Design of LLC Resonant Converters Based on Operation-Mode Analysis for Level Two PHEV Battery Chargers

In this paper, the efficiency-oriented design considerations are discussed based on the operation-mode analysis of the
LLC
converter considering the characteristics of charging profiles. The mode boundaries and distribution are obtained from the precise time-domain model. The operation modes featuring both-side soft-switching capability are identified to design the operating trace of the charging process. Then the design constraints for achieving soft switching with the load varying from zero up to the maximum are discussed. Finally, a charging trajectory design methodology is proposed and validated through experiments on a prototype converting 390 V from the dc power source to the battery emulator in the range of 250–450 V at 6.6 kW with a peak efficiency of 97.96%.