CN202153252U - Induction withstand voltage tester based on AC frequency conversion technology - Google Patents

Abstract

The utility model relates to an induction withstand voltage tester based on AC frequency conversion technology, which is composed of a rectifier circuit, a filter voltage stabilization circuit and an inverter circuit connected in sequence, wherein the rectifier bridge of the rectifier circuit adopts single-phase bridge rectification, and consists of four Composed of two power diodes; the filter and voltage regulator circuit connected after rectification is composed of LC filter circuit and isolation variable filter unit. The inverter circuit adopts pulse width modulation single-phase full-bridge inverter, and the output pulse width is 1-60μs , the output voltage is boosted by the isolation transformer and connected to the detection system, and the port output enters the tested voltage transformer. The utility model is easy to control, convenient and efficient in parameter adjustment, quick in response to parameter adjustment, can adjust voltage and frequency more efficiently and conveniently, and has a wide continuous adjustment range of voltage and frequency.

Description

Induction withstand voltage tester based on AC frequency conversion technology

technical field

The utility model belongs to the field of high-voltage test equipment, and relates to an induction withstand voltage tester, in particular to an induction withstand voltage tester based on AC frequency conversion technology.

Background technique

With the continuous maturity of power electronics technology, AC frequency conversion technology is widely used in various fields. Due to the improvement of control methods, the output voltage of frequency conversion power supply can meet the requirements of voltage transformer induction withstand voltage test and excitation characteristic test. Previously, voltage transformer induced withstand voltage tests were usually performed with triple frequency generators consisting of low saturation single-phase transformer wiring. The primary side of the three single-phase transformers are star-connected without a neutral line, and connected to the three-phase AC power supply. In the state of excitation saturation of the single-phase transformer, the output voltage frequency of the secondary open delta side is mainly 150Hz (accounting for about 50%) , but it contains fundamental waves and higher harmonics, and the equipment is bulky, heavy, and expensive.

Contents of the invention

The purpose of this utility model is to overcome the deficiencies of the prior art and provide an induction withstand voltage tester based on AC frequency conversion technology. The induction withstand voltage tester adopts AC frequency conversion technology to conduct induction withstand voltage tests and Excitation characteristic test.

The utility model solves its technical problem and realizes by taking the following technical solutions:

An induction withstand voltage tester based on AC frequency conversion technology, characterized in that it is composed of a rectifier circuit, a filter voltage stabilization circuit, an inverter circuit, and an isolation transformer connected in sequence, and the rectifier bridge of the rectifier circuit adopts a single-phase bridge rectifier , composed of four power diodes; the filter and voltage regulator circuit connected after rectification is composed of LC filter circuit and isolation variable filter unit, the inverter circuit adopts pulse width modulation single-phase full-bridge inverter, and the output pulse width is in 1-60μs, the output voltage is stepped up by the isolation transformer and connected to the detection system, and the port output enters the voltage transformer under test.

Moreover, the trigger signals of the IGBT1 and IGBT4 constituting the inverter circuit are the same, and the outputs are directly connected to the two gates. At the same time, the trigger signals of IGBT2 and IGBT3 differ from the signals of IGBT1 and IGBT4 by half a period. The gate is connected after a period of time delay.

Advantage and positive effect of the present utility model are:

1. The design of this tester is reasonable. It integrates the functions of induction withstand voltage test and excitation characteristic test. It adopts easy-to-operate single-phase AC power input to realize accurate and wide-range output of voltage and frequency.

2. This tester uses AC frequency conversion technology to replace the induction withstand voltage tester based on the principle of electromagnetic induction. It also has the advantages of low cost, light weight, easy control, and energy saving, which saves work preparation and operation time, and is more suitable for on-site work. The application improves work efficiency and reduces the labor intensity of personnel.

3. This tester is easy to control, convenient and efficient to adjust parameters, and responds quickly to parameter adjustments. It can adjust voltage and frequency more efficiently and conveniently. It has a wide range of continuous adjustment of voltage and frequency. It is comparable to triple frequency generators based on the principle of electromagnetic induction. The utility model has the characteristics of simple operation, accurate and reliable output signal, light weight and low cost, and can save energy by more than 30%.

Description of drawings

Fig. 1 is the schematic diagram of the circuit structure of the utility model;

Fig. 2 is the outline schematic diagram of the utility model;

Fig. 3 is an operation interface diagram of the utility model.

Detailed ways

The utility model will be further described in detail below in conjunction with the accompanying drawings and through specific embodiments. The following embodiments are only descriptive, not restrictive, and cannot limit the protection scope of the present invention.

An induction withstand voltage tester based on AC frequency conversion technology, as shown in Figure 1, adopts an AC-DC-AC frequency conversion circuit, which is composed of a rectifier circuit, a filter voltage stabilization circuit, an inverter circuit, and an isolation transformer connected in sequence, wherein the rectifier circuit The rectifier bridge adopts single-phase bridge rectification, which is composed of four power diodes; the filter and voltage stabilization circuit connected after rectification is composed of LC filter circuit and isolation variable filter unit, and the LC filter circuit matches the appropriate capacitor The inductor acts as a filter and regulator. After the alternating current of the power grid is rectified and filtered and stabilized on the LC filter circuit, it enters the subsequent inverter circuit. The inverter circuit adopts pulse width modulation single-phase full-bridge inverter, and the output pulse width changes within 1-60μs. Due to the IGBT1 and IGBT4 The trigger signals are the same, so the output is directly connected to the two IGBT gates. At the same time, the trigger signals of IGBT2 and IGBT3 are exactly half a cycle time different from the signals of IGBT1 and IGBT4. pole. The output voltage is stepped up by the isolation transformer and connected to the detection system, and the port output enters the voltage transformer under test.

Theoretically speaking, the single-phase bridge inverter controlled by SPWM can produce a standard sinusoidal voltage, but the actual instantaneous output voltage is not necessarily a standard sinusoidal wave, but its average value in a sampling period is the standard sine wave. The isolation transformer is a resistive-inductive load, and the load itself can function as a filter, so the output terminal generally does not need to set up a separate filter circuit.

The control method not only determines the quality of the output voltage waveform, but also plays a vital role in reducing system switching losses and improving system efficiency. The pulse width modulation method of the inverter link is very important to the performance of the power supply. This system uses SPWM to control the switching time of the PWM wave through the optimal selection of the switching time.

The detection unit adopts feedback control, that is, an error amplifier is used to reduce the error between the output voltage and the reference voltage. According to the control method and test requirements, it is necessary to detect the output voltage, current, frequency and power. The power test unit used in the detection unit has an accuracy level of 0.5.

The induction withstand voltage tester based on AC frequency conversion technology is shown in Figure 2. It adopts a split design and is easy to carry.

The induction withstand voltage tester based on AC frequency conversion technology is shown in Figure 3, and its operation panel is easy to operate.

The ordinary single-phase power input circuit outputs direct current through the power diode rectifier bridge, and provides it to the inverter part after being filtered and stabilized. The inverter part is a single-phase full-bridge inverter composed of IGBTs, in which the conduction control of the IGBTs is completed by the control drive circuit, and the operation interface is friendly. For the inverter process, the SPWM technology is used to obtain the SPWM voltage waveform, and the voltage amplitude and frequency can be adjusted. The output voltage is stepped up by the isolation transformer and connected to the detection system, and the port output enters the voltage transformer under test.

The design power of the tester is 2kW, input voltage: single-phase 220V, output voltage range: 0 to 380V continuously adjustable, voltage regulation step size: 0.1V, frequency conversion range: 30 to 300Hz, frequency conversion step size: 0.1Hz, measurement accuracy: Level 0.5.

The performance comparison table between the induction withstand voltage tester and the triple frequency generator is provided below

Claims (2)

1. induced over voltage withstand test appearance based on alternating frequency conversion technique; It is characterized in that: connect and compose successively by rectification circuit, filter regulator circuit, inverter circuit, isolating transformer; What wherein the rectifier bridge of rectification circuit adopted is single-phase bridge rectification, is made up of four electric power diodes; The filter regulator circuit that is connected after the rectification becomes filter unit two parts by LC filtering circuit and isolation and forms; Inverter circuit adopts the inversion of width modulation single-phase full bridge; Output pulse width is at 1-60 μ s; Output voltage is through the isolating transformer access detection system of boosting, and port output gets into by the examination voltage transformer (VT).

2. the induced over voltage withstand test appearance based on alternating frequency conversion technique according to claim 1; It is characterized in that: the IGBT1 of said formation inverter circuit, the trigger pip of IGBT4 are identical; Output directly inserts these two grids; Simultaneously the trigger pip of IGBT2, IGBT3 and IGBT1, the time in IGBT4 signal phase difference of half cycle, insert grid behind the time delays through the adding half period.

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