JP2000206221A - Abnormality detecting device of current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve detecting precision of an abnormality detecting device of a current sensor which device is arranged on a secondary battery. SOLUTION: Abnormality of a current sensor 20 is judged when a voltage detected by a voltage sensor 18 rises and falls at a frequency larger than or equal to a specified value, with at least a specified coefficient of fluctuation, within a specified time, while a value of current detected by the current sensor 20 indicates almost zero. By the above judgement process, e.g. monotonous increase and descending fluctuation of a voltage which are generated when a battery 10 just after charge and discharge is not stable can be prevented from being judged that the current sensor 20 is abnormal. As the result, detecting precision can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality detection device for a current sensor, and more particularly, to an abnormality detection device for detecting an abnormality in a current sensor for detecting a current flowing through a secondary battery.

[0002]

2. Description of the Related Art An electric vehicle or a hybrid vehicle which obtains vehicle driving force by an electric motor is equipped with a secondary battery, and the electric motor is driven by electric power stored in the secondary battery. Such an electric vehicle has regenerative braking, that is, a function in which an electric motor functions as a generator at the time of vehicle braking, and a function of braking by converting kinetic energy of the vehicle into electric energy. The converted electric energy is stored in the secondary battery and reused when accelerating.

[0003] If the secondary battery is overdischarged or overcharged, the battery performance will be degraded.
It is necessary to understand the state of charge (OC) and adjust the charge and discharge. In particular, in a hybrid vehicle of a type in which a generator can be driven by a heat engine mounted on a vehicle to generate electric power and charge the secondary battery, the rechargeable power can be received by recharging the stored amount of the secondary battery. In order to be able to supply electric power to the motor immediately upon request, the amount of stored power is set to the state of full power storage (100%).
In some cases, the control is performed in the vicinity of the state (0%) where power is not stored at all (50% to 60%). in this case,
It is desired to more accurately detect the charged amount of the secondary battery.

As a device for detecting the amount of charge of the secondary battery, a method of detecting the amount of charge based on the terminal voltage of the secondary battery is well known. However, since the terminal voltage changes depending on the current, in recent years, a device that includes a voltage sensor and a current sensor and detects the amount of stored power using both the terminal voltage and the current has been developed. One example is disclosed in JP-A-9-72.
No.984. Also, depending on the type of the secondary battery, in a certain area of the charged amount, the charged amount does not appear in the external characteristics of the secondary battery. In this case, the charge / discharge current detected by the current sensor is integrated. A method of estimating the amount of stored power is used.

In the above-described apparatus, when an abnormality occurs in the current sensor, the amount of charge in the secondary battery cannot be calculated, and the discharge and charge of the secondary battery can be appropriately controlled. Will not be. Therefore, a power storage amount detection device including a current sensor includes a device that detects an abnormality of the current sensor. By providing such an abnormality detection device for the current sensor, for example, when the current sensor fails and the output value of the voltage sensor fluctuates despite the output value being, for example, the value 0, etc. Then, an abnormality of the current sensor is detected.

[0006]

However, in practice, when the relay is turned off after charging the secondary battery, the terminal voltage of the secondary battery tends to drop at first, and then stabilize. Is shown. Therefore, immediately after charging is stopped, the output value of the current sensor becomes the value 0, but the output value of the voltage sensor may fluctuate. Conversely, when the relay is turned off after discharging, the terminal voltage of the secondary battery increases, and eventually stabilizes. Therefore, immediately after the discharge is stopped, the output value of the current sensor becomes “0”, but the output value of the voltage sensor may fluctuate. That is, although the output value of the current sensor is “0”, the output value of the voltage sensor fluctuates even when the current sensor is normal. Therefore, if the output value of the voltage sensor fluctuates only when the output value of the current sensor is “0”, it is erroneously determined that the current sensor is abnormal even though the current sensor is normal. Therefore, in detecting an abnormality of the current sensor, it is necessary to appropriately identify the fluctuation and the amount of fluctuation of the voltage due to the above-described factors, and to perform highly accurate detection.

[0007] An object of the present invention is to provide a current sensor abnormality detecting device for accurately detecting an abnormality in a current sensor. Another object of the present invention is to provide a current sensor abnormality detection device that prevents erroneous determination and enhances detection accuracy.

[0008]

Means for Solving the Problems and Their Functions and Effects The current sensor abnormality detecting device of the present invention employs the following means in order to achieve at least a part of the above object.

An abnormality detecting device for a current sensor according to the present invention is an abnormality detecting device for detecting an abnormality of a current sensor for detecting a current flowing through a secondary battery, and a voltage detecting device for detecting a voltage between terminals of the secondary battery. Means, and a judging means for judging abnormality of the current sensor based on a state of fluctuation of a voltage detected by the voltage detecting means when a current detected by the current sensor is within a predetermined range. And

In the current sensor abnormality detecting device according to the present invention, when the current detected by the current sensor is within a predetermined range, the abnormality of the current sensor is determined based on the state of the voltage fluctuation. It is possible to identify the fluctuation of the voltage that is seen even when the current sensor is normal, such as a monotonous rise or a monotone fall of the voltage immediately after, and it is possible to accurately detect the abnormality of the current sensor.

In the abnormality detecting device for a current sensor according to the present invention, the predetermined range may be a range centered on a value 0 at which the current can be regarded as a value 0. Since detection is performed when the secondary battery is in a stable state where charging and discharging are not performed, the detection accuracy can be increased.

Further, in the abnormality detecting device for a current sensor according to the present invention, the judging means may be means for judging an abnormality based on a rate of change of the voltage detected by the voltage detecting means. In the abnormality detection device for a current sensor according to the aspect of the present invention, the determination means may be a means for determining an abnormality when the rate of change of the voltage exceeds a predetermined width. In this case, the abnormality can be detected more reliably. Further, in the abnormality detecting device for a current sensor according to the aspect of the present invention, wherein the abnormality is detected based on a voltage change rate, the determination unit determines that the voltage change rate exceeds a predetermined width by a predetermined number of times or more within a predetermined time. ,
It may be a means for determining an abnormality. In this way, erroneous determination can be prevented, and the accuracy of abnormality detection can be increased.

Alternatively, in the abnormality detecting apparatus for a current sensor according to the present invention, there is provided a differential calculating means for calculating a differential value of the voltage detected by the voltage detecting means, and the judging means is operated by the differential calculating means. When the absolute value of the differential value of the voltage is within a predetermined value, the current sensor may be configured to determine abnormality. With this configuration, an abnormality is detected when the secondary battery is in a stable state, so that the detection accuracy can be increased and erroneous determination can be prevented. In the abnormality detection device for a current sensor according to the aspect of the present invention, the determination means may be a means for determining an abnormality when a fluctuation width of the voltage exceeds a predetermined width within a predetermined time. In this case, the abnormality can be detected more reliably.

Further, the abnormality detecting device for a current sensor according to the present invention may further comprise an output means for outputting a result of the judgment by the judging means. In this way, when an abnormality is detected, it is possible to respond quickly.

[0015]

Next, embodiments of the present invention will be described with reference to examples. FIG. 1 is a configuration diagram illustrating the overall configuration of a battery provided with a current sensor abnormality detection device according to one embodiment of the present invention.

In FIG. 1, a battery 10 is an assembled battery in which secondary batteries are connected in series, and a load 14 is connected to the battery 10 via a conductor 12. The conducting wire 12 is provided with a relay 16 for turning on and off the supply of current from the battery 10 to the load 14. The secondary battery constituting the battery 10 is not particularly limited, and may be any of nickel hydride, nickel cadmium, and the like. In addition, this load 14
Is a configuration consisting of an inverter and a motor mounted on an electric vehicle, a configuration consisting of an inverter and a generator, a configuration consisting of an inverter and a motor-generator, and connecting two inverters in parallel to each other. In addition to various configurations such as a configuration in which the battery is connected to an electric machine, the present invention is not limited to an electric motor or a generator such as an electric vehicle, and may be an electric device equipped with a secondary battery.

The battery 10 is provided with a voltage sensor 18 for measuring a terminal voltage and a current sensor 20 for detecting a current in order to calculate a charged amount.
8 and the current sensor 20 output from the electronic control unit 3
Connected to 0. The electronic control unit 30 has a CPU
32, a ROM 34 storing a processing program, and a RAM 36 temporarily storing data.
And an input / output port (not shown). A current from the current sensor 20, a voltage from the voltage sensor 18, and the like are input to the electronic control unit 30 via an input port. In addition, from the electronic control unit 30, a lighting signal to the LED 40 which is turned on when an abnormality of the current sensor 20 is detected is output via an output port.
The electronic control unit 30 calculates the amount of stored power based on the output values of the voltage sensor 18 and the current sensor 20. The method of calculating the charged amount in the electronic control unit 30 is not particularly limited, and an appropriate method of calculating the charged amount can be adopted according to the type of the battery, the performance of the device in which the battery is mounted, the usage mode, and the like. .

For example, in the case of a nickel-metal hydride battery used in an electric vehicle or the like, when the battery charge is 20% or less, the voltage greatly decreases in accordance with the charge, and
When the charged amount exceeds 80%, the voltage increases as the charged amount increases due to charging. Therefore, in such a range where the fluctuation of the voltage can be confirmed with the charged amount, the electronic control unit 30 calculates the charged amount mainly based on the value of the voltage sensor 18, and the other range (the charged amount, approximately 20 ~
(80%), the charge / discharge current can be integrated to calculate the charged amount.

Also, as in a hybrid car,
When it is required to maintain the charged amount at about 50 to 60%, in the case of the nickel-metal hydride battery, it is difficult to confirm the charged amount from the voltage value as described above. Therefore, in such a case, the electronic control unit 3
As the calculation of the charged amount at 0, a method of repeating the integration of the charge / discharge current can be adopted. In addition, when such integration of the charging / discharging current is repeated, an error occurs in the charged amount. Therefore, in order to cope with such a problem, the electronic control unit 30 may be provided with a calibration means for calculating the amount of stored power, and may calculate the amount of stored power with higher accuracy. As a calibration method for calculating the amount of stored power, a method described in Japanese Patent Application No. 9-278801 or the like can be employed. The electronic control unit 3
The calculation of the charged amount at 0 is an example, and a method of calculating the charged amount by simply integrating the charge / discharge current from full charge, such as a battery power supply used in a computer, or the like may be adopted.

As described above, the current sensor 20 is important in the calculation of the amount of battery charge in the electronic control unit 30.
In order to detect an abnormality of the voltage sensor 18 having such an important function, the electronic control unit 30 of the embodiment also functions as an abnormality determination unit of the current sensor 20. Hereinafter, regarding the operation when the electronic control unit 30 functions as the abnormality determination unit of the current sensor 20, the current value (lower) of the current sensor 20 and the voltage value of the voltage sensor 18 when the current sensor 20 of FIG. A description will be given based on a graph showing the behavior of (above). The electronic control unit 30 monitors a current value input from the current sensor 20 and measures a voltage value input from the voltage sensor 18 when the current value is constant.
Then, when the voltage value fluctuates up and down as shown in FIG. 2, it is determined that the current sensor 20 is abnormal.
That is, the electronic control unit 30 erroneously determines that a voltage fluctuation such as a monotonous decrease or a monotonous increase in voltage observed when the relay is turned off after charging / discharging as indicated by a broken line in FIG. From being prevented.

However, if the determination time is extended, the output value of the current sensor 20 may be substantially constant and the output value of the voltage sensor 18 may fluctuate. Need to limit to a short time. The time can be arbitrarily set to a time suitable for detecting an abnormality of the current sensor 20, and can be set to, for example, 10 seconds.

The electronic control unit 30 can determine that the voltage is rising or falling once when the current is constant, and determine that the voltage is abnormal. It is preferable to determine that the current sensor 20 is abnormal when the change in the descent is repeatedly detected several times. Further, when detecting a constant current, it is actually necessary to consider noise and the like. Therefore, instead of detecting that the current variation is completely zero, the current variation is 0.5 A or less. It is necessary to determine under conditions such as By the way, the internal resistance of a battery shows a characteristic that increases as the temperature of the battery decreases. Even when it is determined that the current is constant, it is considered that the current actually fluctuates in a minute width, so the voltage also fluctuates, and the voltage fluctuates greatly when the battery temperature is low. ,
If the predetermined fluctuation value is set to a small value, the fluctuation of the output value of the voltage sensor may exceed the fluctuation value even if the output value of the current sensor 20 is almost constant. It is desirable to set an appropriate value accordingly. Thus, by setting the determination parameters in the electronic control unit 30 as desired, it is possible to appropriately determine the abnormality of the current sensor 20.

Next, the determination operation in the electronic control unit 30 will be described based on the abnormality determination routine shown in FIG.
Here, in the electronic control unit 30, when the output value of the voltage sensor 18 fluctuates up and down 10 times within 10 seconds when the output value from the current sensor 20 becomes constant at “0”, the current sensor A case where the abnormality is determined to be 20 will be described as an example.

At the start of the determination operation (S01), the CPU 32 of the electronic control unit 30 performs initialization and sets the count of voltage rise / fall to "0", and sets the flag A when the voltage rise is detected to "0". 0 ”, and the flag B when a voltage drop is detected is set to“ 0 ”(S0
2). When the initialization is completed, the output value of the current sensor 20 is detected, and it is determined whether or not the output value current (I) is “0” (S03). Here, if the output value from the current sensor 20 is not “0”, monitoring is performed until the output value “0” is detected.

On the other hand, when it is detected that the output value of the current sensor 20 is "0", time measurement for making an abnormality determination is started (S04). After the time measurement is started, first, dv / dt is calculated in order to check the voltage fluctuation, and it is determined whether the value exceeds α, for example, 20 [V / s] (S05). If this value does not exceed α, the output value of the current sensor is detected again to determine whether it is “0”. On the other hand, if it exceeds α, the flag A is set as voltage rise detection (S06), and it is confirmed again whether the current is constant (S07). If the output value of the current sensor 20 is not “0”, the operation is repeated from the initial setting (S02).

When the output value of the current sensor 20 is "0", dv / dt is calculated, and it is determined whether or not the current value exceeds a predetermined fluctuation value α, for example, 20 [V / s]. (S08). Here, when the falling fluctuation is not detected, the operation is started from the initial setting (S02), and when the falling fluctuation of the voltage is detected, the flag B is set (S0).
9). When the flags A and B are both standing (S1
0), "1" is added to the count on the assumption that the ascending / descending fluctuation has been detected, and at the same time, the flags A and B are set to "0" (S11). Then, this series of operations is repeated until the count reaches 10 (S12). When the count reaches 10, the measurement time is detected, and it is determined whether the measurement time is within the set time (S14). If the measurement time is exceeded, the operation starts from the initial setting (S02). Let it start. On the other hand, if the measurement time is within the set time, it is determined that the current sensor 20 is abnormal (S15).

Although not shown in FIG. 3, when the electronic control unit 30 determines that an abnormality has occurred as described above, a lighting signal may be output to the LED 40 to light the LED. When the electronic control unit 30 determines that the current sensor 20 is abnormal, the electronic control unit 3
A signal may be input at 0, and the abnormality determination flag may be set assuming that the calculation of the charged amount is not correctly performed. If the abnormality determination flag is checked in a charge / discharge processing routine (not shown) for controlling the charge / discharge of the battery 10, the discharge mode is stopped to avoid overdischarge, and the mode is switched to the charge mode. You can also.

In the description of the case where the electronic control unit 30 functions as the abnormality determination unit, a case where the output value of the current sensor 20 is constant at 0 has been described as an example.
The output value of the current sensor 20 is not always 0
It is not necessary that the value be a constant value. In addition, in the abnormality determination processing routine shown in FIG. 3, whether the output value of the current sensor is constant is detected every time a voltage change is confirmed (S03, S3).
07) It is also possible to provide another circuit so as to always monitor that the current is constant.

Next, a description will be given of a current sensor abnormality detecting apparatus according to a second embodiment of the present invention. The configuration of the abnormality detection device of the second embodiment is the same as the configuration of the abnormality detection device of the first embodiment. Therefore, the same components are denoted by the same reference numerals, and description thereof will be omitted. The abnormality detection device of the second embodiment executes an abnormality determination processing routine illustrated in FIG. 4 instead of the abnormality determination processing routine of FIG. In addition,
The abnormality determination processing routine of FIG. 4 is also repeatedly executed at predetermined time intervals (for example, every 10 minutes).

When this abnormality determination processing routine is executed, the CPU 32 of the electronic control unit 30 first reads the voltage V detected by the voltage sensor 18 (step S100), sets a value 0 to a counter C, and
A process of setting the voltage V read as an initial value to the maximum voltage Vmax and the minimum voltage Vmin is executed (step S).
102). The processing of steps S100 and S102
This routine is an initial process. The counter C will be described later.

After the initial processing is executed, the current I detected by the current sensor 20 and the voltage sensor 18
Is read (step S10).
4) The read voltage V is stored in a predetermined range of addresses in the RAM 36 (step S106), and a process of determining whether the absolute value of the read current I is less than the threshold Ir is performed (step S108). Here, the threshold value Ir
Is provided to determine whether or not the current I is substantially equal to 0, and is set to a value close to 0, such as 0.1 A, based on a normal error of the current sensor 20 or the like. You.

When the absolute value of the current I is equal to or greater than the threshold value Ir, it is determined that the battery 10 is performing charging and discharging, and the processing for detecting an abnormality of the current sensor 20 is not performed, and this routine ends. In the embodiment, when the absolute value of the current I is equal to or larger than the threshold Ir, the processing for detecting the abnormality of the current sensor 20 is not performed.
For example, when the load 14 is a motor or a generator of an electric vehicle, the operating state of the motor or the generator determined by the depression amount of the accelerator pedal or the brake pedal is read, and the state of the battery 14 is not charged or discharged. Alternatively, when the absolute value of the current I is equal to or larger than the threshold Ir, the current sensor 20 may be determined to be abnormal.

When the absolute value of the current I is less than the threshold value Ir, a process for calculating a differential value dV / dt of the voltage V is executed (step S110). Specifically, the calculation is performed by subtracting the stored previous voltage V from the read voltage V, and dividing this by the repetition time Δt in steps S104 to S124. After calculating the differential value dV / dt in this way, the absolute value of the differential value dV / dt is compared with a threshold value β (step S112). Here, the threshold value β is
Is used to determine whether or not is stable. As described above, immediately after charging and discharging, the battery 1
0 is not stable, and the voltage V may change even though the current I is not flowing. This step S
The process of 112 is a determination process for avoiding the abnormality detection process in a normal state in which the voltage V changes even though the current I is not flowing. Differential value dV / dt
If the absolute value of the current sensor 20 is equal to or larger than the threshold value β, it is determined that the current sensor 20 is not in a state of determining an abnormality, and this routine ends.

When the absolute value of the differential value dV / dt is less than the threshold value β, the voltage V is changed to the maximum voltage Vmax and the minimum voltage Vmax.
min (steps S114 and S118), and when the voltage V is higher than the maximum voltage Vmax, the maximum voltage V
The maximum voltage Vmax is updated by substituting the voltage V for max (step S116), and the voltage V is changed to the minimum voltage Vmi.
When n is smaller than n, the minimum voltage Vmin is updated by substituting the voltage V for the minimum voltage Vmin (step S12).
0). Then, it is determined whether or not the counter C has exceeded the threshold value Cr (step S128). Here, the counter C
Is that the absolute value of the current I is less than the threshold value Ir and the differential value dV / d
Steps S104 to S104 when the absolute value of t is less than the threshold value β
This is to count the number of times 124 is repeated, and it is the same as setting the time to repeat this. Therefore, step S122 is a process of determining whether a predetermined number of times or a predetermined time has elapsed. When the counter C is equal to or smaller than the threshold value Cr, it is determined that the predetermined number of times or the predetermined time has not elapsed, the counter C is incremented (step S124), and the process returns to step S104.

If the counter C is larger than the threshold value Cr, it is determined that a predetermined number of times or a predetermined time has elapsed, and the minimum voltage Vmin is subtracted from the maximum voltage Vmax to calculate the fluctuation width ΔV of the voltage V (step S126). The width ΔV is compared with the threshold value Vr (step S128). Here, the threshold Vr is set as a range in which the voltage V can fluctuate even when the current I is 0 and the differential value dV / dt is equal to or smaller than the threshold β, or a value slightly larger than this range even when everything is normal. It is determined whether or not it is within the range in the normal state. Therefore, when the variation width ΔV of the voltage V is equal to or smaller than the threshold value Vr, the current sensor 20 determines that the current sensor 20 is normal and terminates this routine. When the variation width ΔV is larger than the threshold value Vr, the current sensor 2
0 is determined to be abnormal, the abnormality determination flag of the current sensor 20 is set, and the LED 40 is turned on (step S13).
0), end this routine.

The processing in the abnormality determination processing routine will be further described with reference to the explanatory diagram of FIG. Until time t1, the current I is a negative value, and since the battery 10 is being charged by the generator and the battery 10 is being charged by the regenerative braking, the absolute value of the current I is determined to be equal to or greater than the threshold Ir in step S108. No abnormality detection processing is performed. Time t1
Therefore, even if the current I becomes 0, the voltage V is falling because the battery 10 is not in a stable state immediately after the end of charging. Since the absolute value of the differential value dV / dt at this time is larger than the threshold value β, the abnormality detection processing is not performed in step S112. When the battery 10 is gradually stabilized and the absolute value of the differential value dV / dt reaches the threshold value β (time t2), steps S114 to S114 are performed.
The process of S124 is repeatedly executed until time t3 when the counter C becomes larger than the threshold value Cr. At time t3 when the counter C becomes larger than the threshold value Cr, the fluctuation width ΔV of the voltage V
Is compared with the threshold value Vr (step S128), and the abnormality of the current sensor 20 is determined.

According to the current sensor abnormality detecting apparatus of the second embodiment described above, the abnormality of the current sensor 20 is detected after the battery 10 to be charged / discharged is stabilized, so that an erroneous determination is made. The abnormality of the current sensor 20 can be detected without any problem. As a result, the detection accuracy can be increased. In addition, since the abnormality of the current sensor 20 is detected when the current I is not flowing, erroneous determination based on a change in the voltage V caused by the flow of the current I can be prevented.

In the abnormality detecting device for a current sensor according to the first or second embodiment, the electronic control unit 30 functions as an abnormality judging section to thereby reduce the current sensor of the battery storage amount detecting device mounted on the electric vehicle. Although the case of detecting an abnormality has been described, the present invention is not limited to this current sensor, and it is needless to say that the present invention can be applied to a current sensor of a battery storage amount detection device other than an automobile and a current sensor provided in another battery. .

The embodiments of the present invention have been described with reference to the embodiments. However, the present invention is not limited to these embodiments, and various embodiments may be made without departing from the scope of the present invention. Of course, it can be carried out.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a battery equipped with a current sensor abnormality detection device as one embodiment of the present invention.

FIG. 2 is a graph showing the behavior of output values of a current sensor and a voltage sensor when a current sensor abnormality is determined in the current sensor abnormality detection device of the embodiment.

FIG. 3 is a flowchart illustrating an example of an abnormality determination processing routine executed by an electronic control unit 30 of the current sensor abnormality detection device according to the embodiment.

FIG. 4 is a flowchart illustrating an example of an abnormality determination processing routine executed by an electronic control unit 30 of the current sensor abnormality detection device according to the second embodiment.

FIG. 5 is an explanatory diagram illustrating the operation of the current sensor abnormality detection device according to the second embodiment as a time series.

[Explanation of symbols]

10 battery, 18 voltage sensor, 20 current sensor, 3
0 electronic control unit, 32 CPU, 34 ROM,
36 RAM, 40 LEDs.

Claims (8)

[Claims] 1. An abnormality detection device for detecting an abnormality of a current sensor for detecting a current flowing through a secondary battery, comprising: voltage detection means for detecting a voltage between terminals of the secondary battery; An abnormality detection device comprising: a determination unit configured to determine an abnormality of the current sensor based on a state of voltage fluctuation detected by the voltage detection unit when a current flowing within a predetermined range. 2. The abnormality detection device according to claim 1, wherein the predetermined range is a range centered on a value 0 at which the current can be regarded as a value 0. 3. The abnormality detection device according to claim 1, wherein the determination unit determines an abnormality based on a rate of change of a voltage detected by the voltage detection unit. 4. The apparatus according to claim 3, wherein the determining unit determines that the abnormality is abnormal when the rate of change of the voltage exceeds a predetermined width.
Abnormality detection device as described. 5. The abnormality detection device according to claim 3, wherein the determination unit determines that the voltage is in an abnormal state when the rate of change of the voltage exceeds a predetermined width for a predetermined number of times within a predetermined time. 6. The abnormality detection device according to claim 1, further comprising a differential operation unit that calculates a differential value of the voltage detected by the voltage detection unit, wherein the determination unit performs the differential operation by the differential operation unit. An abnormality detection device, which is means for determining abnormality of the current sensor when an absolute value of the calculated differential value of the voltage is within a predetermined value. 7. The abnormality detection device according to claim 6, wherein the determination unit determines that an abnormality occurs when a fluctuation width of the voltage exceeds a predetermined width within a predetermined time. 8. The abnormality detection device according to claim 1, further comprising an output unit that outputs a determination result of the determination unit.