JP2001006750A - Battery inspecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance detection accuracy of very small short circuit in a battery cell level in a secondary battery of a hybrid vehicle. SOLUTION: A decision of very small short circuit is performed by making a decision propriety flag as 1 (S18), only when an SOC (charging state) is 20 to 80% of full charging (S10), charging/discharging of a secondary battery by a traveling can be regarded not to exist in a vehicle stopping state (S12), and an environmental temperature t0 of the secondary battery and when a temperature ti of each battery block are in areas where terminal voltage of the secondary battery is stable (S14 and S16).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid vehicle having a battery pack in which a predetermined number of battery groups are connected in series and controlling the state of charge of the battery by a generator driven by an engine. The present invention relates to a device for detecting an abnormality such as a slight short circuit.

[0002]

2. Description of the Related Art Hybrid vehicles using a combination of an engine and an electric motor as a power source are becoming widespread. In a hybrid vehicle, for example, in a region where the engine efficiency is low, such as when the vehicle is running at a low speed or under a heavy load, the motor assists the engine to increase the energy efficiency of the entire drive train. A secondary battery such as a nickel-metal hydride (Ni-MH) battery is used as a power source for the motor. The charging of the secondary battery is performed by regenerative power generation at the time of deceleration or braking, for example, and the charging operation from commercial power is basically unnecessary.

In a hybrid vehicle, if the state of charge of a secondary battery is too high (close to 100%), power generated by regenerative power generation or the like must be discarded to avoid overcharging.
Conversely, if the state of charge is too low (close to 0%), sufficient motor drive cannot be performed at the time of starting or the like, so in order to avoid such a situation, always monitor the state of charge of the secondary battery and set an appropriate value. Is controlled so that it does not greatly deviate from This control is realized by setting an upper limit value and a lower limit value of the SOC in advance in accordance with the battery characteristics, and issuing a charge / discharge instruction so that the SOC is, for example, near the median of the upper limit value and the lower limit value. .

The secondary battery of a hybrid vehicle is 300 V
In order to obtain a near high voltage output, it is common to configure a large number of cells (unit cells) of about 1.2 V as an assembled battery connected in series. For example, in a conventional battery pack of a hybrid vehicle, five or six nickel-metal hydride batteries are connected in series to form one module battery, and two module batteries are connected in series to form one battery block. The battery block is configured as an assembled battery in which, for example, 18 battery blocks are connected in series.

One of the abnormalities in the power supply battery of a hybrid vehicle is a slight short circuit. A slight short-circuit is a phenomenon in which self-discharge occurs between adjacent cells in a module battery due to slight liquid leakage or the like, and as a result, the terminal voltage of the cells gradually decreases even in a non-discharged state. When a short circuit occurs, in the SOC control, extra charging is performed by an amount corresponding to the energy loss due to the self-discharge of the cell, which is contrary to the main purpose of the hybrid vehicle of improving fuel efficiency. Also, the short circuit causes a problem such as overheating of the battery. In addition to the short circuit, if repetition such as overdischarge occurs, a failure such as loss of the electrolyte occurs. For proper operation, it is necessary to quickly detect a failure such as a micro short circuit and take measures such as battery replacement.

[0006] When a failure such as a slight short circuit occurs in the battery, the terminal voltage of the battery generally drops abnormally. Therefore, in principle, the failure can be detected by monitoring the terminal voltage of each cell. However, the number of cells of the assembled battery mounted on the hybrid vehicle exceeds 200, and monitoring the terminal voltages of all these cells is enormous in circuit scale and is not realistic in terms of cost. . Therefore, conventionally, an abnormality has been detected by detecting the terminal voltage of each battery block connected in series and comparing the terminal voltages with each other.

FIG. 5 shows an example of a conventional battery pack voltage detecting circuit. In this example, the main battery 100 is configured by connecting a plurality of battery blocks 110-1 to 110-n in series. Each battery block 110 is configured by connecting two module batteries each having six nickel-metal hydride batteries connected in series. The bipolar terminals of each of the battery blocks 110-1 to 110-n are sequentially connected to the terminal voltage detectors 210-1 to 210-2 of the battery ECU 200.
10-n. Terminal voltage detector 210-
i (i is an integer) outputs the terminal voltage of the battery block 110-i. The judging section 220 is connected to each terminal voltage detector 210
And compares the outputs with each other to determine the abnormality. In this conventional circuit, when the minimum value of the output terminal voltages of the terminal voltage detectors 210 has a difference of 1.2 V or more from all other terminal voltages, it is determined to be abnormal.
This determination routine has been basically executed periodically at regular time intervals while the vehicle is in a runnable state.

[0008] The threshold value 1.2V for this abnormality determination is determined in consideration of various errors. In other words, even when the battery block 110 is normal, the detected value of the terminal voltage may vary to some extent due to errors in the battery, the detector, and the like. Is the determination threshold, and the battery block 11
Only when the terminal voltage of 0 exceeded the threshold value was judged to be abnormal. This error includes an error due to variations in individual battery blocks 110, an error due to variations in characteristics of each terminal voltage detector 210, and the like. For example, since the characteristics of the battery blocks 110 are slightly different from each other, even if the individual battery blocks are normal, the terminal voltages of the battery blocks 110 vary to some extent during repeated charging and discharging. Conventionally, 0.7 V was expected as an error in the terminal voltage of the battery block itself. This is a value in consideration of both charging and discharging. The characteristics of the detector 210 also vary due to manufacturing errors and the like. Conventionally, as this detector error,
0.4V was expected. The battery block error and the detector error were determined with an additional allowance of 0.1 V.
It was the conventional 1.2V abnormality determination threshold.

[0009]

The detected value of the terminal voltage of the battery includes a charge / discharge state (charge or discharge), S
It depends on the OC (charge state), temperature, and other environmental conditions. The above-mentioned threshold value of 1.2 V is a value determined in consideration of such errors in various possible states. Therefore, even if a fault such as a slight short-circuit actually occurs, the fault cannot be detected as long as the fault is buried in the error range, and as a result, the fault detection may be delayed. From another viewpoint, it can be said that the accuracy of the conventional abnormality determination such as a slight short-circuit was not so good because various errors were taken into account.

[0010] Conventionally, two module batteries are connected to one another.
Since one battery block was provided with one terminal voltage detector 210 to detect abnormal terminal voltage, a total of 36 module batteries (that is, 2 battery cells) were used.
18 terminal voltage detectors 210 were required for 16 cells). To reduce the cost of battery ECU 200,
One method is to reduce the number of terminal voltage detectors 210 and their associated circuits. For this purpose, for example, the number of modules per block is increased, for example, one battery block is replaced with three modules. However, simply increasing the number of modules per block in this way cannot ensure the same determination accuracy as in the past. That is, for example, if the conventional configuration of one terminal voltage detector per two modules and one block is changed to a configuration of one terminal voltage detector per three modules and one block, the voltage drop when one cell is slightly short-circuited is reduced. Since the ratio contributing to the voltage drop of the entire battery block is 2/3, if an error of 1.2 V per block is expected as in the conventional case, there is a possibility that a slight short circuit is buried in the error and cannot be detected. is there. In order to detect an abnormality such as a micro short circuit with the same accuracy as in the past, it is necessary to improve the error (variation) of the entire detection system.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and has as its object to improve the accuracy of detecting an abnormality caused by a part of a battery pack such as a micro short circuit in a hybrid vehicle. It is an object to reduce the number of terminal voltage detectors to reduce the circuit scale for abnormality detection.

[0012]

To achieve the above object, a battery inspection device according to the present invention is a battery inspection device for detecting an abnormality of an assembled battery mounted on a hybrid vehicle, wherein the hybrid vehicle is stopped. A stop determining means for determining whether or not the vehicle is in a state, and when the stop determining means determines that the vehicle is in a stopped state, a terminal voltage of each battery block constituting the assembled battery is detected. Abnormality determination means for determining the presence or absence of an abnormality in the battery.

In this configuration, the terminal voltage of each battery block is checked and an abnormality such as a slight short-circuit is determined in an environment in which the battery is unlikely to be charged or discharged, that is, in a stopped state. Is smaller than in the case of the conventional determination, and the determination error is improved.

In a preferred embodiment, the abnormality is determined while the battery pack is being charged with a predetermined current. In the state where the battery is charged with a predetermined amount of current, the values of the internal currents flowing through all the battery blocks are equal, so that the variation (error) of the terminal voltage of each battery block is reduced, and the accuracy of abnormality detection is improved. I do.

In the present invention, the initial error of each terminal voltage detecting means provided corresponding to each battery block is stored as an offset value in the storage means, and the actual detection value by those means is stored in the offset value. And an abnormality is determined using the corrected terminal voltage value.

According to this configuration, the accuracy of the detected value of the terminal voltage is improved, so that the accuracy of the abnormality determination can be improved.

[0017]

Embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of a voltage testing apparatus according to the present invention. In the figure, the main battery 10
Is a main battery that supplies power to the drive motor and the like of the hybrid vehicle. This main battery 10
It is configured as an assembled battery in which the battery blocks 12-1 to 12-m are connected in series. Each battery block 12 includes three module batteries connected in series and accommodated in one package.
Are connected in series to form one package. The difference from the conventional main battery 110 shown in FIG. 5 is that the number of modules constituting one battery block is increased to three, thereby (unless the terminal voltage of the entire main battery is changed). The number of twelve is ／ of the conventional configuration.

The battery ECU 20 controls charging and discharging so that the SOC (state of charge) of the main battery 10 becomes an appropriate value, and monitors the temperature and voltage of the main battery 10. When an abnormality is detected, operations such as limiting and stopping charge / discharge and outputting an alarm are performed. In the present embodiment, among these various functions of the battery ECU 20, attention is paid to a function of inspecting a voltage abnormality of the battery block 12 due to a slight short circuit or the like. Therefore, in FIG. The explanation is focused on.

The battery ECU 20 is provided with m terminal voltage detectors 22-1 to 22-m in the same number as the battery block 12. Each terminal voltage detector 22-i (i is an integer of 1 to m) includes an operational amplifier, and each of the battery blocks 10-i.
A signal corresponding to the difference between the voltages of the bipolar terminals i, that is, the terminal voltage of the battery block is output. In this embodiment,
As the number of battery blocks becomes 2/3 of the conventional configuration,
The number of terminal voltage detectors 22 is also reduced to 2/3 of the conventional one. Output signal (terminal voltage) of each terminal voltage detector 22-i
Is input to the determination unit 24.

The determination unit 24 performs A / D conversion of the input terminal voltage signals of the m battery blocks 12 and compares them to determine if the battery block 12 whose voltage has abnormally dropped due to a slight short circuit or the like. Inspect for any.

The non-volatile memory 30 stores the offset value of each terminal voltage detector 22. The offset value is
This is a deviation of the output of the terminal voltage detector 22 from a correct voltage value, and is caused by a manufacturing error of the operational amplifier of the terminal voltage detector 22 or a peripheral resistor. This offset value is obtained at the time of inspection at the time of factory shipment or the like. That is, a constant voltage is applied to each terminal voltage detector 22 at the time of inspection, an error between the output value of each detector 22 and a true value is obtained at that time, and this is stored in the nonvolatile memory 30 as an offset value. deep.
The nonvolatile memory 30 may be dedicated to the battery ECU 20 or may be another ECU (hybrid ECU).
) May be used.

Next, a procedure for detecting a battery abnormality such as a slight short-circuit in the present embodiment will be described. The procedure described below is for detecting a voltage drop of the battery due to an abnormality of some cells such as a slight short circuit, and a large short circuit in which the electrode of the battery block is short-circuited to ground (GND). It is not for detecting. In the case of a large short circuit, the voltage of the battery block becomes almost 0 V, so that it can be easily detected (in the case of a slight short circuit, the voltage does not drop to 0 V).
The inspection routine for this large short circuit is separately executed and will not be described here.

The abnormality inspection routine executed by the determination unit 24 of the present embodiment includes two phases. The first phase is a phase for determining whether the current environment and state are suitable for determining a voltage abnormality such as a slight short circuit,
The second phase is a phase in which it is determined whether or not a slight short circuit or the like has occurred in any one of the battery blocks 12 based on information on the terminal voltage of each battery block 12 obtained by each terminal voltage detector 22. In the present embodiment, the determination process in the second phase is performed only when it is confirmed in the first phase that the current environment is suitable for the determination.

FIG. 2 shows the procedure of the first phase of the abnormality inspection routine. In the first phase, first, the SOC of the main battery 10 is 20 to 80 (20 when fully charged).
Is determined (S1).
0). The SOC is always detected and calculated by the battery ECU 20. Since the SOC calculation mechanism is conventionally known,
Here, the description is omitted. The region where 20 ≦ SOC ≦ 80 is known as a region where the voltage of the nickel-metal hydride battery is stabilized.

FIG. 4 is a diagram showing a change in the terminal voltage of the battery block 12 of the nickel-metal hydride battery with respect to the SOC at an environmental temperature of 25 degrees Celsius. This graph is obtained by an experiment. Numerical values shown at the respective points are terminal voltage values, and numerical values in parentheses are terminal voltages in a conventional two-module one-block configuration. As shown in this figure, in the nickel hydrogen battery, the state of charge SOC is 2
Even if the voltage changes from 0 to 80, the terminal voltage of the battery block 12 (3 modules) changes only by about 0.4V.
Although not shown in this figure, in the region where the SOC is 20 or less and 80 or more, the terminal voltage sharply decreases (20 or less) or increases (80 or more).

As described above, in S10, the current SOC is:
It is determined whether or not the battery voltage is in a stable (substantially constant) region. In the case of a nickel-metal hydride battery, this region satisfies 20 ≦ SOC ≦ 80, but if the type of battery changes, the range of this region must be changed accordingly. In this determination, if it is determined that the SOC is in the region where the battery voltage is stable (determination result Y), each battery block 12
Since it is considered that the difference between the terminal voltages is not so large, it can be determined that the environment is easy to find a voltage abnormality due to a slight short circuit or the like.

Conversely, if the determination result in S10 is negative (N), the SOC is in a region where the terminal voltage of each battery block 12 rises or falls sharply. In these areas,
Even if the battery block itself is normal, the difference between the terminal voltages tends to be large. Therefore, even if a slight short-circuit or the like occurs, it is difficult to distinguish from a voltage drop in a normal range. Therefore, in the present embodiment, in order to prevent the abnormality determination from being performed in such a case, the determination availability flag is set to “0” (S19). Note that the determination availability flag is a flag indicating whether or not to enable the abnormality determination process based on the terminal voltage, and is managed by the determination unit 24. The abnormality determination process is activated when the value of the determination availability flag is “1”,
When it is "0", it is invalidated.

If the determination in S10 is affirmative (Y), the determination unit 24 determines whether the hybrid vehicle is currently stopped (S12). "Stopped state" here
Means a state where it can be determined that not only the vehicle is stopped but also the main battery 10 is not charged or discharged. The determination of the "stop state" is (1) the vehicle is in a runnable state (READY ON), and (2) the parking brake is set (PARKING O).
N) and (3) the engine speed is almost 0. When all three conditions are met,
It is determined that the state is “stop state”. The runnable state of the condition (1) is a state in which an SMR (system main relay) for switching between supply and cutoff of power of the main battery 10 to various parts of the vehicle is ON (connected state). Therefore, if the condition (1) is satisfied, the vehicle is in a state where it is possible to supply power to each unit and perform various control operations. If the condition (2) is satisfied, it can be determined that the vehicle is currently stopped and does not start immediately. Therefore, in this case, it can be assumed that the main battery 10 is basically not discharged. If the condition (3) is satisfied, it can be determined that the engine is currently stopped, and it can be assumed that the main battery 10 is not charged. If these three conditions are satisfied, it can be assumed that charging and discharging of the main battery 10 are not currently performed, and that charging and discharging are not performed immediately (there is no cause for starting charging and discharging such as running). In such a state, the terminal voltage of each battery of the main battery 10 is more stable than during normal driving, so that error factors of the terminal voltage are reduced. Also,
As will be described later, in the present embodiment, the main battery 10 is charged with a constant current in response to an instruction from the determination unit 24, and in this state, the battery voltage is determined to be abnormal (S in FIG. 3).
24, S26), if there is no charge / discharge factor (except for the instruction from the determination unit 24), there is an advantage that it is easy to realize such a charge state with a constant current. Therefore, if the determination result of S12 is negative (N), the determination possibility flag is set to "0" (S19), and if affirmative (Y), the process proceeds to the next S14. For example, when the vehicle is started at the time of going to work, or when the parking brake is applied for a long signal, the determination result in S12 is affirmative (Y). In step S12, the operation state of the air conditioner and other components may be further checked to confirm that the battery is not discharged.

In S14, the environmental temperature t0 around the main battery 10 and the temperature ti (i is 1
To m), and it is determined whether or not the condition that “t0 and all ti are 0 ° C. or more and 40 ° C. or less” is satisfied. These various temperatures t0 and ti are data used in the conventional battery control, and a temperature sensor for that is already provided. Therefore, it is not necessary to newly provide a temperature sensor for this embodiment. If this condition is not satisfied (judgment result N), the battery voltage is not stabilized, and the voltages of the individual battery blocks 12 may be greatly shifted. Therefore, the judgment possibility flag is set to “0” (S19). .

If the result of the determination in S14 is affirmative (Y), it is determined whether the change width Δt0 of the battery environment temperature t0 for the past 10 seconds is within 3 degrees (S16). If the determination result is negative (N), it means that the battery environmental temperature changes greatly, and it is not possible to guarantee the stability of the terminal voltage of the main battery (that is, the terminal voltage greatly increases or decreases even in a normal battery block). May be)
The judgment possibility flag is set to "0" (S19).

In this manner, when all of the four condition determinations of S10 to S16 become (Y), it is considered that charging and discharging have not been performed and the terminal voltage of each battery block 12 is stable, and each battery block 12 has a stable voltage. It can be assumed that variations (errors) in the terminal voltages of the block 12 are small. In the present embodiment, when it is determined that such a state exists, the determination possibility flag is set to “1” (S18). Note that S10 to S14
May be determined in any order, and the illustrated example is merely an example.

When the determination flag is set as described above, the first phase ends, and then the process proceeds to the second phase. However, in this embodiment, the availability determination flag is “1”.
Only in the case of, the process proceeds to the next second phase. If the flag is "0", the process is stopped in S19. The process of the first phase is periodically performed at regular time intervals while the vehicle is powered on.

Next, the second phase will be described with reference to FIG. In the second phase, first, the determination unit 24 reads the offset value of each terminal voltage detector 22 from the nonvolatile memory 30 (S20), and corrects the output voltage value of each corresponding terminal voltage detector 22 based on this offset value. . The correction value obtained as a result is a value from which a static error component due to a manufacturing error or the like of the terminal voltage detector 22 is almost eliminated. Next, in S22, it is confirmed that the determination possibility flag is "1". If the result of this check is negative (N), the process ends.

When it is confirmed that the determination flag is "1", the determination unit 24 then controls the hybrid ECU that controls the engine, motor, and generator of the hybrid vehicle.
(Not shown) to instruct charging with "charging current (Ic) =-1C" (S24). Here, the charging current of 1C is the amount of current that charges a battery having a charging state of 0 with a uniform current to be fully charged in one hour. For example, when the battery capacity is 6.5 Ah (ampere hours), 1C Is 6.5
A. It should be noted that the negative value "-1C" is
This is for expressing the discharge with a positive value and the charge with a negative value, and the charging instruction means charging with a current of 1C. The hybrid ECU instructs the generator to generate electric power for charging in consideration of other inputs in the charging instruction. At this point, the vehicle is in the “stopped state”, so the hybrid E
It is conceivable that the CU is rarely given an input that causes charging other than the charging instruction in S24. Therefore, if there is no significant change in the situation, the hybrid ECU operates the engine to rotate the generator, and charges the main battery 10 with the current having the magnitude of 1C according to the instruction in S24. In S26, it is determined whether or not the main battery is actually charged at "Ic = -1C". If the result of this determination is negative (N), this determination routine ends, and the process proceeds only if the result of determination is positive (Y).

In the present embodiment, after the main battery 10 is charged at a constant current of 1 C as described above,
Perform an abnormality determination such as a slight short circuit. This is because, in the state where the battery is charged with a constant current, a current of the same magnitude flows to each battery block 12, and the terminal voltage of each battery block 12 is stabilized. Conventionally, the abnormality is determined based on the terminal voltage regardless of whether the battery is in a charge state or a discharge state. Therefore, the error (variation) of the terminal voltage in a normal state is determined (in two modules and one block). 0.7
Although it was necessary to assume a large value as V, in this embodiment, the abnormality determination is limited to charging during a constant current, so that the terminal voltage variation in a normal state (even in this configuration of three modules and one block) 0.4 V may be assumed. As described above, in the present embodiment, a state in which the vehicle is forcibly charged with a constant current in the "stopped state" in which there is no cause of running or other charging / discharging is made, so that an assumed error of the terminal voltage of each battery block is greatly reduced. Could be reduced. Note that the charging current amount of 1C is a reference current amount when charging the battery. Generally, many batteries have been developed in consideration of charging at 1C. Terminal voltage stability is improved. 1C is the value of the charging current used in the inspection at the time of shipping the battery. Only the battery block whose terminal voltage enters a variation of 0.4 V at the time of this 1C charging is shipped as a normal product.

If the result of the determination in S26 is affirmative (Y), then the determination unit 24 determines that the change (increase) in the terminal voltage (after offset correction) of each battery block 12 since entering the second phase is It is determined whether each is within 0.4 V (S28). This means that even at this point the SOC is 20
This is a step for confirming whether it is within the range of ~ 80. According to the characteristics of FIG. 4, if the voltage rise width is 0.4 or less, it can be estimated that the SOC is in the range of 20 to 80. The process proceeds to the next step only when the result of this determination is affirmative (Y), and ends the routine of the second phase when it is negative (N).

In step S30, after entering the second phase, the charge state with the determination enable / disable flag set to "1" and "Ic = -1C", the increase in each terminal voltage is 0.4V or less,
Is determined for 10 seconds. If the state does not reach 10 seconds, the process returns to S22. Then, when the duration of the state reaches 10 seconds (the determination result in S30 is Y), the process proceeds to the next step. For 10 seconds here, "I
c = −1C ”and then start charging each battery block 12.
Is the time it takes to stabilize the voltage to an acceptable level. Therefore, when the determination result of S30 is affirmative (Y), the terminal voltage of each battery block 12 is stabilized, and there is little variation. In the present embodiment, the terminal voltages of the battery blocks 12 are compared with each other only after such a state is reached.

That is, first, the minimum value Vmin of the terminal voltages (after offset correction) of the m battery blocks 12 is
(S32). Then, the minimum value Vmin is compared with the terminal voltage (after offset correction) of each of the other (m-1) battery blocks, and it is checked whether or not the voltage abnormal condition is satisfied (S34). The voltage anomaly condition is a condition that the difference between each of the (m-1) terminal voltages and Vmin is equal to or greater than a predetermined threshold, and in the present embodiment, when this condition is satisfied. It is determined that a voltage abnormality has occurred due to a slight short circuit or the like. In addition, two or more battery blocks 1
Since the probability that a voltage abnormality such as a slight short-circuit occurs at the same time in Step 2 is considered to be extremely low, the battery block 12 in which the abnormality has occurred can be detected under the condition of S34. Therefore, if the determination result in S34 is affirmative (Y), the determination of a voltage abnormality such as a slight short-circuit is determined (S36), and necessary measures such as stopping charging and discharging and outputting an alarm are taken in accordance with this determination. . If the result of the determination in S34 is negative (N), it is determined that no abnormality such as a slight short-circuit has occurred, and this determination routine ends.

In the present embodiment, the abnormality determination processing (second phase) is performed only when the environmental conditions for stabilizing the terminal voltage of the battery are good (when the determination possibility flag is “1” and the battery is being charged at 1 C). The variation in terminal voltage of the battery block 12 itself is small. In addition, since the detection result of each terminal voltage detector 22 is corrected with the offset value stored in advance, a static error between the detectors 22 can be almost ignored. Further, since all the battery blocks 12 connected in series are charged with the same current (1 C), the dynamic error occurring during charging can be regarded as substantially the same in all the battery blocks 12 (charging under the same conditions). Since the temperature change is medium, the temperature change can be regarded as substantially the same, and the direction and magnitude of the change in the circuit resistance and the operational amplifier characteristics can be regarded as the same.)
When the difference between the terminal voltages between the blocks is obtained in step 4, the dynamic error is almost negligible. Therefore, an error (variation) to be assumed with respect to the terminal voltage detection value in a normal state is reduced. Therefore, even if one battery block 12 is configured with three modules, the battery block 12 is replaced with the conventional one (two modules and one block). Variations in the terminal voltage detection value are reduced, and the threshold value used for the determination in S34 can be made smaller than before. For example, in contrast to the conventional threshold value of 1.2 V, in the present embodiment, the threshold value is set to 0.8 V to secure the same accuracy.
(= 1.2V × 2/3), an abnormality such as a slight short circuit can be detected. Because, in the present embodiment, as described above, the variation in the terminal voltage of the battery block 12 is 0.4 V, and the variation at the time of detection caused by the individual detectors 22 is substantially negligible. Even if it is seen, the variation of the terminal voltage detection value to be assumed in the normal state is about 0.5 V, and if a voltage drop exceeding the 0.8 V threshold occurs, it can be reliably determined to be abnormal.

Therefore, in the present embodiment, even if the number of terminal voltage detectors 22 is reduced to two thirds of the conventional case by using three modules as one battery block without changing the voltage of the main battery 10 as a whole, the same accuracy as the conventional one is obtained. Thus, it is possible to detect a voltage drop of the battery block due to a slight short circuit or the like. Therefore, according to the present embodiment, the circuit scale of the battery ECU 20 can be reduced, and the cost can be reduced. Also,
Since the number of wire harnesses and the number of parts between the battery 10 and the battery ECU 20 can be reduced, the overall failure rate can be reduced.

As described above, according to the present embodiment, the terminal voltage of each battery block is stabilized (that is, the terminal voltage is stable).
Since the abnormality determination process (second phase) is performed only when the environmental conditions are good, the accuracy of the terminal voltage detection value serving as the basis for the determination is increased, and the accuracy of the abnormality determination is improved. Further, in the present embodiment, the initial error (offset value) of each terminal voltage detector is obtained in advance, and the actual terminal voltage detection value is corrected thereby, so that the accuracy of the terminal voltage detection value is further improved, and The accuracy can be further improved. In addition, as a result of the increased accuracy of the terminal voltage detection value, the threshold value of the abnormality determination itself can be made smaller than before, and
Battery abnormality such as a slight short circuit can be detected at an early stage. As a result, even if the number of terminal voltage detectors is reduced, the same determination accuracy as that of the related art can be ensured, and the cost of the battery ECU and its peripheral circuits can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of a battery abnormality determination mechanism according to an embodiment.

FIG. 2 is a diagram illustrating a procedure of a first phase of a processing routine according to the embodiment.

FIG. 3 is a diagram illustrating a procedure of a second phase of a processing routine according to the embodiment.

FIG. 4 SOC- of a battery block of a nickel-metal hydride battery
FIG. 4 is a diagram showing terminal voltage characteristics.

FIG. 5 is a diagram illustrating a configuration of a conventional battery abnormality determination mechanism.

[Explanation of symbols]

Reference Signs List 10 main battery, 12-1 to 12-m battery block, 20 battery ECU, 22-1 to 22-m terminal voltage detector, 24 determination unit, 30 nonvolatile memory.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02J 7/00 H02J 7/00 P 7/02 H 7/02 B60K 9/00 CF term (Reference) 5G003 AA07 BA03 EA09 FA06 GC05 5H030 AA06 AA09 AS08 BB10 DD20 FF43 5H115 PG04 PI16 PI29 PI30 PU01 PU25 QA01 QN03 QN12 SE06 TI01 TI05 TI10 TR19 TU04 TU16 TW10 TZ07

Claims (4)

[Claims] 1. A battery inspection device for detecting an abnormality of an assembled battery mounted on a hybrid vehicle, comprising: a stop determination unit that determines whether the hybrid vehicle is in a stopped state; When it is determined that the state, the terminal voltage of each battery block constituting the battery pack is detected,
An abnormality determining unit that determines whether there is an abnormality in the battery pack based on the detection result. 2. The method according to claim 1, wherein the abnormality determining means includes means for instructing the battery pack to be charged with a predetermined charging current, and determines whether there is an abnormality in the charged state at the predetermined charging current. The battery inspection device according to claim 1, wherein 3. The abnormality determination means is provided for each of the battery blocks, a plurality of terminal voltage detection means for detecting a terminal voltage of each of the battery blocks, and a plurality of terminal voltage detection means which are previously obtained for each of the terminal voltage detection means. Storage means for holding the offset value, and determining whether there is an abnormality based on a value obtained by correcting the detection value of each of the terminal voltage detection means with the offset value corresponding to the terminal voltage detection means. The battery inspection device according to claim 1 or 2, wherein: 4. A battery inspection device for detecting an abnormality of an assembled battery mounted on a hybrid vehicle, wherein a plurality of terminal voltages are provided for each of the battery blocks and detect a terminal voltage of each of the battery blocks. Detecting means, storing means for holding an offset value obtained in advance for each of the terminal voltage detecting means, and determining whether or not each battery block is abnormal from the detected terminal voltage of each battery block by each of the terminal voltage detecting means. A battery inspection apparatus comprising: an abnormality determination unit that performs the determination after correcting a detection value of each of the terminal voltage detection units with the offset value corresponding to the terminal voltage detection unit.