Two-stage three-phase soft-switching current transformer

Abstract

The invention discloses a two-stage three-phase soft-switching current transformer which comprises a front-stage DC / DC transformer and a rear-stage three-phase DC / AC transformer. A resonant branch composed of an auxiliary switching tube having an anti-parallel diode, a clamp capacitor and a resonant inductor is connected between a positive common bus of the front and rear stages and an intermediate DC-side capacitor. A resonant capacitor is connected in parallel with main switching tubes and the auxiliary switching tube. The auxiliary switching tube is synchronized with the driving pulse signals of the main switching tubes in the current transformers in the front and rear stages, so as to realize zero-voltage turning-on of all the switching tubes in each switching period, and suppress thereverse recovery current of the anti-parallel diodes of the main switching tubes. The two-stage three-phase soft-switching current transformer is low in switching loss, high in circuit efficiency, andcontributes to increasing the switching frequency and increasing the system power density.

Description

technical field [0001] The invention relates to the technical field of DC-AC conversion, in particular to a two-stage three-phase soft-switching converter circuit. Background technique [0002] The traditional two-stage three-phase converter circuit includes four sets of half-bridge arms; the first half-bridge arm and the input side inductor form a DC-DC converter, the second half-bridge arm, and the third half-bridge arm The bridge arm, the fourth half-bridge arm and three AC side inductors form a three-phase DC-AC converter connected to the three-phase grid; the upper and lower ends of the four bridge arms are connected in parallel to form positive and negative busbars directly connected to the DC The bus capacitors are connected, and the first half-bridge arm converts the voltage of the input DC source into a DC bus voltage, which is used as the input voltage of the subsequent three-phase DC-AC converter; the traditional two-stage three-phase converter The converter circ...

AI Technical Summary

Problems solved by technology

[0002] The traditional two-stage three-phase converter circuit includes four sets of half-bridge arms; the first half-bridge arm and the input side inductor form a DC-DC converter, the second half-bridge arm, and the third half-bridge arm The bridge arm, the fourth half-bridge arm and three AC side inductors form a three-phase DC-AC converter connected to the three-phase grid; the upper and lower ends of the four bridge arms are connected in parallel to form positive and negative busbars directly connected to the DC The bus capacitors are connected, and the first half-bridge arm converts the voltage of the input DC source into a DC bus voltage, which is used as the input voltage of the subsequent three-phase DC-AC converter; the traditional two-stage three-phase converter The converter circuit works in a hard switching state, there is a diode reverse recovery phenomenon, and the switching loss of the converter device is large, which limits the improvement of the operating frequency, resulting in the need to use a larger filter and reducing the circuit efficiency.

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