JP2003282156A - Abnormality detection device of battery pack and abnormality detection method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and accurately detect an abnormality of cells constituting a battery pack. <P>SOLUTION: An abnormality detection device detects an abnormality of the battery pack 300 constituted by connecting a plurality of cells in series. This abnormality detection device 100 includes an equalization circuit for equalizing capacity of a plurality of cells and a CPU 112 which determines that the cell having a low voltage of each cell measured after each cell is discharged by the same amount using the equalization circuit from a state where capacity of each cell is equalized in the cell whose fully charged capacity is reduced and that the cell having a high voltage of each cell measured when a large current is made to flow into the set battery 300 is the cell whose internal resistance value rises. <P>COPYRIGHT: (C)2004,JPO

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 for an assembled battery, and more particularly to an abnormality detecting device for detecting an abnormality in an assembled battery formed by connecting a plurality of cells in series.

[0002]

2. Description of the Related Art As a battery mounted on a vehicle to supply electric power to a drive source or electric power to an auxiliary machine, there is an assembled battery constituted by connecting a plurality of unit cells in series. The unit cells that make up such an assembled battery deteriorate with the use of each unit cell. This deterioration occurs due to corrosion of the active material inside the battery, etc., and decreases the full charge capacity and battery A phenomenon such as an increase in internal resistance appears.

Further, the voltage of each unit cell varies due to variations in the self-discharge current of the unit cell, variations in the consumption current of the unit cell voltage detection circuit attached to the unit cell, and the like.
In addition to this, the voltage of each single cell varies due to variations in charging efficiency. There has been proposed an equalization device that eliminates the voltage imbalance of an assembled battery composed of such single cells. In this equalization device, the voltage is detected for each unit cell, and the other unit cells are discharged so that the voltage becomes substantially the same as the lowest voltage unit cell, thereby eliminating the voltage imbalance of each unit cell.

Further, regarding such a battery pack equalizing device, Japanese Patent Laid-Open No. 2002-10512 discloses a method for adjusting the capacity of the battery pack.

The capacity adjustment method disclosed in this publication has a setting step of setting the minimum open circuit voltage value of the unit cells constituting the assembled battery as a capacity adjustment target value, and a deviation from the target value for each unit cell. The calculation step for calculating the discharge time corresponding to the above, the discharge step for discharging for the calculated discharge time, and the voltage drop amount being relatively larger than those of many other single cells, the steps corresponding to the passage of time sequentially. If it is not abnormal for a cell that approaches the same level as the voltage of many other cells, it is calculated by averaging the voltages of the cells excluding the maximum voltage value and the minimum voltage value. A determination step of determining that the unit cell whose voltage has dropped is abnormal.

In this capacity adjusting method, the discharge time is calculated for each unit cell, and the unit cell having a normal voltage drop amount and the unit cell having an abnormal voltage drop amount are clearly defined based on the open circuit voltage after discharge. It is possible to identify and detect a cell in which an abnormality has occurred.

[0007]

However, in the abnormality detecting device disclosed in the above publication, the discharge time must be calculated for each unit cell, and the configuration of the abnormality detecting device becomes complicated.

The present invention has been made in order to solve the above-mentioned problems, and is an abnormality detecting device and abnormality for an assembled battery capable of easily and accurately detecting an abnormality in a battery cell that constitutes the assembled battery. It is to provide a detection method.

[0009]

An abnormality detecting device according to a first aspect of the present invention detects an abnormality in an assembled battery formed by connecting a plurality of cells in series. This abnormality detecting device was measured when the cells were uniformly discharged from a capacity equalizing means for equalizing the capacities of the plurality of cells and a state where the capacities of the cells were equalized. An abnormality determining unit for determining abnormality of the unit cells that form the assembled battery based on the voltage of each unit cell.

According to the first aspect of the invention, the capacity of each unit cell is equalized by the capacity equalizing means, and then the discharge amount of each unit cell is made uniform. At this time, for example, a resistor (having the same resistance value) provided in association with each unit cell included in the capacity equalizing unit is discharged for the same discharge time. When the same amount of discharge is discharged in this way,
The drop in the open circuit voltage of the deteriorated single battery whose full charge capacity has decreased is larger than the drop in the open circuit voltage of the single battery in the initial state. Therefore, it is possible to determine that a unit cell whose full-charge capacity has dropped and whose open-circuit voltage has dropped significantly is a battery that has deteriorated and is abnormal. Further, for example, when the assembled battery is connected to a large-capacity load and discharged with a large current, the voltage drop in the unit cell whose deterioration has increased the internal resistance is larger than the voltage drop in the unit cell in the initial state. Therefore, the internal resistance of the unit cell is increased, and the unit cell in which the open circuit voltage is greatly reduced can be determined to be abnormal because it is a deteriorated battery. As a result, it is possible to provide an abnormality detecting device for an assembled battery, which can easily and accurately detect an abnormality in a single battery constituting the assembled battery.

According to a second aspect of the present invention, in addition to the configuration of the first aspect of the invention, the abnormality determining device includes an abnormality determining means that changes the capacity equalizing means from a state in which the capacity of each unit cell is equalized. Means for determining an abnormality of the unit cells forming the assembled battery is included based on the voltage of each unit cell measured when the same amount of each unit cell is discharged.

According to the second aspect of the invention, the capacity of each unit cell is equalized by the capacity equalizing means, and then the discharge amount of each unit cell is made uniform. At this time, the resistors (having the same resistance value) provided in association with the individual cells included in the capacity equalizing unit are discharged for the same discharging time.
When the same amount of discharge is discharged in this way, the decrease in open-circuit voltage in a unit cell with deteriorated full charge capacity is
It is larger than the drop in the open circuit voltage in the initial unit cell. Therefore, it is possible to determine that a unit cell whose full-charge capacity has dropped and whose open-circuit voltage has dropped significantly is a battery that has deteriorated and is abnormal. As a result, it is possible to provide an abnormality detecting device for an assembled battery, which can easily and accurately detect an abnormality in a single battery constituting the assembled battery.

According to a third aspect of the present invention, in addition to the structure of the first aspect of the invention, in the abnormality detecting device of the assembled battery, the abnormality determining means sets the large capacity of the assembled battery from the state where the capacities of the individual cells are equalized. And a unit for determining an abnormality of the unit cells constituting the battery pack, based on the voltage of each unit cell measured when the unit cell is discharged by being connected to the load.

According to the third invention, from the state where the capacity of each unit cell is equalized by the capacity equalizing means, the discharge amount in each unit cell is made uniform and discharged. At this time, when the assembled battery is connected to a large-capacity load and discharged with a large current, the voltage drop in the unit cell with deterioration and increased internal resistance is larger than the voltage drop in the unit cell in the initial state.
Therefore, it is possible to determine that a unit cell in which the internal resistance of the unit cell is increased and the open circuit voltage is greatly reduced is a deteriorated battery and is abnormal. As a result, it is possible to provide an abnormality detecting device for an assembled battery, which can easily and accurately detect an abnormality in a single battery constituting the assembled battery.

In the battery pack abnormality detection device according to the fourth aspect of the invention, in addition to the structure of any one of the first to third aspects of the invention, the unit cell is a lithium battery.

According to the fourth aspect of the present invention, it is possible to provide an abnormality detecting device capable of accurately detecting an abnormality in an assembled battery composed of a plurality of lithium batteries.

The abnormality detecting method according to the fifth aspect of the present invention detects an abnormality in an assembled battery formed by connecting a plurality of unit cells in series. This anomaly detection method consists of a capacity equalization step for equalizing the capacities of a plurality of cells, and each cell measured when the cells are uniformly discharged from the state where the capacities of the cells are equalized. An abnormality determination step of determining abnormality of the unit cells that form the assembled battery based on the voltage of the battery.

According to the fifth aspect of the present invention, the capacity of each unit cell is equalized in the capacity equalizing step, and the discharge amount of each unit cell is made uniform. At this time, for example, the resistors (corresponding to the same resistance value) provided in association with the individual cells, which are used in the capacity equalization step, are discharged for the same discharge time. When the same amount of discharge is discharged in this way, the decrease in the open circuit voltage in the unit cell in which the full charge capacity is deteriorated and deteriorated is larger than the decrease in the open circuit voltage in the initial unit cell. Therefore, it is possible to determine that a single cell whose full-charge capacity has dropped and whose open-circuit voltage has dropped greatly is abnormal because it is a deteriorated battery. Further, for example, when the assembled battery is connected to a large-capacity load and discharged with a large current, the voltage drop in the unit cell whose deterioration has increased the internal resistance is larger than the voltage drop in the unit cell in the initial state.
Therefore, it is possible to determine that a unit cell in which the internal resistance of the unit cell is increased and the open circuit voltage is greatly reduced is a deteriorated battery and is abnormal. As a result, it is possible to provide a method for detecting an abnormality in a battery pack that can easily and accurately detect an abnormality in a single battery that constitutes the battery pack.

In the abnormality detecting method according to the sixth aspect of the present invention, in addition to the configuration of the fifth aspect, the abnormality determining step is performed by using the capacity equalizing step from the state where the capacities of the individual cells are equalized. The method includes a step of determining abnormality of the unit cells forming the assembled battery based on the voltage of each unit cell measured when the unit cells are discharged by the same amount.

According to the sixth aspect of the present invention, the capacity of each unit cell is equalized in the capacity equalizing step, and the discharge amount of each unit cell is made uniform. At this time, the resistors (corresponding to the same resistance value) provided in association with the individual cells used in the capacity equalization step are discharged for the same discharge time. When the same amount of discharge is discharged in this way, the decrease in the open circuit voltage in the unit cell in which the full charge capacity is deteriorated and deteriorated is larger than the decrease in the open circuit voltage in the initial unit cell. Therefore, it is possible to determine that a unit cell whose full-charge capacity has dropped and whose open-circuit voltage has dropped significantly is a battery that has deteriorated and is abnormal. As a result, it is possible to provide a method for detecting an abnormality in a battery pack that can easily and accurately detect an abnormality in a single battery that constitutes the battery pack.

In the abnormality detecting method according to the seventh aspect of the present invention, in addition to the configuration of the fifth aspect, in the abnormality determining step, the assembled battery is loaded into a large-capacity load from a state where the capacities of the individual cells are equalized. The method includes a step of determining an abnormality of the unit cells forming the battery pack, based on the voltage of each unit cell measured when the cells are discharged by being connected.

According to the seventh aspect of the present invention, the capacity of each unit cell is equalized in the capacity equalizing step, and then the discharge amount of each unit cell is made uniform. At this time, if the assembled battery is connected to a large capacity load and discharged with a large current,
The voltage drop in the unit cell whose deterioration has increased the internal resistance is larger than the voltage drop in the unit cell in the initial state. Therefore, it is possible to determine that a unit cell in which the internal resistance of the unit cell is increased and the open circuit voltage is greatly reduced is a deteriorated battery and is abnormal. As a result, it is possible to provide a method for detecting an abnormality in a battery pack that can easily and accurately detect an abnormality in a single battery that constitutes the battery pack.

The abnormality detecting method according to the eighth aspect of the present invention is
In addition to the configuration of any one of the seventh invention, the unit cell is a lithium battery.

According to the eighth aspect of the present invention, it is possible to provide an abnormality detecting method capable of accurately detecting an abnormality in the assembled battery composed of a plurality of lithium batteries.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same parts are designated by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated. In addition, in the following description, it is assumed that the assembled battery is composed of a lithium battery, but the present invention is not limited to this. Further, the battery pack will be described as being installed in a vehicle.

<First Embodiment> FIG. 1 shows an assembled battery abnormality detection system according to the present embodiment. This abnormality detection system includes a relay 200, an assembled battery 300, and an assembled battery 300 connected to a load 400 via the relay 200.
The abnormality detection device 100 for detecting the abnormality. N (N
Is a natural number) cells are connected in series. The abnormality detection device 100 includes a single battery B that constitutes the battery pack 300.
(1) to B (N) connection points and conductive lines L (0) to L
Battery ECU (Electronic Con) connected via (N)
control unit 110 and conductive lines L (0) to L (N)
Transistors T (1) to T connected in series between
(N) and resistors R (1) to R (N) are included. The resistance values of the resistors R (1) to R (N) are all the same.

The assembled battery 300 is constructed by connecting cells B (1) to B (N), which are lithium batteries, in series. A load 40 is applied to the assembled battery 300 via the relay 200.
0 is connected.

The battery ECU 110 includes a CPU 112 and a C
ROM storing programs executed by PU 112
A (Read Only Memory) 114 and a RAM (Random Access Memory) 116 for temporarily storing data are included. From the battery ECU 100, a lighting signal to the indicator 120 that indicates an abnormality of the assembled battery 300, an on / off signal to each of the transistors T (1) to T (N), and the like are output via the output port.

When the transistors T (1) to T (N) are turned on by an on / off signal from the battery ECU 100, a current flows through the resistors connected in series via the turned on transistors, and power is consumed. .

The CPU 112 of the battery ECU 110 controls the voltages VB (1) to VB (N) of the cells B (1) to B (N).
To detect. The CPU 112 uses the individual batteries B (1) to B
The voltage VB (1) to VB (N) of (N) is applied to the conductive line L.
It is detected as the potential difference between the lines (0) to L (N).

The CPU 112 of the battery ECU 110 has a built-in timer capable of measuring that a set charging time has elapsed from a predetermined timing.
The CPU 112 uses this timer to detect the completion of the test discharge time after the equalization process. Resistance R (1) -R
Since the resistance values of (N) are all the same, the discharge amount and the discharge time have a correlation. In the following description, the discharge amount is not directly detected, and after the equalization process, the resistors R (1) to R (N) of the equalization circuit are used to discharge for a discharge time common to each unit cell, The description will be made assuming that an abnormal cell is detected based on the voltage of each cell after the discharge time has passed, but the present invention is not limited to this. For example, a physical quantity other than the discharge time is detected, the discharge quantity is calculated based on that physical quantity, and an abnormal cell is detected based on the voltage after discharging so that the discharge quantity becomes uniform in each cell. It may be one that does.

Referring to FIG. 2, SOC (States Of Charge) and OCV (Open) of the lithium battery which is the object of abnormality detection in the battery pack abnormality detection system according to the present embodiment.
The relationship with (Current Voltage) will be described. As shown in FIG. 2, when SOC is taken on the horizontal axis and OCV is taken on the vertical axis,
Lithium batteries have a tendency for OCV to increase as SOC increases. If the measured OCV is 4.1 volts, the SOC has a relationship of 100%.

Referring to FIG. 3, the lithium battery capacity and O
The relationship with CV will be described. FIG. 3 shows the relationship between the capacity and the OCV of the lithium battery in the initial state and the lithium battery in the deteriorated state. The lithium battery in the initial state and not deteriorated is fully charged when the measured OCV is 4.1 V and is in a state of being charged with an electric quantity of about 12 Ah. On the other hand, in a lithium battery whose full charge capacity has deteriorated due to deterioration over time, the charged electric capacity is about 8 Ah even if the measured OCV is 4.1 V. That is, even when the OCV of the lithium battery is measured to be 4.1 V, which is the same, the capacity of the lithium battery in the initial state is 12 Ah and the capacity of the deteriorated lithium battery is 8 Ah.

As shown in FIG. 3, when the lithium battery is charged, both the capacity and OCV increase, and when the lithium battery is discharged, both the capacity and OCV decrease. Further, as shown in FIG. 3, when the same amount of discharge ΔQ is discharged from the fully charged state to the lithium battery in the initial state and the lithium battery in the deteriorated state, the deterioration state is higher than the OCV of the lithium battery in the initial state. OCV of lithium battery
Will be lower.

Referring to FIG. 4, a control structure of a program executed by battery ECU 110 of battery pack abnormality detection device 100 according to the present embodiment will be described.

Step (hereinafter, step is abbreviated as S) 1
At 00, CPU 112 of battery ECU 110 detects voltage VB (K) (K = 1 to N) of each unit cell. S10
At 2, the CPU 112 determines whether the variation of the voltage VB is smaller than ΔV. The variation of the voltage VB is Δ
If it is smaller than V (YES in S102), the process proceeds to S106. If not (NO in S102), the process proceeds to S104.

At S104, CPU 112 performs equalization processing using the equalization circuit. At this time, the transistor T (K) is turned on and the unit cells are discharged until the voltage of each unit cell becomes the lowest voltage among the unit cell voltages VB (K).

At S106, CPU 112 determines whether or not the test discharge condition is satisfied. This determination is made after the equalization process is completed, and the load 400 and the battery pack 300 are
Are determined by whether or not they are separated. If the test discharge conditions are satisfied (YES in S106),
The process proceeds to S108. If not (S10
(NO in 6), the process is returned to S106 and waits until the test discharge condition is satisfied.

At S108, CPU 112 turns on transistor T (K) (K = 1 to N). In S110, CPU 112 starts a timer. S11
At 2, the CPU 112 determines whether or not a predetermined time has elapsed since the timer was started. When a predetermined time has elapsed from the timer start (YES in S112), the process proceeds to S114. If not (NO in S112), the process is returned to S112 and waits until a predetermined time has elapsed from the timer start.

At S114, CPU 112 turns off transistor T (K) (K = 1 to N). In S116, CPU 112 initializes variable K (K = 1).
In S118, the CPU 112 causes the voltage V of the Kth unit cell to rise to V
B (K) is detected. In S120, the CPU 112
The voltage VB (K) of the Kth unit cell is predetermined,
It is determined whether or not it is lower than the threshold value VBLIM related to the voltage. The voltage VB (K) of the Kth unit cell is the threshold value V
If it is lower than BLIM (YES in S120),
The process proceeds to S122. If not (S12
(NO at 0), the process proceeds to S124.

At S122, CPU 112 sets the abnormality flag of the Kth cell. CP at S124
U112 adds 1 to the variable K. In S126, C
The PU 112 determines whether the variable K is larger than the number N of unit cells. If variable K is larger than the number N of unit cells (YES in S126), the process proceeds to S128. If not (NO in S126), the process returns to S118 and the process for the next unit cell is performed.

At S128, CPU 112 stores the unit cell having the abnormality flag set as an abnormality in RAM 116. After that, the CPU 112 sets the indicator 120.
To display information about the abnormality of the unit cell.

The operation of the CPU 112 of the battery ECU according to the present embodiment will be described based on the above structure and flowchart.

When the vehicle is stopped and the ignition switch is turned off, the voltage VB (K) of each cell (K = 1
~ N) are detected (S100). When the variation in voltage VB is smaller than ΔV (YES in S102), the equalization process is not performed and it is determined whether the test discharge condition is satisfied (S106).

If the test discharge conditions are satisfied (S1
06: YES), the transistor T (K) (K = 1 to 1)
N) is turned on (S108). The timer is started (S110), and when a predetermined time elapses (S1
12 is YES), the transistor T (K) (K = 1 to 1)
N) is turned off (S114). The voltage VB (K) of the Kth unit cell is detected (S118). If the detected voltage VB (K) is lower than the predetermined threshold value VBLIM (YES in S120), the abnormality flag of the Kth cell is set (S122).

At this time, as described with reference to FIG.
Even when discharging the same amount of discharge in a single cell,
The deteriorated lithium battery has a lower OCV measured as compared to the lithium battery in the initial state. Therefore, the voltage VB (K) of the Kth unit cell is set to the predetermined threshold value VB.
If it is lower than LIM, the abnormality flag is set as that the unit cell has deteriorated. Such a process is repeated for the number of unit cells N times. When the process is performed for all the unit cells, the unit cells for which the abnormality flag is set are stored as an abnormality in the RAM 116 (S128).

As described above, according to the abnormality detecting device of the present embodiment, the equalizing circuit eliminates the variation in the capacity of the unit cells, and then is provided corresponding to the unit cells of the equalizing circuit. The same resistance is used to discharge for the same time. At this time, since the resistances of the equalizing circuit have the same resistance value, the same amount of electricity ΔQ is discharged when discharging for the same discharging time. When the same amount of electricity ΔQ is discharged in a plurality of cells, a battery whose OCV has decreased more can be determined as a battery whose full charge capacity has decreased.

In this embodiment, when the voltage VB (K) of the unit cell after the test discharge is lower than the predetermined threshold value VBLIM, it is determined that the unit cell has a reduced full charge capacity. However, the present invention is not limited to this. In the present invention, all the judgments are made that when the voltage VB (K) of the unit cell after the test discharge is relatively lower than the other batteries constituting the assembled battery, it is determined that the unit cell has a reduced full charge capacity. Including the method.

<Second Embodiment> The second embodiment of the present invention will be described below.
2 shows an assembled battery abnormality detection system according to the embodiment.
As shown in FIG. 5, the abnormality detection system according to the present embodiment includes the abnormality detection device 100 according to the first embodiment. The abnormality detection device 100 is connected to the 36-volt battery 302 that is the assembled battery 300 according to the first embodiment. The 36-volt battery 302 is a unit cell B
Internal resistances RB (1) to RB (N) are included in (1) to B (N). Further, the relay 200 includes the DC / DC converter 5
00, the DC / DC converter 500 is connected to a 12 volt battery 600.

When the relay 200 is turned on, a large current flows from the 36-volt battery 302 to the 12-volt battery 600 via the DC / DC converter 500. The hardware configuration other than this is the same as the hardware configuration in the abnormality detection system according to the first embodiment described above, and therefore detailed description thereof will not be repeated here.

Referring to FIG. 6, a control structure of a program executed by battery ECU 110 of abnormality detecting device 100 according to the present embodiment will be described. In the flowchart shown in FIG. 6, the same steps as those in the flowchart shown in FIG. 4 are designated by the same step numbers. The processing for them is also the same. Therefore,
Detailed description thereof will not be repeated here.

At S200, CPU 112 causes relay 2
00 is turned on to supply power to the DC / DC converter 500 to start the test discharge. In S202, CPU
112 initializes the variable K (K = 1). In S204, CPU 112 detects voltage VB (K) of the Kth battery. In S206, the CPU 112 sets the voltage VB
(K) is stored in the RAM 116. CP at S208
U112 adds 1 to the variable K. In S210, C
The PU 112 determines whether the variable K is larger than the number N of unit cells. If variable K is larger than the number N of unit cells (YES in S210), the process proceeds to S212. If not (NO in S210), the process returns to S204 and the process for the next unit cell is performed.

At S212, the CPU 112 causes the relay 2
00 is turned off to end the test discharge. In S214, the CPU 112 sets the lowest voltage VB among the N cells.
Determine MIN. The unit cell determined to have the lowest voltage has the smallest voltage drop due to the increase in the internal resistance of the battery, and is the unit cell that has not deteriorated the most in the assembled battery.

At S216, CPU 112 initializes variable K (K = 1). In S218, the CPU 112
Calculates the evaluation value E as E = voltage VB (K) / VBMIN. In S220, the CPU 112 causes the evaluation value E
Is greater than a predetermined threshold value EMAX. Threshold value EMA where evaluation value E is predetermined
If larger than X (YES in S220), the process proceeds to S222. If not (NO in S220), the process proceeds to S224. At this time, if the internal resistance RB (2) associated with the battery B (2) is larger than the internal resistance RB (1) associated with the first battery B (1), the second battery B ( In 2), a larger voltage drop occurs due to the internal resistance of the battery. for that reason,
The voltage VB (K) is detected high. As a result, the evaluation value E of the second battery B (2) is calculated to be larger than the evaluation value E of the first battery B (1).

In S222, CPU 112 sets the abnormality flag of the Kth cell. CP at S224
U112 adds 1 to the variable K. In S226, C
The PU 112 determines whether the variable K is larger than the number N of unit cells. If variable K is larger than the number N of unit cells (YES in S226), the process proceeds to S128. If not (NO in S226), the process returns to S218 and the process for the next unit cell is performed.

The CP of the abnormality detecting apparatus 100 according to the present embodiment based on the above-described structure and flowchart.
The operation of U112 will be described.

When conditions such as when the vehicle is stopped and the ignition switch is turned off are satisfied, the voltage VB of each unit cell is
(K) (K = 1 to N) is detected (S100). If the variation of the voltage VB is smaller than ΔV (Y in S102
ES), the equalization process is not performed, the relay 200 is turned on, the DC / DC converter 500 is supplied with power from the 36-volt battery, and test discharge is started (S).
200). In this state, the voltage VB (K) of the Kth unit cell
Is detected (S204), and the detected voltage VB (K) is stored in the RAM 116 (S206). Such a process is repeated for all the unit cells.

After that, the relay 200 is turned off and the test discharge ends (S212). The lowest voltage VBMIN among the N cells is determined (S214). The voltage VB (K) stored in the RAM 116 for each unit cell
Is divided by VBMIN to calculate the evaluation value E (S2
18). When the calculated evaluation value E is larger than the predetermined threshold value EMAX (YES in S220), the abnormality flag of the Kth cell is set (S222).
Such processing is repeatedly executed for all the unit cells.

As described above, according to the battery pack abnormality detection apparatus in this embodiment, the DC connected to the battery pack is connected.
Using a / DC converter or the like, the voltage of each cell is measured when a large current of, for example, about 100 amperes flows. The voltage VB (K) that appears as a voltage drop in a unit cell whose internal resistance has risen due to changes over time
Is greatly measured. For a battery having a large voltage drop due to internal resistance, an abnormality flag indicating that the battery is deteriorated is set, and the abnormality of the unit cells constituting the assembled battery can be detected.

In the present embodiment, the evaluation value E, which is the ratio of the voltage VB (K) to the lowest voltage VBMIN cell when a large current is applied, is based on a predetermined threshold value EMAX. However, the present invention is not limited to this. The present invention is applied to the voltage VB (K) of the unit cell during the test discharge.
However, when the battery pack is relatively higher than the other batteries constituting the battery pack, it is judged that the battery cell has a higher internal resistance.

The embodiments disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

[Brief description of drawings]

FIG. 1 is a control block diagram of an abnormality detection system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between SOC and OCV.

FIG. 3 is a diagram showing a relationship between capacity and OCV.

FIG. 4 is a flowchart showing a control structure of a program executed by the battery ECU of the abnormality detection system according to the first embodiment of the present invention.

FIG. 5 is a control block diagram of an abnormality detection system according to a second embodiment of the present invention.

FIG. 6 is a flowchart showing a control structure of a program executed by a battery ECU of the abnormality detection system according to the second embodiment of the present invention.

[Explanation of symbols]

100 abnormality detection device, 110 battery ECU, 112
CPU, 114 ROM, 116 RAM, 200 relay, 300 assembled battery, 302 36V battery, 40
0 load, 500 DC / DC converter, 600 1
2V battery.

Continued front page    F-term (reference) 2G016 CA03 CB05 CB11 CB12 CC01                       CC02 CC04 CC10 CC12 CC27                       CC28 CD04 CD14 CE00                 5G003 BA03 EA08 GC05                 5H030 AA10 AS08 FF44 FF52

Claims (8)

[Claims] 1. An abnormality detecting device for detecting an abnormality in an assembled battery configured by connecting a plurality of unit cells in series, the capacity equalizing means for equalizing the capacities of the plurality of unit cells. And, from the state where the capacity of each of the unit cells is equalized, based on the voltage of each of the unit cells measured when the unit cells are uniformly discharged, abnormality of the unit cells constituting the assembled battery An abnormality detecting device for an assembled battery, comprising: abnormality determining means for determining. 2. The abnormality determining means measures each of the cells measured when the cells are discharged by the same amount using the capacity equalizing means from a state in which the capacities of the cells are equalized. The abnormality detecting device for an assembled battery according to claim 1, further comprising means for determining an abnormality of a single battery forming the assembled battery based on a voltage of the battery. 3. The abnormality determination means measures the voltage of each of the cells when the assembled battery is discharged by connecting the assembled battery to a large-capacity load from a state where the capacities of the cells are equalized. The battery pack abnormality detection device according to claim 1, further comprising means for determining an abnormality of a single battery constituting the battery pack based on the above. 4. The assembled battery abnormality detection device according to claim 1, wherein the unit cell is a lithium battery. 5. An abnormality detection method for detecting an abnormality in an assembled battery configured by connecting a plurality of unit cells in series, which comprises a capacity equalizing step for equalizing the capacities of the plurality of unit cells. From the state where the capacities of the respective unit cells are equalized, based on the voltage of each unit cell measured when the unit cells are uniformly discharged, the abnormality of the unit cells constituting the assembled battery is determined. An abnormality detection method for an assembled battery, comprising: an abnormality determination step. 6. The abnormality determining step includes measuring the cells when the cells are discharged by the same amount using the capacity equalizing step from a state in which the cells have equalized capacities. 6. The method according to claim 5, further comprising the step of determining an abnormality of a single battery included in the assembled battery based on a battery voltage.
The method for detecting an abnormality in the assembled battery according to. 7. The abnormality determining step comprises measuring the voltage of each unit cell measured when the assembled battery is discharged by connecting the assembled battery to a large-capacity load from a state where the capacities of the unit cells are equalized. The method for detecting an abnormality in a battery pack according to claim 5, further comprising the step of determining an abnormality in a battery cell included in the battery pack based on the above. 8. The assembled battery abnormality detection method according to claim 5, wherein the unit cell is a lithium battery.