JP3623181B2 - High voltage semiconductor switch device and high voltage generator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high voltage semiconductor switching device used for an electric dust collection pulse power supply device and the like, and more particularly to a high voltage semiconductor switching device using a voltage control type element having gate turn-off capability such as IGBT and FET.
[0002]
[Prior art]
An example of a conventional pulse power supply device for electrostatic dust collection is disclosed in Japanese Patent Application No. 9-17281, and this pulse charge type electrostatic dust collector utilizes series resonance between the capacitance of a dust collection chamber and a resonance inductance. The dust collection efficiency can be increased in opposition to the reverse ionization action of the high resistance dust, and the resonance energy is recovered as a feedback current by the power source, so that the efficiency is high.
[0003]
FIG. 4 is a circuit diagram showing a conventional pulse power supply device 100 for electrostatic dust collection.
[0004]
Here, a normal dust collection voltage (hereinafter referred to as “base voltage”) Vb is set to −40 kV, and a pulse voltage Vp is set to −50 kV.
[0005]
In the conventional electric dust collecting pulse power supply device 100, 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 a device in which a large number of thyristors are connected in series, for example.
[0006]
The reverse current feedback means 4 is a diode connected in antiparallel with the high voltage semiconductor switch device 3. For example, the reverse current feedback means 4 is connected in antiparallel with each of the thyristors connected in series constituting the high voltage semiconductor switch device 3. It is a diode.
[0007]
A dust collection chamber 7 provided with a resonance inductance 5 which is an element of a resonance circuit for determining a pulse waveform and a coupling capacitor 6 having a capacitance Cc, and including a discharge electrode and a dust collection electrode, And a dust collecting electrode have a capacitance Cp. The electrostatic capacity Cc is several times larger than the electrostatic capacity Cp of the dust collection chamber 7, for example, about 3 times larger. Further, the dust collection electrode on the positive electrode side of the dust collection chamber 7 is grounded.
[0008]
The second DC power supply 8 that supplies the base voltage V applies a base voltage Vb of −40 kV to the dust collection chamber 7.
[0009]
These constitute a pulse generating circuit.
[0010]
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 60 Hz region, an ignition signal of 120 times / s is sent to the high voltage semiconductor switch device 3. 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.
[0011]
In the conventional example, the spark turn-on circuit 11 is connected between the anode and gate of the high-voltage semiconductor switch device 3. When the surge voltage generated at the time of sparking is higher than a predetermined voltage set higher than the voltage applied to the high-voltage semiconductor switch device 3 in the steady state, the high-voltage semiconductor switch device 3 is turned on. It protects against overvoltage and consumes the energy of the coupling capacitor 6 in the circuit.
[0012]
The diode 12 and the resistor 13 are energy consuming circuits. In a steady state, a reverse voltage is applied to the diode 12 and does not affect the series resonance. However, when the voltage of the coupling capacitor 6 is inverted by a resonance reverse current generated during sparking. In addition, the diode 12 becomes conductive and energy is consumed in the resistor 13.
[0013]
Here, it is assumed that the value of the resonance inductance 5 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 frequency of the series circuit of the resonance inductance L, the coupling capacitor 6 and the electrostatic capacity Cp of the dust collection chamber 7 becomes 8.3 kHz, spark (spark discharge) occurs, and the dust collection chamber. When the capacitance Cp of 7 is short-circuited, the resonance frequency of the resonance inductance 5 and the coupling capacitor 6 becomes 4 kHz.
[0014]
FIG. 5 is a diagram showing signal waveforms in a steady operation state in the above-described conventional example.
[0015]
In FIG. 5, Ig is a gate signal of a thyristor constituting the high voltage semiconductor switch device 3.
[0016]
Is is a current flowing through the high-voltage semiconductor switch device 3 or the reverse current feedback means 4, the positive direction is a forward current flowing through the thyristor, and the negative direction is a reverse current flowing through the diode 4.
[0017]
Ve is a pulse superimposed dust collection voltage applied to the dust collection chamber 7, and the pulse voltage Vp is superimposed on the base voltage Vb. Vs is a voltage applied to the high voltage semiconductor switch device 3.
[0018]
Next, the operation during steady operation in the conventional example will be described.
[0019]
When the voltage of Vb = −40 kV is applied to the dust collection chamber 7 from the second DC power supply 8 and +30 kV is applied from the first DC power supply 1, the coupling capacitor 6 has the polarity shown in FIG. 4. The battery is charged up to 70 kV.
[0020]
As shown in FIG. 5, when the ignition signal Ig is sent from the control circuit 9 to the high voltage semiconductor switch device 3 at time t0, the high voltage semiconductor switch device 3 is turned on, and from the coupling capacitor 6 in the period T1, A positive sine half-wave resonance current Is = I1 flows into the dust collection chamber 7 via the resonance inductance 5 and the high-voltage semiconductor switch device 3, and the pulse generation circuit 3 generates a pulse voltage Vp.
[0021]
Since the capacitance Cc of the coupling capacitor 6 is larger than the capacitance Cp of the dust collection chamber 7, the pulse voltage Vp is 50 kV which is almost twice the first DC power supply voltage, and the total pulse voltage W is The peak is -90 kV. Strictly speaking, it is determined by the ratio between the capacitance Cc of the coupling capacitor 6 and the capacitance Cp of the dust collection chamber 7. Since the resonance frequency is 8.3 kHz, the period T1 is 60 μs.
[0022]
Next, when the dust collection voltage Ve, which is the voltage across the dust collection chamber 7, exceeds the peak voltage (−90 kV), the reverse current feedback means from the coupling capacitor 6 and the dust collection chamber 7 in the period T2 (60 μs). 4 and the resonant inductance 5, a negative sinusoidal resonance current Is = I2 flows to the coupling capacitor 6, and the resonance energy is recovered as a feedback current in the coupling capacitor 6.
[0023]
When the high-voltage semiconductor switch device 3 is formed of a thyristor, if a thyristor element having a turn-off time characteristic shorter than 60 μs is selected, for example, a turn-off time characteristic of 20 μs, the reverse current period T2 has a reverse of 20 μs or more. Since the bias is applied, the forward blocking ability is restored, that is, turned off.
[0024]
Thereafter, the same operation as described above is repeated with the gate signal from the control circuit 9.
[0025]
As described above, a pulse superimposed dust collection voltage Ve of −40 kV to −90 kV is applied to the dust collection chamber 7 in a steady state, and a feedback current is supplied to the high voltage semiconductor switch device 3 and the reverse current feedback means 4. A surge voltage, for example, about 45 kV, is applied at the time of turn-off by switching the voltage of +30 kV of the first DC power supply 1 at a time point t2, which is immediately after the end.
[0026]
Next, the case where a spark is generated in the dust collection chamber 7 in the conventional example will be described.
[0027]
At time t3, the gate signal Ig is supplied to the thyristor 3, the thyristor 3 is turned on, and a forward current I1 flows to generate a pulse. Thereafter, when a reverse current starts to flow, at time t4, the dust collection chamber 7 If a spark occurs, the dust collection chamber 7 is short-circuited, and an overvoltage is applied to the high-voltage semiconductor switch device 3 at time t5.
[0028]
With this overvoltage, the turn-on circuit 11 triggers the high-voltage semiconductor switch device 3 when a spark occurs in the dust collection chamber 7. When a spark is generated in the dust collection chamber 7, the resonance capacitor is only the coupling capacitor 6, and the resonance frequency is 4 kHz.
[0029]
That is, the current period T3 increases, and at the same time, the peak of the forward current I3 also increases several times the steady state. In this case, if a thyristor is triggered when a spark occurs in the dust collection chamber 7, it automatically responds to an increase in current period and can be turned off at time T4 of the reverse current I4. In addition, the thyristor has a strong characteristic with respect to a short-time overcurrent, and can easily cope with a spark current.
[0030]
When one cycle of resonance current at the time of occurrence of spark in the dust collection chamber 7 is completed at time t6, the energy of the coupling capacitor 6 is consumed by the resistor 13, so that the peak value of the turn-off voltage applied to the high voltage semiconductor switch device 3 is During the spark, the turn-on circuit 11 is not triggered, and the resonance current is completed in one cycle.
[0031]
[Problems to be solved by the invention]
As described above, a thyristor is convenient as a semiconductor switch used for this pulse power supply. That is, the thyristor is advantageous as a semiconductor switch used for a pulse power supply because it has a characteristic that it is turned on by a trigger pulse, and also automatically follows a change in the resonance current period and is turned off by a reverse current.
[0032]
However, when thyristors are used, it is difficult to generate short-time pulses that can be expected to improve 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. There is.
[0033]
In recent years, the number of thyristors that have been discontinued has increased, and replacement with IGBTs or the like is desired.
[0034]
In other words, the problem to be solved when replacing a thyristor with an IGBT is
(1) Automatic tracking of the on-time that changes during pulse operation and when a spark occurs,
(2) Generation of an off signal of a voltage controlled element at a necessary timing,
(3) Economical and simultaneously insulated signal transmission to a number of voltage-controlled elements connected in series,
(4) Protection of voltage controlled elements against overvoltage during spark
It is.
[0035]
An object of the present invention is to provide a high voltage semiconductor switch device composed of a series circuit of voltage controlled elements having gate turn-off capability such as IGBT, FET and the like.
[0036]
The present invention provides a high voltage semiconductor switch device in which a high voltage semiconductor switch is constituted by a series circuit of voltage controlled elements having gate turn-off capability such as IGBT, FET, etc., and high voltage pulses can be generated at a higher frequency. It is intended to do.
[0037]
[Means for Solving the Problems]
The present invention includes a DC power supply, 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. And a capacitive load connected thereto, the high-voltage semiconductor switch is turned on, and the resonant inductance, the coupling capacitor, and the capacitive load are in series resonance. A high-voltage semiconductor switching device that generates a pulse in the capacitive load, and applies a gate signal at the beginning of the reverse current period to maintain the ON state, and even if a spark occurs, the forward current remains as it is. If the reverse current increases sufficiently after switching to the reverse current, even if a spark occurs, the reverse current becomes zero from that point. Time sufficiently longer than the turn-off time can be secured turn-off time.
[0038]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a circuit diagram showing a high voltage semiconductor switch device 3 according to a first embodiment of the present invention.
[0039]
The high-voltage semiconductor switch device 3 can be used for the conventional pulse power supply device 100 for electrostatic dust collection shown in FIG.
[0040]
In the high voltage semiconductor switch device 3 shown in FIG. 1, the same components as those shown in FIG.
[0041]
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 connects the same number of diodes 22 as the IGBTs 21 in antiparallel with the respective IGBTs 21. It is configured.
[0042]
A parallel resistor 23 is connected to each IGBT 21 in order to maintain a DC voltage balance, and a snubber circuit including a diode 24, a resistor 25, and a capacitor 26 in order to maintain a voltage balance at the time of turn-off. Is connected.
[0043]
Each IGBT 21 is driven by secondary windings 29 of the same number of pulse transformers 28 in which primary windings 27 are connected in series. A full-wave bridge rectifier 30, a smoothing capacitor 31, a resistor 32, a diode 33, and a PNP transistor 34 are connected between the secondary winding 29 of each pulse transformer 28 and the gate of the IGBT 21. .
[0044]
The spark turn-on circuit includes a two-terminal trigger element 35 and a series resistor 36 between the bridge rectifier 30 and the collector of the IGBT 21.
[0045]
When a voltage of a certain value or more 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.
[0046]
The primary winding 27 of the pulse transformer 28 is connected in series to the secondary winding 37 of the push-pull transformer 36. The DC control power supply 38, the two FETs 39 and 40 that are alternately turned on, and the primary winding 41 with a center tap of the push-pull transformer 36 constitute a FET inverter having a push-pull circuit configuration. The high-frequency pulse generator 42 includes signals Q, which are in reverse phase with each other, turning on the FETs 39, 40 alternately. Q Is a high frequency (for example, 100 kHz) pulse generator.
[0047]
The OR circuit 43 controls the pulse generation of the high frequency pulse generator 42, that is, modulates the signal generated by the high frequency pulse generator 42.
[0048]
The periodic pulse generator 44 generates a periodic pulse that determines ON repetition of the high voltage semiconductor switch device 3. The pulse width of this periodic pulse is shorter than ½ of the resonance period in the steady state.
[0049]
When the continuous signal generation circuit 45 determines that the switch current of the high-voltage semiconductor switch device 3 is forward based on the signal output from the current transformer (CT) 46 that detects the switch current, it generates an ON signal. The OR circuit 43 adds the periodic pulse. Further, when the switch current of the high voltage semiconductor switch device 3 is reversed and becomes a reverse current, the generation of the ON signal is stopped.
[0050]
Next, the operation of the above embodiment will be described.
[0051]
FIG. 2 shows the operation of the above embodiment.
[0052]
In FIG. 2, S1 is a pulse signal of the periodic pulse generator 44, S2 is an output signal of the continuous signal generation circuit 45, Ig is a primary winding current of the pulse transformer 27, and Vg is This 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, the positive direction is the forward current of the resonant current flowing through the IGBT 21, and the negative direction is the reverse of the resonant current flowing through the diode 22. Current.
[0053]
Ve is a pulse superimposed dust collection voltage applied to the dust collection chamber 7, and the pulse voltage Vp is superimposed on the base voltage Vb. Vs is a voltage applied to the high-voltage semiconductor switch device 3.
[0054]
Next, the operation of the above embodiment will be described.
[0055]
The periodic pulse generator 44 generates a trigger-on signal S1 shorter than ½ of the series resonance half period T1. For example, if the series resonance half cycle T1 is 60 μs, the time of the trigger on signal S1 is 20 μs, which is shorter than that. This trigger-on signal S1 starts oscillation of the high-frequency pulse generator 42 through the OR circuit 43, and a 100-kHz FET on-signal pulse Q having a phase opposite to each other. Q Are applied to the gates of the FETs 39 and 40, respectively.
[0056]
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 a high frequency current Ig of 100 kHz is supplied to the primary winding 27 of the pulse transformer 28. This high-frequency current Ig induces a 100 kHz high-frequency voltage of about 20 V in the secondary winding 29 of the pulse transformer 28 and is rectified by the rectifier circuit 30. The rectified voltage is a pulsed pulsating voltage, which is converted into a direct current by the capacitor 31 and generates a voltage at the resistor 32. This voltage becomes the gate voltage Vg of the IGBT 21 through the diode 33.
[0057]
Due to the rise of the gate voltage Vg, all the IGBTs 21 are simultaneously turned on, and the forward current I1 of the resonance current flows. The forward current I1 is detected by the current transformer (CT) 46, and the continuous signal generation circuit 45 continues the oscillation of the high-frequency pulse generator 42 until the current I2 becomes the reverse current I2, and the IGBT 21 has a forward current I1. During this period, the gate voltage Vg is applied.
[0058]
That is, if the IGBT 21 is turned on by the trigger on signal S1, even if the trigger on signal disappears at 20 μs, the on signal S2 is continued by the output signal of the continuous signal generating circuit 45 for the time T1, and the high frequency pulse generator 42 The gate voltage Vg is continuously applied to the IGBT 21.
[0059]
Next, when the resonance current is reversed and becomes the reverse current I2, the continuous signal generation circuit 45 does not generate the output signal S2, the oscillation of the high frequency pulse generator 42 is terminated, and the FETs 39 and 40 are turned off. As a result, the induced voltage of 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.
[0060]
As a result, the charges accumulated in the gate of the IGBT 21 are discharged by the transistor 34, the gate signal of the IGBT 21 disappears, and the IGBT 21 is turned off. Thus, once the IGBT 21 is turned on, it can follow the change in the resonance period and can be kept on until the reverse current is obtained.
[0061]
Next, the case where a spark occurs in the dust collection chamber 7 in the above embodiment will be described.
[0062]
The spark in the dust collection chamber 7 may occur when the high-voltage semiconductor switch device 3 is on or may occur when the high-voltage semiconductor switch device 3 is off.
[0063]
First, the spark generated when the high voltage semiconductor switch device 3 is turned on in the above embodiment will be described.
[0064]
When a spark occurs while the high-voltage semiconductor switch device 3 is on, the dust collection chamber 7 (capacitance Cp) of the resonance circuit of the load is short-circuited, and the resonance period and the resonance current peak increase. In response to an increase in the resonance period, 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. For the increase in current, the short-time current rating of the IGBT 21 of the high-voltage semiconductor switch device 3 may be selected, or a plurality may be connected in parallel if necessary.
[0065]
Next, sparks that occur when the high-voltage semiconductor switch device 3 is off in the above embodiment will be described.
[0066]
As shown in FIG. 2, a spark occurs at time t4 in the reverse current period. At time t4, a reverse current flows and the time T2 and several μs or more have elapsed, so an off signal is given to the IGBT 21. Accordingly, the reverse current rapidly decays, and at time t4, 70 kV that is the voltage of the coupling capacitor 6 is applied to the high-voltage semiconductor switch device 3 that is turned off at once.
[0067]
The high-voltage semiconductor switch device 3 is designed with an approximately 50 kV series of withstand voltage with a slight margin from the withstand voltage of the off voltage during pulse operation at a steady voltage from the viewpoint of economy.
[0068]
The two-terminal trigger element 35 connected to the collector of each IGBT 21 is turned on, and a voltage is injected to the output side of the rectifier 30 through the resistor 36. When the diode 33 is turned on by this injection voltage and the gate of the IGBT 21 is charged, the IGBT 21 is turned on to protect against overvoltage. Once turned on, a resonant forward current flows, and the continuous signal generation circuit 45 continuously generates an on-pulse.
[0069]
If the voltage across the coupling capacitor 6 shown in FIG. 4 is reversed by the resonant reverse current, the diode 12 shown in FIG. 1 is turned on, a current flows through the resistor 13, and the energy of the coupling capacitor 6 is consumed.
[0070]
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 is lowered. Therefore, even if the spark in the dust collection chamber 7 continues, the two-terminal trigger element If the resistor 13 is selected so as not to turn on 35, as shown in FIG. 2, the switch voltage Vs after one cycle of the resonance current during spark becomes 50 kV, and the two-terminal trigger element 35 does not turn on again. The high voltage semiconductor switch device 3 can be turned off.
[0071]
Here, even if the reverse current I2 starts to flow, the continuous signal generating circuit 45 does not stop the output signal S2 of the continuous signal generating circuit 45 immediately for the reason described later, but for the short time T2 at the beginning of the reverse current period. It is desirable to continue the ON signal (several μs in this example).
[0072]
Next, in the embodiment described above, the delay time T2 of the continuous signal will be described in detail.
[0073]
The timing at which the resonance current is inverted depends on the peak value of the pulse voltage, and there is a high probability that a spark will occur at this timing. When a spark is generated at this timing and an attempt is made to turn off the IGBT at that moment, due to variations in the turn-off time of all IGBTs, the turned-on IGBT, the turned-off IGBT, and the IGBT being turned off The turn-off becomes unstable, such as being mixed, overvoltage applied to some IGBTs, and the current during the turn-off period increasing.
[0074]
For this reason, in order to avoid dangerous turn-off at this timing, a gate signal is given even at the beginning of the reverse current period so that the ON state can be maintained and even if a spark occurs, the current can be transferred to the forward current as it is. . If the reverse current increases sufficiently after switching to the reverse current, even if a spark occurs, the time from the point until the reverse current becomes zero can be secured for a time sufficiently longer than the turn-off time. . Usually, the delay time T2 of the continuous signal is about 1 μs or more and less than or equal to one half of the reverse current period.
[0075]
Here, when a steady pulse operation, in particular, one cycle of the resonance current in the spark is completed and the high voltage semiconductor switch device 3 is turned off, a snubber circuit is configured with a surge voltage applied to the high voltage semiconductor switch device 3. The charging current I5 of the capacitor 26 flowing at t6 shown in FIG. 2 may cause the sustain signal generating circuit 45 to misrecognize it as a resonance forward current and generate an unnecessary on signal.
[0076]
In order to prevent the generation of this unnecessary ON signal, it is desirable that the sustain signal generation circuit 45 prohibits the generation of the sustain signal for a period T4 or longer after the end of the reverse current.
[0077]
FIG. 3 is a circuit diagram showing a configuration of the continuous signal generation circuit 45 having a function of preventing the generation of the continuous signal in the above embodiment.
[0078]
The continuous signal generation circuit 45 includes a forward current detection circuit 51 that detects a forward current based on a detection current output from the current transformer (CT) 46, a reverse current detection circuit 52 that detects a reverse current, and a forward current. It has a sustain circuit 53 that generates a sustain signal in accordance with the detection signal, a timer 544, and a gate circuit 55.
[0079]
The sustain circuit 53 includes a diode 61, a capacitor 62, and a resistor 63. In the sustain circuit 53, when the forward current detection signal rises, the coupling capacitor 62 is charged at high speed by the diode 61 to eliminate the delay, and when the forward current detection signal falls, the resistor 63 discharges to form a delay time. The width of the pulse is extended by time T2.
[0080]
The timer circuit 54 generates a prohibition pulse for a predetermined time T4 from the disappearance of the reverse current. The gate circuit 55 prevents the generation of the sustain signal by the prohibit signal output from the timer circuit 54.
[0081]
Next, the operation of the continuous signal generating circuit 45 will be described.
[0082]
In normal operation, the forward current detection circuit 51 detects the resonance forward current, and simultaneously with this detection, the resonance forward current is sent to the gate circuit 56 through the diode 61. Output as a continuous signal.
[0083]
Next, when the resonant forward current is inverted from the forward current to the reverse current, the charge charged in the coupling capacitor 62 of the sustain circuit 53 is slowly discharged through the resistor 63, so that the sustain signal has a period shown in FIG. It is extended by T2. Furthermore, 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, the gate circuit 56 is closed only for the prohibition time T4, and the continuous signal Prevent occurrence.
[0084]
Next, another example of a circuit for turning on the IGBT 21 when a spark occurs in the dust collection chamber 7 will be described.
[0085]
A two-terminal trigger element 35 is connected to the snubber capacitor 26 as indicated by a broken line in FIG. In this way, the voltage of the capacitor 26 and the collector voltage of the IGBT 21 are substantially the same, and when an overvoltage occurs, a 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, the gate current is not supplied from the two-terminal trigger element 35 at the moment when the IGBT 21 is turned on. May not turn on.
[0086]
The capacitance load is a capacitor connected to a device using the high voltage semiconductor switch device 3 or a generated capacitance.
[0087]
【The invention's effect】
According to the present invention, a semiconductor switch device having substantially the same function as that of a conventional thyristor can achieve a pulse power supply by using a voltage control element such as IGBT or FET, and in particular, a semiconductor such as IGBT or FET. Since the element is essentially faster than the thyristor, there is an effect that a high-pressure pulse having a shorter duration can be generated.
[Brief description of the 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 of an embodiment of the present invention.
FIG. 3 is a diagram showing an embodiment of a continuous signal generating circuit according to 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 in a steady operation state of a conventional pulse power supply device.
[Explanation of symbols]
3. High voltage semiconductor switch device,
1 ... 1st DC power supply,
4 ... Reverse current feedback means,
5 ... Resonant inductor,
6 ... coupling capacitor,
7 ... Dust collection chamber (capacitive 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 generation circuit,
46 ... Current transformer,
51. Reverse current detection circuit,
52 ... Forward current detection circuit,
53. Sustain circuit,
54 ... Timer,
55: Gate circuit.

Claims (8)

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;
A plurality of pulse transformers in which each primary winding is connected in series, rectifies each secondary winding voltage and supplies a gate signal of the voltage controlled element;
A resonant circuit that resonates by switching of the high voltage semiconductor switch;
A periodic pulse generator for generating a trigger signal having a shorter time than a half period of the series resonance in order to turn on the primary winding of the pulse transformer for triggering the voltage controlled element;
After the voltage controlled element is turned on, a continuous signal is generated to supply a continuous signal that is an on signal from the detection of the forward current of the series resonance current flowing through the voltage controlled element until the reverse current is detected. With circuit;
An OR circuit for combining the output signal of the periodic pulse generator and the output signal of the continuous signal generation circuit;
And a high-frequency pulse generated by driving the voltage-controlled element with a high-frequency signal synthesized by the OR circuit to resonate the resonant circuit. In claim 1,
The high-voltage semiconductor switch device, wherein the voltage control element is an IGBT or an FET. In claim 1,
The continuous signal generation circuit supplies an ON signal for a required time even after the reverse current starts to flow, and prevents the high-voltage semiconductor switch device from turning off due to a spark generated when switching between the forward current and the reverse current. A high-voltage semiconductor switch device characterized by being a circuit to perform In any one of Claims 1-3,
A two-terminal trigger element connected between the collector of the voltage-controlled element and a rectifier output terminal on the secondary side of the pulse transformer;
When the spark is generated in the dust collection chamber, the two-terminal trigger element becomes conductive and gives a trigger signal to the voltage-controlled element. Thereafter, the continuous signal generation circuit detects the reverse current of the resonance current. A high-voltage semiconductor switch device that supplies an on signal until it is done. In claim 4,
A snubber circuit including a capacitor and a resistor and connected in parallel to the voltage controlled element;
A high-voltage semiconductor switch device, wherein a two-terminal trigger element is connected between the capacitor constituting the snubber circuit and an output terminal of the secondary pulse rectifier. In claim 1,
The sustain signal generation circuit is configured to prevent a stray capacitance flowing again in the forward direction after the reverse current disappears or a charging current of the capacitor constituting the snubber circuit from being misrecognized as a forward resonance current. A high-voltage semiconductor switch device characterized by being a circuit that prevents generation. A high voltage semiconductor switch in which voltage controlled elements having gate turn-off capability are connected in series, a reverse current feedback means connected in antiparallel with the high voltage semiconductor switch, and each primary winding are connected in series with each other. A plurality of pulse transformers that rectify each secondary winding voltage and supply a gate signal of the voltage controlled element, a resonance circuit that resonates by switching of the high-voltage semiconductor switch, and a primary winding of the pulse transformer. A periodic pulse generator for generating a trigger signal shorter than a half cycle of the series resonance to turn on the voltage controlled element, and the voltage control after the voltage controlled element is turned on. Persistence signal that supplies a continuation signal that is an on signal from the detection of the forward current of the series resonance current flowing through the mold element to the detection of the reverse current An OR circuit that synthesizes a raw circuit, an output signal of the periodic pulse generator, and an output signal of the sustained signal generator circuit, and the voltage controlled element is a high-frequency signal synthesized by the OR circuit. A high-voltage semiconductor switching device that generates a high-voltage pulse by driving the resonance circuit to resonate;
DC power supply;
With capacitive load;
A resonant inductor and a coupling capacitor connected in series between the capacitive load and the DC power source;
When the high voltage semiconductor switch is turned on, the high voltage semiconductor switch is connected in series with the DC power source, and is also connected in series with the capacitive load, the resonant inductor, and the coupling capacitor. The high-voltage generating device according to claim 1, wherein the resonant circuit of the high-voltage semiconductor switch device is a circuit constituted by the resonant inductor, the coupling capacitor, and a capacitance of the capacitive load. In claim 7,
The high voltage generator is an apparatus used in a pulse charge type electrostatic precipitator.

Images