Analysis of a constant frequency series-parallel multiresonant converter for high power and increased output voltages

For increased output voltages, only resonant switching and capacitive output filters reduce the reverse recovery effect of the rectifier diodes significantly. In high power applications, less switching losses of the active switches like IGBTs result in desired higher switching frequencies. The proposed constant frequency series-parallel multiresonant power converter combines the advantages of resonant switching, capacitive output filter and constant switching frequency. The converter characteristics are obtained with the unified state space analysis. The influence of the ZVS snubber capacitances on the converter operation region is important and therefore considered in the analysis. The analysis presented can also be used for the frequency variable series and series-parallel converters in over- and underresonant regime. The mixed zero current switching (ZCS) and zero voltage switching (ZVS) operation of the converter is shown to be the most favourable operation for minimum component stress. Experimental verification of the analysis is given