| 摘要 |
PROBLEM TO BE SOLVED: To prevent the switching frequency from increasing when an overcurrent protection circuit is actuated. SOLUTION: Current flowing in switching elements SW2, SW4, which compose an inverter 1, is detected by a current detecting circuit 8 and the detected voltage Vc is compared by a comparator 9. When the detected voltage Vc equals or exceeds the reference voltage Vref, an overcurrent detecting signal is output from the comparator 9 and input to the reset terminal of the FF circuit 10. Drive signals Vs2, Vs4 output from the control circuit 5 are input to the control terminals of the switching elements SW2, SW4 via AND circuits 6, 7. Drive signals Vs2, Vs4 are also input to the set terminal of the FF circuit 10 via an OR circuit 10a. The output of the FF circuit 10 is also input in the AND circuits 6, 7. When an overcurrent flows while the switching elements SW2, SW4 are in the ON state, the FF circuit 10 is reset so that the switching elements SW2, SW4 are OFF. When the onset of the next drive signals Vs2, Vs4, the FF circuit 10 is set and the switching elements SW2, SW4 are switched to ON. |
