Optimal Design for Efficiency Improvement in Three Element Resonant Converters Based on their Load Dependent Properties

Resonant converters have become a popular choice for power dense, efficient converters with applications ranging from laptop charging to Electric Vehicle (EV) charging. With the advent of new semiconductor devices like Gallium Nitride (GaN) and Silicon Carbide (SiC) MOSFETs, the usability of the resonant converters have increased to a great extent. Still the design of these converters are challenging and requires critical understanding because the features which make them favourable are dependant on their loading conditions. Unlike the popular DC-DC converters, these converters are inherently capable of Zero Voltage Switching (ZVS) with reduced losses during both turn ON and OFF transitions. Also the circulating currents in these resonant converters pose another limitation in utilising these converters. This paper addresses the optimal and efficient design of three element resonant converters considering the ZVS boundaries and circulating currents by understanding their load dependent properties.