Comparison of Control Techniques for Series Resonant Converter

Abstract

There are many different derivatives of the variable and fixed frequency switching control techniques used in the control of load resonant converters. In this study; among these techniques frequency modulation (FM), phase shift modulation (PSM) and pulse density modulation (PDM) are applied separately to series resonant converter (SRC). The techniques are examined and compared in many respects. An experimental setup was built, which consists of a 400W converter (with the input voltage of 200 V and the output voltage of 36V), a control circuit and a resistive load to verify the theoretical studies. The converter is controlled by FM, PSM and PDM separately for 120 kHz basic operating frequency and different output currents. The experimental results are compared in terms of efficiency, output voltage ripple, soft switching, switch voltage and ease of application and hardware. The comparison results are presented. It is observed that FM has better performance than the other two techniques in many aspects.