| 摘要 |
<p>A winding voltage arising in a first winding on the primary side of a transformer is detected in a winding voltage detector unit formed of a second winding, and current flowing through a resonant circuit is detected in a resonant current detector unit formed of an auxiliary capacitor and a resistor. The timing at which the polarity of the detected winding voltage is inverted is detected in a control and drive unit, and the time at which the polarity of the resonant current, whose phase is delayed with respect to that of the winding voltage, will be inverted is determined in advance. In the event that there is a switch in an on-state when the timing immediately before the inversion of the polarity of the resonant current is detected from the output of the resonant current detector unit, the control and drive unit forcibly turns off the switch.</p> |
