JPS5829682B2 - electric car control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric vehicle control device that uses a chopper device to control the operation of a DC motor, and particularly to an improvement in the protection circuit of its main circuit equipment.

Figure 1 shows a circuit during regenerative braking operation of an electric car using a chopper device. 1 is a pantograph, 2 is a filter reactor, and 3 is a filter capacitor. These reactor 2 and capacitor 3 are connected intermittently by the chopper device. It constitutes a filter that smoothes the current.

4 is a freewheeling diode that prevents current from flowing backwards from the power supply side to the load side, and 5 is a chopper whose on/off period is controlled according to the terminal voltage of the traction motor so as to control the current of the traction motor at a constant current. 6 is a main smoothing axle that smooths the main motor current and regenerates the current to the power supply side when the chopper device 5 is turned off; 7 is the field winding of the main motor; 8 is the electric circuit of the armature 9 of the main motor; A breaker that disconnects from the chopper device 5 and the power supply device; 10 is a high-speed breaker for the purpose of protecting main circuit equipment from overcurrent in the event of an accident;
1 ensures high current breaking operation of the high speed breaker 10,
Furthermore, it is a current limiting resistor for suppressing the current after the circuit breaker 10 is opened.

Since the operation of a regenerative braking circuit using a chopper device is well known, details will be omitted here.

Constant current control of the main motor is achieved by repeating on/off operations of the chopper device 5 at an appropriate cycle. However, if the chopper device 5 continues to be on for some reason, the armature 9 to Breaker 8 ~ Main motor field winding 1 ~ Main flat sliding axle 6 ~ Chopper device 5 ~ High speed breaker 10
~A closed circuit of the armature 9 is formed, and the current flowing through it is (i) Increase in short circuit current (11) Increase in the field of the traction motor (m) The phenomenon of increase in the terminal voltage of the traction motor is m → (ii )→(]:ii→(1) is repeated in the cycle, resulting in an excessive current, and the flashover of the main motor has a great effect on the landowner's circuit equipment.

The fact that the chopper device 5, which is the first cause of the above phenomenon, continues to be in the on state is called a commutation failure phenomenon.

As a method for protecting the main circuit from overcurrent accidents caused by this chopper commutation failure phenomenon, a detector is provided to detect commutation failure, and the detection output of this detector is used to shut off the high-speed breaker 10 to prevent overcurrent. There is a way to suppress it below the allowable value.

However, the breaking operation of high-speed circuit breaker relies on mechanical operation, so there is a limit to increasing the breaking speed.
In order to provide protection even when commutation fails during regenerative braking from high speed, it is necessary to make the main smoothing reactor 6 considerably larger, and a separate reactor must be inserted in the series circuit of the main motor to prevent short circuits. It is necessary to take measures to suppress the current di/dt.

Furthermore, since the high-speed breaker 10 is a device having mechanical contacts, considerable effort must be spent on maintenance.

A protection circuit shown in FIG. 2 is available to eliminate the above drawbacks.

That is, a switch, for example, a semiconductor switching element 12 such as a thyristor, is connected in parallel to the field winding 7, and this switching element 12 is made conductive by the detection output of the chopper commutation failure detector to short-circuit the field winding 7. , the overcurrent is suppressed by reducing the field current and instantaneously lowering the terminal voltage of the main motor.

The circuit of an electric car that employs this protection circuit when it is running in the forward direction is shown in Figure 3. In this circuit, if the switching element 12 is accidentally short-circuited when starting up or driving in the forward direction, , the field winding 7 is short-circuited, the back electromotive force of the traction motor drops instantaneously, the traction motor current becomes excessive, and the traction motor main circuit equipment is adversely affected.

This invention was made in order to eliminate the above-mentioned drawbacks. A current detector is provided in the circuit of the switch connected in parallel to the field winding, and the output of this detector is sent to the circuit breaker of the traction motor circuit. The present invention aims to provide an electric vehicle control device that can provide accurate protection with a relatively simple configuration by issuing a cutoff command.

This invention will be explained below based on the embodiment shown in FIG.

As shown in FIG. 4, connecting a switch, for example, a thyristor 12, in parallel with the field winding T is the same as in the conventional case (FIGS. 2 and 3), but in this embodiment, the electrical circuit of the thyristor 12 is A current detector 13 is provided at , and the output of this detector 13 is used as a shutoff command for the circuit breaker 8 .

The current detector 13 may be a direct current transformer, a magnetic sensing element using a Hall element, a current relay, etc., but it is preferable to use a device that is effective in miniaturization.

Note that the other configurations are the same as the conventional one, so the same or corresponding parts are given the same reference numerals and the explanation thereof will be omitted.

Next, the protection operation of the electric vehicle control device will be explained.

If the thyristor 12 is erroneously short-circuited during continuous operation, the field current flowing through the field winding 7 is shunted to the electrical path of the thyristor 12, and the field current is reduced.

As a result, the terminal voltage of the traction motor decreases and the current increases, but the current detector 13 detects that current is flowing in the electrical path of the thyristor 13, and a command is issued to the breaker 8 to shut off the traction motor. A load circuit consisting of is disconnected from the power supply circuit.

On the other hand, if a commutation failure occurs during regenerative braking operation, when the commutation failure detector operates, the thyristor 12 is turned on.
As described above, the main motor current is suppressed and at the same time, the current detector 13 operates to trip the breaker 8, and this breaking operation disconnects the main motor circuit.

As described above, according to this invention, even if the switch, which is a protection device, malfunctions, the generation of a cutoff command by the current detector can suppress the adverse effects on the main circuit equipment.

Further, since the circuit is opened immediately when the switch is operated, the current capacity of the equipment necessary for the protection operation can be reduced, and the protection circuit equipment can be downsized to the necessary minimum size.

[Brief explanation of drawings]

Figures 1 and 2 are wiring diagrams showing circuits during regenerative braking of a conventional electric vehicle control device, respectively, and Figure 3 is a circuit during forward driving when the protection circuit of the example shown in Figure 2 is adopted. FIG. 4 is a wiring diagram showing one embodiment of the present invention (during power-on operation). 4... Freewheeling diode, 5... Chopper device, 6... Main flat sliding axle, 7... Field winding of traction motor, 8... Breaker, 9... Main motor armature, 12... thyristor, 13... current detector. The same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A switch is connected in parallel to the series field winding of a DC series motor controlled by a chopper device, and this switch is turned on when a commutation failure of the chopper device is detected to divert the field current. An electric vehicle control device, characterized in that a current detector is provided in the electrical circuit of the switch, and the output of the current detector is used as a cutoff signal for the electrical circuit of the electric motor.