JPH0311192B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power conversion device, and in particular, to a power conversion device that controls a self-arc switching element when the current or voltage supplied to the self-arc switching element exceeds its controllable range. This invention relates to a power conversion device suitable for preventing damage to the power converter.

Conventional power conversion devices using self-extinguishing switching elements, such as inverter devices using gate turn-off thyristors (GTOs) as self-extinguishing switching elements, are designed to prevent destruction of the switching elements due to phase short circuit accidents. ,all
Generally, methods have been used to make GTO conductive or non-conductive. These methods switch the switching element (GTO) from non-conductive to conductive or from conductive to non-conductive when a phase short circuit occurs, and this switching has a drawback. More specifically, the method of protecting the switching element by making it conductive has the disadvantage that a turn-on signal is not given during the turning-off operation of the switching element, and the method of protecting the switching element by making it non-conductive has the following disadvantages: The drawback was that a large-capacity gate circuit was required to control (extinguish) the large current.

The above drawbacks will be explained based on an example of a conventional power conversion device shown in FIG.

In Fig. 1, the power conversion device is a GTO10 as a self-extinguishing switching element as shown in the figure.
1 to 106 and each GTO101 to 1
Freewheel diode 111~ in antiparallel to 06
116 respectively and each of the GTOs 101 to 1
DC power supply 1 by on/off control of 06
a converter 10 that converts the electric power taken out from the converter 2 through a filter 14 and supplies it to an induction motor 16 as a load; and GTOs 101 to 1 as self-extinguishing switching elements of the converter 10.
GTO101 and 102, GTO103 and 104, and GTO1
DC voltage detector 18 connected to 05 and 106
The detection signals from U, 18V and 18W are taken in, and when an abnormality is detected, the GTO101 to 10
and a control protection circuit 20 that protects the 6. More specifically, the DC power supply 12 is connected to a filter 14 via a circuit breaker 22, and is connected to the converter 10 via this filter 14. The filter 14 is composed of a filter reactor 141 and a filter capacitor 142 as shown in the figure. In addition, during normal operation, the control protection circuit 20 amplifies the gate signal from the gate signal control circuit 201 with the amplifier circuit 202, and transmits the gate signal to each
Each GTO is supplied to the gates of GTO101 to 106.
101 to 106 are controlled to be turned on and off. Further, the control protection circuit 10 inputs detection signals from the DC voltage detectors 18U, 18V, and 18W into the phase short circuit detection circuit 203, and based on these detection signals, when the converter 10 is abnormal,
The gate signal synchronization circuit 204 outputs a protection signal to protect the GTOs 101 to 106, and the gate signal synchronization circuit 204 takes in the protection signal and also takes in the signal from the gate signal control circuit 201 and synchronizes the protection signal and the gate signal. The signal is amplified via the signal amplification circuit 205, and the amplified protection signal is supplied to the gates of the GTOs 101-106.

The operation of the power conversion circuit configured in this manner will be described below.

In Figure 1, if a phase short circuit occurs, for example, the anode of one GTO 101 and the GTO 1 of its pair
A DC voltage detector 203 that detects the voltage between the cathode and the cathode 02 operates. This phase short circuit detector 203
The output of is input to the gate signal synchronization circuit 204. In this gate signal synchronization circuit 204, the protection signal is synchronized with the signal from the gate signal control circuit 201, and then passed through an amplifier 205.
Supplied to GTO101~106 and GTO101~
106 is protected.

Here, the functions of the control protection circuit 20 will be explained with reference to FIGS. 2 and 3.

FIG. 2 is a circuit diagram for explaining the function of the control protection circuit 20, and FIG. 3 is an operation explanatory diagram for explaining the operation of FIG. The pulse transformer 24 has one end of its primary winding connected to the collector of a transistor 28 which is switched on by an on signal 26, and the other end of its primary winding connected to the collector of a transistor 32 which is switched by an off signal 30. Connect the middle tap of the winding to DC power supply 3.
4, the negative electrode of the DC power supply 34 is connected to the emitters of the transistors 28 and 32, and its secondary winding is connected, for example, between the gate and cathode of the GTO 101.

In FIG. 2, currents in opposite directions must be applied to the gate of the GTO 101 via the pulse transformer 24 during turn-on and turn-off. Therefore, if a mode occurs in which a turn-on signal is given while a turn-off signal is applied during phase short circuit protection, in the circuit shown in FIG. 2, the period during which transistors 28 and 32 are simultaneously conductive is Control protection circuit 20
There were problems in that the turn-on signal was not outputted due to short-circuiting, and that the control protection circuit 20 was damaged.

FIG. 3 shows a waveform diagram for explaining the operation of FIG. 2, in which the horizontal axis represents time t, and the vertical axis represents the gate signal, gate voltage i _g , and GTO anode/cathode voltage E _AK. are said to be each. As shown at times t ₁ to _{t 2} in the operating waveform diagram of FIG. 3, the anode-cathode voltage E _AK of the GTO 101 immediately after turn-off rises above the power supply voltage, so
Turn-on operation from this voltage E _AK0 may lead to element destruction. That is, in a power conversion device (inverter device) using a GTO, the GTO 101 is turned on during a period when a turn-off signal is applied to the gate of the GTO, or during a period when a voltage is applied between the terminals immediately after turn-off. It has the disadvantage that it cannot give a signal. Therefore, each GTO has a gate signal synchronization circuit 204.
The turn-on signal is output in synchronization with the operation signal of the

The output of the gate signal synchronization circuit 204 is sent to the amplifier circuit 2.
When the protection method is amplified by 05 and makes all GTOs conductive, it becomes a signal that turns on the large current that flows due to the conduction of all GTOs. Also, when using the all-GTO non-conducting protection method, it serves as a signal to extinguish the large current flowing. As described above, the method of making all GTOs conductive or non-conductive requires the gate signal synchronization circuit 204, the amplification circuit 202, and the amplification circuit 205, which has the disadvantage that the circuit configuration becomes large and complicated. Furthermore, in the case of such a three-phase inverter device, the amplification circuits 202 and 205 must be provided for each GTO, resulting in the inconvenience that a total of six signal amplification circuits are required. The same thing can also be said during overvoltage protection.

An object of the present invention is to prevent the self-extinguishing switching element from turning on or off when the voltage applied to the self-extinguishing switching element exceeds its controllable range. It is an object of the present invention to provide a power converter device that can prevent arcuate switching elements from being damaged by switching.

In order to achieve the above-mentioned object, the present invention has been devised so that when a voltage applied to a self-extinguishing switching element exceeds a predetermined voltage, all self-extinguishing switching elements constituting the inverter The self-extinguishing switching element is prevented from being turned on or turned off (the gate signal is held in the current state) to prevent switching damage of the self-extinguishing element at the time of overvoltage.

Embodiments of the present invention will be described below based on the drawings.

FIG. 4 is a block diagram showing an embodiment of the power conversion device according to the present invention. In FIG. 4, the same components as in FIG. 1 are given the same reference numerals and their explanations will be omitted. The difference between the embodiment shown in FIG. 4 and the configuration shown in FIG. 1 is that the control circuit 200 is
GTO10 as a self-extinguishing switching element
When a predetermined current or a predetermined voltage is applied to 1 to 106 that exceeds their controllable range,
GTO101 as the self-switching element
- 106 are configured to output a control signal to maintain the current state. To explain in more detail, as mentioned above, the DC voltage detectors 18U, 18
V and 18W are the upper GTOs 101 and 10 of each phase.
3 and 105 anodes and lower GTO 102,1
It is connected between the cathodes of 04 and 106 to detect the voltage of each phase. The output terminals of the DC voltage detectors 18U, 18V and 18W are connected to the input terminal of the phase short circuit detector 203 of the control protection circuit 20,
The detection signal of 8V and 18W is set as a cutoff command _SLB for the circuit breaker 22 and is also supplied to the gate signal holding circuit 250. Further, the output signal of the gate control circuit 201 is amplified by an amplification circuit 202 via the gate signal holding circuit 250 and supplied to the gates of each of the GTOs 101 to 106.

As an example of an abnormality in the power conversion device (three-phase inverter device) configured as described above, a protective operation in the event of a phase short circuit will be described with reference to FIGS. 4 and 5.

FIG. 5 is a waveform diagram shown for explaining an embodiment of the present invention. In Figure 5, the gate signal S _G
An on signal is given to the GTO at the rising edge of , and an off signal is given at the falling edge of the gate signal S _G , and the horizontal axis shows time, and the vertical axis shows the gate signal S _G of GTOs 101 to 106, phase short detection signal, and The breaking operation of the circuit breaker 22 is shown respectively. Furthermore, in FIG. 5, the solid line after time _t1 shows the operating state of the gate signal in this embodiment, and the broken line shows the operating state in normal times.

First, during normal operation of the inverter device, the U-phase _lower arm is
If the GTO 102 is ignited incorrectly for some reason and a phase short circuit occurs, the output of the U-phase DC voltage detector 18U shown in FIG. 4 becomes zero. Then, the phase short circuit detection circuit 203 detects this, and the phase short circuit detection circuit 203 detects this.
3 outputs a phase short circuit detection signal. At this time,
The gate signal holding circuit 250 is controlled by the phase short circuit detection signal, and holds the output of the gate signal control circuit 201 in the operating state of the gate signal at time t ₁ when the phase short circuit detection signal is generated. This state is shown by gate signal S _G in FIG. In other words, when a phase short circuit is detected
Regardless of the operating state of the gate signal at _t1 , the gate signal in that state is held and the switching operation of the GTO as a self-extinguishing switching element is stopped. and gate signal holding circuit 250
is reset when the circuit breaker 22 is cut off, and the gate signal S _G enters the normal circuit cutoff state.

According to this embodiment, it is possible to prevent destruction of the self-extinguishing switching element at the time of a phase short circuit, which is an example of an abnormality in the power conversion device (GTO inverter device), and the amplifier circuit 205 used in the event of an abnormality.
Also, the gate signal synchronization circuit 204 can be omitted, and the control protection circuit 200 can be simplified. Further, a similar effect can be obtained during overvoltage protection.

As described above, according to the present invention, the self-arc-extinguishing switching element is maintained in the switching state in the event of an abnormality in which a voltage is applied to the self-arc-extinguishing switching element beyond a controllable range. In the event of a phase short-circuit failure, switching signals that may cause the switch to ignite are not input to all GTOs, and in the event of overvoltage, all GTOs are not switched, thereby preventing damage to self-extinguishing switching elements. The effect is that it can be done.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a conventional power converter, Fig. 2 is a circuit diagram showing the basic configuration of a control protection circuit of a conventional power converter, and Fig. 3 is shown to explain the operation of Fig. 2. A waveform diagram, FIG. 4 is a block diagram showing an embodiment of the power conversion device according to the present invention,
FIG. 5 is a waveform diagram shown to explain the operation of one embodiment of the present invention. 10...Converter, 12...DC power supply, 14...Filter, 16...Induction motor, 18U, 18V, 18W
...DC voltage detector, 200...Control protection circuit, 20
1... Gate signal control circuit, 202... Amplification circuit, 2
03...Phase short circuit detection circuit, 250...Gate signal holding circuit.

Claims (1)

[Claims] 1 Turn on and off multiple self-extinguishing switching elements.
An inverter that converts direct current into alternating current and supplies it to the load by off-controlling, and a self-arc-extinguishing switching element of this inverter, and when an abnormality is detected, the self-arc-extinguishing switching element In the power conversion device, the control protection circuit protects all the self-switching elements constituting the inverter when a voltage exceeding a predetermined voltage is applied to the self-extinguishing switching element. A power conversion device characterized in that it is configured to output a gate signal that maintains an arc-extinguishing switching element in its current state.