KR20010088926A - Pulsed or step-like high-voltage generator composed of semiconductor switches and high-frequency transformers - Google Patents

Abstract

PURPOSE: The pulse type and step wave type high voltage generation equipment combining with semiconductor switch and high frequency wave transformer is provided, in which has long life and is able to vary output voltage width, frequency and voltage, and input power source uses voltage rectified from low DC voltage or power frequency voltage. CONSTITUTION: The pulse type and step wave type high voltage generation equipment combining with semiconductor switch and high frequency wave transformer comprises a single phase high frequency inverter(200) to transfer low voltage DC power source(100) to AC, a high frequency wave transformer(300) to rise to necessary voltage, a diode bridge(D1) to transfer to DC, a capacitor(C1) to charge and store V1. The third wiring(T13) of the high frequency wave transformer(300) rises voltage according to turn ratio(N13/N11) of the first winding(T11) and delivers energy to following the other high frequency wave transformer(310). The high voltage generating circuit is connected to have cascade type energy transfer and delivery structure, and outputs desirable voltage to connect to the multiple transformers(300,310) and a transfer circuit(410) in series.

Description

Pulsed and Stepped Waveform High Voltage Generator Combining Semiconductor Switches and High Frequency Transformers {PULSED OR STEP-LIKE HIGH-VOLTAGE GENERATOR COMPOSED OF SEMICONDUCTOR SWITCHES AND HIGH-FREQUENCY TRANSFORMERS}

The present invention is a high voltage generator using a semiconductor switch and a high-frequency transformer, in particular, a high voltage generation having a structure capable of adjusting the magnitude, width (or period) and frequency of the output voltage by generating a high voltage of pulse waveform or step waveform from low voltage direct current. Relates to a device.

In general, high voltage pulse generator circuits are widely used for various applications such as test equipment and low voltage and high temperature plasma generator laser power supplies.

Until now, various pulse generation circuits have been used in the industry for each purpose. Conventional high voltage pulse generation circuits have problems such as device life, variable pulse width, increase of operating frequency, adjustment of pulse voltage, and need for DC high voltage power supply. It has its own disadvantages in terms of.

In other words, the existing high voltage pulse generator device uses a Marx generator method using a spark gap widely used in the impulse test of an electric device, and stores energy in a charging device using a high voltage DC power source, and then switches the voltage to a high voltage switch to switch the pulse. There is a method of shaping or boosting low voltage pulse to high pressure by using pulse transformer. Conventional method using spark gap or vacuum tube high voltage switch has short life span and requires high voltage power circuit. Therefore, there is a disadvantage in that the circuit is complicated, and the method of directly using the pulse transformer has a lot of difficulty in obtaining the rise time as the boost ratio is large.

FIG. 1 illustrates a conventional pulse voltage generation circuit using a spark gap, and FIG. 2 illustrates a conventional pulse voltage generation circuit using a thyratron or a thyristor, and the pulse voltage of FIG. 1. The generator circuit is used in high power fields of several megavolts (MV) and mega amps (XA), and the pulse voltage generator circuit of FIG. 2 is connected to an energy storage circuit by using a high-voltage switch for input such as cyratron or thyristors. By discharging the charged high voltage, it produces a high voltage pulse at the output stage, and is mainly used in the medium capacity pulse generating circuit.

Conventional pulse voltage generation circuits as shown in FIGS. 1 and 2 have the advantage of easily making high voltage and high power pulses with a simple structure, but the structure of FIG. 1 basically requires a DC high voltage at an input terminal to operate a spark gap. Special trigger circuits are required to meet the timing of the generation of pulse voltages. The circuit of FIG. 2 is mainly used for generating pulses of several tens of kV and several kA by input switch method. Such a circuit is not suitable for small-capacity pulse generating circuits. To do this, a pulse shaping circuit must be added, and the pulse width control is very difficult.

In addition, the pulse generating circuit has a direct boosting method using a pulse transformer. However, if the boosting ratio is large, the leakage inductance of the transformer is increased, and thus the pulse generation circuit does not satisfy the characteristics such as the rise time and width of the pulse voltage. In addition, the pulse compression circuit using the saturation inductor reduces the pulse width and increases the current size, so that only one or two stage compression is possible in a special case, and the required core is very expensive.

Briefly summarized the problems in the conventional pulse generating circuits mentioned above are as follows.

The circuit of FIG. 1 has a disadvantage of short device life due to damage of the spark gap, and the circuit of FIG. 2 has a disadvantage of low voltage rating and average switching current of the cyratron and thyristors. All must use high voltage DC power as input power. In addition, since the switches used in FIG. 1 and FIG. 2 have only a turn-on structure, a pulse shaping circuit must be added to obtain a square wave pulse, and there is a problem in that the width of the output pulse cannot be changed. In addition, the method using a pulse transformer that is frequently used also can not obtain the desired pulse due to the slow rise time in the structure of large boost ratio. In addition, there is a pulse generator using a pulse compression circuit, but the pulse width is not variable, and since a DC high voltage circuit is required at the input terminal, the conversion efficiency is low.

Accordingly, an object of the present invention is to provide a long life, variable output voltage, frequency and voltage, and to rectify the input terminal power supply from a low DC voltage or a commercial voltage.

Still another object of the present invention is to use a high voltage input power supply when a high voltage is required, and to freely obtain a fast voltage rise and an output voltage of a desired size.

Still another object of the present invention is to reduce the size of the device and to provide a high voltage output voltage circuit having a pulse waveform and a step waveform, by considering only the dielectric strength of the input voltage and the output pulse voltage.

1 is a conventional pulse voltage generation circuit diagram using a spark gap,

2 is a conventional pulse voltage generation circuit diagram using a thyrrone or a thyristor, etc.

3 is a high voltage generation circuit diagram according to an embodiment of the present invention;

4 (a), (b) and (c) are detailed configuration diagrams of the high frequency transformer of the present invention;

5A and 5B are waveform diagrams showing operating characteristics of the present invention;

6 is a waveform diagram showing an operating characteristic of the present invention;

7 is a waveform diagram showing an operating characteristic of the present invention.

(Explanation of symbols for the main parts of the drawing)

100: low voltage DC power supply 200: single phase high frequency inverter

300, 310: high frequency transformer 410: conversion circuit

500: Load

D ₁ , D ₂ D _n : Diode Bridge

d ₁ , d ₂ d _n : bypass diode

C ₁ , C ₂ C _n : Capacitor

S ₁ , S ₂ S _n : semiconductor switch (IGBT)

V ₁ , V ₂ V _n : Charge voltage of capacitor

T ₁₁ , T ₁₂ T _n3 , T _1a T _na : transformer winding

Vout: Output Voltage

V _GS , V _GS1 V _GSn : Kate voltage of IGBT

t ₁ , t ₃ , t _2n-1 : Switch turn-on time

t ₂ , t ₄ , t _{2 n} : switch turn-off time

t _on : switch on-time

t _off : switch off-time

T: period of pulse voltage or step waveform

N ₁₁ , N ₁₂ , N ₁₃ , N _1a : Low-power auxiliary winding for primary, secondary and tertiary windings and switch drive power of three-winding transformer

In order to achieve the above object, it will be described in detail with reference to the accompanying drawings.

3 is a high voltage generating circuit according to the present invention, which converts from a low voltage DC power supply 100 into an alternating current in a single phase high frequency inverter 200 and boosts the voltage required by the high frequency transformer 300 (V ₁₂ = N ₁₂ V). ₁₁ / N _11), and a diode bridge (which D ₁₎ to the storage charging the direct current converted by then, V ₁ to a capacitor (C ₁₎ energy storage capacity castle. The third winding T ₁₃ of the high frequency transformer 300 of the first stage is boosted by the winding ratio N ₁₃ / N ₁₁ of the first winding T ₁₁ to energize the high frequency transformer 310 of the next stage. It is connected to have a cascade-type energy conversion and transmission structure having a structure to transmit the power, and outputs a desired voltage by connecting a plurality of transformers 300 and 310 and the conversion circuit 410 in series. have.

As such, the energy stored in capacitors C ₁ , C ₂ , and C _n is connected in series by the IGBT switches S ₁ , S ₂ , and S _n to the maximum peak voltage (V ₁ + V ₂ ++ V _n ). It is a structure that can produce output voltage up to. Meanwhile, when one or a plurality of switches of the IGBT switches S ₁ , S ₂ , and S _n are not turned on, capacitors and switch pairs C ₁ -S ₁ , C ₂ -S ₂ , which are connected in series C _n -S _n ) is a structure in which a circuit is connected through a corresponding diode among the bypass diodes (d ₁ , d ₂ , d _n ) connected in parallel.

This structure can solve the overvoltage problem of the switch which may occur according to the difference in the operation characteristics of each IGBT switch.

As described above, by using the IGBT which is a semiconductor switch capable of easily controlling the circuit structure according to the present invention by using a small-weight transformer and a control circuit using a high frequency, the operating frequency, the pulse width variable, the magnitude of the output voltage and the waveform are varied. The lifetime and variability of the existing high voltage pulse generator have been solved.

4 (a), (b) and (c) are detailed structural diagrams of the high frequency transformer constituting the present invention. First, FIG. 4 (a) shows that the output voltage V ₁₁ of the single phase high frequency inverter 200 is It is connected to a primary winding (T ₁₁₎ of the high-frequency transformer (300) having a number of turns of N ₁₁ is output to the second primary winding (T _12), the tertiary winding (T _13), the transformer of the next stage through the And connected to 310. On the other hand, the auxiliary winding (T _1a ) is for supplying the power required by the drive circuit of each switch is converted to a low voltage (V _1a = V ₁₁ N _1a / N ₁₁ ) is supplied.

Figure 4 (b) is a transformer structure used in a plurality of stages having the same structure as the first stage transformer 300, the n stage of the last stage of the entire circuit composed of n stages are shown in (c) of FIG. Similarly, a transformer having only a primary winding T _n1 , a secondary winding T _n2 , and a low power auxiliary winding T _na for supplying a switch driving power is shown.

5, 6, and 7 are views showing a preferred operation example of the present invention, and FIG. 5A shows the gate signals V _GS of the IGBT switches S ₁ , S ₂ , and S _n at the same time point. After turning on t ₁ to t ₂ and then turning on t ₃ to t ₄ , the output voltage is the voltage (V ₁ , V ₂ , V _n ) stored in each capacitor (C ₁ , C ₂ , C _n ). The superimposed rectangular pulse waveforms can be adjusted by adjusting the number of turn-on switches, and the fine voltage adjustment is possible by controlling the magnitude of the DC voltage.

5 (b) shows that the output voltage (V ₁ + V ₂ + + V _i ) can be output when the switch up to i stages is turned on.

6 and 7 show that a stepped waveform high voltage output can be obtained by controlling the time difference and the time of the gate signal V _GS of each switch.

As described above, the circuit and the device according to the present invention have the following effects.

First, it is possible to generate an output capable of controlling the pulse width, the frequency, and the magnitude of the output voltage by using a rectified DC power source or a commercial AC power source without using a high voltage DC power source and using a high frequency transformer and a conversion circuit.

Second, long life transformers and semiconductor switches are used to make the life of the device semi-permanent.

Third, since the insulation of the driving circuit required for driving the switch of the high voltage device is possible by the insulation between each transformer, the insulation structure can be reduced by the insulation between the transformer windings.

Fourth, if the AC power supply is connected and rectified in front of the DC power supply of the input, fine adjustment of the output voltage can be facilitated.

Lastly, it is possible to construct a power supply unit capable of generating a very high voltage without being limited by the voltage rating of the power semiconductor developed to date.

Claims (5)

In the high voltage generator, Low voltage DC power supply, A single phase high frequency inverter for converting the DC power into AC; A transformer consisting of three windings stepped up to the required voltage, With diode rectifier to convert alternating current into direct current, A structure comprising a conversion circuit for connecting a storage capacitor and a semiconductor switch in series, Each of a plurality of high frequency transformer and each conversion circuit is connected in series and composed of multiple stages, In addition, the connection between each unit is composed of a semiconductor switch (IGBT), And a high voltage transformer in combination with a semiconductor switch and a high frequency transformer, wherein the voltage stored in the capacitor generates a high voltage by turning on an IGBT element. The method of claim 1, Pulse type and stepped high voltage generator in combination with a semiconductor switch and a high frequency transformer, characterized in that the bypass circuit in parallel with the conversion circuit has a protection function. The method of claim 1, Pulse type and step waveform high voltage generator in combination with a semiconductor switch and a high frequency transformer, characterized in that the auxiliary winding is added to the high frequency transformer to supply a switch driving power to minimize the insulation between the switch and each conversion circuit. The method of claim 1, A pulsed and stepped high voltage generator incorporating a semiconductor switch and a high frequency transformer, wherein the semiconductor switch can be replaced by MCT, IGCT, MOSFFT, or thyristor. The method of claim 1, Pulse type that combines a semiconductor switch and a high frequency transformer, which can minimize the number of transformer cores by using one primary winding, a plurality of secondary and tertiary windings, and auxiliary windings in one core of the transformer. And step waveform high voltage generator.