| 摘要 |
PROBLEM TO BE SOLVED: To suppress application of overvoltage to a switching element caused by increase in power source voltage to prevent failure of the switching element by setting an applying electric power by weighting addition of signal levels of a DC voltage generating means and an input voltage detecting means. SOLUTION: Outputs of a DA conversion circuit 12 and a power source voltage detecting circuit 13 are inputted into a weighting adding circuit 14, two input voltage values are weighted, then converted into voltage suitable for a comparing circuit 15. Resonance voltage generated in a switching element 7 is detected, and a trigger pulse is outputted from a trigger circuit 10. A self oscillator 11 is an oscillator for outputting almost a chopping wave capable of triggering, and synchronizes with a resonance state after starting of operation of an inverter. The comparing circuit 15 compares voltage of the self oscillator 11 with that of the weighting adding circuit 14, and outputs the on/off pulse of the switching element 7 according to the large or small relation. A driving circuit 16 converts the pulse into driving output suitable for the driving of the switching element 7. |
