Patent ID: 7515443

Claim:
An inverter circuit having plural sets of a drive transformer and a balancer-transformer, wherein a primary coil of the drive transformer and a primary coil of the balancer-transformer are connected in series, both ends of each of the series-connections of the plural sets are connected in parallel between output terminals of a switching circuit, and secondary coils of all the balancer-transformers of the plural sets are connected in series and connected between the output terminals of the switching circuit, the inverter circuit comprising: voltage detecting means for detecting a voltage at any of a connecting-midpoint of the series-connected secondary coils of the balancer-transformers; and voltage comparing means for comparing the voltage at any of the connecting-midpoint of the series-connected secondary coils of the balancer-transformers with a reference voltage, wherein the voltage comparing means outputs a signal indicating an abnormal operation when the voltage at said any of the connecting-midpoint exceeds the reference voltage.