ZVT DC-DC PWM converters with magneticallycoupled auxiliary voltage source: a unifying analysis

A generalised circuit diagram for ZVT PWM converters with magnetically-coupled auxiliary voltage source is proposed. The generalised circuit is presented and analysed; its operation modes and constraints are defined. By means of the proposed generalised topology, published ZVT PWM converters with magnetically coupled auxiliary voltage source can be systematised and better evaluated. Based on the approach presented, the transformer (or coupled inductor) turns ratio N is determined for each topology analysed, guaranteeing a more realistic soft-switching boundary. In addition, a comparative analysis concerning the volume of magnetic ferrite cores is carried out. The comparative analysis addresses some of the most important ZVT converters with magnetically-coupled auxiliary voltage sources. The efficiency performance of these converters is evaluated and experimental results given, obtained from 1 kW-100 kHz laboratory prototypes, which confirm the value of the proposal and theoretical analysis