JP5083242B2 - Switch device and vehicle ground fault detection system - Google Patents

Description

  The present invention enables a self-diagnosis of a ground fault by connecting two or more withstand voltage switches in series between the high voltage generator and the ground, and connecting the switch device between the inverter and the vehicle body. The present invention relates to a ground fault detection system for vehicles such as electric vehicles and hybrid vehicles.

  Conventionally, as a ground fault detection system for a vehicle, there is a system capable of self-diagnosis as to whether or not the ground fault detection system itself is operating normally as described in Patent Document 1. As shown in FIG. 1, the ground fault detection system A includes a ground fault trial circuit 1 that includes a relay 11 and a resistor 12 and is connected between the vehicle body 10 and the bus 61, and a rectangular wave 411 output from the buffer 41. A comparator 2 and a coupling capacitor 3 to be applied to the bus 61 and a signal (rectangular wave) 412 at the connection point p are input to the inverting input terminal 41 and a reference voltage Vr is input to the non-inverting input terminal 42. 4, a controller 5 having an oscillating unit 50, a transistor 51, an LED controller 52, and an LED 53, and an in-vehicle battery 6, a traveling AC motor 7, and the input side are electrically connected to the buses 61 and 62. It is assembled in an electric vehicle having a DC / AC inverter 8 connected and having an output side electrically connected to the AC motor 7 via AC power supply lines 81, 82, 83.

  In such a configuration, the ground fault is simulated by the ground fault trial circuit 1. That is, when the driver switches the key switch from OFF to ON (at the time of ground fault trial), the excitation power 502 is energized from the controller 5 for a predetermined time, and the contact of the relay 11 is turned on for a substantially predetermined time. The bus 61 and the vehicle body 10 are connected (simulated ground fault) via the resistor 12. Here, the LED 53 is turned on when the trial ground fault cannot be detected. Further, during normal monitoring, the LED 53 is turned on when a ground fault (resistance R) occurs.

  In this ground fault detection system, the high breakdown voltage relay 11 is used for the ground fault trial circuit 1, but in order to make it inexpensively configured, for example, two withstand voltages as in the technique described in Patent Document 2 are used. It is conceivable to connect switches in series. In this configuration, as shown in FIG. 2A, a switch device 20 in which switches SW1 and SW2, which are cheaper and have a lower withstand voltage than the high withstand voltage relay 11, are connected in series is connected between the vehicle body 10 and the resistor 12 on the bus bar 61 side. The switches SW1 and SW2 may be turned on when the excitation power 502 is energized. Note that two switches SW1 and SW2 have the same breakdown voltage as the relay 11 and are much less expensive than the relay 14 because they are general-purpose products.

JP-A-10-221395 Japanese Patent No. 4047558

  However, in the switch device 20 shown in FIG. 2A, since the switches SW1 and SW2 are connected in series, they are not turned on at the same time when energized, and a short time deviation occurs. For example, when the voltmeter V1 is connected to both ends of the switch SW1 and the voltmeter V2 is connected to both ends of the switch SW2, when the switches SW1 and SW2 are turned off, as shown in FIG. In each case, a voltage Va / 2 which is 1/2 of the high voltage Va between the bus 61 and the vehicle body 10 is measured. When only one switch SW1 is turned on first at time t1 when energized in this off state, the high voltage Va is applied to the other switch SW2 until the switch SW2 is turned on at time t2. Since the high voltage Va is higher than the withstand voltage of one switch SW2, the switch SW2 may be damaged. This is the same when the switches SW1 and SW2 are turned off.

  The present invention has been made in view of such circumstances, and a switch device and a vehicle ground that can prevent damage due to application of a high voltage due to a shift at the time of startup of two or more switches connected in series. An object is to provide a fault detection system.

  In order to achieve the above object, the invention according to claim 1 is directed to a switch device comprising two or more switches connected in series between a high voltage generator and a ground, the high voltage generator and the high voltage A resistor is connected in series between the switches on the generator side and between the switches, and a capacitor is connected in parallel to one of the switches and resistors connected in series, and a capacitor is connected to the other switch and resistor. It is characterized by being connected in parallel.

  According to this configuration, for example, when two switches having a breakdown voltage of about ½ of the high voltage Va generated by the high voltage generator are connected in series, when each switch is off, the high voltage Va 1/2 voltage Va / 2 is applied. In this OFF state, when an ON command is input to both of them, when only one switch is turned ON first, a resistor is connected in series to this switch, and a capacitor is connected in parallel to the switch and the resistor. Therefore, the voltage applied to the switch gradually decreases due to the CR characteristics in which the voltage stored in the capacitor is gradually discharged. At this time, the capacitor connected in parallel to the other switch is gradually charged with the high voltage Va, and the voltage applied to the other switch gradually increases.

  When the other switch is turned on with a predetermined time difference, the voltage applied to this switch gradually decreases to 0 V in accordance with the CR characteristics. Here, when the other switch is turned on, the voltage applied to the first switch that has been turned on first gradually decreases, so the voltage applied to the other switch does not reach the high voltage Va and rises. On the way, the voltage gradually decreases to 0 V by turning on the other switch. Therefore, even when only one of the two switches is turned on first, the voltage applied to the other switch can be reduced. As a result, it is possible to prevent the switch from being damaged due to the high voltage Va higher than the withstand voltage being applied to one switch as in the prior art.

  In addition, since the switch device can be configured using two or more switches that are inexpensive general-purpose products, it can be manufactured at a lower cost than when an expensive switch with a high breakdown voltage is used.

  The invention according to claim 2 detects a ground fault of the vehicle in a vehicle that drives the motor by converting the DC power of the battery into a three-phase alternating current with an inverter, and performs a self-diagnosis of the ground fault when the vehicle is started. In a vehicle ground fault detection system equipped with a ground fault detector having a function to be performed, the switch device according to claim 1 is connected between a bus connected to the inverter and a vehicle body of the vehicle, and the vehicle When the switch is started, the switch device is energized for a predetermined time, and when the switch is energized, the switch device is turned on and self-diagnosis of a ground fault is performed by a simulated ground fault in which the bus bar and the vehicle body are connected via a resistor. It is characterized by that.

  According to this configuration, since the switch device that can be manufactured at low cost is used in the ground fault detection system, the ground fault detection system can be manufactured at low cost.

  As described above, according to the present invention, there is provided a switch device and a vehicle ground fault detection system capable of preventing damage due to application of a high voltage caused by a deviation at the time of activation of two or more switches connected in series. There is an effect that can be.

It is a figure which shows the structure of the conventional ground fault detection system. It is a figure which shows the structure of the ground fault detection system using the conventional switch apparatus. It is a figure which shows the structure of the ground fault detection system of the vehicle using the switch apparatus which concerns on embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. However, parts corresponding to each other in all the drawings in this specification are denoted by the same reference numerals, and description of the overlapping parts will be omitted as appropriate.

  FIG. 3 is a diagram illustrating a configuration of a vehicle ground fault detection system using the switch device according to the embodiment of the present invention.

  The ground fault detection system A1 shown in FIG. 3 is mounted on an electric vehicle that converts the DC power of the battery 6 into three-phase AC by the inverter 8 and outputs it to the AC motor 7, thereby driving the AC motor 7. The switch device 30 as the ground fault trial circuit 1 connected between the bus 61 connected to the inverter 8 and the vehicle body 10, the ground fault detector 9 for detecting the occurrence of the ground fault, and the LED 53 for informing the ground fault. It is prepared for.

  A feature of the present embodiment is a switch device 30, in which resistors R1 and R2 are interposed between the switches SW1 and SW2, and the switches SW1 and SW2 are connected in series. One switch SW1 and the resistor connected in series are connected. The capacitor C1 is connected in parallel to R1, and the capacitor C2 is connected in parallel to the other switch SW2 and the resistor R2.

  In such a switch device 30, for example, when the voltmeter V1 is connected to both ends of the switch SW1 and the voltmeter V2 is connected to both ends of the switch SW2, the voltage at the time of on / off is measured, as shown in FIG. It becomes like this. When each of the switches SW1 and SW2 is off, the voltmeters V1 and V2 measure a voltage Va / 2 that is ½ of the high voltage Va between the bus 61 and the vehicle body 10, respectively. Assume that only one switch SW1 is turned on first at time t11 when energized in this off state. In this case, since the capacitor C1 is connected in parallel to the switch SW1 to which the resistor R1 is connected in series, the voltage applied to the switch SW1 by the CR characteristics in which the voltage stored in the capacitor C1 is gradually discharged. Gradually decreases. At this time, the capacitor C2 connected in parallel to the other switch SW2 is gradually charged with the high voltage Va, and the voltage applied to the switch SW2 gradually increases.

  When the switch SW2 is turned on at time t2 after a predetermined time difference, the voltage applied to the switch SW2 gradually decreases according to the CR characteristics. Here, when the switch SW2 is turned on, the voltage applied to the switch SW1 that was previously turned on gradually decreases, so the voltage that is gradually applied to the switch SW2 and rises does not reach Va, but rises. On the way, the voltage gradually decreases to 0 V by turning on the switch SW2.

  Therefore, since the withstand voltage applied to one switch SW2 can be reduced, the voltage Va higher than the withstand voltage is not applied as in the prior art.

  In the ground fault detection system A1 using such a switch device 30, when performing a ground fault self-diagnosis, when the driver switches the key switch from OFF to ON (at the time of ground fault trial), the excitation power 502 is switched. The device 30 is energized for a predetermined time. During this energization, the switches SW1 and SW2 of the switch device 30 are turned on as described above, and the bus bar 61 and the vehicle body 10 are connected (simulated ground fault) via the resistors R1 and R2. Here, the LED 53 is turned on when the trial ground fault cannot be detected. Further, during normal monitoring, the LED 53 is lit when the ground fault detector 9 detects the occurrence of a ground fault (resistance R).

  As described above, the switch device 30 of the present embodiment is configured by connecting two or more switches SW1 and SW2 in series between the high voltage generating device such as the inverter 8 and the ground of the vehicle body 10 or the like. A resistor R1 is connected in series between the generator and the switch SW1 on the high voltage generator side, and a resistor R2 is connected in series between the switches SW1 and SW2, and the one switch SW1 and resistor connected in series are connected. A capacitor C1 is connected in parallel to R1, and a capacitor C2 is connected in parallel to the other switch SW2 and resistor R2.

  With this configuration, when one switch SW1 of the switches SW1 and SW2 that are turned on / off with a time difference is turned on, the applied voltage is gradually increased due to the discharge due to the CR characteristic from the stored capacitor C1. Accordingly, the voltage applied to the other switch SW2 is gradually increased, and the other switch SW2 is turned on during the increase, so that the voltage application to the switch SW2 can be gradually eliminated. Therefore, since the voltage applied to one switch SW2 can be reduced, it is possible to prevent the switch SW2 from being damaged due to the application of the voltage Va higher than the withstand voltage as in the prior art.

  In addition, since the switch device 30 can be configured by using two or more switches that are inexpensive general-purpose products, the switch device 30 can be manufactured at a lower cost than when an expensive switch with a high breakdown voltage is used. For this reason, the ground fault detection system A1 using the switch device 30 can be manufactured at a lower cost.

A1 Ground fault detection system 6 Battery 8 Inverter 9 Ground fault detector 10 Car body 30 Switch device 53 LED
SW1, SW2 switch R1, R2 resistor C1, C2 capacitor

Claims (2)

In a switch device comprising two or more switches connected in series between a high voltage generator and ground,
A resistor is connected in series between the high voltage generator and the switch on the high voltage generator side and between the switches, and a capacitor is connected in parallel to the one switch and the resistor connected in series. A switch device comprising a capacitor connected in parallel to the other switch and resistor. A ground fault detector having a function of detecting a ground fault of the vehicle and performing a self-diagnosis of the ground fault when starting the vehicle in a vehicle that drives a motor by converting DC power of a battery into three-phase alternating current by an inverter. In the installed vehicle ground fault detection system,
The switch device according to claim 1 is connected between a bus bar connected to the inverter and a vehicle body of the vehicle, and the switch device is energized for a predetermined time when the vehicle is started, and the switch device is energized at the time of energization. The vehicle ground fault detection system is characterized in that a ground fault self-diagnosis is performed by a simulated ground fault in which the switch is turned on and the bus bar and the vehicle body are connected via a resistor.

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