Commutation processes in a multiresonant ZVS bridge inverter regulated by phase shifting the control of the two legs

We present in this paper an analytical study of an indirect DC-DC converter using a bridge series resonant inverter operating above the resonant frequency. If the operation is in the ZVS mode, the snubbers reduce to capacitors in parallel with the inverter power electronic components. The aim of the paper is to determine the conditions allowing one to obtain ZVS commutation in the inverter when a phase shift is introduced between the controls of the two legs. We show that when the ZVS mode is possible, two operating modes must be considered: in the first operating mode the converter is multiresonant with two resonant frequencies, while in a second operating mode three resonant frequencies are involved. The limits corresponding to each operating mode have been determined according the values of the frequency and shift angle.