Analysis and Comparison of Three Typical Resonant DC-DC Converters

HF transformer isolated resonant converters are well-suited for high-power DC-DC systems. Investigation of three typical series and parallel resonant (SPR) topologies are presented. Expressions of each circuits are derived to exhibit their natural voltage and current characteristics based on the approximate analysis approach. Design criteria incorporated with the soft switching and gain requirements are developed for key parameters for each topology. Soft simulation results for three converters are presented in this paper. Simulation result shows that the CLLC-type leads to the highest efficiency for full-load range, but the LCL-type shows better economic performance. It's recommended that the LCL-type could be a good alternative for the CLLC-type in some special applications.