DC (direct current)/AC (alternating current) inverter circuit

Abstract

The invention relates to a DC (direct current) / AC (alternating current) inverter circuit, comprising a buck chopper and a commutation rectification circuit, wherein the buck chopper comprises a power switching tube, a diode, an inductor and a capacitor modulated by an SPWM (sinusoidal pulse width modulation). An SPWM mode is adopted to regulate the duty ratio of a high-frequency switching tube in the buck chopper so as to convert DC energy into sine half-waves; and the commutation rectification circuit formed by four controlled rectifiers carries out commutation rectification on the sine half-waves so as to finish the invertion from DC to sine AC. Compared with a common full-bridge inverter circuit, in the novel DC / AC inverter circuit, the structure is simple, the fewer high-frequency tubes are used, the invertion efficiency is improved and the cost is reduced. In the commutation process, the inverted AC is output to generate constant common-mode voltages so as to suppress common-mode currents; and the switching tube in the buck chopper can separate low-frequency input from high-frequency output when the switching tube is switched off, thus reducing the EMI (electro magnetic interference).

Description

technical field [0001] The invention relates to an inverter circuit, in particular to a DC / AC inverter circuit. Background technique [0002] The function of the inverter circuit is to convert the DC voltage into a sinusoidal AC that can be supplied to electrical appliances or connected to the grid for new energy generation. High efficiency and low harmonic distortion are key indicators of this technology. [0003] The existing inverter technology mostly adopts four-tube full-bridge circuit structure, such as figure 2 shown. In the full-bridge bipolar modulation circuit, the four switching tubes (shown in the dotted line box) all work at a relatively high switching frequency. The loss of the switching tubes is large, which affects the efficiency, and there is a large current ripple amplitude. In the full-bridge unipolar modulation circuit, the amplitude of the common-mode voltage generated by the inverter varies greatly, and the resulting common-mode current increases lin...

AI Technical Summary

Problems solved by technology

In the full-bridge bipolar modulation circuit, the four switching tubes (shown in the dotted line box) all work at a high switching frequency, the loss of the switching tube is large, which affects the efficiency, and there is a large current ripple amplitude

In the full-bridge unipolar modulation circuit, the amplitude of the common-mode voltage generated by the inverter varies greatly, and the resulting common-mode current increases linearly with the increase of the switching frequency, and the harmonic distortion is serious

In the full bridge structure, multiple power switch tubes need to be selected, and the cost is relatively high

Images