Design oriented analysis of reactive power in resonant converters

An analysis of reactive (circulating) power and RMS currents in a number of resonant converters is presented. The analyzed converter topologies include the half-bridge zero-current-switching quasi-resonant-converter (HB ZCS-QRC), the half-bridge zero-voltage-switched multiresonant-converter (HB ZVS-MRC), the constant frequency half-bridge zero-voltage-switched multiresonant-converter (CF HB ZVS-MRC), the HB ZVS that uses the magnetizing inductance as a resonant element (HB ZVS-MRC (L/sub M/)), and the full-bridge series-parallel-resonant-converter (FB SPRC). It is shown that the HB ZCS-QRC and the soft-switched HB ZVS-MRC (L/sub M/) circulate relatively small amounts of power. However, the circulating power in the HB ZVS-MRC, CF HB ZVS-MRC, and SPRC is found to be considerably larger. The analysis is used to generate sets of characteristics for each converter that can be used in their design optimization based on the minimization of the circulating power. Several design examples are presented for the HB XVS-MRC and SPRC.