JP5541743B2 - Contactor welding detector - Google Patents

Description

The present invention relates to an apparatus for detecting welding of a contactor by using a leakage detection device used for detecting leakage of a DC power supply, for example, in an electric vehicle.

  In an electric vehicle, a high-voltage DC power source for driving a motor or on-vehicle equipment 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.

  Some leakage detection devices have a so-called self-diagnosis function that can diagnose whether or not leakage detection can be normally performed. Patent Documents 1 and 2 to be described later describe a leakage detecting device having a self-diagnosis function.

  In Patent Document 1, a self-diagnosis resistor and a switching element are connected in series between a connection point between a detection resistor and an insulation resistor and a ground. At the time of self-diagnosis, if 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 switching element turned on, it is determined that the detection resistance is deteriorated or failed.

  In Patent Document 2, an insulation performance is determined by applying a pulse voltage to a ground insulation circuit through a coupling capacitor and determining 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. In the diagnostic apparatus, a pseudo insulation lowering circuit that causes the same signal change as when the ground insulation resistance of the ground insulating circuit is lowered is provided.

  Patent Document 3 described later describes a battery pack inspection device including an external forced leakage circuit and a self-diagnosis circuit. In this inspection device, an external forced leakage circuit is connected to a battery pack via a contactor, and after the self-diagnosis circuit is turned on, the external forced leakage circuit is activated to detect the presence or absence of leakage.

  Further, Patent Document 4 described later describes a welding detection device that uses a leakage sensor equipped with a self-diagnosis circuit to detect whether or not a contactor provided between a battery and an external charger is welded.

  FIG. 12 is a schematic configuration diagram of the welding detection apparatus described in Patent Document 4. The leakage detection device 50 includes a pulse generator 51, a leakage determination unit 52, a coupling capacitor 53, a ground relay 54, and a resistor 55. The ground relay 54 and the resistor 55 constitute a pseudo electric leakage circuit. One end of the coupling capacitor 53 is connected to the pulse generator 51. The other end of the coupling capacitor 53 is connected to the negative electrode of the battery 60. The leakage determination unit 52 is connected to a connection point between the coupling capacitor 53 and the pulse generator 51. One end of the ground relay 54 is connected to the other end of the coupling capacitor 53. The other end of the ground relay 54 is connected to one end of the resistor 55. The other end of the resistor 55 is grounded.

  Contactors (charging relays) 71 and 72 are connected between the battery 60 and the external charger 70. One end of the contactor 71 is connected to the negative electrode of the battery 60. The other end of the contactor 71 is connected to a connection point between the ground relay 54 and the resistor 55 via a welding detection relay 73. One end of the contactor 72 is connected to the positive electrode of the battery 60. The other end of the contactor 72 is connected to a connection point between the ground relay 54 and the resistor 55 via a welding detection relay 74. The battery control unit 80 is a host device and controls the operations of the leakage detection device 50 and the contactors 71 and 72.

  In the apparatus of FIG. 12, in order to perform self-diagnosis of the leakage detection device 50, the ground relay 54 is turned on. When the earth relay 54 is turned on, a current path from the battery 60 to the ground through the earth relay 54 and the resistor 55 is formed. As a result, the battery 60 enters a pseudo-leakage state. For this reason, the voltage of the coupling capacitor 53 decreases, and based on this voltage change, the leakage determination unit 52 determines that the leakage detection device 50 is functioning normally.

  Further, in the apparatus shown in FIG. 12, in order to detect the welding of the contactors 71 and 72, the ground relay 54 is turned off. Then, the welding detection relays 73 and 74 are alternately closed, and the contactors 71 and 72 are connected to the resistor 55 via the welding detection relays 73 and 74, respectively. At this time, if no welding occurs in the contactors 71 and 72, a current path from the contactors 71 and 72 to the ground via the welding detection relays 73 and 74 and the resistor 55 is not formed. Therefore, since the voltage of the coupling capacitor 53 does not decrease, the leakage determination unit 52 determines that welding has not occurred in the contactors 71 and 72.

  On the other hand, when welding has occurred in one or both of the contactors 71 and 72, a current path from the contactors 71 and 72 to the ground through the welding detection relays 73 and 74 and the resistor 55 is formed. For this reason, the voltage of the coupling capacitor 53 decreases, and the leakage determination unit 52 determines that welding has occurred in the contactors 71 and 72.

  Thus, in the welding detection apparatus of patent document 4, the presence or absence of welding of the contactors 71 and 72 can be detected using the leakage detection apparatus 50. On the other hand, in this device, a pseudo earth leakage circuit including an earth relay 54 and a resistor 55 is connected to a connection point between the coupling capacitor 53 and the battery 60. Further, the contactors 71 and 72 are connected to the connection point between the ground relay 54 and the resistor 55 via the welding detection relays 73 and 74. Then, when welding is detected, the ground relay 54 needs to be turned off. Therefore, in order to detect the welding of the contactors 71 and 72, the welding detection relays 73 and 74 must be provided separately from the ground relay 54, and the circuit configuration becomes complicated.

JP 2005-127721 A JP 2007-163291 A JP 2010-181368 A JP 2010-178454 A

  An object of the present invention is to realize a welding detection device that can detect the presence or absence of welding of a contactor using a leakage detection device with a simple configuration.

  The contactor welding detection apparatus according to the present invention includes a coupling capacitor having one end connected to one pole of a DC power supply, a pulse generator for supplying a pulse to the other end of the coupling capacitor, and the pulse charged by the pulse. A voltage detection unit that detects the voltage of the coupling capacitor, a leakage determination unit that determines whether or not there is a leakage of the DC power source based on the voltage detected by the voltage detection unit, and a switching element, and the switching element Whether or not the leakage determination unit determines that there is a leakage when the DC power supply is set to a pseudo-leakage state by this pseudo-leakage circuit and the pseudo-leakage circuit that makes the DC power supply pseudo-leakage by turning on. To connect the other end of the first cable, one end of which is connected to one pole of the DC power supply, to one end of the coupling capacitor The first terminal, the second terminal for connecting the other end of the second cable, one end of which is connected to one or the other pole of the DC power supply via the contactor, to the pseudo-leakage circuit, and opening / closing of the contactor And controlling means for determining whether or not the contactor is welded based on the open / closed state of the contactor and the determination result of the leakage determination unit. When the contactor is in the closed state and the switching element is in the on state, the pulse generator passes through the coupling capacitor, the first terminal, the first cable, the contactor, the second cable, and the second terminal. Thus, a current path to the pseudo leakage circuit is formed.

  In this way, in the failure diagnosis performed with the contactor in the open state, when welding occurs in the contactor, when the switching element of the pseudo-leakage circuit is turned on, the pseudo-leakage circuit from the contactor via the second terminal Current flows through For this reason, since the leakage determination unit determines that “leakage is present”, the control unit can detect welding of the contactor based on the determination result. In addition, since a current path from the contactor to the switching element is formed, it is possible to detect welding only with the switching element without providing a welding detection relay as in Patent Document 4.

In the present invention, the control means outputs a command signal for opening or closing the contactor, and outputs a command signal for opening the contactor, and when the switching element is turned on, When the determination unit determines that there is a leakage, the leakage determination unit determines that the contactor has been welded and the switching element is turned on while the command signal for closing the contactor is output. when it is determined that the pears, you determined that the abnormality other than the welding of the contactor has occurred.

  In the present invention, the contactor includes a first contactor connected to the negative electrode of the DC power supply and a second contactor connected to the positive electrode of the DC power supply, and the connection between the first contactor and the second terminal, Switching means for switching the connection between the two contactors and the second terminal may be provided.

  ADVANTAGE OF THE INVENTION According to this invention, the welding detection apparatus which can determine the welding presence or absence of a contactor using an electrical leakage detection apparatus is realizable by simple structure.

It is the circuit diagram which showed the welding detection apparatus which concerns on embodiment of this invention. It is a timing chart which shows the operation | movement at the normal time of a leak detection apparatus. It is a timing chart which shows the operation | movement at the time of the failure diagnosis of a leak detection apparatus. It is a flowchart of a failure diagnosis when a contactor is made into a closed state. It is a circuit diagram of a normal state when a contactor is made into a closed state. It is a circuit diagram of an abnormal state when a contactor is made into a closed state. It is a flowchart of a failure diagnosis when a contactor is made into an open state. It is a circuit diagram of a normal state when a contactor is made into an open state. It is a circuit diagram of the abnormal state when a contactor is made into an open state. It is the circuit diagram which showed the welding detection apparatus which concerns on other embodiment of this invention. It is the circuit diagram which showed the welding detection apparatus which concerns on other embodiment of this invention. It is the circuit diagram which showed the conventional welding detection apparatus.

  Embodiments of the present invention will be described with reference to the drawings. In each figure, the same code | symbol is attached | subjected to the same part or a corresponding part. Below, the case where this invention is applied to the electrical leakage detection apparatus mounted in an electric vehicle is mentioned as an example.

  In FIG. 1, a leakage detection device 100 detects a leakage of a battery 30 that is a DC power supply, and is connected to an ECU (electronic control unit) 200 that is a host device. The leakage detection device 100 and the ECU 200 constitute a contactor welding detection device. The ECU 200 is an example of the “control unit” in the present invention.

  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, and terminals T1 to T4.

  The CPU 1 controls the operation of the leakage detection device 100 and includes a voltage detection unit 6, a leakage determination unit 7, and a self-diagnosis unit 8. Actually, the functions of these blocks 6 to 8 are 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 is a capacitor for separating the battery 30 and the leakage detection device 100 in a DC manner, and is connected between the resistor R1 and the terminal T1 (first terminal).

  The filter circuit 3 is provided between the connection point (point a) between the resistor R1 and the coupling capacitor C1 and the CPU1. 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 a. 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 the body of the electric vehicle.

  A coupling capacitor C3 is connected between the pseudo earth leakage circuit 4 and the terminal T2 (second terminal). The coupling capacitor C3 is a capacitor for separating the battery 30 and the leakage detection device 100 in a DC manner, like the coupling capacitor C1.

  The pseudo leakage circuit 4 includes a transistor Q 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 transistor Q is an example of the “switching element” in the present invention.

  The memory 5 includes a ROM, a RAM, and the like. 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 detector 6 detects the voltage of the coupling capacitor C 1 based on the input voltage V taken into the CPU 1 through the filter circuit 3 from the point a.

  The leakage determination unit 7 compares the voltage detected by the voltage detection unit 6 with the threshold value SH, and determines whether or not the battery 30 has a leakage based on the comparison result.

  The self-diagnosis unit 8 drives the pseudo-leakage circuit 4 to put the battery 30 in a pseudo-leakage state at the time of self-diagnosis for diagnosing whether or not the leakage detection device 100 operates normally. And it is diagnosed whether the earth leakage determination part 7 determined with "there is electric leakage" in this pseudo electric leakage state.

  The battery 30 is connected to the high voltage unit 20 via the contactors 11 and 12. The contactor 11 (first contactor) is connected between the negative electrode of the battery 30 and the high voltage unit 20, and the contactor 12 (second contactor) is connected between the positive electrode of the battery 30 and the high voltage unit 20. Has been. The high voltage unit 20 includes a DC-DC converter, an inverter circuit, and the like, and supplies power to a motor and an in-vehicle device (not shown).

  One end of the cable L1 (first cable) is connected to the negative electrode of the battery 30 at point b. The other end of the cable L1 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 L2 (second cable) is connected to a point c between the contactor 11 and the high voltage unit 20, and is connected to the negative electrode of the battery 30 via the contactor 11. The other end of the cable L2 is connected to the terminal T2 of the leakage detection device 100, and is connected to the pseudo leakage circuit 4 via the terminal T2 and the coupling capacitor C3.

  Terminals T3 and T4 of the leakage detection device 100 are connected to the CPU1. A failure diagnosis command signal is input from the ECU 200 to the terminal T3 when performing failure diagnosis described later. For example, the command signal is output from the ECU 200 after a predetermined time has elapsed since the ignition switch (not shown) is turned on. From the terminal T4, when leakage is detected, a leakage detection signal is output to the ECU 200. In addition to the terminals T3 and T4, the leakage detection device 100 includes a terminal that communicates with the ECU 200, but is not shown because it is not directly related to the present invention.

  Next, the basic operation of the leakage detection device 100 will be described.

  The pulse generator 2 outputs a rectangular wave pulse as shown in FIG. This pulse is supplied to the coupling capacitor C1 through the resistor R1 to charge the coupling capacitor C1. Actually, stray capacitance exists between the terminals T1 and T2 and the vehicle body, and the stray capacitance is also charged by the pulse. Due to the charging of the coupling capacitor C1, the potential at point a in FIG. 1 rises. The potential at point a is input to the CPU 1 as the input voltage V through the filter circuit 3. The input voltage V has a waveform as shown in FIG.

  When the failure diagnosis command signal is not input from the ECU 200 to the terminal T3 (FIG. 2B), the CPU 1 does not output a drive signal to the pseudo-leakage circuit 4. For this reason, the transistor Q of the pseudo leakage circuit 4 is turned off.

  The voltage detection unit 6 of the CPU 1 detects the voltage of the coupling capacitor C1 based on the input voltage V. This voltage detection is performed at the time (or immediately before) when the pulse supplied to the coupling capacitor C1 falls. The detected voltage of the coupling capacitor C1 is hereinafter referred to as “detection voltage”.

The leakage determination unit 7 compares the detection voltage detected by the voltage detection unit 6 with the threshold value SH stored in the memory 5 and determines the presence or absence of leakage based on the comparison result. If no leakage has occurred in the battery 30, the detection voltage exceeds the threshold SH as indicated by A in FIG. Therefore, the leakage determination unit 7 determines “no leakage”, and the leakage detection signal is not output from the CPU 1 to the ECU 200 via the terminal T4 (the leakage detection signal is OFF in FIG. 2D).

On the other hand, when leakage occurs in the battery 30, the voltage of the coupling capacitor C1 decreases due to the leakage impedance. Therefore, as indicated by B in FIG. 2C, the detected voltage does not exceed the threshold value SH, and the leakage determination unit 7 determines that “leakage is present”. Then, the leakage detection signal is output from the CPU 1 to the ECU 200 via the terminal T4 (the leakage detection signal is ON in FIG. 2D).

  Next, failure diagnosis performed by the ECU 200 will be described. There are two types of failure diagnosis: failure diagnosis performed with the contactors 11 and 12 closed and failure diagnosis performed with the contactors 11 and 12 opened. Contactors 11 and 12 are closed when receiving a “close” command signal from ECU 200, and are opened when receiving an “open” command signal from ECU 200.

  The flowchart of FIG. 4 shows the procedure of failure diagnosis performed with the contactors 11 and 12 closed. When a failure diagnosis command signal is input from the ECU 200 to the terminal T3 of the leakage detection device 100 (the failure diagnosis command signal is ON in FIG. 3B), a drive signal is supplied from the CPU 1 to the pseudo leakage circuit 4 and the transistor Q Is turned on (step S101). Thereafter, ECU 200 determines whether or not a leakage detection signal has been received from leakage detection device 100 (step S102).

  If no abnormality has occurred, the contactors 11 and 12 are closed by the “close” command signal output from the ECU 200, as shown in FIG. A path X is formed. That is, a current flows through the path of pulse generator 2 → resistor R1 → coupling capacitor C1 → terminal T1 → cable L1 → contactor 11 → cable L2 → terminal T2 → coupling capacitor C3 → pseudo-leakage circuit 4.

  Since the emitter of the transistor Q of the pseudo-leakage circuit 4 is grounded to the ground G (vehicle body), a current flows through the path, which is similar to the case where a leakage actually occurs between the battery 30 and the vehicle body. A pseudo leakage condition is created.

  In this pseudo-leakage state, the coupling capacitor C1 is charged and the coupling capacitor C3 is charged by the pulse output from the pulse generator 2. For this reason, the potential at the point a, that is, the input voltage V decreases. As a result, as indicated by B in FIG. 3C, the detected voltage of the coupling capacitor C1 is less than the threshold value SH, so that the leakage determination unit 7 determines “leakage”.

When the leakage determination unit 7 determines as described above, as shown in FIG. 5, the CPU 1 outputs a leakage detection signal to the terminal T4 (the leakage detection signal is ON in FIG. 3D), and the ECU 200 detects this leakage. A detection signal is received (step S102; YES).

  The ECU 200 receives the leakage detection signal when the transistor Q is turned on while outputting the “closed” command signal to the contactors 11 and 12, so that the leakage detection device 100, the cables L 1 and L 2, and the contactor 11 receive the leakage detection signal. It is determined that no abnormality has occurred (step S103).

  On the other hand, when an abnormality (abnormality other than contactor welding described later) such as failure of the pseudo earth leakage circuit 4, disconnection of the cables L1 and L2, or open failure of the contactor 11 occurs, as shown in FIG. 5) is not formed. FIG. 6 shows a case where an open failure has occurred in which the contactor 11 does not switch from the open state to the closed state. As a result, since a pseudo leakage state is not created, the leakage determination unit 7 determines “no leakage”. Therefore, ECU 200 does not receive a leakage detection signal from CPU 1 (step S102; NO).

  The ECU 200 determines that an abnormality as described above has occurred by not receiving the leakage detection signal when the transistor Q is turned on in a state where the “close” command signal is being output to the contactors 11 and 12 (step S100). S104). When an abnormality occurs, the ECU 200 performs a measure such as outputting an alarm.

  The flowchart of FIG. 7 shows the procedure of failure diagnosis performed with the contactors 11 and 12 in the open state. When a failure diagnosis command signal is input from the ECU 200 to the terminal T3 of the leakage detection device 100 (the failure diagnosis command signal is ON in FIG. 3B), a drive signal is supplied from the CPU 1 to the pseudo leakage circuit 4 and the transistor Q Is turned on (step S201). Thereafter, ECU 200 determines whether or not a leakage detection signal has been received from leakage detection device 100 (step S202).

  If the contactor 11 is not welded, as shown in FIG. 8, the contactor 11 is opened by the “open” command signal output from the ECU 200, so that the current path X in FIG. 5 is formed. Not. That is, a pseudo electric leakage state is not created. For this reason, the leakage determination unit 7 determines “no leakage”. Therefore, ECU 200 does not receive a leakage detection signal from CPU 1 (step S202; NO).

  The ECU 200 determines that no welding has occurred in the contactor 11 by not receiving the leakage detection signal when the transistor Q is on in the state where the “open” command signal is being output to the contactors 11 and 12 ( Step S204).

  On the other hand, if the contactor 11 is welded, as shown in FIG. 9, even if an “open” command signal is output from the ECU 200, the contactor 11 remains in the closed state, so that the transistor Q is turned on. Thus, the same current path X as in FIG. 5 is formed. As a result, since a pseudo leakage state is created, the leakage determination unit 7 determines that “leakage is present”. Therefore, ECU 200 receives a leakage detection signal from CPU 1 (step S202; YES).

  The ECU 200 determines that welding has occurred in the contactor 11 by receiving a leakage detection signal when the transistor Q is turned on while outputting an “open” command signal to the contactors 11 and 12 (step S203). ). When the contactor 11 is welded, the ECU 200 performs a measure such as outputting an alarm.

  Thus, in the present embodiment, in the failure diagnosis performed with the contactors 11 and 12 in the open state, when the contactor 11 is welded, when the switching element Q of the pseudo leakage circuit 4 is turned on, A current flows from the contactor 11 to the pseudo leakage circuit 4 through the terminal T2. For this reason, since leakage determination unit 7 determines that “leakage is present”, ECU 200 can detect welding of contactor 11 based on the determination result. In addition, since a current path from the contactor 11 to the switching element Q is formed, it is possible to detect welding only with the switching element Q without providing a welding detection relay as in Patent Document 4. Thereby, the number of parts can be reduced and the circuit configuration can be simplified.

  Apart from the above-described failure diagnosis by the ECU 200, the leakage detection device 100 has a self-diagnosis function by itself. In the self-diagnosis, the connection point at one end of the cable L2 is changed from the point c to the point b, the transistor Q of the pseudo-leakage circuit 4 is turned on, and the battery 30 is set in a pseudo-leakage state. Then, the diagnosis unit 8 determines whether or not the leakage determination unit 7 determines that “leakage is present” in the simulated leakage state. When the determination unit 7 determines that “leakage is present”, the diagnosis unit 8 diagnoses that the leakage detection device 100 is operating normally. On the other hand, when the determination unit 7 determines that “no leakage”, the diagnosis unit 8 diagnoses that the leakage detection device 100 is not operating normally. The diagnosis result of the diagnosis unit 8 is notified to the ECU 200 via a terminal (not shown).

  In the above-described embodiment (FIG. 1), since one end of the cable L2 is connected to the point c, the case where the presence / absence of welding of the contactor 11 out of the two contactors 11 and 12 is detected is taken as an example. On the other hand, in order to detect whether the contactor 12 is welded, one end of the cable L2 may be connected to a point d between the contactor 12 and the high voltage unit 20, as shown in FIG. That is, one end of the cable L2 may be connected to the positive electrode of the battery 30 via the contactor 12.

  Further, in order to detect the presence or absence of welding for both the contactors 11 and 12, as shown in FIG. 11, a switch 40 for switching the connection between the contactor 11 and the terminal T2 and the connection between the contactor 12 and the terminal T2 is provided. Good. Switching of the switch 40 is performed by the ECU 200. As the switching means, a relay, a transistor, or the like can be used in addition to the switch.

  In the present invention, various embodiments other than those described above can be adopted. For example, in the above-described embodiment, the case where the leakage detection device 100 and the ECU 200 are separate units and the welding detection device is configured by two units has been described as an example. On the other hand, the leakage detection device 100 and the ECU 200 may be integrated into one unit, and the welding detection device may be configured by the unit.

  Moreover, in the said embodiment, although the example which comprised the switching element of the pseudo earth leakage circuit 4 with the transistor Q was shown, you may use FET and a relay as a switching element.

  Furthermore, although the example which applied this invention to the leak detection apparatus mounted in an electric vehicle was given in the said embodiment, this invention is applicable also to the leak detection apparatus used for uses other than an electric vehicle. it can.

1 CPU
2 Pulse generator 4 Pseudo leakage circuit 6 Voltage detection unit 7 Leakage determination unit 8 Self-diagnosis unit 11 Contactor (first contactor)
12 Contactor (second contactor)
30 battery (DC power supply)
40 switches (switching means)
100 Electric leakage detection device 200 ECU (control means)
C1 coupling capacitor G ground T1 terminal (first terminal)
T2 terminal (second terminal)
L1 cable (first cable)
L2 cable (second cable)
Q transistor (switching element)
X current path

Claims (2)

A coupling capacitor with one end connected to one pole of the DC power supply;
A pulse generator for supplying a pulse to the other end of the coupling capacitor;
A voltage detection unit for detecting a voltage of the coupling capacitor charged by the pulse;
On the basis of the voltage detected by the voltage detection unit, a leakage determination unit that determines presence or absence of leakage of the DC power supply,
A pseudo-leakage circuit having a switching element, and when the switching element is turned on, makes the DC power supply pseudo-leakage;
A self-diagnosis 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 simulated leakage circuit;
A first terminal for connecting the other end of the first cable having one end connected to one pole of the DC power supply to one end of the coupling capacitor;
A second terminal for connecting the other end of the second cable, one end of which is connected to one pole or the other pole of the DC power supply via a contactor, to the pseudo-leakage circuit;
Control means for controlling the opening and closing of the contactor, and based on the contactor opening and closing state and the determination result of the leakage determination unit, the control means for determining the presence or absence of welding of the contactor,
When the contactor is in a closed state and the switching element is in an on state, from the pulse generator, the coupling capacitor, the first terminal, the first cable, the contactor, the second cable, and In the contactor welding detection device in which a current path to the pseudo-leakage circuit is formed via the second terminal ,
The control means includes
Outputting a command signal to open or close the contactor;
When the switching element is turned on in the state where the command signal for opening the contactor is output, when the leakage determination unit determines that there is a leakage, it is determined that welding has occurred in the contactor,
When the switching element is turned on while outputting a command signal for closing the contactor, when the leakage determination unit determines that there is no leakage, an abnormality other than welding of the contactor has occurred. A contactor welding detection apparatus characterized by determining . In the contactor welding detection apparatus according to claim 1,
The contactor comprises a first contactor connected to the negative electrode of the DC power source and a second contactor connected to the positive electrode of the DC power source,
A contactor welding detection apparatus comprising switching means for switching the connection between the first contactor and the second terminal and the connection between the second contactor and the second terminal.

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