JP4882336B2 - Earth leakage detector - Google Patents

Description

  The present invention relates to a leakage detector that detects a leakage of a high voltage system.

For example, Patent Literature 1 discloses a technique for detecting a leakage between a high voltage system (such as a high voltage battery) and a ground insulated from the high voltage system. In this method, a square wave signal is output to a high voltage system via a detection resistor and a coupling capacitor. Then, the leakage of the high voltage system is detected based on the voltage fluctuation at the connection point between the coupling capacitor and the detection resistor. By the way, when the voltage of the high voltage system fluctuates, the influence of the voltage fluctuation also appears in the fluctuation of the voltage at the connection point, which becomes a noise and erroneously detects a leakage. Therefore, according to the method of Patent Document 1, the voltage fluctuation of the high voltage system is directly detected, and when the voltage fluctuation occurs in the high voltage system, it is determined that a false detection has occurred, and the leakage detection is performed. Canceled.
JP 2004-286523 A

  However, according to the technique of Patent Document 1, when a large voltage fluctuation of the high voltage system occurs, the frequency of detecting leakage is increased, and it is not possible to effectively detect the leakage. There is. In other words, depending on the speed and amount of voltage fluctuation of the high-voltage system, the influence on the voltage fluctuation at the connection point may be small, and in this case, even though it is a situation where leakage can be detected, There is an inconvenience that the detection of leakage is stopped.

  The present invention has been made in view of such circumstances, and an object of the present invention is to accurately determine the occurrence of a false detection due to voltage fluctuations in a high-voltage system in detecting leakage.

In order to solve this problem, the present invention provides a leakage detection device. The leakage detection device includes a high voltage system, a detection resistor, a coupling capacitor, a rectangular wave output unit, a leakage detection unit, and an erroneous detection determination unit. Here, the high voltage system is insulated from the ground by an insulation resistance. The rectangular wave output means outputs a rectangular wave signal to the high voltage system via the detection resistor and the coupling capacitor. The leakage detection means detects a leakage of the high voltage system based on a change in voltage at the connection point between the detection resistor and the coupling capacitor. Erroneous detection judgment means, based on the variation of the voltage at the connection point, to determine the occurrence of erroneous detection due to leak detection means, in the transition of the voltage at the connection point corresponding to the sampling period of Jo Tokoro, the peak voltage of the high side Based on the low-side peak voltage, the evaluation voltage calculation means for calculating the evaluation voltage for evaluating the fluctuation of the voltage at the connection point due to the voltage fluctuation of the high-voltage system, and the leakage detection means normalize the leakage detection The condition setting means for setting the allowable condition that defines the range of the evaluation voltage that can be performed and the evaluation voltage calculated by the evaluation voltage calculation means do not have the allowable condition set in the condition setting means And an evaluation voltage determination means having a second voltage comparison means for determining occurrence of erroneous detection by the leakage detection means. The evaluation voltage calculation means calculates the average value of the high-side peak voltage and the low-side peak voltage as the evaluation voltage. The condition setting means includes a reference average value setting means in which an average value of the maximum voltage and the minimum voltage of the rectangular wave signal output from the rectangular wave output means is set as a reference average value, and no erroneous detection by the leakage detection means. A difference upper limit setting means for setting an upper limit value of the difference between the reference average value and the evaluation voltage that can be regarded as a difference upper limit value is provided. The second voltage comparison means calculates the absolute value of the difference between the evaluation voltage calculated by the evaluation voltage calculation means and the reference average value as a difference absolute value, and the calculated difference absolute value is set as a difference upper limit value. When the difference upper limit value set in the means is larger, occurrence of erroneous detection by the leakage detection means is determined.

  According to the present invention, the occurrence of erroneous detection of leakage detection due to voltage fluctuation of the high voltage system is determined using the voltage fluctuation itself of the connection point. Therefore, it is possible to determine a situation in which the voltage at the connection point varies due to voltage variation of the high voltage system, and as a result, it is possible to accurately determine the occurrence of erroneous detection.

  Embodiments according to the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a configuration diagram of a fuel cell vehicle to which a leakage detection device 10 according to a first embodiment of the present invention is applied. The fuel cell vehicle charges the fuel cell 1 that generates the generated power, the drive motor 2 that generates the driving force by the generated power from the fuel cell 1, and the generated power from the fuel cell 1 or discharges the power. A secondary battery 3 that is supplied to the drive motor 2 is mainly used. The high voltage system including the fuel cell 1, the drive motor 2 and the secondary battery 3 is electrically insulated from the vehicle body (ground) 5 by the insulation resistance 4.

  The leakage detection device 10 is a device that detects leakage of a high-voltage system, that is, leakage between the high-voltage system and the body body 5 that is insulated from the high-voltage system. The rectangular-wave output unit (rectangular wave output) Means) 20, detection resistor 30, coupling capacitor 40, erroneous detection determination unit (false detection determination unit) 50, and leakage detection unit (leakage detection unit) 60.

  The rectangular wave output unit 20 generates a rectangular wave signal (pulse signal) having a predetermined frequency with a duty ratio of 50%, and outputs this to the high voltage system via the detection resistor 30 and the coupling capacitor 40 (specifically, Is output at any point on the circuit connecting the fuel cell 1, the drive motor 2 and the secondary battery 3 (for example, in the vicinity of the secondary battery 3). Since the high voltage system is insulated from the ground 5 via the insulation resistor 4, the rectangular wave signal is output to the high voltage system via the detection resistor 30 and the coupling capacitor 40. And output to the insulation resistor 4. Here, as a premise for performing leakage detection, the detection resistor 30 and the coupling capacitor 40 are connected in series, and are arranged in the order of the detection resistor 30 and the coupling capacitor 40 from the rectangular wave output unit 20 to the high voltage system. .

  As the rectangular wave output unit 20, a transmission circuit can be used. As the erroneous detection determination unit 50 and the leakage detection unit 60, a microcomputer mainly composed of a CPU, a ROM, a RAM, and an input / output interface can be used. However, the false detection determination unit 50 and the leakage detection unit 60 may realize these functions by using an arithmetic circuit as well as realizing these functions described later by a calculation process of a microcomputer. The rectangular wave output unit 20 may output a rectangular wave signal using a microcomputer.

  FIG. 2 is a block configuration diagram illustrating the false detection determination unit 50 according to the first embodiment. The erroneous detection determination unit 50 detects the voltage Vp at the connection point P between the detection resistor 30 and the coupling capacitor 40, and the occurrence of erroneous detection by the leakage detection unit 60 based on the detected fluctuation of the voltage Vp. Determine. Specifically, the false detection determination unit 50 calculates an evaluation voltage for evaluating the fluctuation of the voltage Vp at the connection point P due to the voltage fluctuation of the high voltage system based on the voltage Vp at the connection point P. An evaluation voltage determination unit (evaluation voltage determination means) 51 that determines the occurrence of erroneous detection based on the evaluation voltage is provided. When this evaluation voltage determination unit 51 grasps this functionally, the evaluation voltage calculation unit (evaluation voltage calculation unit) 52, the condition setting unit (condition setting unit) 53, and the voltage comparison unit (second voltage comparison) Means) 54.

FIG. 3 is a block configuration diagram showing the evaluation voltage calculation unit 52. The evaluation voltage calculation unit 52 has a function of calculating the evaluation voltage, and includes a high-order peak voltage detection unit 520, a low-order peak voltage detection unit 521, and an average value calculation unit 522. The high-side peak voltage detection unit 520 detects the high-side peak voltage Vpu in the transition of the voltage Vp at the connection point P corresponding to a predetermined sampling cycle (in this embodiment, the transmission cycle of the rectangular wave pulse), and the low-side peak voltage detection unit 520 The peak voltage detector 521 detects the lower peak voltage Vpl in the transition of the voltage Vp at the connection point P corresponding to a predetermined sampling period. Here, the high-side peak voltage Vpu indicates the voltage Vp at the connection point P corresponding to the maximum voltage (high voltage level side (High)) of the rectangular wave signal corresponding to one cycle, and the low-side peak voltage Vpl is The voltage Vp at the connection point P corresponding to the minimum voltage (low voltage level (low)) of the rectangular wave signal corresponding to one period.

The high-side peak voltage Vpu detected by the high-side peak voltage detection unit 520 and the low-side peak voltage Vpl detected by the low-side peak voltage detection unit 521 are output to the average value calculation unit 522. The average value calculator 522 calculates the average value ((Vpu + Vpl) / 2) as the evaluation voltage Vpc based on the high-side peak voltage Vpu and the low-side peak voltage Vpl. Here, when calculating the evaluation voltage ( average value) Vpc, the average value calculation unit 522 calculates this value using the peak voltages Vpu and Vpl detected within the same sampling period. The evaluation voltage Vpc calculated by the average value calculation unit 522 is output to the voltage comparison unit 54 described later.

FIG. 4 is a block diagram showing the condition setting unit 53. The condition setting unit 53 is set with a permissible condition that defines a range of the evaluation voltage Vpc that allows the leakage detection unit 60 to normally detect leakage, and a reference average value setting unit (reference average value setting unit). 530 and a difference upper limit value setting unit (difference upper limit value setting means) 531. In the reference average value setting unit 530, the theoretical value of the evaluation voltage Vpc in the case where it can be considered that there is no voltage fluctuation of the high voltage system, that is, the maximum voltage Vmax and the minimum voltage Vmin of the rectangular wave signal output from the rectangular wave output unit 20 average of ((Vmax + Vmin) / 2 ) is set as a reference average value VPCS. In the difference upper limit setting unit 531, an upper limit value of the difference between the reference average value Vpcs and the evaluation voltage Vpc, which can be regarded as no erroneous detection by the leakage detection unit 60, is set as the difference upper limit value Vul. Based on the reference average value Vpcs and the difference upper limit value Vul set in these setting units 530 and 531, a range in which the difference upper limit value Vul is added in the positive / negative direction of the value based on the reference average value Vpcs is an allowable condition. These values Vpcs and Vul are read as necessary and referred to by the voltage comparison unit 54.

When the evaluation voltage Vpc calculated by the evaluation voltage calculation unit 52 does not satisfy the allowable condition set in the condition setting unit 53, the voltage comparison unit 54 determines the occurrence of erroneous detection by the leakage detection unit 60. Specifically, the voltage comparison unit 54 calculates the absolute value of the difference between the evaluation voltage Vpc and the reference average value Vpcs as the difference absolute value. And the voltage comparison part 54 determines generation | occurrence | production of the misdetection by the leak detection part 60, when the calculated difference absolute value is larger than the difference upper limit value Vul, ie, when not satisfy | filling tolerance conditions. On the other hand, when the calculated difference absolute value is equal to or smaller than the difference upper limit value Vul, that is, when the allowable condition is satisfied, the voltage comparison unit 54 determines that the false detection by the leakage detection unit 60 does not occur. The determination result by the voltage comparison unit 54 is output to the leakage detection unit 60.

  Referring to FIG. 1 again, the leakage detection unit 60 refers to the determination result from the erroneous detection determination unit 50 (specifically, the voltage comparison unit 54), and detects the detection resistor 30 and the coupling capacitor as necessary. 40, the voltage Vp of the connection point P between them is detected, and the leakage of the high voltage system (that is, the decrease in the resistance value of the insulation resistance 4) is detected based on the detected fluctuation of the voltage Vp. More specifically, the leakage detection unit 60 detects the high-side peak voltage Vpu and the low-side peak voltage Vpl, as in the evaluation voltage calculation unit 52 described above, and the low-side peak from the high-side peak voltage Vpu. A value obtained by subtracting the voltage Vpl is calculated as the leakage determination value Vd. And the leak detection part 60 detects the leak of a high voltage system, when the calculated leak determination value Vd falls rather than the preset reference leak determination value.

Hereinafter, the operation of the leakage detection device 10 will be described. FIG. 5 is a diagram showing a transition of voltage fluctuation at the connection point P. In FIG. First, when a rectangular wave signal is output by the rectangular wave output unit 20, the false detection determination unit 50 detects the high-side peak voltage Vpu and the low-side peak voltage Vpl based on the voltage Vp at the connection point P. Then, an evaluation voltage Vpc which is an average value thereof is calculated. Similarly to the erroneous detection determination unit 50, the leakage detection unit 60 detects the higher-side peak voltage Vpu and the lower-side peak voltage Vpl based on the voltage Vp at the connection point P, and determines the leakage from these values. The value Vd is calculated.

  Next, the erroneous detection determination unit 50 compares the calculated evaluation voltage Vpc with an allowable condition, and determines whether or not the evaluation voltage Vpc satisfies the allowable condition. When the evaluation voltage Vpc does not satisfy the permissible condition (| Vpc−Vpcs |> Vul), the erroneous detection determination unit 50 determines the occurrence of erroneous detection by the leakage detection unit 60. On the other hand, when the allowable condition is satisfied (| Vpcs−Vpc | ≦ Vul), the erroneous detection determination unit 50 determines that the erroneous detection by the leakage detection unit 60 does not occur.

  When it is determined that no erroneous detection is made by the leakage detection unit 60, the leakage detection unit 60 determines whether or not the calculated leakage determination value Vd is smaller than the reference leakage determination value. . When the leakage determination value Vd is smaller than the reference leakage determination value, the leakage detection unit 60 detects a leakage of the high voltage system and detects the leakage using an alarm device (not shown). Alarm. On the other hand, when the leakage determination value Vd is greater than or equal to the reference leakage determination value, the leakage detection unit 60 determines that there is no leakage in the high-voltage system, and then executes the above-described series of procedures again.

  On the other hand, when the occurrence of erroneous detection by the leakage detection unit 60 is determined, the leakage detection unit 60 cancels the leakage detection of the high voltage system after discarding the calculated leakage determination value Vd. Again, the above-described series of procedures is executed.

  The leakage detection concept of the leakage detection device 10 having such a configuration and operation will be described. When leakage occurs in the high-voltage system, that is, when the resistance value of the insulation resistance 4 decreases, the fluctuation of the voltage Vp at the connection point P includes the high-side peak voltage Vpu and the low-side peak voltage Vpl. Accordingly, the leakage judgment value Vd, which is the difference value (precisely, the value obtained by subtracting the lower peak voltage Vpl from the higher peak voltage Vpu) tends to decrease. Indicates. Therefore, the leakage detection unit 60 monitors the fluctuation of the leakage determination value Vd, and when this value becomes smaller than a predetermined determination value (a reference leakage determination value in the present embodiment), this is used as a trigger. Detect electrical leakage.

  However, when the voltage of the high-voltage system fluctuates, such as charging / discharging of the secondary battery 3, the influence of the voltage fluctuation also affects the voltage Vp at the connection point P, resulting in the leakage determination value Vd. Since noise is included, there is an inconvenience that leakage detection cannot be accurately performed. For example, when the leakage determination value Vd is lower than the reference leakage determination value due to the influence of noise even though the resistance value of the insulation resistance 4 is not decreased, this is detected as leakage. Yes (occurrence of false detection).

In this embodiment, such an inconvenience is solved by referring to the evaluation voltage Vpc that is an average value of the high-side peak voltage Vpu and the low-side peak voltage Vpl. When the resistance value of the insulation resistance 4 decreases, the high-side peak voltage Vpu tends to decrease and the low-side peak voltage Vpl tends to increase. At this time, since the decrease range of the high-side peak voltage Vpu and the increase range of the low-side peak voltage Vpl are substantially the same value, the average value (evaluation voltage Vpc) of these peak voltages Vpu and Vpl is insulated. Regardless of whether or not the resistance value decreases, the value near the average value (reference average value Vpcs) of the maximum voltage Vmax and the minimum voltage Vmin of the rectangular wave signal changes.

However, when a voltage fluctuation occurs in the high voltage system, the same level deviation (same amount / same direction deviation) occurs between the high-side peak voltage Vpu and the low-side peak voltage Vpl. Also, a relative deviation occurs and tends to deviate from the reference average value Vpcs. In other words, when the evaluation voltage Vpc is deviated from the reference average value Vpcs, the voltage Vp of the connection point P due to the voltage variation of the high voltage system is meant that fluctuates.

  Of course, if there is a similar shift between the high-side peak voltage Vpu and the low-side peak voltage Vpl, the leakage determination value Vd will not decrease, so this is not detected as leakage. . However, in the actual voltage Vp at the connection point P, the difference between the high-side peak voltage Vpu and the low-side peak voltage Vpl decreases due to the influence of the voltage fluctuation of the high-voltage system, and the leakage determination value Vd is the reference. There may be a tendency to deviate from the leakage determination value. This is because these peak voltages Vpu and Vpl are limited in the upper limit value or the lower limit value due to limitations on the system, or the respective phases are shifted. Therefore, in such a case, an erroneous detection may still occur.

Therefore, in this embodiment, on condition that the evaluation voltage Vpc is deviated from the reference average value VPCS, it determines that fluctuates the voltage Vp of the connection point P due to the voltage variation of the high voltage system Thus, occurrence of erroneous detection by the leakage detection unit 60 is determined.

  In view of such a detection concept, the leakage detection device 10 according to the present embodiment acquires the following information in advance through experiments and simulations as a premise for detecting leakage in the high voltage system. Specifically, after setting the resistance value of the insulation resistance 4 for determining the leakage on the condition that the value is lower than that value, the leakage determination value Vd corresponding to this resistance value is obtained as the reference leakage determination value. . The reference leakage determination value is held by the leakage detection unit 60, and is compared with the leakage determination value Vd calculated based on the voltage Vp at the connection point P when leakage detection is performed.

  When these pieces of information are available, an experiment is performed to actually generate voltage fluctuations in the high-voltage system that is the target of leakage detection. As a method of changing the high voltage, increase / decrease in the load of the load device such as the drive motor 2, charge / discharge of the secondary battery 3, and the like are conceivable. In determining the conditions for changing the voltage of the high voltage system, the frequency and amplitude are set in advance. When setting the frequency and amplitude, the operation method of the target high voltage system is investigated, and this is divided into several points within a range where actual voltage fluctuation is expected to occur.

Next, a voltage fluctuation of the high voltage system is generated by combining conditions of amplitude and frequency, and a rectangular wave signal is output from the rectangular wave output unit 20. Then, after referring to the voltage Vp at the connection point P, the evaluation voltage Vpc is calculated based on the high-side peak voltage Vpu and the low-side peak voltage Vpl, and the difference from the reference average value Vpcs is evaluated. Specifically, a condition where the leakage determination value Vd is lower than the reference leakage determination value is extracted, and the value of the difference (absolute value) between the reference average value Vpcs and the evaluation voltage Vpc in the extracted condition Is set as the difference upper limit value Vul. Further, the average value of the maximum voltage Vmax and the minimum voltage Vmin of the rectangular wave signal is set as the reference average value Vpcs. The set reference average value Vpcs and the difference upper limit value Vul are held by the erroneous detection determination unit 50 (more precisely, the reference average value setting unit 530 and the difference upper limit value setting unit 531). And the evaluation voltage Vpc calculated based on the voltage Vp at the connection point P.

  As described above, according to the present embodiment, the occurrence of erroneous detection of leakage detection due to the voltage fluctuation of the high voltage system is determined using the fluctuation of the voltage Vp at the connection point P itself. In the method of directly detecting the voltage fluctuation of the high voltage system and determining the false detection based on the voltage fluctuation, if the voltage fluctuation of the high voltage system has occurred, the voltage at the connection point P resulting from the voltage fluctuation Even in the case where the influence on the fluctuation is small, there is an inconvenience that the occurrence of erroneous detection is determined. However, according to the present embodiment, by using the fluctuation of the voltage Vp at the connection point P itself, a situation where the voltage Vp at the connection point P fluctuates due to the voltage fluctuation of the high voltage system, that is, leakage detection. A situation in which erroneous detection by the unit 60 occurs can be determined. As a result, occurrence of erroneous detection can be accurately determined.

  In addition, when the erroneous detection determination unit 50 determines the occurrence of erroneous detection by the leakage detection unit 60, the leakage detection unit 60 stops detecting the leakage of the high voltage system. Therefore, according to the present embodiment, since the occurrence of erroneous detection can be accurately determined, the frequency at which leakage detection is stopped can be suppressed.

  Further, according to the present embodiment, the fluctuation of the voltage Vp (the voltage at the connection point P) due to the voltage fluctuation of the high voltage system is evaluated based on the high-side peak voltage Vpu and the low-side peak voltage Vpl. When the evaluation voltage Vpc is calculated and the evaluation voltage Vpc does not satisfy the permissible condition, the occurrence of erroneous detection by the leakage detection unit 60 is determined. By using the evaluation voltage Vpc, it is possible to determine the influence of the connection point P on the voltage Vp due to the voltage fluctuation of the high voltage system, thereby accurately determining the situation in which a false detection occurs. can do.

Here, the evaluation voltage calculation unit 52 calculates an average value of the high-side peak voltage Vpu and the low-side peak voltage Vpl as the evaluation voltage Vpc. As a feature of the capacitor coupling type leakage detection device 10 shown in the configuration of the present embodiment, the peak voltage Vpu on the higher side and the peak voltage on the lower side in the fluctuation of the voltage Vp at the connection point P, which is the response result of the rectangular wave signal. The average value of Vpl (evaluation voltage Vpc) will remain constant regardless of the insulation resistance if there is no voltage fluctuation in the high voltage system (if the insulation resistance changes, the higher side peak voltage Vpu and the lower side will be The peak voltage Vpl changes, but the average value is constant). On the other hand, when the voltage fluctuation of the high voltage system occurs, the high-side peak voltage Vpu and the low-side peak voltage Vpl basically shift in the same direction by almost the same value, so that the evaluation voltage Vpc also becomes the result. Change. As described above, the evaluation voltage Vpc is not affected by the change in the insulation resistance to be detected, and fluctuates in the voltage fluctuation of the high voltage system. Thereby, since the influence of the voltage fluctuation of the high voltage system on the voltage Vp at the connection point P can be appropriately separated, it is possible to accurately determine a situation in which a false detection occurs.

In addition, according to the present embodiment, the condition setting unit 53 includes the reference average value setting means for setting the reference average value Vpcs and the difference upper limit value setting means for setting the difference upper limit value. The condition is based on the reference average value Vpcs, and in the positive / negative direction of this value, is a range that takes into account the difference upper limit value Vul. As a result, it is possible to accurately determine the occurrence of erroneous detection under the condition that the evaluation voltage Vpc does not satisfy the permission condition.

Further, according to the present embodiment, the voltage comparison unit 54 calculates the absolute value of the difference between the evaluation voltage Vpc and the reference average value Vpcs as the difference absolute value, and the calculated difference absolute value is the difference upper limit value. When larger than Vul, the occurrence of erroneous detection by the leakage detection unit 60 is determined. As described above, by determining the erroneous detection according to the difference between the reference average value Vpcs and the evaluation voltage Vpc, the determination can be performed by a simple calculation method.

  In the present embodiment, the leakage detection unit 60 is configured to detect leakage on the condition that the leakage determination value Vd is smaller than the reference leakage determination value, but the present invention is not limited to this. For example, the leakage detection unit 60 counts the elapsed time after the leakage determination value Vd is smaller than the reference leakage determination value, and the elapsed time when the leakage determination value Vd is smaller than the reference leakage determination value is predetermined. A leak may be detected on condition that the time has been reached. According to such a configuration, the influence of temporary voltage fluctuation is eliminated, and leakage can be detected with higher accuracy.

(Second Embodiment)
Hereinafter, a leakage detection apparatus according to the second embodiment of the present invention will be described. The difference between the leakage detection device according to the second embodiment and that of the first embodiment is the configuration of the erroneous detection determination unit 50a. Specifically, as illustrated in FIG. 6, the erroneous detection determination unit 50 a further includes an upper and lower limit voltage determination unit (upper and lower limit voltage determination unit) 55 in addition to the evaluation voltage determination unit 51 illustrated in the first embodiment. I have. Note that parts similar to those in the above-described embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 7 is a block diagram showing the upper / lower limit voltage determination unit 55. The upper / lower limit voltage determination unit 55 includes an upper limit value setting unit (upper limit value setting unit) 56, a lower limit value setting unit (lower limit value setting unit) 57, and a voltage comparison unit (first voltage comparison unit) 58. ing. The upper limit value setting unit 56 is set with an upper limit value of the voltage that can be detected by the leakage detection unit 60, and the lower limit value setting unit 57 is set with a lower limit value of the voltage that can be detected by the leakage detection unit. . When the voltage Vp at the connection point P is equal to or higher than the upper limit value set in the upper limit value setting unit 56, or the voltage Vp at the connection point P is the lower limit value set in the lower limit value setting means. In the following cases, occurrence of erroneous detection by the leakage detection unit 60 is determined. On the other hand, when the voltage Vp at the connection point P is smaller than the upper limit value set in the upper limit value setting unit 56 and larger than the lower limit value set in the lower limit value setting means, the voltage comparison unit 58 Then, it is determined that no erroneous detection by the leakage detection unit 60 occurs.

  The fluctuation of the voltage Vp at the connection point P changes within a range that can be measured as the leakage detecting device 10, that is, a value within a range limited by the voltage limiting function by circuit protection. If it exceeds this range, the reliability of the leakage determination value Vd and the evaluation voltage Vpc decreases, and it is difficult to normally detect leakage. Therefore, as a constraint condition for detecting leakage, it is determined whether or not the voltage Vp at the connection point P exceeds the upper limit value and lower limit value regulated in the system. The upper limit value set in the upper limit value setting unit 56 and the lower limit value set in the lower limit value setting unit 57 are acquired in advance through experiments and simulations. Specifically, the upper and lower limit voltages of the protection circuit may be set as they are, or the value of the upper and lower limit voltages limited by the detection circuit may be set as it is by actually increasing the amplitude of the rectangular wave signal. .

Hereinafter, the operation of the leakage detection apparatus according to the second embodiment will be described. First, when a rectangular wave signal is output by the rectangular wave output unit 20, the false detection determination unit 50 detects the high-side peak voltage Vpu and the low-side peak voltage Vpl based on the voltage Vp at the connection point P. Then, an evaluation voltage Vpc which is an average value thereof is calculated. Similarly to the erroneous detection determination unit 50, the leakage detection unit 60 detects the higher-side peak voltage Vpu and the lower-side peak voltage Vpl based on the voltage Vp at the connection point P, and determines the leakage from these values. The value Vd is calculated.

  Next, the erroneous detection determination unit 50 determines whether the voltage Vp at the connection point P (that is, the higher-side peak voltage Vpu or the lower-side peak voltage Vpl) is equal to or higher than the upper limit value set in the upper limit value setting unit 56. Or whether or not it is equal to or lower than a lower limit value set in the lower limit value setting means. Further, the erroneous detection determination unit 50 compares the calculated evaluation voltage Vpc with an allowable condition, and determines whether or not the allowable voltage value Vpc satisfies the allowable condition. When the voltage Vp at the connection point P is equal to or higher than the upper limit value, when the voltage Vp at the connection point P is lower than the lower limit value, or when the evaluation voltage Vpc does not satisfy the permissible condition (| Vpc−Vpcs | > Vul), the erroneous detection determination unit 50 determines the occurrence of erroneous detection by the leakage detection unit 60. On the other hand, when the voltage Vp at the connection point P is smaller than the upper limit value, the voltage Vp at the connection point P is larger than the lower limit value, and an allowable condition is satisfied (| Vpcs−Vpc | ≦ Vul), The erroneous detection determination unit 50 determines that no erroneous detection by the leakage detection unit 60 occurs.

  If the erroneous detection determination unit 50 determines that the erroneous detection by the leakage detection unit 60 does not occur, the leakage detection unit 60 determines that the calculated leakage determination value Vd is equal to or less than the reference leakage determination value. Determine whether or not. When the leakage determination value Vd is equal to or less than the reference leakage determination value, the leakage detection unit 60 detects that there is a leakage in the high voltage system and alerts the detection result using an alarm device (not shown). . On the other hand, when the leakage determination value Vd is larger than the reference leakage determination value, the leakage detection unit 60 determines that there is no leakage in the high-voltage system, and then executes the above-described series of procedures again.

  On the other hand, when the erroneous detection determination unit 50 determines the occurrence of erroneous detection by the leakage detection unit 60, the leakage detection unit 60 discards the calculated leakage determination value Vd, and then The detection of leakage is stopped, and the above-described series of procedures is executed again.

  As described above, according to the second embodiment, when the voltage Vp at the connection point P exceeds the limit associated with the detectable upper and lower limit values due to the influence of the voltage fluctuation of the high voltage system, the voltage limiting function is performed. Limited by. Therefore, in actuality, even when the insulation resistance is not lowered, but the leakage determination value Vd is reduced due to the voltage limit, the leakage detection unit 60 may erroneously detect the leakage. There is sex. However, according to the present embodiment, it is possible to determine the occurrence of a false detection by detecting that the voltage Vp at the connection point P has reached the upper limit value and the lower limit value. It is possible to accurately determine the occurrence of the erroneous detection that is caused.

  In addition, according to the present embodiment, the upper / lower limit voltage determination unit 55 can solve the problem due to the measurement specification of the leakage detection device, and can achieve both the effects resulting from the configuration of the first embodiment. It is possible to accurately determine the occurrence of false detection due to voltage fluctuations.

  In the present embodiment, the erroneous detection determination unit 50 includes both the evaluation voltage determination unit 51 and the upper and lower limit voltage determination unit 55. However, the erroneous detection determination unit 50 alone includes the upper and lower limit voltage determination unit 55. The structure provided may be sufficient.

( Reference example )
Hereinafter, a leakage detection apparatus according to a reference example of the present invention will be described. The difference between the leakage detection device according to this reference example and that of the first embodiment is the configuration of the evaluation voltage determination unit 51a. Specifically, as shown in FIG. 8, in the evaluation voltage determination unit 51a, the condition setting unit 53a refers to the voltage Vp at the connection point P and sets the allowable condition. Note that parts similar to those in the above-described embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

FIG. 9 is a block diagram of the condition setting unit 53a according to the reference example . The condition setting unit 53a includes a reference average value learning unit 532 instead of the reference average value setting unit 530 shown in the first embodiment, and also includes a difference upper limit value setting unit 531 as in the first embodiment. ing. The reference average value learning unit 532 has a function of optimizing the reference average value Vpcs by learning. After detecting the voltage on the high voltage system side, the voltage fluctuation of the high voltage system is detected together with the voltage Vp at the connection point P. The reference voltage Vhvs indicating is input. As a learning method of the reference average value Vpcs, on the premise that the voltage fluctuation of the high voltage system is not more than a predetermined value (the upper limit value of the reference voltage Vhvs that can be considered that there is no voltage fluctuation of the high voltage system), Based on the peak voltage Vpu and the lower peak voltage Vpl, the average value ((Vpu + Vpl) / 2) is calculated as the evaluation voltage Vpc. Then, weighted average processing the calculated evaluation voltage Vpc, or averaging is performed over the last several points, the calculated value is calculated as the reference average value VPCS. Regarding the setting of the fluctuation range of the voltage fluctuation as the learning condition, the minimum value of the resolution of the voltage sensor of the high voltage system or the fine fluctuation degree is set even in a stable state in the actual measurement result. A reference average value VPCS calculated in reference average value learning unit 532, by the difference upper limit Vul set to the difference upper limit setting unit 531, based on the reference average value VPCS, the difference upper limit the positive and negative directions of the value The range including Vul is an allowable condition. These values Vpcs and Vul are read out as necessary, and are referred to by the voltage comparison unit 54 as in the first embodiment.

As described above, according to this reference example , the evaluation voltage ( average value of the high-side peak voltage and the low-side peak voltage) Vpc corresponding to the rectangular wave signal from the rectangular wave output unit 20 is basically constant. However, the average value varies exceptionally due to manufacturing variations in the circuit of the leakage detection device. By learning this variation by the reference average value learning unit 532, it is possible to improve the determination accuracy of the erroneous detection determination unit 50.

( Third embodiment)
Hereinafter, a leakage detection apparatus according to the third embodiment of the present invention will be described. The difference between the leakage detection device according to the third embodiment and that of the first embodiment is the configuration of the voltage comparison unit 54 a in the evaluation voltage determination unit 51. Note that parts similar to those in the above-described embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

FIG. 10 is a block diagram showing a voltage comparison unit 54a according to the third embodiment. The voltage comparison unit 54 a includes a difference calculation unit 540, an absolute value processing unit 541, a weighted average processing unit 542, and a determination unit 543. The difference calculation unit 540 calculates a difference value between the evaluation voltage Vpc and the reference average value Vpcs. The calculated difference value is output to the absolute value processing unit 541. The absolute value processing unit 541 performs absolute value processing on the input difference value, and outputs this value (difference absolute value) to the weighted average processing unit 542. The weighted average processing unit 542 performs a weighted average process using the difference absolute value as a processing target, and outputs the processed value (weighted average calculation value) to the determination unit 543. By performing the weighted average process, the difference absolute value can obtain the same effect as that passed through a low-pass filter that removes high-frequency noise, and thus suppresses local noise. Here, the weighted average coefficient (weight coefficient) is preferably set based on the rectangular wave frequency output by the rectangular wave output unit 20. For example, a coefficient is set so as to be a low-pass filter that passes fluctuations of a frequency of about 10 times the rectangular wave frequency. The determination unit 543 compares the weighted average calculation value and the difference upper limit value Vul, and when the weighted average calculation value is larger than the difference upper limit value Vul, that is, when the allowable condition is not satisfied, the erroneous detection by the leakage detection unit 60 Determine the occurrence of On the other hand, when the weighted average calculation value is equal to or less than the difference upper limit value Vul, that is, when the allowable condition is satisfied, the voltage comparison unit 54 determines that the false detection by the leakage detection unit 60 does not occur. The determination result by the voltage comparison unit 54 is output to the leakage detection unit 60 as in the first embodiment.

As described above, according to the third embodiment, it is possible to expect the effect of the low-pass filter by performing the weighted average process on the difference absolute value, and the erroneous detection determination unit 50 causes the erroneous detection by the leakage detection unit 60 due to instantaneous noise. It can suppress that generation | occurrence | production is determined. Thereby, the determination accuracy of the erroneous detection determination unit 50 can be improved.

  In addition, according to the present embodiment, in order to suppress the influence of the instantaneous noise, the weighted average is performed using the weighting coefficient based on the transmission frequency of the rectangular wave signal, thereby eliminating the influence of the instantaneous noise, and the high voltage. It is possible to exclude the influence of the system voltage fluctuation.

The first to third embodiments described above describe preferred embodiments, respectively, and the present invention is not limited to this, and these embodiments can be applied in any combination. it can. Further, in the present embodiment, the fuel cell 1, the drive motor 2 and the secondary battery 3 are illustrated as a high voltage system on the premise of the fuel cell vehicle, but other than this, a load device for high voltage and the like are included. In addition, these can be applied to leakage detection of various high voltage systems that are used alone or in any combination.

1 is a configuration diagram of a fuel cell vehicle to which an electric leakage detection device according to a first embodiment of the present invention is applied. It is a block block diagram which shows the misdetection determination part concerning 1st Embodiment. It is a block block diagram which shows the evaluation voltage calculation part in FIG. It is a block block diagram which shows the condition setting part in FIG. FIG. 6 is a diagram illustrating a change in voltage fluctuation at a connection point P. It is a block block diagram which shows the misdetection determination part concerning 2nd Embodiment. It is a block block diagram which shows the upper / lower limit voltage determination part in FIG. It is a block block diagram which shows the evaluation voltage determination part concerning 3rd Embodiment. It is a block block diagram which shows the condition setting part in FIG. It is a block block diagram which shows the voltage comparison part concerning 4th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Drive motor 3 Secondary battery 4 Insulation resistance 5 Body body (ground)
DESCRIPTION OF SYMBOLS 10 Leakage detection apparatus 20 Rectangular wave output part 30 Detection resistance 40 Coupling capacitor 50 False detection determination part 51 Evaluation voltage determination part 52 Evaluation voltage calculation part 53 Condition setting part 54 Voltage comparison part 55 Upper / lower limit voltage determination part 56 Upper limit value setting part 57 Lower limit setting part 58 Voltage comparison part 60 Leakage detection part

Claims (4)

A high voltage system isolated from ground by an insulation resistor;
A rectangular wave output means for outputting a rectangular wave signal to the high voltage system via a detection resistor and a coupling capacitor;
A leakage detection means for detecting a leakage of the high voltage system based on a change in voltage at a connection point between the detection resistor and the coupling capacitor;
An erroneous detection determination means for determining occurrence of erroneous detection by the leakage detection means based on a voltage fluctuation at the connection point;
The erroneous detection determination means is
Based on the high-side peak voltage and the low-side peak voltage in the transition of the voltage at the connection point corresponding to a predetermined sampling period, the voltage change at the connection point due to the voltage fluctuation of the high-voltage system is determined. Evaluation voltage calculating means for calculating an evaluation voltage for evaluation;
Condition setting means for setting a permissible condition that defines a range of the evaluation voltage, and capable of normally detecting leakage by the leakage detection means;
A second voltage comparison unit for determining occurrence of a false detection by the leakage detection unit when the evaluation voltage calculated by the evaluation voltage calculation unit does not satisfy the allowable condition set in the condition setting unit;
An evaluation voltage determining means having
The evaluation voltage calculation means calculates an average value of the high-side peak voltage and the low-side peak voltage as the evaluation voltage,
The condition setting means includes:
Reference average value setting means in which an average value of the maximum voltage and the minimum voltage of the rectangular wave signal output by the rectangular wave output means is set as a reference average value;
A difference upper limit value setting means in which an upper limit value of a difference between the reference average value and the evaluation voltage, which can be regarded as no occurrence of erroneous detection by the leakage detection means, is set as a difference upper limit value;
The second voltage comparison unit calculates an absolute value of a difference between the evaluation voltage calculated by the evaluation voltage calculation unit and the reference average value as a difference absolute value, and the calculated difference absolute value is wherein when greater than the difference upper limit difference upper limit value set in the setting means, the electric leakage detecting device which is characterized that you determine the occurrence of erroneous detection due to the earth leakage detecting means. The earth leakage detecting means, by said erroneous detection judgment means, when the occurrence of erroneous detection due to the electric leakage detection means is determined, in claim 1, characterized in that stops the detection of the leakage of the high voltage system The leakage detection device described . The second voltage comparison unit calculates a weighted average calculation value by performing a weighted average process using the calculated difference absolute value as a processing target, and the calculated weighted average calculation value is the difference upper limit value. The leakage detection device according to claim 1 or 2 , wherein occurrence of a false detection by the leakage detection means is determined when the difference upper limit value set in the setting means is larger . The said 2nd voltage comparison means sets the weighting coefficient used for the said weighted average process based on the transmission frequency of the said rectangular wave signal output from the said rectangular wave output means, The Claim 3 characterized by the above-mentioned. Earth leakage detector.

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