JP6394428B2 - Leakage determination device - Google Patents

Description

  The present invention relates to a leakage determination device that determines whether or not there is a leakage between a high-voltage circuit mounted on a vehicle and a vehicle body.

  Although the high voltage circuit mounted on the vehicle and the vehicle body are electrically insulated, the insulation performance may be reduced. Therefore, it has been conventionally determined whether or not there is a leakage between the high voltage circuit and the vehicle body.

  For example, in Patent Literature 1, an alternating-current signal having a first frequency and an alternating-current signal having a second frequency different from the first frequency are output from the oscillating unit at different timings. A plurality of AC signals having different frequencies are applied. And detecting a peak value of the first AC signal corresponding to the first frequency and a second peak value corresponding to the second frequency, and detecting the first peak value and the second peak value. The common capacity of the high voltage circuit is estimated based on the electrical characteristics of the high voltage circuit (electric system) specified by. Then, a threshold value for leakage detection is set based on the estimated value of the common capacity, and when the peak value of the AC signal is lower than the threshold value, it is determined that the insulation resistance is reduced.

JP 2014-155329 A

  However, separately applying the first AC signal and the second AC signal to the high-voltage circuit is a restriction when trying to shorten the leakage determination time.

  This invention is made | formed in view of the above, and makes it a main objective to provide the leak determination apparatus which can implement more suitable leak determination.

  The present invention is an electrical leakage determination device (20) for determining the presence or absence of electrical leakage between a high-voltage circuit (100) mounted on a vehicle and a vehicle body, the first alternating current signal having a first frequency, and the first AC signal output means (24, 25) for outputting a composite wave of an AC signal including a second AC signal having a second frequency higher than the frequency to the high voltage circuit via a resistor (26). The first AC signal is generated from the combined wave of the AC signal divided by the resistor and the insulation resistance component of the high voltage circuit in a state where the combined wave of the AC signal is output by the AC signal output means. A peak value acquisition means (50a) for acquiring a peak value (V1) of the second AC signal and a peak value (V2) of the second AC signal, and the first AC signal and the second AC acquired by the peak value acquisition means Leakage judgment that determines the presence or absence of leakage based on the peak value of the signal Characterized in that it comprises a means (56), the.

  According to the present invention, a composite wave of an AC signal including a first AC signal having a first frequency and a second AC signal having a second frequency higher than the first frequency is output to the high voltage circuit. I did it. In this case, the first AC signal and the second AC signal having different frequencies can be applied to the high voltage circuit at the same time, and the peak value of the first AC signal and the peak value of the second AC signal are simultaneously set. Therefore, it is possible to shorten the time required for the leakage determination.

1 is an overall configuration diagram including a leakage determination device. The figure which shows an electrical leakage determination apparatus. The figure which shows the example of the earth-leakage determination when not using this embodiment. The figure which shows the example of the earth-leakage determination which concerns on this embodiment. The figure which shows other embodiment of an electrical leakage determination apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The leakage determination device of the present embodiment is applicable to a vehicle such as a hybrid vehicle or an electric vehicle that can travel using the power of the DC power source as a travel drive source and can charge the DC power source with external power. .

  In FIG. 1, the high voltage circuit 100 includes a DC power supply 11 and a power conversion circuit 10. DC power supply 11 and power conversion circuit 10 are connected via a system main relay (hereinafter referred to as SMR 12). In addition, a leakage determination device 20 is connected to the high voltage circuit 100.

  The DC power supply 11 is a battery group configured by connecting a plurality of secondary batteries such as rechargeable lithium ion batteries in series. The SMR 12 is connected when power is supplied from the DC power supply 11 to the power conversion circuit 10 or when power is supplied from the power conversion circuit 10 to the DC power supply 11.

  The power conversion circuit 10 includes various electric devices (not shown) such as a converter, an inverter, and an MG. The voltage of the DC power source 11 is boosted by the converter, and the AC power generated by the MG is converted by the inverter. The DC power is converted into DC power, and the converted DC power is stepped down by a converter and supplied to the DC power supply 11.

  The high voltage circuit 100 configured as described above and the vehicle body are electrically insulated. Therefore, a ground insulation resistance (hereinafter referred to as an insulation resistance Rg) is generated between the DC power source 11 and the vehicle body, and between the power conversion circuit 10 and the vehicle body.

  Further, since the high voltage circuit 100 is insulated from the vehicle body, a common capacitance Cg is generated between the DC power source 11 and the vehicle body, and between the power conversion circuit 10 and the vehicle body. The common capacitance Cg is an electrostatic capacitance of the high voltage circuit 100 with respect to the vehicle body, and is also referred to as a stray capacitance. FIG. 1 shows an equivalent circuit of these insulation resistance Rg and common capacitance Cg for convenience of explanation.

  When this insulation resistance Rg is lowered, an electric leakage in which an unintended current flows through the vehicle body may occur. Therefore, the leakage determination by the leakage determination device 20 is performed.

  In FIG. 2, the leakage determination device 20 includes a capacitor 22, an oscillator 24, a resistor 26, a signal input unit 28, and a microcomputer 50. In FIG. 2, the high voltage circuit 100 is shown as an equivalent circuit of an insulation resistance Rg and a common capacitor Cg.

  The capacitor 22 insulates the high voltage circuit 100 and the leakage determination device 20 in a DC manner, and has one end connected to the high voltage circuit 100 and the other end connected to the resistor 26.

  The oscillator 24 generates and outputs an AC signal. Specifically, the oscillator 24 generates a rectangular wave voltage signal and outputs the voltage signal to the wiring path (common path) of the high voltage circuit 100 connected to the capacitor 22 via the resistor 26. The common path is a wiring path that connects the DC power supply 11 and the resistor 26, and more specifically, a wiring that connects the other end of the capacitor 22 and the resistor 26.

  The oscillator 24 according to the present embodiment can synthesize at least two alternating signals having different frequencies and output the synthesized signal S. For example, a first AC signal having a frequency f1 and a second AC signal having a frequency f2 greater than the frequency f1 are combined and output as a combined wave S. Thus, AC signals having different frequency components can be applied to the high voltage circuit 100 at the same time. The frequency f1 is set in a range of 2 to 10 Hz, for example. The frequency f2 is set to a value larger than the frequency f1, for example, in the range of 4 Hz to 100 Hz.

  The signal input unit 28 inputs a voltage applied to a connection point D between the resistor 26 and the capacitor 22 in the common path as a detection signal, and outputs the detection signal to an A / D converter (not shown). The A / D converter converts the detection signal detected by the signal input unit 28 into a digital signal and outputs it to the microcomputer 50. In the present embodiment, the microcomputer 50 and the A / D converter are configured separately, but the microcomputer 50 may include an A / D converter.

  The microcomputer 50 is mainly configured by a microcomputer including a CPU, RAM, ROM, flash memory, and the like, and the CPU executes various processes relating to leakage determination according to a program stored in the ROM.

  The microcomputer 50 according to the present embodiment includes a digital filter processing unit 50a and an electric leakage determination processing unit 50b. The digital filter processing unit 50a extracts, for example, components of the frequency band of the AC signal output from the oscillator 24 and its peripheral band from the digital AC signal after A / D conversion by a finite impulse response. By doing so, the noise component contained in the AC signal is removed.

  Specifically, the digital filter processing unit 50 a includes a first filter 51 and a second filter 52. The first filter 51 extracts a signal in a predetermined frequency band having the frequency f1 as the center frequency from the first AC signal after A / D conversion. The second filter 52 extracts a signal in a predetermined frequency band having the frequency f2 as the center frequency from the second AC signal after A / D conversion.

  The leakage determination processing unit 50b sets the frequency f1 of the first AC signal and the frequency f2 of the second AC signal output from the oscillator 24, and the peak value V1 and the first AC signal extracted by the digital filter processing unit 50a. 2 Leakage determination is performed using the peak value V2 of the AC signal. Specifically, the leakage determination processing unit 50 b includes a common capacity estimation unit 55 and a leakage determination unit 56.

  The common capacity estimating unit 55 calculates a difference ΔV between the peak value V1 of the first AC signal extracted by the first filter 51 and the peak value V2 of the second AC signal extracted by the second filter 52. Then, an estimated value of the common capacitance Cg is calculated using the difference ΔV between the peak values. For example, the estimated value of the common capacitance Cg is calculated using an arithmetic expression or a map that defines the relationship between the peak value difference ΔV and the common capacitance Cg.

  The leakage determination unit 56 corrects the peak value of the AC signal using the estimated value of the common capacity Cg calculated by the common capacity estimation unit 55. Further, the leakage determination is performed using the peak value of the corrected AC signal. For example, the leakage determination unit 56 corrects the peak value V1 of the AC signal after the filter processing by the first filter 51 using the estimated value of the common capacitance Cg. More specifically, the capacitance impedance Zc at the frequency f1 is calculated using the estimated value of the common capacitance Cg. Then, a voltage error caused by the capacitive impedance Zc is subtracted from the peak value V1 of the AC signal to obtain a corrected peak value of the AC signal. Then, the presence or absence of electric leakage is determined based on whether or not the peak value of the corrected AC signal is equal to or greater than a predetermined threshold value. That is, when the peak value of the corrected AC signal is equal to or greater than a predetermined threshold value, it is determined that no leakage has occurred (normal state), and the corrected AC signal peak value is less than the predetermined threshold value. It is determined that there is a leakage.

  In the above configuration, when the leakage determination is performed, the oscillator 24 outputs a combined wave S of the AC signal having the frequency f1 and the AC signal having the frequency f2. Then, the detection signal of the composite wave S detected by the signal input unit 28 is input to the microcomputer 50. The microcomputer 50 uses the first filter 51 to extract an AC signal having the frequency f1 as the center frequency from the AC signal synthesized wave S, and uses the second filter 52 to extract the frequency f2 from the AC signal synthesized wave S as the center frequency. The AC signal is extracted. Then, the common capacity estimation unit 55 calculates an estimated value of the common capacity from these AC signals, and then the leakage detection unit 56 uses the peak value of the corrected AC signal using the estimated value of the common capacity to detect the leakage. The presence or absence of is determined.

  As described above, in the present embodiment, since the first AC signal having the frequency f1 and the second AC signal having the frequency f2 are applied to the high voltage circuit 100 at the same time, the peak values V1 and V2 of the AC signal are obtained. It can be acquired at the same timing. Therefore, it is possible to shorten the time required for the leakage check. Moreover, since the error which generate | occur | produces when a 1st alternating current signal and a 2nd alternating current signal are separately applied with respect to the high voltage circuit 100 is suppressed, the precision of a leak determination is improved.

  Next, an operation when the leakage determination device 20 of the present embodiment is used will be described. FIG. 3 shows an example of leakage determination when this embodiment is not used. FIG. 4 is an example in the case of using the leakage determination according to the present embodiment. 3 shows an example in which an AC signal having a single frequency is used. After the AC signal having the frequency f1 is first output, the peak value of the AC signal is switched by switching to the AC signal having the frequency f2. Is causing changes.

  In FIG. 3, when the leakage determination is started at time t1, an AC signal having a frequency f1 is output from the oscillator, and a peak value V1 of the AC signal is detected. Thereafter, the peak value V2 of the AC signal is detected by changing to the frequency f2 at time t2. In this case, time Ta is required until the leakage determination is performed at time t3.

  In the case of FIG. 3, the noise component included in each AC signal is different between when the AC signal having the frequency f1 is output to the high voltage circuit 100 and when the AC signal having the frequency f2 is output to the high voltage circuit 100. Different things can happen. Therefore, the process of FIG. 3 needs to be performed under a situation where the influence of noise is small, such as when the SMR 12 is off or charging / discharging of the power conversion circuit 10 is stopped.

  On the other hand, in the case of the leakage determination of the present embodiment shown in FIG. 4, when the leakage determination is started at time t11, the oscillator 24 outputs a combined wave S of the AC signal having the frequency f1 and the AC signal having the frequency f2. The The first filter 51 detects the peak value V1 of the first AC signal, and the second filter 52 detects the peak value V2 of the second AC signal at the same time. That is, in this embodiment, since the peak value V1 of the first AC signal and the peak value V2 of the second AC signal are acquired at the same time, the time Tb (<Ta) until the leakage determination is performed at time t12. Can be shortened. Further, since the peak value V1 of the first AC signal and the peak value V2 of the second AC signal are detected at the same time, the common capacitance Cg using the peak value V1 of the first AC signal and the peak value V2 of the second AC signal. The calculation accuracy of the estimated value can be improved, and as a result, the accuracy of the leakage determination can be improved.

  In the case of FIG. 4, since the AC signal of frequency f1 and the AC signal of frequency f2 are output to the high voltage circuit 100 at the same time, the noise components included in the AC signals are the same (substantially equal). ). Therefore, the process of FIG. 4 can be continuously performed regardless of whether the SMR 12 is on or off and whether the power conversion circuit 10 is charged or discharged.

  According to the above, the following excellent effects can be achieved.

  -By using a plurality of alternating current signals with different frequencies, it is possible to make a leakage check considering the common capacity. In this case, if the current leakage determination is performed by changing the frequency of the AC signal output to the high voltage circuit 100, the time required to change the frequency of the AC signal is a restriction on reducing the time for determining the current leakage. It becomes. Therefore, the synthesized wave S of the AC signal including the first AC signal having the first frequency and the second AC signal having the second frequency higher than the first frequency is output to the high voltage circuit 100. did. In this case, the first AC signal and the second AC signal having different frequencies can be applied to the high voltage circuit 100 at the same time, and the peak value V1 of the first AC signal and the peak value V2 of the second AC signal Can be detected at the same time, so that the time required for determining leakage can be shortened.

  In order to remove the influence of the common capacitance Cg at the time of leakage check, when AC signals of different frequencies are output separately to the high voltage circuit 100, a difference occurs in the noise component included in each AC signal, This may affect the accuracy of leakage determination. Therefore, the synthesized wave S of AC signals including the first AC signal and the second AC signal having different frequencies is output to the high voltage circuit 100. In this case, since the first AC signal and the second AC signal having different frequencies can be applied to the high voltage circuit 100 at the same time, it is possible to suppress errors caused by different noise components included in each AC signal, By improving the calculation accuracy of the estimated value of the common capacity, the accuracy of the leakage determination can be improved.

  The first filter 51 for extracting the first AC signal and the second filter 52 for extracting the second AC signal from the synthesized wave S of the AC signal, and the first AC from the synthesized wave S of the AC signal. The signal and the second AC signal can be extracted at the same time.

  The noise component can change during charging / discharging of the power conversion circuit 10. Therefore, when AC signals having different frequencies are output to the high voltage circuit 100 at different timings, the noise components included in each AC signal are different, which affects the leakage determination. In this regard, since the composite wave including the first AC signal and the second AC signal is applied to the high voltage circuit 100, the difference in noise components included in the first AC signal and the second AC signal can be suppressed. As a result, even during charging / discharging of the power conversion circuit 10, the leakage determination can be performed with high accuracy. In addition, since leakage determination can be performed during charging / discharging of the power conversion circuit 10, when a leakage occurs during charging / discharging of the power conversion circuit 10, the leakage state immediately can be detected.

  In addition, this invention is not limited above, You may implement as follows. In the following description, the same components as those described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the above, the example in which the leakage determination processing unit 50b sets the frequency of the AC signal output from the oscillator 24 has been described. In addition to this, as shown in FIG. 5, an oscillator 24a that outputs the frequency f1 and an oscillator 24b that outputs the frequency f2 are provided separately. Then, the synthesized signal S of the AC signal may be generated by synthesizing the AC signal output from these oscillators 24 a and 24 b by a known adding circuit 25. Also in this case, the leakage determination can be performed using the composite wave S of a plurality of alternating current signals having different frequencies at the same timing. For this reason, it is possible to shorten the time required for the leakage determination as described above, and to improve the accuracy of the leakage determination.

  In the above, the oscillator 24 may output a composite wave of AC signals having three or more frequencies. In this case, the frequency band extracted by each of the plurality of filters may be set in the digital filter processing unit 50a corresponding to the AC signal component of each frequency included in the synthesized wave of the AC signal. In this case, the accuracy of leakage determination can be further improved.

  In the above, when the oscillator 24 can output an AC signal having a single frequency, the state of outputting the AC signal having a single frequency and the state of outputting the synthesized wave S of the AC signal are switched. Alternatively, the determination of leakage using an AC signal having a single frequency and the determination of leakage using the synthesized wave S of the AC signal may be switched.

  For example, when the charge / discharge state of the power conversion circuit 10 is constant, an AC signal having a single frequency is output. When the charge / discharge state of the power conversion circuit 10 is switched, a composite wave S of an AC signal is output.

  That is, when the charge / discharge state of the power conversion circuit 10 is switched, the common capacitance can change. At this time, when the first AC signal and the second AC signal are separately applied to the high voltage circuit 100, the change in the common capacitance affects the leakage determination. Therefore, when the charge / discharge state of the power conversion circuit 10 is switched, a composite wave of an AC signal is output. In this case, the influence of the common capacitance Cg in the first AC signal and the second AC signal can be made substantially equal, and when the charge / discharge state of the power conversion circuit 10 is switched, the leakage determination is performed while suppressing the influence of the change in the common capacitance. Can be implemented accurately. In addition, since the leakage determination can be performed in the charge / discharge state of the power conversion circuit 10, when a leakage occurs in the driving state of the power conversion circuit 10, the leakage state can be detected immediately.

  In the above description, when the charge / discharge state of the power conversion circuit 10 is switched, when it is determined that the leakage has not occurred when the composite wave S of the AC signal is output and the leakage determination is performed, the oscillator 24 May be switched to an AC signal having a single frequency, and a leakage check using the AC signal having a single frequency may be performed. In this case, the leakage determination can be performed with high accuracy while reducing the calculation load in the leakage determination using the composite wave S of the AC signal.

  In the above description, the peak value of the detected AC signal changes between when the synthesized signal S of the AC signal is output from the oscillator 24 and when the AC signal having a single frequency is output. Specifically, the peak value of the AC signal is smaller when a composite wave of the AC signal is output than when an AC signal having a single frequency is output. Therefore, the second threshold value for the leakage determination when the composite wave of the AC signal is output is set to a smaller value than the first threshold value for the leakage determination when the single frequency AC signal is output. In this case, it is possible to accurately determine the presence or absence of electric leakage in each of the AC signal combined wave S and the single-frequency AC signal.

  In the above, leakage judgment is performed using the peak value V1 of the AC signal, but the peak value V2 of the AC signal is corrected using the estimated value of the common capacitance Cg, and the peak value of the AC signal after the correction is corrected. You may perform electric leakage determination using V2.

  DESCRIPTION OF SYMBOLS 20 ... Leakage determination apparatus, 24 ... Oscillator, 25 ... Adder circuit, 26 ... Resistor, 50a ... Digital filter process part, 56 ... Leakage determination part, 100 ... High voltage circuit.

Claims (5)

An earth leakage determination device (20) for determining whether or not there is an electric leakage between a high voltage circuit (100) mounted on a vehicle and a vehicle body,
A composite wave of an AC signal including a first AC signal having a first frequency and a second AC signal having a second frequency higher than the first frequency is converted into a resistor (26) and a coupling capacitor (22). AC signal output means (24, 25) for outputting to the high voltage circuit via
In a state where a composite wave of the AC signal is output by the AC signal output means, the first AC signal is generated from a composite wave of the AC signal divided by the resistor and an insulation resistance component of the high voltage circuit. A peak value acquisition means (50a) for acquiring a peak value (V1) and a peak value (V2) of the second AC signal;
A leakage determining means (56) for determining the presence or absence of a leakage based on the peak values of the first AC signal and the second AC signal acquired by the peak value acquiring means;
Equipped with a,
The high voltage circuit includes a DC power source (11) and an electric device (10) for charging and discharging the DC power source,
The AC signal output means can switch between a state of outputting a composite wave of the AC signal and a state of outputting a third AC signal having a single frequency, and the charge / discharge state of the electric device is constant. Output the third AC signal, and in the charging / discharging state of the electrical device, if the charging / discharging state is to be switched, output a composite wave of the AC signal,
The leakage determining means determines whether or not there is a leakage when the electrical device is in a charge / discharge state, and determines whether or not there is a leakage based on the third AC signal when the third AC signal is being output. In the state in which the composite wave of the AC signal is being output, the presence / absence of electrical leakage is determined based on the composite wave of the AC signal . Common capacitance calculating means (55) for calculating an estimated value of the common capacity from the difference between the peak value of the first AC signal acquired by the peak value acquiring means and the peak value of the second AC signal;
Crest value correcting means (56) for correcting the crest value of the first AC signal or the crest value of the second AC signal using the estimated value of the common capacity,
2. The leakage determination according to claim 1, wherein the leakage determination unit determines whether or not there is a leakage using the peak value of the first AC signal or the peak value of the second AC signal after correction by the peak value correction unit. apparatus. The peak value acquisition means includes a first filter (51) for extracting the first AC signal from a composite wave of the AC signal, and a second filter (52) for extracting the second AC signal,
The peak value acquisition means acquires the peak value of the first AC signal extracted by the first filter, and acquires the peak value of the second AC signal extracted by the second filter. The leakage determination device described. In state of outputting composite wave of the AC signal, wherein when the leakage is determined not to, leakage determination apparatus according to any one of claims 1 to 3 and outputs the third AC signal . In the case where the leakage determination means determines whether or not there is a leakage based on whether or not the peak value of the AC signal is equal to or greater than a predetermined threshold, and performs the leakage determination by outputting the third AC signal The leakage determination apparatus according to any one of claims 1 to 4 , wherein the second threshold value is set to a smaller value when the leakage determination is performed by outputting a composite wave of the AC signal than the first threshold value.

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