Comparison of half-bridge ZCS-QRC and ZVS-MRC for offline applications

Performance comparisons of the half-bridge (HB) half-wave zero-current-switched (ZCS) quasi-resonant converter (QRC) and the zero-voltage-switched (ZVS) multiresonant converter (MRC) are presented. The two converters were compared with respect to their efficiency, input voltage range, semiconductor-component stresses, power density, and reliability. A qualitative loss analysis reveals that the efficiency of the HB ZVS-MRC can be significantly lower at a nominal operating voltage when the input-voltage range is wide. The maximum efficiency of the HB ZCS-QRS is almost independent of the input-voltage range. These findings were verified experimentally by measuring efficiencies of 100 W offline HB ZCS-QRCs and ZVS-MRCs designed for various input-voltage ranges.