JP2017083388A - Electric leakage detection device and electric leakage detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric leakage detection device and an electric leakage detection method capable of making electric leakage determination even when a low frequency noise occurs.SOLUTION: The electric leakage detection device includes: a signal output part for outputting an inspection signal via a detection resistor and a coupling capacitor to a high voltage circuit insulated by an insulation resistor: a signal extraction part for adjusting the inspection signal at a node between the detection resistor and the coupling capacitor, and for outputting an extraction signal; and an electric leakage determination part for detecting the electric leakage of the high voltage circuit on the basis of amplitude of the extraction signal. When a difference between a central value of amplitude in a current cycle of the extraction signal and a reference value set on the basis of the central value of the amplitude in the past cycle of the extraction signal is within a predetermined allowable range, the electric leakage determination part outputs an electric leakage detection result based on the amplitude in the current cycle, and when the difference is outside the predetermined allowable range, the electric leakage determination part does not output any effective electric leakage detection result based on the amplitude in the current cycle.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a leakage detection device and a leakage detection method for detecting leakage in a high voltage circuit.

  For example, a vehicle such as an electric vehicle is equipped with a high voltage circuit including a high voltage power source such as a storage battery as a power source. Such a high voltage circuit is insulated from the vehicle body grounded to the ground, the low voltage circuit for driving the in-vehicle device, and the like for the safety of the vehicle user. However, for some reason, leakage may occur between the high voltage power supply and the ground or the low voltage circuit. Since such electric leakage leads to the danger of the user, devices for detecting electric leakage are widespread.

  In such a leakage detection device, for example, an AC signal is applied to a high voltage circuit via a coupling capacitor, and the leakage is detected from the amplitude fluctuation amount of the AC signal. However, the amplitude fluctuation amount of the AC signal is changed due to noise or the like, so that it may be erroneously detected that the leakage detection device has a leakage even though the leakage has not actually occurred. For example, Patent Literature 1 discloses a leakage detection device that avoids such erroneous detection.

JP 2007-108074 A

  In Patent Document 1, a median value between a high-side peak value and a low-side peak value of a voltage value at a connection point between a detection resistor and a coupling capacitor is calculated, and the median value and a predetermined reference value are calculated. In the case where the difference is equal to or greater than a predetermined upper limit value, a leakage detection device is disclosed in which the leakage detection unit determines that an erroneous detection has occurred.

  However, in the leakage detection device disclosed in Patent Document 1, the reference value serving as a reference for determining whether or not there is a false detection is a predetermined fixed value. For this reason, in the leakage detection device disclosed in Patent Document 1, for example, when a state in which the voltage value is separated from the reference value by a predetermined upper limit value or more continues over a plurality of amplitude periods, it is determined as a false detection during that time. There is a disadvantage that it is not possible to carry out a leakage check. Such a disadvantage can occur, for example, when low-frequency noise occurs on the high-voltage circuit side and the voltage value at the connection point fluctuates due to the influence. However, voltage fluctuations due to low-frequency noise are often not large enough to prevent leakage detection (when the amplitude waveform does not collapse), so it is desirable to detect leakage even when low-frequency noise occurs. Has been.

  The present invention has been made to eliminate such disadvantages, and provides a leakage detection device and a leakage detection method capable of performing leakage determination even when low-frequency noise is generated. Objective.

  The leakage detection device of the present invention includes a signal output unit that outputs a test signal to a high voltage circuit insulated by an insulation resistor via a detection resistor and a coupling capacitor, and a node between the detection resistor and the coupling capacitor. A signal extraction unit that adjusts the inspection signal at a point and outputs an extraction signal; and a leakage determination unit that detects a leakage of the high-voltage circuit based on an amplitude of the extraction signal. , When the difference between the median amplitude of the extracted signal in the current cycle and the reference value set based on the median amplitude of the extracted signal in the past cycle is within a predetermined allowable range, The leakage detection result based on the amplitude in the current cycle is output, and when the difference is outside the predetermined allowable range, the effective leakage detection result based on the amplitude in the current cycle is output. There.

  The leakage detection method of the present invention includes a test signal output step of outputting a test signal to a high voltage circuit insulated by an insulation resistor via a detection resistor and a coupling capacitor, and between the detection resistor and the coupling capacitor. An extraction signal output step for adjusting the inspection signal at the node and outputting an extraction signal; and a leakage detection step for detecting a leakage in the high-voltage circuit based on the amplitude of the extraction signal. The step determines whether or not the difference between the median amplitude of the extracted signal in the current cycle and a reference value set based on the median amplitude of the extracted signal in the past cycle is within a predetermined allowable range. A determination step for determining whether the difference is within a predetermined allowable range, or a leakage detection result based on the amplitude in the current period Output, the difference has a determination result output step does not output a valid leakage detection results based on the amplitude of the current period when it is determined to be outside a predetermined tolerance.

  According to the present invention, it is possible to make a leakage check even when low-frequency noise is generated.

The block diagram which shows an example of a structure of the earth-leakage detection apparatus of embodiment of this invention The figure which shows an example of the waveform of the extraction signal when there is no influence of electric leakage and all the high voltage circuits are operating normally The figure which shows an example of the waveform of the extraction signal when a leak occurs The figure which shows an example of the waveform of the extraction signal when low frequency noise occurs The figure which shows an example of the waveform of the extraction signal when the high frequency noise occurs Flowchart for explaining an operation example of the leakage detection device The figure for _{demonstrating} the calculation method of the median value Vc in a certain period when there is no low frequency noise The figure for demonstrating the case where the amplitude of an extraction signal is calculated smaller than the original amplitude under the influence of low frequency noise The figure for explaining the case where the amplitude of the extraction signal is calculated larger than the original amplitude due to the low frequency noise The figure which shows the case where the start of a leak determination cycle is the increase timing of an extraction signal The figure which shows the case where the start of a leak determination cycle is the decrease timing of the extracted signal The _figure for _{demonstrating} the setting method of threshold value _Vthn for noise detection

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<Description of configuration>
FIG. 1 is a configuration diagram showing an example of the configuration of a leakage detection device 10 according to an embodiment of the present invention.

  The leakage detection device 10 according to the embodiment of the present invention is a device that is mounted on, for example, a vehicle and detects a leakage of the high voltage circuit 100. The high voltage circuit 100 includes a battery 110 that supplies a high voltage, and a load (for example, a drive motor for an electric vehicle) 120 that is driven by the high voltage. The high voltage circuit 100 is separated from the ground through an insulation resistor 111. In the high voltage circuit 100, it is assumed in advance that low frequency noise and high frequency noise are generated.

  The leakage detection device 10 includes a coupling capacitor C0, a signal output unit 11, a detection resistor R0, a signal extraction unit 12, a noise determination unit 13, and a leakage determination unit 14.

  The coupling capacitor C0 connects the leakage detection device 10 and the high voltage circuit 100 in an AC manner, and insulates the leakage detection device 10 and the high voltage circuit 100 in a DC manner. One end of the coupling capacitor C0 is connected to the high voltage circuit 100 (for example, the negative electrode of the battery 110).

  The signal output unit 11 outputs an AC inspection signal. The signal output unit 11 is supplied with an offset voltage that is an intermediate voltage of the power supply voltage of the leakage determination unit 14. The signal output unit 11 outputs an AC voltage (for example, a sine wave) whose voltage changes around the offset voltage as a test signal. The signal output unit 11 outputs a test signal to the other end of the coupling capacitor C0 through the detection resistor R0.

  The detection resistor R0 is a resistor for causing a voltage drop in the inspection signal when a current flows to the high voltage circuit 100 via the coupling capacitor C0.

  The signal extraction unit 12 adjusts the inspection signal output to the node n1 between the detection resistor R0 and the coupling capacitor C0, and outputs an extraction signal. The signal extraction unit 12 includes, for example, a low-pass filter, a high-pass filter, and an amplifier circuit (all not shown). The signal extraction unit 12 removes high-frequency noise and low-frequency noise from the inspection signal output to the node n1 using a low-pass filter and a high-pass filter, and adjusts the signal (extraction signal) that can be determined by the noise determination unit 13 using an amplifier circuit. To do. Note that the configuration (type and number) of the filter of the signal extraction unit 12 may be selected as appropriate, and may further include only an amplifier circuit without having a filter.

  Even if the signal extraction unit 12 tries to remove high-frequency and low-frequency noise using a filter such as a low-pass filter and a high-pass filter in this way, it is difficult to remove all high-frequency noise and low-frequency noise. Noise may be superimposed on the signal.

  The noise determination unit 13 determines whether noise is occurring. For example, when noise is generated in the high voltage circuit 100, the voltage value of the extraction signal varies due to the noise. The noise determination unit 13 determines the presence or absence of noise generation based on the voltage fluctuation of the extracted signal. Details of the method of determining the occurrence of noise by the noise determination unit 13 will be described later.

  When the noise determination unit 13 does not determine that noise has occurred, the leakage determination unit 14 determines whether or not leakage has occurred based on the extracted signal adjusted by the signal extraction unit 12. Do. Hereinafter, this determination is referred to as “leakage determination”. Specifically, the leakage determination is performed by a microcomputer or the like constituting the leakage determination unit 14 A / D (analog / digital) conversion of the extracted signal, and the voltage value of the extracted signal is compared with a predetermined threshold value. To do. Then, the leakage determination unit 14 outputs the determination result to the outside, for example, a control system (not shown) of a vehicle on which the leakage detection device 10 is mounted. That is, the leakage determination unit 14 outputs whether or not it is determined that leakage has occurred as a leakage detection result. When the leakage detection unit 14 outputs a leakage detection result indicating that leakage has occurred, the vehicle control system (not shown in FIG. 1) electrically disconnects the high voltage circuit 100 from the vehicle body and the like. It is possible to prevent a person who is in contact with the person from getting an electric shock.

<Description of operation>
Hereinafter, the operation of the leakage detection device 10 will be described. When the signal output unit 11 outputs an inspection signal that is an alternating current signal having a predetermined period, the signal extraction unit 12 adjusts the inspection signal in which the voltage drop is generated by the detection resistor R0, and the noise determination unit 13 and the leakage determination unit are extracted signals. 14 for output. The noise determination unit 13 determines whether noise is generated based on the extracted signal. Moreover, the leakage determination part 14 determines the presence or absence of a leakage based on the voltage fluctuation amount of an extraction signal.

  FIG. 2 shows an example of the waveform of the extracted signal. FIG. 2A is a diagram illustrating an example of a waveform of an extraction signal when there is no influence of leakage and noise and all the high voltage circuits are operating normally. As shown in FIG. 2A, when there is no leakage, the waveform of the extracted signal is a sine wave and the amplitude is constant.

  FIG. 2B is a diagram illustrating an example of a waveform of an extraction signal when leakage occurs. In FIG. 2B, the amplitude is different between time t1 and after time t1, and the amplitude is smaller after time t1. This is because the voltage value of the extracted signal is attenuated due to the influence of leakage.

  As shown in FIG. 2B, when a leakage occurs, the waveform of the extracted signal is attenuated as compared to the case where no leakage occurs. Based on such properties, the leakage determination unit 14 determines that leakage has occurred when the amount of fluctuation in the amplitude of the extracted signal is greater than or equal to a predetermined threshold value.

  Next, the behavior of the leakage detection device 10 when noise occurs in the circuit will be described. FIG. 3 shows an example of the waveform of the extracted signal when noise occurs. FIG. 3A is a diagram illustrating an example of a waveform of an extraction signal when low-frequency noise occurs. In FIG. 3, “x” indicates the median value of the amplitude of the extracted signal, and as illustrated in FIG. 3A, the median value of the amplitude of the extracted signal increases and decreases with time due to low-frequency noise.

  However, the amount of fluctuation in the voltage value of the extracted signal due to low-frequency noise is small (the amplitude waveform of the extracted signal does not collapse due to noise) and often does not interfere with the determination of leakage by the leakage determination unit 14. When such low frequency noise occurs, the median value of the amplitude of the extracted signal varies gently. For this reason, in the present embodiment, the noise determination unit 13 allows the fluctuation of the voltage value due to the low frequency noise. Therefore, if the fluctuation amount of the median value of the extracted signal is within a predetermined allowable range, the noise is generated. It is determined that it has not occurred. This predetermined allowable range is referred to as a noise allowable range in the present embodiment. Note that the low frequency noise means noise having a lower frequency than the extracted signal.

  More specifically, the noise determination unit 13 sets a noise allowable range for allowing a fluctuation in voltage value due to low frequency noise for each period of the extraction signal, and the median value of the amplitude of the extraction signal in a certain period is the noise. If it is within the allowable range, it is determined that no noise is generated. That is, when no noise is generated or when low-frequency noise is generated to such an extent that the waveform does not collapse, the median value of the amplitude of the extracted signal is within the allowable noise range. 13 determines that no noise is generated. In this case, the leakage determination unit 14 determines the leakage based on the extracted signal. On the other hand, the noise determination unit 13 determines that noise has occurred when the median value of the amplitude of the extracted signal in the period is outside the allowable noise range. In this case, the leakage determination unit 14 does not perform leakage determination in order to prevent erroneous determination of leakage due to noise.

  FIG. 3B is a diagram illustrating an example of a waveform of an extraction signal when high-frequency noise occurs. A peak Pn shown in FIG. 3B is a peak whose voltage value fluctuates due to high frequency noise. When noise with a steep voltage value variation (disruption of the amplitude waveform of the extracted signal) occurs in a short time in this manner, the leakage determination unit 14 determines that the leakage is not actually occurring even though the leakage has not actually occurred. It may be erroneously determined that the error occurred. When such high-frequency noise occurs, the median value of the amplitude of the extracted signal fluctuates greatly, and as shown in FIG. 3B, the median value of the amplitude of the extracted signal in that period is outside the allowable noise range. For this reason, when such a change in voltage value is detected, the noise determination unit 13 determines that noise has occurred, and the leakage determination unit 14 does not perform leakage determination based on the determination of the noise determination unit 13. The high frequency noise means noise having a high frequency compared with the inspection signal. The allowable noise range is set for each cycle of the extracted signal by the noise determination unit 13.

  Next, an operation example of the leakage detection device 10 will be described. FIG. 4 is a flowchart for explaining an operation example of the leakage detection device 10.

In step S <b> 1, the noise determination unit 13 determines whether noise is generated for each cycle of the extracted signal. This determination is performed by determining whether or not the fluctuation amount of the median value of the amplitude of the extracted signal in a certain cycle is within the allowable noise range shown in FIG. More specifically, when the median value of the amplitude of the extracted signal in a certain cycle is V _c , the noise detection reference value is V _{c_std} , and the noise detection threshold is V _thn , the noise determination unit 13 When Expression (1) is satisfied, it is determined that the fluctuation amount of the voltage value of the extracted signal is within the allowable noise range and no noise is generated. And when the numerical formula (1) is not satisfied, the noise determination unit 13 determines that the amount of fluctuation in the median value of the amplitude of the extracted signal is outside the allowable noise range, and determines that noise has occurred. The method for setting these parameters will be described in detail later.

In other words, Expression (1) is an expression for determining whether or not the median value V _c of the amplitude of the extracted signal is within the noise detection range V _{c — std} ± V _thn .

  As shown in FIG. 4, when the noise determination unit 13 determines in step S1 that no noise is generated, the flow proceeds to step S2. On the other hand, when the noise determination unit 13 determines in step S1 that noise has occurred, the flow proceeds to step S6.

Note that, as described above, in the noise determination in step S1, it is not determined that noise is generated even if low-frequency noise such as that illustrated in FIG. 3A is generated. Then, when noise that causes a steep waveform change in a short time as illustrated in FIG. 3B has occurred, it is determined that noise has occurred. As will be described in detail later, the noise detection threshold value V _thn in the above formula (1) is set to be larger than the change in waveform caused by low frequency noise as exemplified in FIG. 3A. For this reason, in step S1, when low frequency noise is generated, the fluctuation of the voltage value due to the low frequency noise is smaller than the threshold value V _thn , so that the noise determination unit 13 generates noise. Judge that it is not.

When it is determined in step S1 that no noise has occurred, in step S2, the leakage determination unit 14 determines whether or not a leakage has occurred in the circuit. The determination of leakage by the leakage determination unit 14 is performed by detecting whether or not the amplitude of the extracted signal in the current period is attenuated as compared to the case where no leakage has occurred, as shown in FIG. 2B. . Specifically, the leakage determination unit 14 operates the high-voltage circuit 100 and the leakage detection device 10 in a state where no leakage (and noise) has occurred in advance, acquires the amplitude of the extracted signal in advance, and holds that value. In addition, when determining leakage, the amplitude in the current cycle is compared with a value acquired in advance, and the difference between the amplitude of the extracted signal in the current cycle and the amplitude when no leakage has occurred, If it is equal to or greater than the leakage detection threshold value V _thl, it is determined that leakage has occurred. Here, the leakage detection threshold value V _{thl, which} is a determination criterion for leakage detection, is determined in advance based on, for example, the voltage value of the extracted signal when leakage is experimentally generated in the high voltage circuit 100. Just do it.

  In step S2, if the leakage determination unit 14 determines that leakage has occurred, the flow proceeds to step S3. On the other hand, if the leakage determination unit 14 determines in step S2 that leakage has not occurred, the flow proceeds to step S4.

  In step S3, the leakage determination unit 14 outputs a determination result that leakage has occurred. On the other hand, in step S4, the leakage determination unit 14 outputs a determination result that leakage has not occurred.

In step S5, the noise determination unit 13 outputs the determination result in step S3 or S4, and then sets the noise detection reference value V _{c_std} in the next period based on the amplitude value or the like of the current period. Details of the method of setting the noise detection reference value V _{c_std} will be described later.

  If it is determined in step S1 that noise has occurred, in step S6, the leakage determination unit 14 does not determine leakage in the current cycle, and determines the result of leakage determination in the previous cycle, for example, vehicle control. Output to system etc. Thereby, even when the leakage determination cannot be performed due to the influence of noise, the leakage determination result having a certain degree of reliability, that is, the latest leakage determination result can be output. In step S7, the process in the current cycle is completed, and the process proceeds to the next cycle.

  The operation example of the leakage detection device 10 has been described above. Next, a method for setting each parameter in step S1 shown in FIG. 4 will be described.

First, FIG. 5 shows an example of a method for calculating the median value V _c of the amplitude of the extracted signal when there is no low frequency noise. FIG. 5A is a diagram for explaining a method of calculating the median value V _c in a certain cycle when there is no low frequency noise. As described above, the operation of the noise determination unit 13 is performed every one cycle (leakage determination cycle) of the extraction signal as shown in FIG. 4, and the maximum value V _max of the voltage value of the extraction signal in that cycle is the median and the minimum value V _min is the median V _c of the current cycle. Specifically, the median value V _c is calculated using the following mathematical formula (2).

  When low frequency noise is generated, as shown in FIG. 5B or 5C, the waveform of the extracted signal varies due to the influence of the low frequency noise. FIG. 5B is a diagram for describing a case where the amplitude of the extracted signal is calculated to be smaller than the original amplitude due to the influence of low-frequency noise. FIG. 5C is a diagram for explaining a case where the amplitude of the extracted signal is calculated larger than the original amplitude due to the influence of low frequency noise.

  As described above, when the waveform of the extracted signal is fluctuated due to the influence of the low frequency noise, the amplitude of the extracted signal is different from the original value. Therefore, when low frequency noise is generated, it is necessary to calculate the median amplitude based on the amplitude considering the influence.

  6A and 6B are diagrams for explaining a method of calculating the median amplitude when the waveform of the extracted signal varies due to the influence of low-frequency noise. FIG. 6A shows a case where the start of the leakage determination cycle is the increase timing of the extraction signal. FIG. 6B shows a case where the start of the leakage determination cycle is the extraction signal decrease timing.

6A and 6B, _{Vmax_t0} is the maximum value in the leakage determination cycle t0. _{Vmax_t1} is the maximum value in the leakage determination cycle t1. Moreover, _{Vmin_t0} is the minimum value in the leakage determination cycle t0. V _{min_t1} is the minimum value in the leakage determination cycle t1. _{Also, V min} is the median of the _{V Min_t0} and _{V min_t1.} That is, V _min is calculated using the following formula (3).

In the case shown in FIG. 6A, that is, when the start of the leakage determination cycle is the increase timing of the extracted signal, the median value V _c is calculated using the following formula (4).

On the other hand, in the case shown in FIG. 6B, that is, when the start of the leakage determination cycle is the decrease timing of the extracted signal, the median value V _c is calculated using the following formula (5).

For example, measured values may be used as the parameters of V _max , V _min , V _{max_t0} , V _{max_t 1} , V _{min_t 0} , and V _{min_t 1} .

Next, a method for setting the noise detection reference value V _{c_std} will be described. The noise detection reference value V _{c_std} is the median value of the amplitude of the extracted signal when no noise (or leakage) occurs in the high voltage circuit 100. As a specific method for calculating the noise detection reference value V _{c_std} , for example, there is the following method.

As a first method, for example, when it is not determined that noise has occurred in the n-th cycle, the noise detection reference value V _{c_std} in the next cycle n + 1 cycle is used as the median value V in the n-th cycle that is the current cycle. There is a method of setting to _c . Alternatively, as a second method, for example, when the median of the amplitude of the extracted signal in the past several cycles is observed and it is determined that no noise is generated in all the cycles, the moving average for the several cycles A method of setting the value to the noise detection reference value V _{c_std} in the next period may be adopted.

As described above, the noise detection reference value V _{c_std} is changed for each cycle of the extracted signal. Note that the initial value of the noise detection reference value V _{c_std} is, for example, the median value of the amplitude of the ideal extracted signal when noise (or leakage) is not generated in the design of the high voltage circuit 100, That value may be adopted as the initial value. Alternatively, in consideration of variation due to each component (not shown) constituting the high voltage circuit 100, the extraction was performed in a quasi-ideal environment free from noise and leakage when the high voltage circuit 100 and the leakage detection device 10 were shipped. The median value obtained from the actual measurement value of the signal may be set as the initial value of the noise detection reference value V _{c_std} .

Further, a method for setting the noise detection threshold value V _thn will be described. FIG. 7 is a diagram for describing a method for setting the threshold value V _thn for noise detection. In FIG. 7, the dotted sine curve indicates the waveform of the low frequency noise, and the solid curve indicates the waveform of the extracted signal.

As shown in FIG. 7, the waveform of the extracted signal fluctuates due to the influence of low frequency noise. The noise detection threshold V _thn is set so as to allow the influence on the extracted signal by the maximum low-frequency noise in a range not exceeding the voltage measurement range. Specifically, in FIG. 7, when the amplitude of the extracted signal is V _amp , the voltage measurement range is V _range , the period of the extracted signal is t, and the period of the low frequency noise is T, the amplitude of the low frequency noise is (V _range). −V _amp ), the threshold value V _thn for noise detection, which is an amplitude fluctuation amount allowable for one period of the extracted signal, is calculated as in the following formula (6).

The method for setting the threshold value V _thn for noise detection described above is _merely an example, and the present invention is not limited to this. In general, the noise detection threshold value V _thn may be set to a value that allows some variation in the extracted signal due to low-frequency noise.

  As described above, the leakage detection device according to the embodiment of the present invention includes the signal output unit that outputs the inspection signal to the high voltage circuit insulated by the insulation resistance via the detection resistor and the coupling capacitor, and the detection resistor. A signal extraction unit that adjusts a test signal at a node between the coupling capacitor and the coupling capacitor, and outputs an extraction signal; and a leakage determination unit that detects a leakage of a high-voltage circuit based on the amplitude of the extraction signal When the difference between the median amplitude in the current cycle of the extracted signal and the reference value set based on the median amplitude in the past cycle of the extracted signal is within a predetermined allowable range, The leakage determination result based on the amplitude in the current cycle is output, and if the difference is outside the predetermined allowable range, the effective leakage determination result based on the amplitude in the current cycle is not output.

  With such a configuration, the reference value for calculating the difference from the median amplitude of the extracted signal is not a fixed value, but the median amplitude of the extracted signal in the past cycle. For this reason, when noise (for example, high-frequency noise) having a short period and a large waveform fluctuation amount occurs, the difference is outside a predetermined allowable range (noise allowable range). On the other hand, when noise (for example, low frequency noise) having a long period and a short waveform variation occurs, the difference is within a predetermined allowable range. For this reason, even when low frequency noise occurs, the noise determination unit 13 does not determine that noise has occurred, and the leakage determination unit 14 can perform leakage determination.

  Furthermore, when the noise determination unit determines that noise has occurred, the leakage determination unit maintains the result of the leakage determination in the previous cycle as the result of the leakage determination in the current cycle. For this reason, an accurate leakage determination result can be obtained even when the leakage determination is not performed, for example, when high-frequency noise occurs.

  When the noise determination unit determines that noise has occurred (difference between the median amplitude of the extracted signal in the current cycle and the reference value set based on the median amplitude of the extracted signal in the past cycle Is not within the predetermined allowable range), the leakage determining unit has explained that the determination of the leakage in the current cycle is not performed, but is not limited thereto, and the determination of the leakage in the current cycle may be performed. .

  In this case, since the leakage determination result in the current cycle may be erroneously determined, the leakage determination result in the current cycle is not output (for example, the leakage determination result itself is not output or the leakage detection result in the previous cycle is not detected). Output the result), or if the leakage determination result in the current cycle is output, it is preferable to output that the leakage determination result is not valid (possibly with a false detection) due to a flag or the like. .

  That is, when the noise determination unit determines that noise has occurred (difference between the median amplitude in the current cycle of the extracted signal and the reference value set based on the median amplitude in the past cycle of the extracted signal Is not within a predetermined allowable range), the leakage determination unit does not output an effective leakage detection result based on the amplitude in the current period.

  The present invention can be applied to a leakage detection device that detects a leakage of a high-voltage circuit mounted on a vehicle, for example.

DESCRIPTION OF SYMBOLS 10 Leakage detection apparatus 11 Signal output part 12 Signal extraction part 13 Noise determination part 14 Leakage determination part 100 High voltage circuit 110 Battery 111 Insulation resistance C0 Coupling capacitor

Claims (8)

A signal output unit that outputs a test signal to the high voltage circuit insulated by the insulation resistance via the detection resistor and the coupling capacitor;
A signal extraction unit that adjusts the inspection signal at a node between the detection resistor and the coupling capacitor and outputs an extraction signal;
A leakage determination unit that detects leakage of the high-voltage circuit based on the amplitude of the extracted signal;
Have
The leakage determination unit
When the difference between the median amplitude of the extracted signal in the current cycle and the reference value set based on the median amplitude of the extracted signal in the past cycle is within a predetermined allowable range, the current Output the leakage detection result based on the amplitude in the cycle,
Do not output an effective leakage detection result based on the amplitude in the current period when the difference is outside a predetermined tolerance;
Earth leakage detection device. A noise determination unit that determines that no noise is generated when the difference is within a predetermined allowable range, and that determines that noise is generated when the difference is outside the allowable range;
The leakage detection device according to claim 1. The allowable range is a range that allows the waveform fluctuation of the extraction signal due to low frequency noise,
The leakage detection device according to claim 1 or 2. When the difference is outside the allowable range, the leakage detection unit maintains the leakage detection result in the previous cycle as the leakage detection result in the current cycle.
The leakage detection device according to claim 1 or 2. When the difference is within the allowable range, the reference value in the next period is the median value of the amplitude of the extracted signal in the current period.
The leakage detection device according to any one of claims 1 to 4. When the difference is within the allowable range, the reference value in the next period is a moving average value of the median value of the amplitudes of the extracted signals in a predetermined number of periods past the current period.
The leakage detection device according to any one of claims 1 to 4. When the difference is outside the allowable range, the reference value in the next period is the same reference value as the current period.
The leakage detection device according to any one of claims 1 to 6. A test signal output step for outputting a test signal to the high voltage circuit insulated by the insulation resistance via the detection resistor and the coupling capacitor;
An extraction signal output step of adjusting the inspection signal at a node between the detection resistor and the coupling capacitor and outputting an extraction signal;
A leakage detection step of detecting leakage of the high voltage circuit based on the amplitude of the extracted signal;
Have
The leakage detection step includes
Determination of whether or not the difference between the median amplitude of the extracted signal in the current cycle and the reference value set based on the median amplitude of the extracted signal in the past cycle is within a predetermined allowable range A determination step for performing
When it is determined that the difference is within a predetermined allowable range, a leakage detection result based on the amplitude in the current cycle is output, and when it is determined that the difference is outside the predetermined allowable range, the current A determination result output step that does not output an effective leakage detection result based on the amplitude in the period of
A leakage detection method.

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