JP2003069406A - High voltage semiconductor switch device and high voltage generating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high voltage semiconductor switch device that can produce pulses with higher frequency by configuring a high voltage semiconductor switch with a series connection of a voltage controlled elements with a gate turn-off capability such as an IGBT and a FET. SOLUTION: The high voltage semiconductor switch device includes a synchronous pulse generator that generates a trigger signal in a shorter time than a half period of series resonance to apply turn-on trigger to the voltage controlled elements, a duration signal generating circuit that supplies a duration signal being an ON signal until detecting a reverse direction current after detecting a forward current of the series resonance current flowing to the voltage controlled elements, and an OR circuit that ORs the output signal from the synchronous pulse generator and the output signal from the duration signal generating circuit, and the high frequency signal composed by the OR circuit drives the voltage controlled elements.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-voltage semiconductor switch device used in a pulse power supply device for electrostatic precipitator, etc. Regarding the switch device.

[0002]

2. Description of the Related Art An example of a conventional pulse power supply device for electrostatic precipitator is disclosed in Japanese Patent Application No. 9-17281. This pulse-charging type electrostatic precipitator has a capacitance of a dust collecting chamber and a resonance inductance. Since the series resonance is utilized, the dust collection efficiency can be improved in opposition to the reverse ionization action of the high resistance dust, and the resonance energy is recovered as a feedback current in the power source, so that the efficiency is high.

FIG. 4 is a circuit diagram showing a conventional pulse power supply device 100 for electrostatic dust collection.

Here, a description will be given assuming that the normal dust collecting voltage (hereinafter referred to as "base voltage") Vb is -40 kV and the pulse voltage Vp is -50 kV.

In the conventional pulse power supply device 100 for electrostatic precipitator, the first DC power supply 1 supplies +30 kV to the pulse generating circuit. The choke coil 2 for current limitation is provided, and the high-voltage semiconductor switch device 3 is, for example, a device in which a large number of thyristors are connected in series.

The reverse current feedback means 4 is a diode connected in antiparallel with the high voltage semiconductor switch device 3,
For example, it is a diode connected in anti-parallel to each of the thyristors connected in series that form the high voltage semiconductor switch device 3.

Further, the resonance chamber 5 which is one element of the resonance circuit for determining the pulse waveform and the coupling capacitor 6 having the electrostatic capacitance Cc are provided, and the dust collecting chamber 7 having the discharge electrode and the dust collecting electrode is provided. , Has a capacitance Cp between the discharge electrode and the dust collecting electrode. The electrostatic capacitance Cc is several times larger than the electrostatic capacitance Cp of the dust collection chamber 7, and is, for example, about three times larger. Further, the dust collecting electrode on the positive electrode side of the dust collecting chamber 7 is
It is grounded.

A second DC power supply 8 for supplying a base voltage V
Applies a base voltage Vb of −40 kV to the dust collecting chamber 7.

A pulse generation circuit is constituted by these components.

The control circuit 9 sends an ignition signal synchronized with the commercial power supply frequency to the high-voltage semiconductor switch device 3 in a steady operation state. For example, in the 60Hz area, 1
A high voltage semiconductor switch device 3 is used to output an ignition signal of 20 times / s.
To send. The reverse voltage blocking diode 10 prevents the pulse voltage applied to the dust collection chamber 7 from being applied to the second DC power supply 8.

In the above conventional example, the spark turn-on circuit 11 is connected between the anode and the gate of the high-voltage semiconductor switch device 3. The surge voltage generated during sparking is higher than the predetermined voltage set higher than the voltage applied to the high-voltage semiconductor switch device 3 in the steady state,
When the voltage rises, the high-voltage semiconductor switch device 3 is turned on to protect from overvoltage, and the energy of the coupling capacitor 6 is consumed in the circuit.

The diode 12 and the resistor 13 are an energy consuming circuit. In a steady state, a reverse voltage is applied to the diode 12 and does not affect series resonance, but the voltage of the coupling capacitor 6 is changed by the resonance reverse current generated at the time of sparking. When inverted, the diode 12 conducts and energy is consumed in the resistor 13.

Here, the value of the resonance inductance 5 is
It is assumed that the value of the capacitance 6 is 2.4 mH, the value of the capacitance 6 is 0.64 μF, and the capacitance of the dust collection chamber 7 is 0.2 μF. In the steady pulse operation, the resonance inductance L and the coupling capacitor 6
And the electrostatic capacitance Cp of the dust collecting chamber 7 has a resonance frequency of 8.3 kHz, spark (spark discharge) is generated, and the electrostatic capacitance Cp of the dust collecting chamber 7 is short-circuited to cause resonance. The resonance frequency of the inductance 5 and the coupling capacitor 6 becomes 4 kHz.

FIG. 5 is a diagram showing signal waveforms in a steady operation state in the above conventional example.

In FIG. 5, Ig is a gate signal of the thyristor which constitutes the high voltage semiconductor switch device 3.

Is is a current flowing through the high-voltage semiconductor switching device 3 or the reverse current feedback means 4, a forward direction is a forward current flowing through the thyristor, and a negative direction is a reverse current flowing through the diode 4.

Ve is a pulse superposed dust collection voltage applied to the dust collection chamber 7, and the pulse voltage Vp is superposed on the base voltage Vb. Vs is a voltage applied to the high voltage semiconductor switch device 3.

Next, the operation of the above conventional example during steady operation will be described.

The dust collecting chamber 7 is supplied with V from the second DC power source 8.
When a voltage of b = −40 kV is applied and +30 kV is applied from the first DC power supply 1, the coupling capacitor 6 becomes
It is charged to 70 kV with the polarity shown in FIG.

As shown in FIG. 5, at time t0, the ignition signal I is sent from the control circuit 9 to the high-voltage semiconductor switch device 3.
When g is sent, the high-voltage semiconductor switching device 3 is turned on, and in the period T1, the sine in the positive direction is transferred from the coupling capacitor 6 to the dust collecting chamber 7 via the resonance inductance 5 and the high-voltage semiconductor switching device 3. Half-wave resonant current Is = I
1 flows, and the pulse generation circuit 3 generates the pulse voltage Vp.

Since the electrostatic capacitance Cc of the coupling capacitor 6 is larger than the electrostatic capacitance Cp of the dust collecting chamber 7, the pulse voltage Vp
Becomes 50 kV, which is almost twice the first DC power supply voltage, and the peak of the total pulse voltage W becomes -90 kV. Strictly speaking, the capacitance Cc of the coupling capacitor 6 and the dust collection chamber 7
Is determined by the ratio with the electrostatic capacitance Cp. Resonance frequency is 8.3
Since the frequency is kHz, the period T1 is 60 μs.

Next, when the dust collection voltage Ve, which is the voltage across the dust collection chamber 7, exceeds the peak voltage (-90 kV), the period T
2 (60 μs), coupling capacitor 6 and dust collection chamber 7
From the above, the negative sinusoidal half-wave resonance current Is = I2 flows to the coupling capacitor 6 via the reverse current feedback means 4 and the resonance inductance 5, and the resonance energy is collected in the coupling capacitor 6 as a feedback current.

When the high-voltage semiconductor switch device 3 is composed of a thyristor, if a thyristor element having a turn-off time characteristic shorter than 60 μs is selected and the turn-off time characteristic is, for example, 20 μs, the reverse current period T2 is:
Since the reverse bias of 20 μs or more is applied, the forward blocking ability is restored, that is, the transistor is turned off.

Thereafter, the same operation as above is repeated by the gate signal from the control circuit 9.

As described above, in the steady state, the dust collection chamber 7 has a pulse-overlaid dust collection voltage Ve of -40 kV to -90 kV.
Is applied to the high-voltage semiconductor switch device 3 and the reverse current feedback means 4 at the time t2, which is immediately after the end of the feedback current, by switching the voltage of +30 kV of the first DC power supply 1 to turn off the surge voltage, For example, about 4
5 kV is applied.

Next, a case where a spark occurs in the dust collecting chamber 7 in the above conventional example will be described.

At time t3, the gate signal Ig is given to the thyristor 3, the thyristor 3 is turned on, the forward current I1 is caused to flow, and a pulse is generated. Then, at the time t4, the current is collected. If the dust chamber 7 is sparked, the dust chamber 7 is short-circuited, and at time t5, an overvoltage is applied to the high-voltage semiconductor switch device 3.

The turn-on circuit 11 triggers the high-voltage semiconductor switch device 3 when a spark occurs in the dust collecting chamber 7 due to this overvoltage. When a spark is generated in the dust collection chamber 7, the resonance capacitor is only the coupling capacitor 6 and has a resonance frequency of 4 kHz.

That is, the current period T3 increases, and at the same time, the peak of the forward current I3 also increases to several times the steady state.
In this case, if a thyristor is triggered when a spark occurs in the dust collecting chamber 7, it is possible to automatically respond to an increase in the current period and turn off the reverse current I4 at time T4. Further, the thyristor has a strong characteristic against a short-time overcurrent, and easily copes with a spark current.

At time t6, when one cycle of the resonance current at the time of spark generation in the dust collecting chamber 7 is completed, the energy of the coupling capacitor 6 is consumed by the resistor 13, so that the turn-off voltage applied to the high voltage semiconductor switch device 3 is reduced. The peak value does not trigger the turn-on circuit 11 when sparking, and the resonance current ends in one cycle.

[0031]

As described above, a thyristor is convenient as a semiconductor switch used for this pulse power supply. That is, since the thyristor has the characteristics of turning on with a trigger pulse, automatically following changes in the resonance current cycle, and turning off with a reverse current, the thyristor is convenient as a semiconductor switch used for a pulse power supply.

However, when a thyristor is used, there is a problem that it is difficult to generate a short-time pulse that can be expected to improve the dust collection efficiency. That is, for example,
In order to generate a high voltage pulse of 20 μs, a thyristor whose turn-off time is guaranteed to be 10 μs is required, but it is difficult to obtain such a high speed thyristor.

In recent years, many thyristors have been discontinued and it is desired to replace them with IGBTs or the like.

That is, the problems to be solved in the case of replacing the thyristor with the IGBT are to automatically follow the on-time which changes during the pulse operation and when the spark occurs, the generation of the off signal of the voltage control type element at a necessary timing, Economical, simultaneously isolated signal transmission to a large number of voltage-controlled elements connected in series, protection of the voltage-controlled elements against overvoltage during sparking.

It is an object of the present invention to provide a high voltage semiconductor switch device composed of a series circuit of voltage control type elements having a gate turn-off capability such as IGBT and FET.

The present invention uses a high voltage semiconductor switch as an IG
An object of the present invention is to provide a high voltage semiconductor switch device which is composed of a series circuit of voltage control type elements having a gate turn-off capability such as BT and FET and which can generate a high voltage pulse at a higher frequency.

[0037]

SUMMARY OF THE INVENTION The present invention comprises a DC power supply,
A pulse generator including a series resonance circuit, a high-voltage semiconductor switch connected to the DC power supply, a reverse current feedback means connected in antiparallel to the high-voltage semiconductor switch, a resonance inductance, and a coupling capacitor. A circuit and an electrostatic capacitance load connected to the circuit, turning on the high-voltage semiconductor switch, causing the resonance inductance, the coupling capacitor, and the electrostatic capacitance load to resonate in series, and A high-voltage semiconductor switch device that generates a pulse, and even at the beginning of the reverse current period, a gate signal is applied to maintain the ON state, and even if a spark occurs, it is possible to shift to the forward current as it is, If the reverse current increases sufficiently after switching, even if a spark occurs, the time from that point until the reverse current becomes zero is at turn-off. A sufficiently long period of time than can be secured the turn-off time.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a circuit diagram showing a high voltage semiconductor switch device 3 according to a first embodiment of the present invention.

The high-voltage semiconductor switch device 3 can be used in the conventional pulse power supply device 100 for electrostatic precipitator shown in FIG.

In the high-voltage semiconductor switch device 3 shown in FIG. 1, the same parts as those shown in FIG. 4 are designated by the same reference numerals, and their description will be omitted.

In the high voltage semiconductor switch device 3, a large number of IGBTs 21 are connected in series to form a high voltage semiconductor switch, and the reverse current feedback means 4 includes the IGBTs 21 and the same number of diodes 22 in antiparallel with the respective IGBTs 21. Connected and configured.

A parallel resistor 23 is connected to each IGBT 21 in order to maintain a DC voltage balance, and a diode 24 is connected in order to maintain a voltage balance at turn-off.
, A resistor 25 and a capacitor 26 are connected to the snubber circuit.

Each IGBT 21 is driven by the secondary windings 29 of the same number of pulse transformers 28 in which the primary windings 27 are connected in series. The secondary winding 29 of each pulse transformer 28 and the IG
Between the gate of BT21, full-wave bridge rectifier 30
, Smoothing capacitor 31, resistor 32, diode 3
3 and the PNP transistor 34 are connected.

In addition, the bridge rectifier 30 and the IGBT 21
Is a turn-on circuit during sparking which is constituted by a two-terminal trigger element 35 and a series resistor 36 between the collector and the collector.

When a voltage higher than a certain value is applied to the collector of the IGBT 21, the two-terminal trigger element 35 breaks down and becomes conductive, and a current flows through the gate circuit of each IGBT.

The primary winding 27 of the pulse transformer 28 is connected in series with the secondary winding 37 of the push-pull transformer 36. DC control power supply 38 and two Fs that are alternately turned on
The ETs 39, 40 and the primary winding 41 with a center tap of the push-pull transformer 36 form a FET inverter having a push-pull circuit configuration. High frequency pulse generator 42
Is a high frequency (for example, 100 k) that generates signals Q 1 and Q 2 which are in opposite phases to alternately turn on the FETs 39 and 40.
Hz) pulse generator.

The OR circuit 43 includes a high frequency pulse generator 42.
Pulse generation, that is, the signal generated by the high frequency pulse generator 42 is modulated.

The periodic pulse generator 44 generates a periodic pulse which determines ON repetition of the high voltage semiconductor switch device 3. The pulse width of this periodic pulse is shorter than 1/2 of the resonance period in the steady state.

When the continuous signal generating circuit 45 determines that the switch current of the high-voltage semiconductor switching device 3 is in the forward direction based on the signal output from the current transformer (CT) 46 that detects the switch current, the ON signal is generated. Generates an OR circuit 4
At 3, it is added to the periodic pulse. Further, when the switch current of the high-voltage semiconductor switch device 3 is inverted and becomes a reverse current, the generation of the ON signal is stopped.

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

FIG. 2 is a diagram showing the operation of the above embodiment.

In FIG. 2, S1 is a pulse signal of the periodic pulse generator 44, and S2 is a continuous signal generating circuit 4.
5 is an output signal of 5 and Ig is 1 of the pulse transformer 27.
It is a secondary winding current, and Vg is a gate signal of each IGBT. Is is a current flowing through the high voltage semiconductor switch device 3 or the reverse current feedback means 4, and its positive direction is IG
It is the forward current of the resonant current flowing through the BT 21, and its negative direction is the reverse current of the resonant current flowing through the diode 22.

Ve is a pulse superposed dust collection voltage applied to the dust collection chamber 7, and the pulse voltage Vp is superposed on the base voltage Vb. Vs is a voltage applied to the high voltage semiconductor switch device 3.

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

The periodic pulse generator 44 generates a trigger-on signal S1 shorter than 1/2 of the series resonance half period T1. For example, if the series resonance half period T1 is 60 μs, the time of the trigger-on signal S1 is 2 which is shorter than that.
It is assumed to be 0 μs. This trigger-on signal S1 is OR
The oscillation of the high-frequency pulse generator 42 is started through the circuit 43, and the FET ON signal pulses Q and Q of 100 kHz which are in opposite phases to each other are given to the gates of the FETs 39 and 40, respectively.

When the FETs 39 and 40 are alternately turned on, a high frequency voltage is induced in the secondary winding 37 of the push-pull transformer 36, and 100 is applied to the primary winding 27 of the pulse transformer 28.
A high frequency current Ig of kHz is passed. This high frequency current Ig
Is induced in the secondary winding 29 of the pulse transformer 28 at a high frequency voltage of about 20 V at 100 kHz, and is rectified by the rectifying circuit 30. The rectified voltage is a pulsed pulsating voltage, which is converted into a direct current by the capacitor 31 to generate a voltage in the resistor 32. This voltage is applied to the IGB through the diode 33.
It becomes the gate voltage Vg of T21.

By increasing the gate voltage Vg, all I
The GBT 21 is turned on at the same time, and the forward current I1 of the resonance current
Flows. This forward current I1 is applied to the current transformer (CT) 46.
The continuous signal generation circuit 45 keeps the high frequency pulse generator 42 oscillating until the reverse current I2 is reached.
The gate voltage Vg is applied to the GBT 21 during the forward current I1.
Is given.

That is, if the IGBT 21 is turned on by the trigger on signal S1, the trigger on signal is 20 μs.
Even if it disappears, the ON signal S2 continues with the output signal of the sustain signal generating circuit 45 during the time T1, the high frequency pulse generator 42 continues to oscillate, and the gate voltage Vg continues to the IGBT 21. Is applied.

Next, when the resonance current is inverted and becomes the reverse current I2, the sustain signal generating circuit 45 stops generating the output signal S2, the oscillation of the high frequency pulse generator 42 is terminated, and the FE
T39 and 40 turn off. As a result, the induced voltage in the secondary winding 29 of the pulse transformer 28 disappears, and the voltage across the resistor 32 also disappears. As a result, the potential of the emitter of the PNP transistor 34 becomes higher than the potential of the base due to the potential due to the charge accumulated in the gate of the IGBT 21, and the PNP transistor 34 is forward biased and turned on.

As a result, the transistor 34 discharges the electric charge accumulated in the gate of the IGBT 21 and the IG
The gate signal of BT21 disappears, and IGBT21 turns off. In this way, once the IGBT 21 is turned on,
It is possible to follow the change of the resonance period and continue to turn on until the reverse current is reached.

Next, a case where a spark occurs in the dust collecting chamber 7 in the above embodiment will be described.

Sparks in the dust collection chamber 7 may occur during the period when the high voltage semiconductor switching device 3 is on, or may occur during the high voltage semiconductor switching device 3 being off.

First, a description will be given of the spark generated when the high voltage semiconductor switch device 3 is turned on in the above embodiment.

When a spark occurs while the high-voltage semiconductor switch device 3 is on, the dust collection chamber 7 (electrostatic capacitance Cp) of the load resonance circuit is short-circuited, and the resonance cycle and the resonance current peak increase. . As the resonance period increases, the sustain signal generation circuit 45 automatically continues the gate signal during the forward current period, so that the resonance current is not turned off. Regarding the increase of the current, the short-time current rating of the IGBT 21 of the high-voltage semiconductor switch device 3 may be selected, or a plurality of IGBTs may be connected in parallel if necessary.

Next, the spark that occurs when the high voltage semiconductor switch device 3 is turned off in the above embodiment will be described.

As shown in FIG. 2, time t4 in the reverse current period
Then, a spark occurs. At time t4, a reverse current flows, time T2, and several μs or more have elapsed, so the IGBT
An OFF signal is given to 21. Therefore, the reverse current is rapidly attenuated, and at time t4, 70 kV, which is the voltage of the coupling capacitor 6, is applied to the high-voltage semiconductor switch device 3 which is off at once.

From the viewpoint of economy, the high-voltage semiconductor switch device 3 has a withstand voltage of about 50 kV, which is a withstand voltage of the number of series with a slight margin to the withstand voltage of the off voltage during pulse operation at a steady voltage.
Is designed with.

2 connected to the collector of each IGBT 21
The terminal trigger element 35 is turned on, and a voltage is injected to the output side of the rectifier 30 through the resistor 36. This injection voltage turns on the diode 33, and the IGBT 21
When the gate of is charged, the IGBT21 turns on,
Over voltage protection. Once turned on, a resonance forward current flows, and the sustain signal generation circuit 45 continuously generates an on pulse.

When the voltage across the coupling capacitor 6 shown in FIG. 4 is reversed by the resonance reverse current, the diode 12 shown in FIG. 1 becomes conductive and a current flows through the resistor 13 to consume the energy of the coupling capacitor 6.

When the high-voltage semiconductor switch device 3 is turned off and one cycle of the resonance current is completed, the energy of the coupling capacitor 6 is attenuated and the voltage drops. Therefore, even if the spark in the dust collecting chamber 7 continues, 2 If the resistor 13 is selected so that the terminal trigger element 35 does not turn on, the switch voltage Vs after one cycle of the resonance current during spark becomes 50 kV as shown in FIG.
5 does not turn on again, the high-voltage semiconductor switch device 3 can be turned off.

Here, the sustain signal generating circuit 45 does not immediately stop the output signal S2 of the sustain signal generating circuit 45 even if the reverse current I2 starts to flow, for the reason to be described later.
A short time T2 at the beginning of the reverse current period (several μs in this example),
It is desirable to continue the ON signal.

Next, the delay time T2 of the continuous signal in the above embodiment will be described in detail.

The timing at which the resonance current inverts depends on the peak value of the pulse voltage, and there is a high probability that sparks will occur at timings near this value. When a spark is generated at this timing and the IGBTs are to be turned off at that moment, the IGBTs that are on and the IGBTs that are off due to variations in the turn-off times of all the IGBTs.
T and the IGBT being turned off are mixed, and some IG
Turn-off becomes unstable, for example, an overvoltage is applied to BT or a current increases during the turn-off period.

For this reason, in order to avoid dangerous turn-off at this timing, the gate signal is applied even at the beginning of the reverse current period, the ON state is maintained, and even if a spark occurs, the forward current can be directly transferred. To do so. If the reverse current increases sufficiently after switching to the reverse current, even if a spark occurs, the time until the reverse current becomes zero from that point can be ensured for a time sufficiently longer than the turn-off time. . Normally, the delay time T2 of the continuous signal
Is from about 1 μs or more to half or less of the reverse current period.

Here, when the steady pulse operation, in particular, one cycle of the resonance current in the spark is finished and the high voltage semiconductor switching device 3 is turned off, the snubber voltage is applied by the surge voltage applied to the high voltage semiconductor switching device 3. The charging current I5 of the capacitor 26 forming the circuit is t6 shown in FIG.
There is a possibility that the continuous signal generation circuit 45 may erroneously recognize this as a resonance forward current and generate an unnecessary ON signal.

In order to prevent the generation of this unnecessary ON signal, the sustain signal generating circuit 45 is arranged so that after the reverse current is finished,
It is desirable to prohibit the generation of the sustain signal for a period T4 or more when the snubber charging ends.

FIG. 3 is a circuit diagram showing the configuration of the sustain signal generating circuit 45 having the function of preventing the generation of the sustain signal in the above embodiment.

The continuous signal generating circuit 45 is a current transformer (CT).
A forward current detection circuit 51 that detects a forward current, a reverse current detection circuit 52 that detects a reverse current, and a sustain circuit 53 that creates a sustain signal according to the forward current detection signal, based on the detection current output by 46. , A timer 544 and a gate circuit 55.

The sustain circuit 53 has a diode 61, a capacitor 62, and a resistor 63. In the sustain circuit 53, when the forward current detection signal rises, the diode 6
1, the coupling capacitor 62 is charged at high speed to eliminate the delay, and when the forward current detection signal falls, it is discharged by the resistor 63 to form a delay time, and the width of the input pulse is extended by the time T2.

The timer circuit 54 generates an inhibition pulse for a predetermined time T4 after the reverse current disappears. Gate circuit 55
Inhibits the generation of the sustain signal by the inhibit signal output from the timer circuit 54.

Next, the operation of the sustain signal generating circuit 45 will be described.

In normal operation, the forward current detection circuit 51 detects the resonant forward current, and at the same time as this detection, the diode 61 is detected.
A resonant forward current is sent to the gate circuit 56 through
Since it is not after the reverse current, there is no inhibit signal and it is output as a sustain signal.

Next, when the resonance forward current is reversed from the forward current to the reverse current, the electric charge charged in the coupling capacitor 62 of the sustaining circuit 53 is slowly discharged through the resistor 63, so that the sustaining signal of FIG. The period T2 shown in is extended.
Further, when the reverse current disappears and one cycle ends, the reverse current signal of the reverse current detection circuit 52 disappears, the timer circuit 54 operates, and the gate circuit 56 operates only for the inhibition time T4.
To prevent the continuous signal from being generated.

Next, another example of a circuit for turning on the IGBT 21 when a spark occurs in the dust collecting chamber 7 will be described.

As shown by the broken line in FIG. 1, the two-terminal trigger element 35 is connected to the snubber capacitor 26. By doing so, the voltage of the capacitor 26 and the collector voltage of the IGBT 21 are substantially the same, and when an overvoltage occurs, the gate current can be supplied from the snubber capacitor 26 for a period of several μS. . When the IGBT 21 is directly connected to the collector of the IGBT 21, if the gate current is not supplied from the 2-terminal trigger element 35 at the moment when the IGBT 21 is turned on and the sustaining ON signal from the sustaining signal generating circuit 45 is delayed, the IGBT 21 is completely removed. May not be turned on.

The capacitance load is a capacitor connected to a device using the high voltage semiconductor switch device 3 or a generated capacitance.

[0087]

According to the present invention, a semiconductor switching device having almost the same function as that of a conventional thyristor is provided with IGBTs, Fs.
There is an effect that a pulse power source can be realized by using a voltage control element such as ET. Particularly, since a semiconductor element such as an IGBT or FET is essentially faster than a thyristor,
It is possible to generate a high-voltage pulse having a shorter time width.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a first embodiment of the present invention.

FIG. 2 is a diagram showing a specific example of a switch portion according to the embodiment of the present invention.

FIG. 3 is a diagram showing an embodiment of a sustain signal generating circuit of the present invention.

FIG. 4 is a diagram for explaining a form of a conventional pulse power supply device.

FIG. 5 is a waveform diagram for explaining an operation of a conventional pulse power supply device in a steady operation state.

[Explanation of symbols]

3 ... High voltage semiconductor switch device, 1 ... first DC power supply, 4 ... Reverse current feedback means, 5 ... Resonant inductor, 6 ... coupling capacitor, 7. Dust collection chamber (capacitance load), 8 ... second DC power supply, 21 ... IGBT, 28 ... Pulse transformer, 30 ... Full wave bridge rectifier, 31 ... smoothing capacitor, 35 ... 2-terminal trigger element, 36 ... Push-pull transformer, 38 ... DC control power supply, 42 ... High-frequency pulse generator, 43 ... OR circuit, 44 ... Periodic pulse generator, 45 ... Continuous signal generating circuit, 46 ... current transformer, 51 ... Reverse current detection circuit, 52 ... Forward current detection circuit, 53 ... sustaining circuit, 54 ... timer, 55 ... Gate circuit.

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Claims (8)

[Claims] 1. A high-voltage semiconductor switch in which voltage-controlled elements having gate turn-off capability are connected in series; reverse current feedback means connected in antiparallel with the high-voltage semiconductor switch; each primary winding. A plurality of pulse transformers whose lines are connected to each other in series and rectify each secondary winding voltage to supply the gate signal of the voltage control type element; a resonance circuit which resonates by switching of the high voltage semiconductor switch; A periodic pulse generator for generating a trigger signal in the primary winding of the transformer for turning on the voltage-controlled element in a time shorter than a half cycle of the series resonance; and the voltage-controlled element turned on. After that, a continuous signal, which is an ON signal, is supplied until the reverse current is detected after the forward current of the series resonance current flowing in the voltage-controlled element is detected. An OR circuit for synthesizing the output signal of the periodic pulse generator and the output signal of the sustain signal generating circuit; and a high frequency signal synthesized by the OR circuit, A high-voltage semiconductor switch device, wherein a high-voltage pulse is generated by causing a resonance circuit to resonate by driving a control element. 2. The high voltage semiconductor switch device according to claim 1, wherein the voltage control type element is an IGBT or an FET. 3. The continuous signal generating circuit according to claim 1, wherein the reverse signal starts flowing even when a reverse current starts flowing.
A high-voltage semiconductor switching device, which is a circuit that supplies an ON signal for a required time and prevents the high-voltage semiconductor switching device from turning off due to a spark generated when switching between a forward current and a reverse current. 4. The collector of the voltage controlled element according to any one of claims 1 to 3, and 2 of a pulse transformer.
It has a two-terminal trigger element connected to the output terminal of the rectifier on the next side, and when the spark is generated in the dust collection chamber, the above two-terminal trigger element becomes conductive, and the above voltage control type element A high voltage semiconductor switch device, wherein a trigger signal is applied, and thereafter, an ON signal is supplied until the sustain signal generating circuit detects a reverse current of a resonance current. 5. The secondary pulse rectifier according to claim 4, further comprising a snubber circuit including a capacitor and a resistor, the snubber circuit being connected in parallel to the voltage-controlled element, and the capacitor forming the snubber circuit. A high-voltage semiconductor switch device, characterized in that a two-terminal trigger element is connected between the output terminal and the output terminal. 6. The continuous signal generating circuit according to claim 1, wherein the stray capacitance flowing again in the positive direction after the reverse current disappears or the charging current of the capacitor forming the snubber circuit is defined as a forward resonance current. A high-voltage semiconductor switch device, which is a circuit for preventing generation of the sustain signal so as not to be erroneously recognized. 7. A high-voltage semiconductor switch in which voltage-controlled elements having gate turn-off capability are connected in series, reverse current feedback means connected in antiparallel with the high-voltage semiconductor switch, and each primary winding. A plurality of pulse transformers whose lines are connected in series with each other to rectify each secondary winding voltage to supply a gate signal of the voltage control type element; a resonance circuit which resonates by switching of the high voltage semiconductor switch; In order to turn on the primary winding of the transformer to turn on the voltage-controlled element, the periodic pulse generator that generates a trigger signal for a time shorter than the half cycle of the series resonance and the voltage-controlled element are turned on. After that, a continuous signal, which is an ON signal, is supplied until the reverse current is detected after the forward current of the series resonance current flowing in the voltage-controlled element is detected. And an OR circuit for synthesizing the output signal of the periodic pulse generator and the output signal of the sustain signal generation circuit.
A high-voltage semiconductor switch device that resonates the resonance circuit to generate a high-voltage pulse by driving the voltage-controlled element with a high-frequency signal synthesized by the R circuit; a DC power supply; a capacitive load; A resonance inductor and a coupling capacitor connected in series between the capacitance load and the DC power supply; and the high voltage semiconductor switch is connected in series to the DC power supply when turned on, and The capacitive load, the resonant inductor, and the coupling capacitor are also connected in series, and the resonant circuit of the high-voltage semiconductor switch device includes the resonant inductor, the coupling capacitor, and the capacitive load. A high-voltage generator, which is a circuit configured by an electrostatic capacitance. 8. The high voltage generator according to claim 7, wherein the high voltage generator is a device used in a pulse charge type electrostatic precipitator.