Analysis of a series resonant converter pulse width-modulated or current-controlled for low switching loss

Pulse width modulation (PWM) and current-controlled switching are applied to a full-bridge series resonant converter to regulate the output from no load to full load with low switching loss and with a narrow range of frequency variation. Drive strategies, control law, component stress, and other steady-state functions are analyzed for both switching modes. The range of frequency variation of the resulting switching scheme is narrower than that of a normal square-wave drive. It is noted that the advantages of low switching stress and narrow band frequency variation can be extended over the entire range of voltage gain or load by combining PWM with current-controlled switching