High-Efficiency•Low-Noise DC Link Resonant Three-Phase Inverter and Commutation Current Control

Abstract

This paper discusses a soft switching circuit and a control system utilizing resonance operation. The main circuit is composed of a full bridge PWM inverter-converter connecting a capacitor in parallel with each switch and a commutation circuit for DC link voltage resonance. The commutation circuit consists of two switches, a DC capacitor and a reactor. Compared with the ordinary soft switching system, the proposed system has low part count. To control the commutation circuit, commutation switches are controlled, based on the detected values of input-output currents and DC capacitor voltage. This control methodology enables all the switches to softly switch. An experiment on a 10kVA system has verified that the proposed system reduces conduction noise by about 20dB and improves input-output efficiency from 86.9% to 88.7% as contrasted with the hard switching system.