Realization of digital audio amplifier using zero-voltage-switched PWM power converter

Abstract

This paper presents a simple methodology to convert a hard-switched pulse-width-modulated (PWM) H-bridge converter used in a classical digital audio amplifier into a zero-voltage-switching (ZVS) converter. The ZVS is simply achieved by connecting an L-C series branch across the converter output. ZVS occurs during the dead time interval of the PWM signals, giving an effective improvement in the conversion efficiency, output frequency spectrum, and total harmonic distortion. A simplified design procedure is provided for choosing the value of the components. A prototype digital amplifier with an output power of 20 W and switching frequency of 705.6 kHz has been implemented. Experimental results are presented and favorably verified with theoretical predictions.