PURPOSE: To prevent the overload of a semiconductor element by generating regulated zero voltage generating pulses only when a current does not flow to a coil, which converts DC power into high frequency AC, and a capacitor even if zero voltage command pulses are inputted from a switching power converter.
CONSTITUTION: DC voltage E is converted into a high frequency AC with a network comprising semiconductor switches D1-D4, switches S1-S3, a coil L, and capacitors C1 and C2, and it is inputted into a switching power converter. The zero voltage generating pulses Ps from the converter is inputted into a control circuit 400. At that time, when a CT does not detect the voltage VC of the capacitor C1 and the current IL of a coil L, this generates regulated zero voltage generating command pulses. When CT detects voltage VC and a current IL, this ceases to generate regulated zero voltage command pulses. Hereby, the occurrence of overvoltage or overcurrent by the malfunction of the semiconductor of a resonance circuit by L and C1 is generated.
INUDOU HIROSHI
KUWATA YUTAKA
