Analysis and design of LCL-type series resonant converter

A series resonant power converter modified by adding an inductor in parallel with the transformer primary (or secondary) is presented. This configuration is referred to as ´LCL-type series resonant converter´. A simplified steady-state analysis using complex circuit analysis is presented. Based on the analysis, a simple design procedure is given. Detailed experimental results obtained from a MOSFET-based 500 W converter are presented to verify the analysis. A narrow variation in switching frequency is required to regulate the output voltage constant for a very wide change in load, and the converter has load short circuit capability. It is shown that by placing the parallel inductor on the secondary-side, the parasitics of the high-frequency transformer can be used profitably.<>