Natural commutation technique to reduce voltage surges and switching losses in a cycloconverter-type high frequency-link inverter

Abstract

This paper presents an isolated cycloconverter-type high-frequency (HF) link inverter that consists of three arms of bidirectional switches at the transformer secondary. This topology has the advantages of light weight and reduced switch count, when compared to other types of HF link inverters. However, like all HF link inverter topologies, this topology suffers from a high-voltage surge problem and power device switching loss. In order to overcome these problems, the natural commutation method that enables soft-switching operation is applied. To verify the viability of the scheme, a low-power laboratory prototype based on the Siemens 80C167 fixed-point microcontroller is constructed. In addition, the simulation of the inverter is also carried out. The prototype inverter is able to supply output voltage at 120 Vrms, with a total harmonics distortion of less than 1%. The total power conversion efficiency reaches 86% when the output power is over 300 W.