A generic soft switching converter topology with a parallel nonlinear network for high power application

A soft switching concept which combines the best features of resonant hard switching converters is applied to a phase arm. The induction of the resonant LC circuit is designed to saturate, thus having effectively two inductance values: a very large value during the conduction period and a small value which is only active during switching. The advantage of this technique is that a resonant tank with smaller continuous ratings can be used, without giving up the component count advantage of resonant converters. Another feature, contrary to other resonant topologies, is that semiconductor switches need not be overdiminished for voltage and current rating. The converter is free running, with the switching instances being determined by threshold current levels, while the PWM (pulse width modulation) output is controlled by an external current source. A nonlinear inductor is included in the resonant tank, which reduces the RMS current rating of the inductor and switches.<>