Implementing method of high-voltage square-wave generator

Abstract

The invention relates to an implementing method of a high-voltage square-wave generator. The generator comprises a high-voltage DC (Direct Current) source, a resistor, an energy storage capacitor, a triggering pulse width adjusting module, a rising edge circuit, a falling edge circuit and a synchronous control triggering module; the rising edge circuit comprises a solid switch MOSFET (Metal Oxide Semiconductor Field Effect Transistor) and an optical coupling isolation driving circuit; the falling edge circuit comprises a solid switch MOSFET circuit and avalanche transistor string; the high-voltage DC source, the resistor, the energy storage capacitor, the triggering pulse width adjusting module, the solid switch MOSFET and the optical coupling isolation driving circuit are connected to the avalanche transistor string in sequence. The implementing method comprises the steps of: (1) pre-charging the energy storage capacitor by the high-voltage DC source; (2) converting an outer triggering signal into a pulse width adjustable square wave signal by the triggering pulse width adjusting module; (3) controlling the optical coupling isolation driving circuit to drive the MOSFET to be in on-state so as to charge a load and form the rising edge circuit; (4) driving the MOSFET and avalanche transistors of the falling edge circuit to be in on-state so as to cut off an output pulse rapidly and form the falling edge circuit.

Description

technical field [0001] The invention belongs to an electric power system, and in particular relates to a method for realizing a high-voltage square wave generator. Background technique [0002] In the power system, in order to test the ability of power equipment to withstand lightning overvoltage and operating overvoltage, it is necessary to perform an impulse voltage withstand test before leaving the factory. Therefore, all major high-voltage laboratories across the country are equipped with high-voltage impulse voltage generators and impulse voltage dividers. Instruments, secondary measuring instruments and other measuring equipment. Among them, the wave front time of the lightning full wave is (0.84-1.56) μs, the steep wave front time is <0.5 μs, and the wave front cut-off time of the lightning cut-off wave also needs to be <0.5 μs, which requires the measuring voltage divider to have a good Transient response characteristics, otherwise it will lead to large measur...

AI Technical Summary

Problems solved by technology

[0003] The square wave generator based on the mercury switch is usually used. The advantages of this type of generator are: easy to use, good repetition frequency characteristics, and the rise time of the square wave can reach ns level, which can meet the requirements of the step wave response test, but Mercury switches have limited withstand voltage, and ordinary mercury switches can only generate (100-300) V low-voltage square waves

With the increase of the voltage level, the voltage division ratio of the impact voltage divider continues to increase. When the low-voltage square wave signal is applied to the high-voltage side of the voltage divider, the signal measured on the low-voltage side is quite weak, and it is susceptible to surrounding electromagnetic interference. It cannot be distinguished on the measurement digital oscilloscope, let alone analysis and calculation

In addition, for a pulse generator that uses a pulse forming line or a Marx circuit and is designed based on the steepening switch principle, although the rise time of the output square wave can be very short (several ns or even ps level), and the amplitude can also reach Tens of kilovolts, but its output pulse width is very short, usually only a few hundred ns, and the jitter is large

Since the stabilization time of the impact resistance voltage divider is generally about 200ns, the stabilization time of the weak damping voltage divider is longer, so the exact stabilization time of the voltage divider cannot be calculated if the pulse width is too small, and the measurement results cannot be distinguished when the jitter is large Is the oscillation in the waveform caused by the power supply or the transient response of the voltage divider itself

[0004] In recent years, various researchers have tried to use solid switches instead of gas discharge switches as the main switch to conduct research on square wave generators. The solid switches are mainly MOSFETs and avalanche transistors. This type of solid switch has the advantages of stable on-off and good repeatability. However, its pressure resistance is low and its flow capacity is poor

The square wave generator with MOSFET as the main switch is not suitable for capacitive loads with large capacitance values ​​due to the slow turn-on speed of the MOSFET tube and the slow front (back) edge of the output square wave; the main switch is the avalanche triode The square wave generator of the switch, because the flow capacity of the avalanche tube is poor, the output square wave pulse width is narrow, and when the capacitance value of the capacitive load is large, the front edge (or trailing edge) of the square wave becomes slow, and the avalanche tube Easy to burn out due to overcurrent

Therefore, using the above-mentioned type of square wave generator, it is difficult to calibrate the step wave response of the voltage divider conveniently, comprehensively and reliably

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