To provide a current resonance type converter that solves a problem that a voltage across a switching element is oscillated enormously being affected by parasitic capacitance built in the switching element.
A current resonance circuit 5 is provided that supplies a sine-wave resonance current to the switching element S1 after the switching element S1 is put into an ON state. The switching element S1 incorporates a parasitic capacitance Cs connected between its one end and the other end and a body diode Dbody connected reversely in parallel. Here, a diode Dc, which is conducted when the parasitic capacitance Cs is charged by the resonance current of the current resonance circuit 5 after the switching element S1 is turned on and when a voltage between the drain and the source VDS of the switching element S1 is increased up to an output voltage Vo, is connected between one end of the switching element S1 and the line of the output voltage Vo.
Masayoshi Yoshida
Shimizu Sakaematsu