JP2014081229A - Leakage detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a leakage detection device capable of decreasing the capacity of a coupling capacitor.SOLUTION: A leakage detection device 100 includes: a pulse generator 2; coupling capacitors C1 and C3 charged by the output pulse of the pulse generator 2; an artificial leakage circuit 4 artificially bringing a battery 300 into a leakage state; a switch SW1 for switching a connection state of the coupling capacitors C1 and C3; and a switch control portion 10 for controlling the turning on/off of the switch SW1. In a self-diagnostic mode, the switch control portion 10 turns off the switch SW1, thereby connecting the coupling capacitor C1, the coupling capacitor C3, and the artificial leakage circuit 4 in series to the pulse generator 2. On the other hand, in a normal mode, the switch control portion 10 turns on the switch SW1, thereby connecting the coupling capacitor C1 and the coupling capacitor C3 in parallel to the pulse generator 2.

Description

  The present invention relates to a leakage detection device used for detecting leakage of a DC power supply.

  For example, in an electric vehicle, a high-voltage DC power source for driving a motor or a vehicle-mounted device is mounted. This DC power supply is electrically insulated from the vehicle body that is grounded. However, when an insulation failure or a short circuit occurs between the DC power source and the vehicle body for some reason, a current flows in a path from the DC power source to the ground, resulting in leakage. Therefore, a leakage detection device for detecting this leakage is attached to the DC power supply. Patent Documents 1 to 3 described below describe such a leakage detection device.

  Some leakage detection devices have a so-called self-diagnosis function that can check whether or not leakage detection can be normally performed. The leakage detection devices of Patent Literatures 2 and 3 have such a self-diagnosis function.

  In Patent Document 1, a positive terminal of a DC power source is connected to one end of a coupling capacitor, a rectangular wave pulse signal is applied to a measurement point on the other end of the coupling capacitor, and the capacitor is charged. There is described a ground fault detection device that detects a ground fault of a DC power source by detecting a voltage signal generated at a measurement point at this time. In this document, the voltage value measured at the measurement point when the rectangular wave pulse signal becomes the first phase and the measurement value at the measurement point when the rectangular wave pulse signal becomes the second phase. Find the difference from the voltage value. And based on this differential voltage, the ground fault of DC power supply is detected.

  Patent Document 2 describes an insulation resistance lowering detector in which a self-diagnosis resistor and a switch element are connected in series between a connection point between a detection resistor and an insulation resistor and a ground. In this document, at the time of self-diagnosis, when the value of the voltage appearing at the connection point between the detection resistance and the insulation resistance is different from the reference value with the switch element turned on, it is determined that the detection resistance has deteriorated or failed.

  In Patent Literature 3, a pulse voltage is applied to a ground insulation circuit through a coupling capacitor, and insulation is performed to determine whether the ground insulation circuit is insulated according to the magnitude of a signal voltage substantially proportional to a leakage current flowing through the ground insulation circuit. A performance diagnostic device is described. In this document, a pseudo insulation lowering circuit that causes the same signal change as that when the ground insulation resistance of the ground insulating circuit is lowered is provided.

  FIG. 13 shows an example of a conventional leakage detection device having a self-diagnosis function. The leakage detection device 200 includes a CPU 1, a pulse generator 2, a filter circuit 3, a pseudo leakage circuit 4, a memory 5, a resistor R1, and coupling capacitors C1 and C3. The CPU 1 includes a voltage detection unit 6, a leakage determination unit 7, and a diagnosis unit 8. The filter circuit 3 includes a resistor R2 and a capacitor C2. The pseudo leakage circuit 4 includes a transistor Q and resistors R3 to R5. The negative electrode side of the high voltage battery (DC power supply) 300 is connected to the coupling capacitors C1 and C3 of the leakage detection device 200 via the cable W. The positive electrode side of the battery 300 is connected to a load such as a motor or an in-vehicle device. A stray capacitance Cs exists between the battery 300 and the ground G, and a leakage resistance Rs also exists when the battery 300 leaks.

  The pulse generator 2 outputs a pulse as shown in FIG. This pulse charges the coupling capacitor C1 through the resistor R1, and this charging increases the potential at the point P. The potential at the point P is input to the CPU 1 as the input voltage V through the filter circuit 3. Based on the input voltage V, the voltage detection unit 6 of the CPU 1 detects the voltage of the coupling capacitor C1. The detected voltage of the coupling capacitor C1 is hereinafter referred to as “detection voltage”.

  When there is no leakage in the battery 300, the detection voltage rises sharply as shown by the solid line in FIG. For this reason, the detection voltage exceeds the threshold SH between the time when the pulse rises at time to and the time when the pulse falls at time t1. On the other hand, when a leakage occurs between the battery 300 and the ground G, the detection voltage gradually increases due to the leakage resistance Rs, as shown by the broken line in FIG. For this reason, the detection voltage does not exceed the threshold value SH from the time to to the time t1.

  The voltage detector 6 detects the voltage of the coupling capacitor C1 at time t1 when the pulse falls. When there is no leakage, the detection voltage is Va. When there is a leakage, the detection voltage is Vb. The leakage determination unit 7 of the CPU 1 compares the detection voltage with the threshold value SH, and if the detection voltage is equal to or higher than the threshold value SH (Va), determines that there is no leakage, and if the detection voltage is less than the threshold value SH (Vb). If it is determined that there is a leak, it is determined. In the case of “leakage”, a leakage detection signal is output from the CPU 1.

  When performing self-diagnosis of the leakage detection device 200, a pre-check request signal is input to the CPU 1 from the host device. The diagnosis unit 8 of the CPU 1 receives this signal and turns on the transistor Q of the pseudo-leakage circuit 4 as shown in FIG. 15B in order to create a pseudo-leakage state. As a result, a current path from the pulse generator 2 through the resistor R1 and the coupling capacitors C1 and C3 to the pseudo-leakage circuit 4 is formed as indicated by a broken line arrow in FIG. For this reason, the coupling capacitors C1 and C3 are both charged by the pulse output from the pulse generator 2. As a result, the potential at the point P, that is, the input voltage V rises gradually. Therefore, as shown in FIG. 15C, while the transistor Q is on, the detection voltage of the coupling capacitor C1 is less than the threshold value SH, so the leakage determination unit 7 determines that “leakage is present”. Based on this determination, a leakage detection signal is output from the CPU 1 as shown in FIG. Thereby, the diagnosis part 8 determines with the earth-leakage detection being performed normally.

JP 2003-250201 A JP 2005-127721 A JP 2007-163291 A

  In FIG. 13, since the stray capacitance Cs exists between the battery 300 and the ground G, the stray capacitance Cs is also charged by the pulse output from the pulse generator 2. Therefore, when the capacitance of the coupling capacitor C1 is smaller than the stray capacitance Cs, the coupling capacitor C1 is fully charged before the stray capacitance Cs is completely charged and saturated in a short time. As a result, the voltage change as shown in FIG. 14 cannot be obtained, and normal leakage detection cannot be performed. Therefore, the capacitance of the coupling capacitor C1 must be a value sufficiently larger than the stray capacitance Cs. For this reason, the outer shape of the coupling capacitor C1 becomes large, and the mounting area on the substrate increases.

  An object of the present invention is to provide a leakage detecting device capable of reducing the capacitance of a coupling capacitor.

  The leakage detection device according to the present invention includes a first coupling capacitor having one end connected to a DC power supply, a pulse generator for supplying a pulse to the other end of the first coupling capacitor, and a first coupling capacitor. A voltage detection unit that detects the voltage at the end, a leakage detection unit that compares the voltage detected by the voltage detection unit with a threshold value and determines whether or not there is a leakage of the DC power source based on the comparison result, and a pseudo DC power source When the DC power supply is made to be in a pseudo-leakage state by a pseudo-leakage circuit that has a pseudo-leakage circuit, a second coupling capacitor having one end connected to the DC power supply and the other end connected to the pseudo-leakage circuit, and a pseudo-leakage circuit And a diagnostic unit for diagnosing whether or not the leakage determination unit has determined that there is leakage.

  According to the present invention, in the above leakage detector, a first switch provided between the other end of the first coupling capacitor and the other end of the second coupling capacitor, and on / off of the first switch are controlled. And a switch control unit. And, in the self-diagnosis mode in which the DC power supply is pseudo-faulted by the pseudo-leakage circuit and the diagnosis by the diagnosis unit is performed, the switch control unit turns off the first switch, The first coupling capacitor, the second coupling capacitor, and the pseudo leakage circuit are connected in series. In the normal mode in which the DC power supply is not artificially leaked by the pseudo-leakage circuit and the determination by the leak determination unit is performed, the switch controller turns on the first switch, The first coupling capacitor and the second coupling capacitor are connected in parallel.

  In this case, in the normal mode, the first coupling capacitor and the second coupling capacitor are connected in parallel by turning on the first switch, so that their combined capacitance is only the first coupling capacitor. It becomes larger than the case. Therefore, for example, when the capacities of both capacitors are the same, even if the capacities of the respective capacitors are halved compared to the conventional capacity, the combined capacity is the same as the conventional capacity. For this reason, a small-capacitance capacitor can be used as the first and second coupling capacitors. As a result, the external shape of the capacitor is reduced, and the mounting area on the substrate can be reduced. Further, since the second coupling capacitor is originally provided in the leakage detection device, it is not necessary to newly provide a capacitor connected in parallel with the first coupling capacitor.

  In this invention, you may provide the 2nd switch by which a switch control part controls on-off between the connection point of the other end of a 2nd coupling capacitor, and a 1st switch, and a pseudo earth leakage circuit. In this case, the switch control unit turns off the first switch and turns on the second switch in the self-diagnosis mode, and turns on the first switch and turns off the second switch in the normal mode.

  In the present invention, in addition to the first terminal for connecting the other end of the first cable whose one end is connected to the DC power supply to one end of the first coupling capacitor, and the second cable whose one end is connected to the DC power supply. A second terminal for connecting the end to one end of the second coupling capacitor may be further provided. In this case, in the self-diagnosis mode, the pseudo-leakage circuit is passed from the pulse generator via the first coupling capacitor, the first terminal, the first cable, the second cable, the second terminal, and the second coupling capacitor. A current path leading to is formed. In the normal mode, a current path from the pulse generator to the ground via the first coupling capacitor, the first terminal, the first cable, and the second cable, and the first switch from the pulse generator. , A second coupling capacitor, and a current path to the ground via the second terminal.

  In this invention, you may further provide the disconnection detection part which detects that one or both of the 1st cable and the 2nd cable disconnected. In this case, the disconnection detection unit detects disconnection based on the fact that the voltage detected by the voltage detection unit is equal to or higher than the threshold value in the self-diagnosis mode.

  ADVANTAGE OF THE INVENTION According to this invention, there exists an effect which can provide the leak detection apparatus which can make the capacity | capacitance of a coupling capacitor small.

1 is a circuit diagram illustrating a leakage detection device according to a first embodiment of the present invention. It is the circuit diagram which showed the electric current path in the self-diagnosis mode of 1st Embodiment. FIG. 3 is a circuit diagram illustrating a current path in a normal mode according to the first embodiment. It is the timing chart which showed the operation | movement (at the time of a disconnection) of 1st Embodiment. 3 is a timing chart showing an operation (at the time of disconnection) of the first embodiment. It is the circuit diagram which showed the leak detection apparatus by 2nd Embodiment of this invention. It is the circuit diagram which showed the electric current path in the self-diagnosis mode of 2nd Embodiment. It is the circuit diagram which showed the electric current path in the normal mode of 2nd Embodiment. It is the timing chart which showed the operation | movement (at the time of a disconnection) of 2nd Embodiment. It is the timing chart which showed the operation | movement (at the time of a disconnection) of 2nd Embodiment. It is the circuit diagram which showed the leak detection apparatus by 3rd Embodiment of this invention. It is the circuit diagram which showed the leak detection apparatus by 4th Embodiment of this invention. It is the circuit diagram which showed the conventional electric leakage detection apparatus. It is a wave form diagram of a detection voltage at the time of electric leakage and non-electric leakage. It is the timing chart which showed the operation | movement of the conventional electric leakage detection apparatus.

  Embodiments of the present invention will be described with reference to the drawings. Below, the example which applied this invention to the earth-leakage detection apparatus mounted in an electric vehicle or a hybrid car is given. However, the application range of the present invention is not limited to the on-vehicle leakage detection device.

  First, the configuration of the leakage detection device according to the first embodiment will be described with reference to FIG. In FIG. 1, the leakage detection device 100 is connected to the negative electrode side of a battery 300 that is a DC power supply for vehicles via cables W1 and W2. The positive electrode side of the battery 300 is connected to a load (not shown) such as a motor or an in-vehicle device. The battery 300 is a high voltage battery having an output voltage of several hundred volts.

  The leakage detection device 100 includes a CPU 1, a pulse generator 2, a filter circuit 3, a pseudo leakage circuit 4, a memory 5, a resistor R1, coupling capacitors C1 and C3, a switch SW1, and terminals T1 to T5.

  The CPU 1 constitutes a control unit that controls the operation of the leakage detection device 100, and includes a voltage detection unit 6, a leakage determination unit 7, a diagnosis unit 8, a disconnection detection unit 9, and a switch control unit 10. Actually, each function of these blocks 6 to 10 is realized by software. The pulse generator 2 generates a pulse having a predetermined frequency based on a command from the CPU 1. The resistor R1 is connected to the output side of the pulse generator 2. The coupling capacitor C1 (first coupling capacitor) is a capacitor for DC-separating the battery 300 and the leakage detector 100, and one end of the battery 300 is connected to the battery 300 via the terminal T1 (first terminal). The other end is connected to the pulse generator 2 via a resistor R1.

  The filter circuit 3 is provided between the CPU 1 and a connection point (point P) between the resistor R1 and the coupling capacitor C1. The filter circuit 3 is for removing noise of the voltage input to the CPU 1, and includes a resistor R2 and a capacitor C2. One end of the resistor R2 is connected to the point P. The other end of the resistor R2 is connected to the CPU 1 and to one end of the capacitor C2. The other end of the capacitor C2 is grounded to the ground G. In the present embodiment, the ground G is a vehicle body.

  The coupling capacitor C3 (second coupling capacitor) is a capacitor for separating the battery 300 and the leakage detection device 100 in a DC manner, like the coupling capacitor C1. One end of the coupling capacitor C3 is connected to the negative electrode of the battery 300 via the terminal T2 (second terminal), and the other end is connected to the pseudo leakage circuit 4.

  The pseudo leakage circuit 4 includes a transistor Q as a switching element and resistors R3 to R5. A resistor R3 is connected to the collector of the transistor Q, and the coupling capacitor C3 is connected in series with the resistor R3. The emitter of the transistor Q is grounded to the ground G. The base of the transistor Q is connected to the CPU 1 via the resistor R5. The resistor R4 is connected across the base and emitter of the transistor Q.

  The switch SW1 (first switch) is provided between the other end of the coupling capacitor C1 and the other end of the coupling capacitor C3. Specifically, one end of the switch SW1 is connected to a connection point (P point) between the coupling capacitor C1 and the resistor R1, and the other end of the switch SW1 is connected to a connection point between the coupling capacitor C3 and the resistor R3. Has been. The switch SW1 is turned on / off by a control signal from the CPU 1 and switches the connection state between the coupling capacitors C1 and C3 as will be described later. As the switch SW1, for example, a photo relay in which an input element (LED or the like) and an output element (MOS type FET or the like) are incorporated and the input side and the output side are electrically insulated can be used.

  The memory 5 includes a ROM, a RAM, and the like, and constitutes a storage unit. The memory 5 stores an operation program of the CPU 1 and control data, and a threshold value SH for determining whether there is a leakage, which will be described later.

  In the CPU 1, the voltage detection unit 6 detects the voltage at the point P based on the input voltage V taken into the CPU 1 from the filter circuit 3. This voltage detection is performed at the time when the output pulse of the pulse generator 2 falls.

  The leakage determination unit 7 compares the voltage at the point P detected by the voltage detection unit 6 (hereinafter referred to as “detection voltage”) with a threshold value SH, and determines whether or not the battery 300 has a leakage based on the comparison result.

  During the self-diagnosis, the diagnosis unit 8 drives the pseudo leakage circuit 4 to put the battery 300 in a pseudo leakage state, and diagnoses whether or not the leakage determination unit 7 determines that “leakage is present” in this state. .

  The disconnection detection unit 9 detects that one or both of the cables W1, W2 are disconnected based on the voltage state detected by the voltage detection unit 6.

  The switch control unit 10 controls on / off of the switch SW <b> 1 according to the operation mode (normal mode and self-diagnosis mode) of the leakage detection device 100.

  One end of the cable W <b> 1 (first cable) is connected to the negative electrode of the battery 300. The other end of the cable W1 is connected to the terminal T1 of the leakage detection device 100, and is connected to one end of the coupling capacitor C1 via this terminal T1.

  One end of the cable W <b> 2 (second cable) is connected to the negative electrode of the battery 300. The other end of the cable W2 is connected to the terminal T2 of the leakage detection device 100, and is connected to one end of the coupling capacitor C3 via this terminal T2.

  Actually, for example, one end of the cable W1 is connected to one of two terminals (not shown) of the same potential constituting the negative electrode of the battery 300, and one end of the cable W2 is connected to the other of the two terminals. The

  Terminals T <b> 3 to T <b> 5 of the leakage detection device 100 are connected to the CPU 1. A leakage detection signal is output from terminal T3 when leakage is detected. A disconnection detection signal is output from the terminal T4 when a disconnection is detected. A pre-check request signal is input to the terminal T5 when performing self-diagnosis.

  Next, the operation of the leakage detection device 100 having the above configuration will be described.

  The pulse generator 2 outputs a rectangular wave pulse as shown in FIG. When the ignition switch (not shown) of the vehicle is turned on, a pre-check request signal is input from the host device (not shown) to the terminal T5. In response to this signal, the CPU 1 sets the operation mode of the leakage detection device 100 to the self-diagnosis mode. The self-diagnosis mode is a mode in which the diagnosis is performed by the diagnosis unit 8 (diagnosis as to whether or not the leakage can be normally detected) by setting the battery 300 in a pseudo leakage state by the simulated leakage circuit 4. FIG. 2 shows a circuit state in the self-diagnosis mode.

  In the self-diagnosis mode, the diagnosis unit 8 of the CPU 1 outputs a control signal for turning on the transistor Q. The transistor Q is turned on as shown in FIG. 4B when this control signal is applied to the base via the resistor R5. On the other hand, the switch control unit 10 of the CPU 1 does not output a control signal for turning on the switch SW1 during the self-diagnosis mode. Therefore, the switch SW1 is turned off as shown in FIG. Therefore, in the self-diagnosis mode, as can be seen from FIG. 2, the coupling capacitor C <b> 1, the coupling capacitor C <b> 3, and the pseudo leakage circuit 4 are connected in series to the pulse generator 2.

  When the transistor Q is turned on, as indicated by a broken line arrow in FIG. 2, the pulse generator 2 → the resistor R1 → the coupling capacitor C1 → the terminal T1 → the cable W1 → the cable W2 → the terminal T2 → the coupling capacitor C3 → the pseudo leakage circuit 4 current paths X are formed. Actually, the stray capacitance Cs exists between the battery 300 and the ground G (vehicle body), and the stray capacitance Cs is also charged by the pulse. In addition, when leakage occurs in the battery 300, a leakage resistance Rs exists between the battery 300 and the ground G (vehicle body). Since the emitter of the transistor Q of the pseudo-leakage circuit 4 is grounded to the ground G (vehicle body), the pseudo-leakage circuit 4 is turned on in a pseudo manner similar to the case where a leakage actually occurs between the battery 300 and the vehicle body when the transistor Q is turned on. A fault condition is created.

  In this pseudo-leakage state, the coupling capacitors C1 and C3 are charged by the pulse output from the pulse generator 2. Here, since the coupling capacitors C1 and C3 are connected in series, compared with the case where the coupling capacitors C1 and C3 are connected in parallel (the normal mode described later), the potential at the point P, that is, the input voltage V The rise will be moderate. As a result, as indicated by t1 in FIG. 4D, the voltage detected by the voltage detection unit 6 is less than the threshold value SH, so the leakage determination unit 7 determines that “leakage is present”. And based on this determination, as shown in FIG.4 (e), a leakage detection signal is output from CPU1. Thereby, the diagnosis part 8 determines with the earth-leakage detection being performed normally. When no breakage occurs in the cables W1 and W2, the breakage detection unit 9 does not output a breakage detection signal as shown in FIG. Details of the disconnection detection will be described later.

  When the self-diagnosis ends, the CPU 1 switches the operation mode of the leakage detection device 100 from the self-diagnosis mode to the normal mode. The normal mode refers to a mode in which the battery leakage is not pseudo-faulted by the pseudo-leakage circuit 4 and the determination by the leakage determination unit 7 (determination of whether or not leakage actually occurs). FIG. 3 shows a circuit state in the normal mode.

  In the normal mode, the diagnosis unit 8 of the CPU 1 stops outputting the control signal that has turned on the transistor Q. For this reason, the transistor Q is turned off as shown in FIG. On the other hand, the switch control unit 10 of the CPU 1 outputs a control signal for turning on the switch SW1. The switch SW1 is turned on by this control signal as shown in FIG. Therefore, in the normal mode, as can be seen from FIG. 3, the coupling capacitor C1 and the coupling capacitor C3 are connected in parallel to the pulse generator 2.

  If the transistor Q is turned off and the switch SW1 is turned on in the state where no leakage has occurred in the battery 300, the pulse generator 2 → the resistor R1 → the coupling capacitor C1 → the terminal T1 → as shown by the broken line arrow in FIG. Cable W1 → cable W2 → stray capacitance Cs → current path Y of ground G and pulse generator 2 → resistor R1 → switch SW1 → coupling capacitor C3 → terminal T2 → stray capacitance Cs → current path Z of ground G are formed. Is done.

  As a result, the coupling capacitors C1 and C3 are charged by the output pulse of the pulse generator 2. Here, since the transistor Q changes from the on state to the off state, that is, from the state where the resistor R3 is connected to the ground G, the transistor Q is not connected, so the coupling capacitors C1 and C3 are connected in series. In comparison with the case (the above self-diagnosis mode), the potential at the point P, that is, the input voltage V rises sharply. Accordingly, as indicated by t2 in FIG. 4D, the voltage detected by the voltage detection unit 6 is equal to or higher than the threshold value SH, and thus the leakage determination unit 7 determines “no leakage”. As a result, as shown in FIG. 4E, the leakage detection signal is not output from the CPU 1.

  On the other hand, if a leakage occurs between the battery 300 and the ground G, the potential at the point P gradually increases due to the presence of the leakage resistance Rs. Therefore, as shown at t3 in FIG. The detection voltage at 6 is less than the threshold SH. For this reason, the leakage determination unit 7 determines that “leakage is present”. And based on this determination, as shown in FIG.4 (e), a leakage detection signal is output from CPU1.

  Next, disconnection detection by the disconnection detection unit 9 will be described. When one or both of the cables W1 and W2 are disconnected, the current path X in FIG. 2 is not formed. Therefore, even if the transistor Q is turned on to enter the self-diagnosis mode, a pseudo leakage state is created by the pseudo leakage circuit 4. I can't. On the other hand, even if the cables W1 and W2 are disconnected, there is actually a stray capacitance (not shown) between the terminal T1 and the ground G. Therefore, charging from the pulse generator 2 to the coupling capacitor C1 is performed. A route is secured.

  Therefore, in the self-diagnosis mode at the time of cable disconnection, only the coupling capacitor C1 is charged with a pulse. Become. For this reason, since the leakage determination unit 7 determines “no leakage”, the leakage detection signal is not output as shown in FIG. Then, the disconnection detection unit 9 detects that a disconnection has occurred in one or both of the cables W1, W2 when the state where the detection voltage is equal to or higher than the threshold value SH continues for a certain time T in the self-diagnosis mode. When disconnection is detected, a disconnection detection signal is output from the CPU 1 as shown in FIG. This disconnection detection signal is sent to the host device via the terminal T4, and abnormality processing (for example, output of an alarm for notifying disconnection) is performed in the host device.

  As described above, in the first embodiment, when the switch SW1 is turned on in the normal mode, the coupling capacitors C1 and C3 are connected in parallel, so that their combined capacitance is only when the coupling capacitor C1 is used. Compared to larger. Therefore, when the capacitors C1 and C3 have the same capacity, the combined capacity is the same as the conventional capacity even if the capacity of each capacitor is half that of the conventional one. For this reason, a small-capacitance capacitor can be used as the coupling capacitors C1 and C3. As a result, the outer dimensions of the coupling capacitors C1 and C3 are reduced, and the mounting area on the substrate can be reduced. Moreover, since the coupling capacitor C3 is originally provided in the leakage detection device 100, it is not necessary to newly provide a capacitor connected in parallel with the coupling capacitor C1. Furthermore, in 1st Embodiment, the disconnection detection part 9 can detect the disconnection of cable W1, W2.

  Next, a leakage detection device according to the second embodiment will be described with reference to FIGS. 6 to 8, the same or corresponding parts as those in FIGS. 1 to 3 are denoted by the same reference numerals. Therefore, the description of the overlapping part is omitted.

  FIG. 6 shows a configuration of a leakage detection device 101 according to the second embodiment. 6 is different from FIG. 1 in that a switch SW2 (second switch) is provided between a connection point between the coupling capacitor C3 and the switch SW1 and the pseudo leakage circuit 4. The switch SW2, like the switch SW1, is composed of a photo relay or the like, and is turned on / off by the switch control unit 10.

  In the self-diagnosis mode, as shown in FIG. 7, the switch control unit 10 turns off the switch SW1 and turns on the switch SW2. The diagnosis unit 8 turns on the transistor Q. In this state, the coupling capacitor C1, the coupling capacitor C3, and the pseudo leakage circuit 4 are connected in series to the pulse generator 2. Then, as indicated by a broken line arrow, the current path of the pulse generator 2 → resistor R1 → coupling capacitor C1 → terminal T1 → cable W1 → cable W2 → terminal T2 → coupling capacitor C3 → switch SW2 → pseudo-leakage circuit 4 X ′ is formed. Thereby, a pseudo electric leakage state is created. Since the operation of the leakage detection device 101 in the self-diagnosis mode is the same as that in the first embodiment, detailed description thereof is omitted.

  On the other hand, in the normal mode, as shown in FIG. 8, the switch control unit 10 turns on the switch SW1 and turns off the switch SW2. The diagnosis unit 8 turns off the transistor Q. In this state, the coupling capacitor C1 and the coupling capacitor C3 are connected in parallel to the pulse generator 2. Then, as indicated by the broken line arrow, pulse generator 2 → resistor R1 → coupling capacitor C1 → terminal T1 → cable W1 → cable W2 → floating capacitance Cs → current path Y of ground G and pulse generator 2 → resistor A current path Z of R1 → switch SW1 → coupling capacitor C3 → terminal T2 → floating capacitance Cs → ground G is formed.

  The operation of the leakage detection device 101 in the normal mode is basically the same as that in the first embodiment. However, the second embodiment is different from the first embodiment in that the pseudo leakage circuit 4 is electrically disconnected from the coupling capacitors C1 and C3 by turning off the switch SW2 in the normal mode.

  In the case of the first embodiment, the pseudo leakage circuit 4 is electrically connected to the coupling capacitors C1 and C3 in the normal mode (see FIG. 3). For this reason, for example, part of the current flowing through the current path Z may flow through the pseudo-leakage circuit 4 due to a stray capacitance existing between the collector and emitter of the transistor Q. Then, the potential at point P varies, and the voltage value compared with the threshold value in the leakage determination unit 7 varies. Therefore, the leakage determination unit 7 cannot accurately determine the presence or absence of the leakage.

  However, as in the second embodiment, the potential at the point P varies due to the stray capacitance of the transistor Q described above by electrically disconnecting the pseudo leakage circuit 4 from the coupling capacitors C1 and C3 by the switch SW2. Thus, the leakage determination unit 7 can accurately determine the presence or absence of leakage. Note that if the characteristics of the transistor Q, such as stray capacitance, are known in advance, the threshold value of the leakage determination unit 7 may be set in consideration of the characteristics, so there is no problem even if the first embodiment is adopted. Absent.

  Also in the second embodiment, disconnection of the cables W1, W2 can be detected. Since the principle is the same as that of the first embodiment, a detailed description thereof will be omitted. FIG. 9 is a timing chart showing the operation when the second embodiment is not disconnected, and FIG. 10 is a timing chart showing the operation when the second embodiment is disconnected. 9 and 10 are the same as FIGS. 4 and 5 except that the operation of the switch SW2 is added to (d).

  FIG. 11 shows a leakage detection device 102 according to a third embodiment of the present invention. In the third embodiment, the terminal T2 and the cable W2 of the first embodiment (FIG. 1) are omitted, and one end of the coupling capacitor C3 is connected to the terminal T1 in the leakage detector 102. In this embodiment, since the disconnection of the cable W1 cannot be detected, the disconnection detection unit 9 is not provided in the CPU 1, and the terminal T4 that outputs a disconnection detection signal is also not provided.

  In this leakage detection device 102, the formation of current paths X, Y, and Z in FIGS. 2 and 3 is different, but the basic operation is the same as in the first embodiment except for disconnection detection. is there. Therefore, since the operation can be easily understood from the operation described in the first embodiment, a detailed description is omitted.

  FIG. 12 shows a leakage detection device 103 according to the fourth embodiment of the present invention. In the fourth embodiment, the terminal T2 and the cable W2 of the second embodiment (FIG. 6) are omitted, and one end of the coupling capacitor C3 is connected to the terminal T1 in the leakage detection device 103. Even in the present embodiment, since the disconnection of the cable W1 cannot be detected, the disconnection detection unit 9 is not provided in the CPU 1, and the terminal T4 that outputs the disconnection detection signal is not provided.

  In this leakage detection device 103, the way of forming the current paths X ′, Y, and Z in FIGS. 7 and 8 is different, but the basic operation is the same as in the second embodiment except for disconnection detection. It is. Therefore, since the operation can be easily understood from the operation described in the second embodiment, a detailed description is omitted.

  In the present invention, various embodiments other than those described above can be adopted. For example, in the above-described embodiment, the photorelay is exemplified as the switches SW1 and SW2, but an electromagnetic relay may be used instead of the photorelay. Further, the transistor Q of the pseudo leakage circuit 4 may be replaced with an FET, a relay, or the like.

  In the above embodiment, the filter circuit 3 including the resistor R2 and the capacitor C2 is provided. However, the filter circuit 3 is not essential for the present invention and may be omitted. Moreover, you may add the discharge circuit for forcibly discharging the charge of coupling capacitor C1, C3 as needed.

  In the above-described embodiment, the voltage detection unit 6 detects the voltage at the point P and the leakage determination unit 7 determines whether there is a leakage at the falling timing of the pulse output from the pulse generator 2. However, the present invention is not limited to this. For example, the voltage detection by the voltage detection unit 6 and the leakage presence / absence determination by the leakage determination unit 7 may be performed at a predetermined time before the pulse falls.

  In the above embodiment, one end of the coupling capacitor C1 is connected to the negative electrode of the DC power supply 300, but one end of the coupling capacitor C1 may be connected to the positive electrode of the DC power supply 300. Similarly, one end of the coupling capacitor C3 may be connected to the positive electrode of the DC power supply 300.

  Furthermore, in the above-described embodiment, the leakage detection device mounted on the electric vehicle or the hybrid car is taken as an example. However, the present invention is not limited to the vehicle, but the leakage detection mounted on various devices including a DC power supply. Can be widely applied to the device.

2 Pulse generator 4 Pseudo-leakage circuit 6 Voltage detection unit 7 Leakage determination unit 8 Diagnosis unit 9 Disconnection detection unit 10 Switch control unit 100, 101, 102, 103 Leakage detection device 300 Battery (DC power supply)
C1 coupling capacitor (first coupling capacitor)
C3 coupling capacitor (second coupling capacitor)
G Ground SW1 switch (first switch)
SW2 switch (second switch)
T1 terminal (first terminal)
T2 terminal (second terminal)
W1 cable (first cable)
W2 cable (second cable)
X, X ', Y, Z Current path

Claims (4)

A first coupling capacitor having one end connected to a DC power source;
A pulse generator for supplying a pulse to the other end of the first coupling capacitor;
A voltage detector for detecting a voltage at the other end of the first coupling capacitor;
A leakage detection unit that compares the voltage detected by the voltage detection unit with a threshold value and determines the presence or absence of leakage of the DC power supply based on the comparison result;
A pseudo-leakage circuit that quasi-leaks the DC power supply; and
A second coupling capacitor having one end connected to the DC power source and the other end connected to the pseudo-leakage circuit;
A diagnostic unit for diagnosing whether or not the leakage determination unit determines that there is a leakage when the DC power supply is in a pseudo leakage state by the pseudo leakage circuit;
In the earth leakage detector with
A first switch provided between the other end of the first coupling capacitor and the other end of the second coupling capacitor;
A switch control unit for controlling on / off of the first switch,
In the self-diagnosis mode in which the DC power supply is artificially leaked by the pseudo-leakage circuit and the diagnosis by the diagnosis unit is performed, the switch control unit turns off the first switch, whereby the pulse generator In contrast, the first coupling capacitor, the second coupling capacitor, and the pseudo-leakage circuit are connected in series,
In the normal mode in which the determination by the leakage determination unit is not performed in a pseudo-leakage state by the pseudo-leakage circuit, the switch control unit turns on the first switch, thereby the pulse generator. On the other hand, the leakage detecting device is characterized in that the first coupling capacitor and the second coupling capacitor are connected in parallel. In the electric leakage detection apparatus according to claim 1,
A second switch that is controlled to be turned on and off by the switch controller is provided between a connection point between the other end of the second coupling capacitor and the first switch and the pseudo-leakage circuit,
The switch control unit
In the self-diagnosis mode, the first switch is turned off and the second switch is turned on,
In the normal mode, the first switch is turned on and the second switch is turned off. In the electric leakage detection apparatus according to claim 1 or claim 2,
A first terminal for connecting the other end of the first cable having one end connected to the DC power supply to one end of the first coupling capacitor;
A second terminal for connecting the other end of the second cable having one end connected to the DC power supply to one end of the second coupling capacitor;
In the self-diagnosis mode, the pulse generator passes through the first coupling capacitor, the first terminal, the first cable, the second cable, the second terminal, and the second coupling capacitor. , A current path to the pseudo-leakage circuit is formed,
In the normal mode, a current path from the pulse generator to the ground via the first coupling capacitor, the first terminal, the first cable, and the second cable, and from the pulse generator And a current path that reaches the ground via the first switch, the second coupling capacitor, and the second terminal. In the electric leakage detection apparatus according to claim 3,
A disconnection detector that detects that one or both of the first cable and the second cable are disconnected;
In the self-diagnosis mode, the disconnection detection unit detects disconnection based on the fact that the voltage detected by the voltage detection unit is equal to or higher than the threshold value.

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