshold value as the estimated internal resistance value of the assembled battery increases . Detects an overcharged state or an overdischarged state of an assembled battery in which a plurality of single cells (hereinafter referred to as cells) are connected in series, or an assembled battery in which a plurality of cell parallel circuits in which a plurality of cells are connected in parallel are connected in series. An assembled battery abnormality detection device,
When the voltage across the cell or the cell parallel circuit exceeds an overcharge threshold, an overcharge detection signal is output, and when the voltage across the cell or the cell parallel circuit falls below the overdischarge threshold Overcharge / discharge detection means for outputting an overdischarge detection signal;
Internal resistance estimating means for estimating the internal resistance of the assembled battery;
An abnormality of the assembled battery , comprising: an overcharge / discharge threshold value changing means for lowering the overcharge threshold value and increasing the overdischarge threshold value as the estimated internal resistance of the assembled battery increases. Detection device. In the assembled battery abnormality detection device according to claim 3,
The overcharge / discharge threshold value changing means simultaneously changes the overcharge threshold value and the overdischarge threshold value according to an estimated internal resistance value of the assembled battery, and detects an abnormality in the assembled battery. apparatus. In the abnormality detection apparatus of the assembled battery as described in any one of Claims 1-4,
When the overcharge detection signal or the overdischarge detection signal is output before reaching the target charge / discharge capacity during charging / discharging of the assembled battery, the internal resistance estimating means outputs any cell of the assembled battery or An assembled battery abnormality detection device characterized by estimating that the internal resistance of a cell parallel circuit is increased . In the abnormality detection apparatus of the assembled battery as described in any one of Claims 1-4,
Battery temperature detecting means for detecting the temperature of the assembled battery;
The assembled battery abnormality detecting device, wherein the internal resistance estimating means estimates that the internal resistance of the assembled battery has increased when a temperature detection value of the assembled battery falls below a threshold value . In the abnormality detection apparatus of the assembled battery as described in any one of Claims 1-4,
Charge / discharge time integration means for integrating the charge / discharge time of the assembled battery,
The assembled battery abnormality detecting device, wherein the internal resistance estimating means estimates that the internal resistance of the assembled battery has increased when the integrated charge / discharge time of the assembled battery reaches a threshold value . In the abnormality detection apparatus of the assembled battery as described in any one of Claims 1-4,
An operation time measuring means for measuring the operation time from the time of turning on the battery pack,
The internal resistance estimating means estimates that the internal resistance of the assembled battery is high until the operation time from the time when the battery is turned on reaches a predetermined operation time. apparatus.

Images