JPS6036962Y2 - Electric vehicle ground fault detection device - Google Patents

Description

[Detailed explanation of the idea] This invention relates to an electric vehicle ground fault detection device.

In an electric vehicle, if the battery is electrically insulated from the vehicle body and mounted on the vehicle, a ground fault may occur between the vehicle body and either the positive or negative side of the battery, and then a ground fault may occur on one side. When this occurs, a large current flows through the wires, and this large current causes the wires to heat up and cause a fire, or a temporary contact can cause a fire.

This fire may cause the vehicle to catch fire.

This idea was created in view of the above circumstances, and uses a simple configuration to detect when one of the batteries installed in the vehicle has a ground fault, thereby preventing the occurrence of a vehicle fire. The purpose is to provide a detection device.

An embodiment of this invention will be described below with reference to the drawings.

In the figure, numerals 1 and 2 are first and second batteries mounted on an electric vehicle and electrically insulated from the vehicle body 11, and both batteries 1 and 2 are connected in series.

The positive side of the second battery 2 is connected to the negative side of the first battery 1 via an electric vehicle drive motor 3, a field switching contactor 4, and a chopper control circuit 5.

Reference numeral 6 denotes a control circuit, which is inserted between the positive and negative sides of the first battery 1 and generates signals for controlling the field switching contactor 4 and the chopper control circuit 5.

Reference numerals 7.8 denote first and second comparators, and a voltage dividing circuit, which will be described later, is connected to the non-inverting and inverting input terminals of the first and second comparators 7.8.

9 is a first resistor consisting of resistors R1, R2, and R3 connected in series.
This first voltage dividing circuit 9 is a voltage dividing circuit, and is inserted between the positive side and negative side of the first and second batteries 1 and 2.

A common connection point between resistors R2 and R3 of the first voltage dividing circuit 9 is connected to a non-inverting input terminal of the first comparator 7.

Further, a common connection point between the resistors R1 and R2 is connected to the vehicle body 11 via a first switch 10 for detecting a ground fault.

12 is a second voltage dividing circuit consisting of resistors R4 and R5 connected in series, and this second voltage dividing circuit 12 is connected to the first and second batteries 1.
, 2 and the negative side of the first battery 1, and the resistor R4
, R3 are connected to the inverting input terminal of the first comparator 7.

Between the output end of the first comparator 7 and the auxiliary line 14, there is a ground fault confirmation switch 15 interlocked with the first switch 10, a limiting resistor 16, and a first light emitting diode 17 which is a light emitter for ground fault detection. A series circuit is inserted.

Reference numeral 18 denotes a third voltage dividing circuit consisting of resistors R6 and R7 connected in series, and this third voltage dividing circuit 18 is inserted between the auxiliary line 14 and the negative side of the first battery 1.

The common connection point of resistors R6 and R7 of this voltage divider circuit 18 is the second
It is connected to the non-inverting input terminal of comparator 8.

19 is a resistor series body consisting of resistors R8 and R8 connected in series, one end of this resistor series body 19 is connected to the negative side of the first battery 1, and the other end is connected to the second switch 2 for ground fault detection.
0 to the vehicle body 11.

A common connection point between the resistors R8 and R9 is connected to the inverting input terminal of the second comparator 8.

Note that a resistor R1o is connected in parallel to the resistor series body 19.

A ground fault confirmation switch 21 interlocked with a second switch 20 is connected between the output end of the second comparator 8 and the auxiliary line 14.
, a limiting resistor 22, and a second light emitting diode 23 which is a light emitter for detecting a ground fault.

Next, the operation of the above embodiment will be described.

To detect that the negative side of the first battery 1 is grounded to the vehicle body 11, the first grounding detection switch 10 is closed a.

By closing this first switch 10, the first comparator 7
The non-inverting input terminal of is at a lower potential than the inverting input terminal.

Therefore, the output of the first comparator 7 becomes low, and the first light emitting diode 17 emits light when the ground fault confirmation switch 15, which is connected to the first switch 10, is closed.

Next, when the second ground fault detection switch 20 is closed, the inverting input terminal of the second comparator 8 has a lower potential than the non-inverting input terminal, so even if the ground fault confirmation switch 21 is closed, the second light emitting diode 23 does not light up.

From the light emitting states of the first and second light emitting diodes 17.23, it can be detected that there is a ground fault on the negative side of the first battery 1.

Next, detection when the positive side of the second battery 2 is grounded will be described.

First, when the first ground fault detection switch 10 is closed, a voltage obtained by dividing the voltages of the first and second batteries 1 and 2 by resistors R2 and R3 is applied to the non-inverting input terminal of the first comparator 7. .

Since this divided voltage value becomes higher than the voltage applied to the inverting input terminal of the first comparator 7, the output voltage of the comparator 7 becomes higher.

Therefore, even if the ground fault confirmation switch 15 is closed, the first light emitting diode 17 does not emit light.

On the other hand, the second comparator 8 is connected to the second switch 2 for ground fault detection.
0 is closed, the voltage at the inverting input terminal becomes higher than the voltage at the non-inverting input terminal, so the output voltage of the comparator 8 becomes low, and by closing the switch 21, the voltage at the second light emitting diode 2
3 is emitted.

In this way, when the positive side of the second battery 2 has a ground fault, the first light emitting diode 17 does not emit light, but the second light emitting diode 23 emits light, so that a ground fault can be detected.

In addition, if the auxiliary line 14 connected to the common connection point 13 of the first and second batteries 1 and 2 has a ground fault, detection is performed by the first and second batteries.
The determination is made based on the fact that both the light emitting diodes 17 and 18 emit light.

That is, if the values of the resistors R2, R3 and R4, R5 are set so that when the first switch 10 is closed, the inverting input terminal of the first comparator 7 is higher than the non-inverting input terminal, the first light emitting diode 17 is emitted.

On the other hand, if the resistors R6, R7 and R8 to R1o are set so that the non-inverting input terminal of the second comparator 8 is higher than the inverting input terminal when the second switch 20 is closed, the second light emitting diode 23 is emitted.

FIG. 2 is a circuit diagram showing another embodiment of the invention, in which the same parts as in FIG. 1 are denoted by the same reference numerals.

In FIG. 2, the battery 24 is a single battery.

As described above, according to this invention, battery ground faults can be detected reliably with a simple configuration using two comparators and two light emitters, thereby making it possible to prevent ground faults from occurring. There is an effect that can be done.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing one embodiment of this invention, and FIG. 2 is a circuit diagram showing another embodiment of this invention. 1゜2...First and second batteries, 3...Electric motor, 4...Contactor, 5...Chopper control circuit, 7゜8... ...First and second comparators, 9...
・First voltage dividing circuit, 10゜20...First and second switch for ground fault detection, 1...Vehicle body, 12...Second voltage dividing circuit, 13 ...Common connection point, 14...Auxiliary wire, 7゜23...First and second switch for ground fault detection, 8.
...Third voltage divider circuit, 19...Resistor series body.

Claims (1)

[Scope of utility model registration request] In an electric vehicle in which a battery is electrically insulated from a vehicle body and a motor, a contactor, and a chopper control circuit are interposed in series between the batteries, a first voltage dividing circuit connected between a positive side and a negative side of the battery. , second
a voltage dividing circuit, a third voltage dividing circuit, a first comparator to which a predetermined voltage of the first voltage dividing circuit is applied to a non-inverting input terminal, and a divided voltage of the second voltage dividing circuit to an inverting input terminal; A ground fault detection first switch inserted between a predetermined divided voltage part of the first voltage dividing circuit and the vehicle body, and a predetermined voltage of the third voltage dividing circuit are applied to the non-inverting input terminal, and the inverting input A second comparator is connected to the midpoint of the resistor series body, with one end connected to the negative side of the battery, and a second comparator connected to the midpoint of the resistor series body, with one end connected to the negative side of the battery, and the other end connected to the vehicle body. A series circuit consisting of a resistor connected to the other end of the resistor series body and a second ground fault detection switch; An electric vehicle ground fault detection device comprising first and second light emitters for fault detection.