Method for inhibiting second harmonic current of preceding-stage inverter of two-stage inverter and control circuit of preceding-stage inverter of two-stage inverter

Abstract

The invention relates to a method for inhibiting second harmonic current of a preceding-stage inverter of a two-stage inverter and a control circuit of the preceding-stage inverter of the two-stage inverter. By the method, the low-frequency pulse current of the preceding-stage direct current inverter can be inhibited obviously, the dynamic performance can be improved and the dynamic response speed is increased. The control circuit of the preceding-stage inverter consists of a band-pass filter, a voltage regulator, a summator, a power-width modulation (PWM) modulator and a driving circuit. The work principle is as follows: a voltage sampling circuit detects intermediate bus voltage, compares the intermediate bus voltage with a voltage reference signal to generate an error signal and transmits the error signal to the voltage regulator; a current sampling circuit detects the inductive current of the preceding-stage direct current inverter; the inductive current of the preceding-stage direct current inverter, an output signal of band-pass filter and an output signal of the voltage regulator are added by the summator to generate a modulation signal; the modulation signal is transmitted to a PWM modulation circuit; and a driving signal of a switch tube is acquired by the driving circuit, so that operation of the preceding-stage direct current inverter is controlled.

Description

technical field [0001] The invention relates to a method for suppressing low-frequency pulsating current of a front-stage converter in a two-stage inverter and a control circuit thereof, belonging to the category of new energy generation and power electronic conversion. Background technique [0002] With the increasingly serious energy crisis and environmental pollution, the development and utilization of new energy sources are paid more and more attention by people. At present, the main way of development and utilization of new energy is distributed power generation, of which the inverter is an important component core. According to the number of stages of the inverter, it can be divided into two categories: single-stage and two-stage. Due to the gap and randomness of the new energy power supply unit, the input voltage range of the inverter is often wide. The two-stage inverter can use the front-stage DC converter to regulate voltage, which is beneficial to the optimal de...

AI Technical Summary

Problems solved by technology

However, this method makes the cut-off frequency of the front-stage DC converter voltage outer loop lower, resulting in poor dynamic characteristics. When the load changes suddenly, the intermediate bus voltage will drop and overshoot obviously.

The obvious drop of the bus voltage may cause the output voltage of the inverter to "cut the top", thus affecting the power supply quality of the load in the dynamic process, and the obvious overshoot of the bus voltage will greatly increase the voltage of the switching tube of the subsequent inverter stress

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