High efficiency two‐channel single‐stage switching amplifier with power switches multiplexing

Abstract

A two-channel single-stage switching amplifier (SSA) based on highfrequency link inverter is proposed. The audio input signals are modulated by phase shift between primary-side switches and secondary-side switches, thus independent amplifications of two channels can be obtained. Benefiting from multiplexing of primary-side power switches for two channels, only a half bridge inverter is utilised at primary side. Clamp circuits at the secondary side of transformer eliminate spike voltages across the secondary-side switches during the current commutation of the cycloconverters. Zero voltage switching of primary-side switches and clamp switches are achieved by utilising magnetising inductor current. A 320 V/250W prototype is presented to verify the analysis results of the proposed two-channel SSA.