JPH0458245B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention connects the main motor circuit of an electric vehicle in series with the main power supply, connects a chopper in parallel to this, and connects a brake thyristor and a side brake thyristor in parallel to the chopper. This invention relates to a chopper for driving an electric vehicle in which a series circuit of road resistors is connected.

[Technical background of the invention and its problems]

In this type of chopper for driving an electric vehicle, a circuit has been proposed in which a series circuit consisting of a thyristor and a bypass resistor is connected in parallel to the chopper to use both regenerative braking and dynamic braking.

FIG. 1 shows an example of such a chopper for driving an electric vehicle.

In the circuit shown in FIG. 1, a current breaker 2 and a high-speed breaker 3 are connected in series from a pantograph 1, and a parallel connection circuit of a current breaker 4 and a charging resistor 5 and a filter reactor 6 are connected to the pantograph 1. A power supply section that reaches the filter capacitor 7 via the filter capacitor 7 is configured. Filter reactor 6 and filter capacitor 7
A smoothing filter 8 is constructed by the above.

A main motor (hereinafter referred to as the motor) 9 consisting of an armature 10 and a field winding 11 connected in series with the armature 10 acts as a generator during braking. A current interrupter 12 , a main smoothing reactor 13 , and a high-speed shield interrupter 14 are connected in series to the electric motor 9 . A current limiting resistor 15 is connected in parallel to the high speed shear breaker 14 . A freewheeling diode 19 is connected to the connection point between the main smoothing reactor 13 and the filter reactor 6, and the freewheeling diode 19 is connected to the connection point between the freewheeling diode 19 and the main smoothing reactor 13, a current limiting resistor 15, and a high speed shunt breaker. A series circuit 168 consisting of a chopper 16, a brake thyristor 17, and a bypass resistor 18 is connected to the connection point between the filter capacitor 14 and the filter capacitor 7. Further, a current detector 20 is provided in series with the armature 10 to detect the current of the electric motor 9. A series circuit consisting of a resistor 21 and a voltage detector 22 is connected in parallel to the filter capacitor 7.

In the circuit shown in Figure 1, if there is no regenerative load vehicle such as another power running vehicle during regenerative braking, there is no place for the regenerative current to go, and the filter capacitor 7
When the voltage rises and exceeds a predetermined overvoltage value, the high-speed circuit breaker 3 is tripped via the voltage detector 22 and a protection device (not shown) to open the main circuit, and regenerative braking is disabled. It becomes impossible. Once the main circuit is opened, the electric vehicle is decelerated by the supplementary air brake until the brake command is turned off. Even if a regenerative load occurs again after the main circuit is opened, regenerative braking can no longer be expected unless the brake command is turned off and a new brake command is input.

In order to avoid such inconvenience, when the regenerative load is removed and the voltage of the filter capacitor 7 rises above a certain value, the thyristor 17 is fired and the shunt resistor 18 is connected to stop the motor. The braking current is diverted to the filter capacitor 7.
A method has been proposed to prevent the voltage increase.

According to this method, when the chopper 16 is turned off, the motor current flows through the thyristor 17 and the bypass resistor 18 and weakens, so that low current control is possible and stable braking action can be continued. If a regenerative load occurs during dynamic braking and the voltage of the filter capacitor 7 drops, it is possible to return to regenerative braking by turning off the thyristor 17.

As described above, in order to perform control that allows switching from regenerative braking to dynamic braking whenever necessary, or from dynamic braking to regenerative braking, Chiyotsupa 1 is required.
During the ON period of 6 or at the same time as the chopper 16 is turned off, it is necessary to also turn off the thyristor 17 by some method.

For this reason, a conventional tipper 16 constructed as shown in FIG. 2 is known. The chopper 16 in FIG. 2 includes a reverse conducting type main thyristor 161, a saturable reactor 163, and a commutation reactor 16
5, a reverse conduction type auxiliary thyristor 162, and a saturable reactor 164.
and a second series circuit 169 consisting of a commutating capacitor 166 are connected in parallel. The chipper 16 in FIG. 2 is the main thyristor 16.
This circuit is intended to apply a reverse bias to the brake thyristor 17 to commutate the current, and to turn off the thyristor 17 at the same time when the main thyristor 161 turns off.

According to the circuit shown in FIG. 2, commutating capacitor 1
By dividing the discharge current of 66 into both the main thyristor 161 and the brake thyristor 17 circuit, the commutation ability is reduced compared to when the original current flowing only to the main thyristor 161 is commutated.
Therefore, there is a possibility that the main thyristor 161 may fail in commutation. In order to prevent such a commutation failure, it is necessary to design a commutation constant so that both the brake thyristor 17 and the main thyristor 161 can be extinguished reliably. From this point of view, it may be possible to increase the capacitance of the commutation capacitor 166, but this would lead to an increase in the size of the device, and an increase in the commutation current would also lead to an increase in commutation loss, so this is not an option from an energy saving perspective. It is also undesirable. Furthermore, in order to increase the commutation capability, the peak value of the commutation current must be increased, but this is done by the main thyristor 161 or the auxiliary thyristor 16.
This also affects the number of parallel elements of No. 2 and leads to an increase in the number of elements used, resulting in a significant increase in cost.

As described above, the circuit shown in FIG. 2 has various problems, so it is difficult to say that it is a preferable circuit system. Further, when switching from regenerative braking to dynamic braking and then returning to regenerative braking again, it is necessary to extinguish the brake thyristor 17 within the operating cycle of the chopper 16. However, once the braking is switched to dynamic braking, it will not switch to regenerative braking until the brake command is turned off, and even if the braking is left in dynamic braking, the brake thyristor 17 will always be turned off for the following reasons. It is necessary to That is, when the brake is off during dynamic braking, if the freewheeling diode 19 is composed of a series connection of two or more diode elements, the current due to the voltage of the filter capacitor 7 flows through the freewheeling diode. The current flows to the brake thyristor 17 through the equalizing resistance between each element of 19, and until the voltage of the filter capacitor 7 decreases to a certain degree due to discharge, a current higher than the holding current flows to the brake thyristor 17.
The arc may not extinguish naturally.

If the vehicle is switched to power running in such a state, the brake thyristor 17 will remain in the on state and power running will occur, which may damage the bypass resistor 18. Also, if a protection circuit is provided to prevent burnout, it will operate and powering will no longer be possible.

From the above, when the power generation control circuit shown in FIG. 1 is used, it is necessary to reliably turn off the brake thyristor 17 at every chopper cycle, regardless of the brake system.

[Purpose of the invention]

An object of the present invention is to provide a chopper for driving an electric vehicle that does not reduce the commutation ability for turning off the main thyristor.

[Summary of the invention]

In order to achieve the above object, the present invention is constructed as follows.

That is, a first series circuit consisting of a reverse conduction main thyristor, a saturable reactor, and a commutation reactor, and a second series circuit consisting of a reverse conduction auxiliary thyristor, a saturable reactor, and a commutation capacitor are connected in parallel. , a chopper for driving an electric vehicle, in which the main thyristor and the saturable reactor of the first series circuit are connected in parallel to a brake thyristor and a bypass resistor.

[Embodiments of the invention]

Hereinafter, the present invention will be explained with reference to the drawings. FIG. 3 is a circuit diagram showing only the essential parts of an embodiment of the present invention, in which a first series circuit 167 consisting of a reverse conduction main thyristor 161, a saturable reactor 163, a commutating reactor 165, and a reverse conduction auxiliary thyristor 162. A chopper 16 is configured by connecting a second series circuit 169 consisting of a saturable reactor 164 and a commutating capacitor 166 in parallel. and the main thyristor 161 of the first series circuit 167
A series circuit 168 of a brake thyristor 17 and a bypass resistor 18 is connected in parallel to the saturable reactor 163.
is connected.

According to such a circuit configuration, the main thyristor 1
When commutating 61, saturable reactor 163
Until the brake thyristor 17 is saturated,
A reverse voltage is applied to the Compared to the commutation period, the saturable reactor 16
Since the non-saturation time of No. 3 is short, the commutation ability does not decrease.

As described above, according to the electric vehicle drive chipper of the embodiment of the present invention, wiring connections can be easily changed without making any major changes to the conventional circuit configuration or adding a large number of large-capacity parts. Alternatively, the commutation ability for turning off the main thyristor 161 in the chopper 16 will not be reduced by simply adding parts.

FIG. 4 is a time chart showing a method for reliably extinguishing the brake thyristor 17 in the circuit shown in FIG. In the figure, 51 is the ON signal of the main thyristor 161, and 52 is the auxiliary thyristor 16.
2 is an ON signal, 53 is a current waveform of the main thyristor 161, 54 is an ON signal of the brake thyristor 17, 55 is a current waveform of the brake thyristor 17, 56 is a dynamic braking start command, and 57 is a chopper off command. The main thyristor 161 is fired by the on signal shown at 60, and the main thyristor 1 is forcibly turned on by the on signal of the auxiliary thyristor 162 shown at 61.
After extinguishing 61, the dynamic braking start command 56
When this happens, the hookah thyristor 17 is fired with the ON signal 62.

Repeat this action several times until you reach Chiyotsupa 1.
When extinguishing the main thyristor 161 and extinguishing the brake thyristor 17 every 6 operation cycles, if the brake thyristor 17 is activated and the chip off command 57 is issued, the brake thyristor 17 is activated as follows. After the thyristor 17 is surely extinguished, it is stopped.

That is, as shown in FIG. 4, once the main thyristor 161 is fired by the ON signal 64, the current waveform 55 of the brake thyristor 17 becomes as shown in the figure, and this current is transferred to the main thyristor 161.
After confirming that the current waveform 53 of the thyristor 161 has sufficiently attenuated, the ON signal 65 is applied to the auxiliary thyristor 162 to ensure that the thyristor 17 is extinguished.

The decay time 63 is calculated from a time constant determined by the resistance value and inductance of the bypass resistor 18. The above is the control method for extinguishing the brake thyristor 17.

FIG. 5 is a block diagram showing part of a control device for actually carrying out the method shown in FIG. 4.
70 is an on-signal generation circuit that generates the on-signal 51 at a predetermined frequency, and 73 is an amplifier circuit. 71 is a circuit that generates the ON signal 52, and the decay time 63 is created by this circuit. 74 is an amplifier circuit. 72 is an ON signal generation circuit for the brake thyristor 17, and 75 is an amplifier circuit.

According to the embodiment described above, the brake thyristor 17 is reliably turned off every operation cycle of the chopper 16, and the brake thyristor 17 is also turned off when the brake is turned off, thereby making it possible to turn off the brakes of the electric vehicle. A driving tip is obtained.

〔Effect of the invention〕

According to the present invention, it is possible to provide a chopper for driving an electric vehicle that can reliably turn off a brake thyristor without reducing the commutation ability for turning off the main thyristor in the chopper.

[Brief explanation of drawings]

Fig. 1 is a connection diagram showing the main circuit of an electric car, Fig. 2 is a connection diagram showing the circuit configuration of a conventional chopper for driving electric cars that uses both regenerative braking and dynamic braking, and Fig. 3
The figure is a connection diagram showing one embodiment of the chopper for driving an electric vehicle according to the present invention, and FIG. 4 is a diagram for explaining a control method for reliably extinguishing the brake thyristor implemented in the circuit of FIG. 3. The time chart in FIG. 5 is a block diagram showing a part of a control device for carrying out the control method shown in FIG. 4. DESCRIPTION OF SYMBOLS 1... Pantograph, 2... Current breaker, 3... High speed breaker, 4... Current breaker, 5... Charging resistor, 8 ... Smoothing filter consisting of filter reactor 6 and filter capacitor 7, 9 ... Armature 10 and a main motor consisting of a field coil 11, 16...Chopper,
167...First series circuit, 161...Reverse conducting main thyristor, 163...Saturable reactor, 165...Commuting reactor, 169...Second series circuit, 162
...Reverse conducting auxiliary thyristor, 164...Saturable reactor, 166...Commuting capacitor, 168...Series circuit, 17...Brake thyristor, 18...Shunt resistor.

Claims (1)

[Claims] 1. A first series circuit 167 consisting of a reverse conduction main thyristor 161, a saturable reactor 163, and a commutation reactor 165, and a reverse conduction auxiliary thyristor 162.
, saturable reactor 164 and commutating capacitor 16
The main thyristor 16 of the first series circuit 167 is configured by being connected in parallel with a second series circuit 169 consisting of 6
1 and a saturable reactor 163 are connected in parallel to a brake thyristor 17 and a bypass resistor 18.