Novel Selection Criteria of Primary Side Transistors for LLC Resonant Converters

An insightful evaluation of commercial high-voltage power MOSFETs for soft-switching converters is reported in this paper with special emphasis on elucidating power loss contributions and electrical parameter requirements. Experimental tests have been carried out to evaluate different Silicon Super-Junction technologies used in the primary side of a 600 W half-bridge LLC resonant converter operating in inductive mode. Unexpectedly, none of the existing figures of merit, inferred from datasheets, can predict the performance ranking due to the additional soft-switching losses (Esw _{_SOFT} ). Subsequently, a new characterization test based on a pulsed I-V system is suggested and proved to quantify E _{SW_SOFT} .