A fixed-frequency soft switching series resonant converter with adaptive auxiliary circuit for transportation applications

Frequency modulation is often used in series resonant converters to gain output voltage regulation. Variable frequency however brings challenges for EMI filter and switch driver design and the desirable zero voltage switching cannot be maintained at light load conditions. This paper presents a fixed-frequency series resonant converter with phase shift modulation and an adaptive passive auxiliary circuit proposed to ensure the zero voltage switching of the converter in all three operation modes with reduced losses for the lagging leg.