| The PS-FB-ZVS PWM converter is widely used in many applications. There are two problems existing in this kind of converters,one is that lagging leg has narrow zero-voltage-switching ranges, the other is that the output rectifier diodes suffer the parasitic oscillation and voltage spike resulted by the reverse recovery of the rectifier diodes.To alleviate these problems, in this paper, two improved designs are given.An improved phase-shifted full-bridge zero-voltage-switching PWM converter which adopts two clamping diodes is introduced in this paper. Based on the improved design, one 500W Zero-voltage-switching (ZVS) soft-switching power supply on the phase shift control is designed. The procedures of circuit design are presented. The experimental waveforms show that not only this power supply can realize ZVS for leading leg at the condition of more than one-fifth of full load, but also the parasitic oscillation and voltage spike are climinated.An improved PS-FB-ZVZCS PWM converter is also introduced in this paper. Based on the improved design,one 270W Zero-voltage and Zero-current switching (ZVZCS)soft-switching power supply on the phase shift control is designed. The procedures of main circuit design are presented.The experimental results prove that this power supply can realize ZVS for leading leg at the condition of more than one-fifth of full load and ZCS for legging leg in the whole range of load.
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