JPS6346673B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for controlling on/off of a gate turn-off (GTO) thyristor in a high voltage device using the GTO thyristor as a high voltage switch element.

Figure 1 shows the waveforms of the gate current I _g and gate voltage V _G required to operate the GTO thyristor reliably.

In the same figure, the ON side, where the gate is at a positive potential with respect to the cathode of the GTO thyristor, is the gate current required to transition the thyristor from blocking to conduction. The current I _gp is 5 times the catalog value or
Unless it is multiplied by 10, it will be difficult to turn on each thyristor at the same time. Further, the firing time t _po is the time required for reliable firing of the thyristor, and is approximately 10 to 20 μsec. Furthermore, it is necessary to keep the gate current I _gp flowing during the conduction time t _cpod of the thyristor. This is because the thyristor is maintained in a conductive state even when the load current decreases below the holding current of the thyristor due to current oscillations depending on the load conditions.

Then the gate of the thyristor is brought to a negative potential
The OFF side is the gate current required to transition the thyristor from the conducting state to the blocking state, and the current
Turn off by instantly applying I _grp . After turn-off, a reverse bias voltage V _GR is applied. Here, the current I _grp requires 1/3 to 1/5 of the current flowing through the thyristor, and the current width is approximately
It will be about 10μsec. Further, the reverse bias voltage V _GR is set to 2 volts or more to prevent re-ignition due to dv/dt, etc.

In this way, the GTO thyristor requires relatively large gate power for its on/off control,
When connecting multiple GTO thyristors in series to achieve high voltage resistance, there was a problem with the power transformer. That is, there is an adverse effect on the withstand voltage of the power transformer and the resulting voltage division. Furthermore, since the GTO thyristor is controlled on and off by the gate current, the reliability of the gate circuit is important in ensuring uniform voltage distribution, and a gate circuit for the GTO thyristor with a small number of parts is desired.

These problems occur not only when GTO thyristors are connected in series, but also when they are used as high-voltage switch elements in high-voltage equipment.

The present invention is capable of supplying sufficient power and gate current at a sufficient speed to the GTO thyristor using a gate circuit with a simplified configuration, and furthermore, the gate circuit has high insulation properties so that gate power can be reliably transmitted. The purpose of this invention is to provide a control device with

FIG. 2 shows an embodiment of the present invention, which is applied to a high voltage GTO thyristor device connected in three stages in series. GTO thyristor 1 ₁ connected in series,
1 ₂ and 1 ₃ are provided with voltage dividers 2 ₁ , 2 ₂ , and 2 ₃ between their anodes and cathodes, respectively, and gate overvoltage suppressing elements 3 ₁ , 3 ₂ , and 3 ₃ are provided between their gates and cathodes, respectively. . The voltage dividers 2 ₁ , 2 ₂ , and 2 ₃ are equipped with cutting diodes D1 and 2 ₁ , respectively, as shown in 2 1 .
It includes a capacitor C1, a discharge resistor R1, and a voltage dividing resistor R2.

The respective gate circuits 4 ₁ , 4 ₂ , 4 ₃ of the GTO thyristors 1 ₁ to 1 ₃ are connected in series to high frequency power transmission lines 5 ₁ , 5 ₂ that reduce the circuit loss of the high frequency power source 5 .
Power is continuously supplied from GT transformers 6 ₁ , 6 ₂ , and 6 ₃ . Gate circuits 4 ₁ , 4 ₂ , 4 ₃ , as shown in 4 ₁ , half-wave rectify the high frequency current (e.g. 5KHz to 10KHz) extracted from the secondary winding of the CT transformer using diodes D2 and D3. Then, positive and negative DC voltages are obtained at capacitors C2 and C3. and,
A series circuit of current limiting resistors R3, R4 and switch transistors TR1, TR2 is provided between the capacitors C2, C3 and the gate of the GTO thyristor, respectively.
Base current control of the transistors TR1 and TR2 is performed by photothyristors THP1 and THP2 to which optical inputs are applied from optical fibers 7 ₁ and 7 ₂ .

Optical fibers 7 ₁ , 7 ₂ and gate circuits 4 ₂ , 4 ₃
The optical fibers 7 ₃ , 7 ₄ , 7 ₅ , and 7 ₆ are given optical inputs corresponding to on commands and off commands from the on/off control command section 8 . The on/off control command unit 8 connects the light emitting diodes D4, D5, D6 to the optical fiber 7 by closing the on command switch circuit SW _ON .
₁ , ₇₃ , and ₇₅ at the same time, and the light emitting diode D is turned off when the off command switch circuit SW _OFF is closed.
7, D8, D9 to optical fibers 7 ₂ , 7 ₄ , 7 ₆
give optical input to.

To explain the operation in Figure 2, to turn on GTO thyristors 1 ₁ , 1 ₂ , and 1 ₃ simultaneously, a switch circuit SW _{ON is} used.
The transistor TR1 side is turned on by the ON command from the transistor TR1, and the current required for the initial gate current I _gp (see Figure 1) is supplied by discharging the capacitor C2.
The holding current is supplemented from CT transformers 6 ₁ to 6 ₃ .
To turn off the GTO thyristors 1 ₁ , 1 ₂ , and 1 ₃ simultaneously, the transistor TR2 side is turned on by the off command from the switch circuit SW _OFF , and the off-gate current I _grp is supplied by discharging the capacitor C3, and the bias voltage V _GR is performed by the voltage of capacitor C3.

Therefore, the power supply for the gate circuit is obtained by taking out the high-frequency current from the CT transformer connected in series to obtain the on power supply and the off power supply, so the configuration is simple and each power supply is related, so some power supplies Multiple units are connected in series to minimize failures.
There is no risk that the voltage sharing in the GTO thyristor will break down either steadily or transiently. In addition, the gate circuit can be simplified by configuring an on/off circuit with a rectifier diode, a capacitor, and an optical switch element, making it possible to create a circuit with excellent insulation and high reliability, and also to easily create a parallel redundant configuration. Become. Note that when the gate current of the optical switch element is small, the transistors TR1 and TR2 themselves can be replaced with phototransistors or photothyristors, and when an auxiliary switch element is included, the transistors TR1 and TR2 can be replaced with phototransistors or photothyristors.
General thyristor, GTO instead of TR1, TR2
Thyristors can be used. Furthermore, the insulation with the on/off control command section 8 is not limited to the optical method, but also the electromagnetic method.
It can be replaced by a sound wave method, etc.

Next, since the power supply of the control device is constantly oscillated as a high-frequency power supply, it is operationally more stable than a conventional on/off power supply, and the parallel redundant configuration of the high-frequency power supply 5 is facilitated. This means that if the GTO thyristor is controlled on and off when the charging voltage of capacitors C2 and C3 is insufficient due to a failure in power supply 3, its destruction will occur.In particular, in the case of a GTO thyristor, if the gate current is small when it is off, it will definitely be destroyed. Therefore, in the conventional case where the power supply 5 cannot be configured in a parallel redundant configuration, it is necessary to have a function to open the main circuit power supply (GTO thyristor power supply) at high speed, but in the present invention, it is necessary to have this function. disappears.

FIG. 3 shows another embodiment of the present invention, which is applied to a high voltage thyristor device having bridge-connected GTO thyristors 9 ₁ , 9 ₂ , 9 ₃ , 9 ₄ .
In Figure 3, 10 ₁ , 10 ₂ , 10 ₃ , 10 ₄ are
This is the gate circuit for each of the GTO thyristors ₉₁ to ₉₄ , and has the same configuration as that in Figure 2, and is turned on and off.
ON command output insulated from the OFF control command unit 11
The thyristors 9 ₁ , 9 ₄ and 9 ₂ , 9 ₃ are controlled to be turned on and off alternately by C _ON1 , C _ON2 and off commands C _OFF1 , C _OFF2 . 12 ₁ , 12 ₂ , 12 ₃ , 12 ₄ supply high frequency current to gate circuits 10 ₁ to 10 ₄ respectively.
It is a CT transformer, and its primary winding is connected in series to a high frequency power source 13 to transform an insulated high frequency current. 14 is controlled on/off
This is a load to which alternating current whose phase is controlled by GTO thyristors 9 ₁ to 9 ₄ is supplied.

As shown in this example, even in cases where the on/off control phases are different, such as in a high-voltage device with bridge-connected GTO thyristors, the gate circuit power supplies can be connected in series, and a parallel redundant configuration can be configured, resulting in high reliability. It can be made into something. It goes without saying that the GTO thyristors 9 ₁ to 9 ₄ can also be configured by using the same gate circuit power supply and gate circuit even when a plurality of GTO thyristors are connected in series or connected in parallel.

As described above, the control device according to the present invention can perform on/off control of a GTO thyristor used as a switch element of a high voltage device with a relatively simple configuration and high reliability. In particular, each gate circuit has a capacitor to obtain a current waveform specific to the GTO thyristor, and even if there is a partial failure in the power input system of the circuit from the high frequency power supply to the diode, the thyristor can be turned on or off. This is effective in improving reliability by ensuring the gate current necessary for In addition, since the on/off control signal is configured to generate on/off control signals in series, it is possible to prevent some control signals from being lost and some thyristors to fail to turn on or off. It is possible to prevent accidents caused by

[Brief explanation of drawings]

Fig. 1 is a gate current waveform for explaining on/off control of the GTO thyristor, Fig. 2 is a configuration diagram of a control device showing one embodiment of the present invention, and Fig. 3 is a diagram showing another embodiment of the present invention. FIG. 3 is a block configuration diagram. 1 ₁ , 1 ₂ , 1 ₃ , 9 ₁ , 9 ₂ , 9 ₃ ...GTO thyristor, 4 ₁ , 4 2 , 4 _{3 ,} 10 ₁ , 10 ₂ , 10 ₃ , 1
0 ₄ ...Gate circuit, 5,13...High frequency power supply,
6 ₁ , 6 ₂ , 6 ₃ , 12 ₁ , 12 ₂ , 12 ₃ , 12 ₄ ...
CT transformer, 7 ₁ to 7 ₆ ... optical fiber, 8,
11...On/off control command unit.

Claims (1)

[Claims] 1. A device that uses multiple gate turn-off thyristors as high-voltage switching elements includes a high-frequency power source that generates high-frequency power, multiple CT transformers whose primary windings are connected in series to this high-frequency power source, and these multiple CT transformers. A plurality of gates provided for each thyristor, including a pair of capacitors each charged with positive and negative polarity outputs obtained by rectifying the secondary winding output of the transformer, and a switching element provided between the charging terminals of these capacitors and the gate of the thyristor. an on/off control command unit that insulates the on/off control signals generated in series by the on/off command signals of the respective thyristors and supplies the on/off signal to one switching element of each of the gate circuits; A control device for a gate turn-off thyristor, comprising: