Soft-single-switched dual forward-flyback PWM DC-DC converter with non-dissipative LC circuit

In this paper, a new soft switching forward-flyback DC-DC converter is proposed. Due to the leakage inductance of the transformer, conventional forward-flyback converter suffers from low efficiency and high switch stress. For practical implementation of this converter, snubber and clamp circuits are necessary. RCD snubber can limit the voltage spike across the primary switch however the energy of the leakage inductance is dissipated in a resistor. In this study a forward-flyback DC-DC converter is introduced. The auxiliary circuit has only passive elements and thus, the control circuit is simple and is like a regular PWM DC-DC converter. The auxiliary circuit provides ZVS condition for primary switch at turn-off instances. In this paper, operating principles and theoretical analysis are given. Also, simulation results are presented to verify the validity of theoretical analysis.