| 摘要 |
PURPOSE:To suppress power loss and to protect a switching element by inserting a monostable multivibrator, which sustains an OFF signal for a predetermined time in response to lock signal and outputs the sustained OFF signal, between a comparator and a switching control circuit. CONSTITUTION:When overcurrent control of DC current I is carried out, a monostable multivibrator 10 is started by a lock signal L fed from a comparator 5 to produce an OFF signal F for a predetermined time thus turning the AND gate G in a switching control circuit 7 OFF and lowering the level of the DC current I. Consequently, a limit value VR is not exceeded upon elapse of a short time even if a switching pulse P is outputted again upon application of the OFF signal F, and thereby a PWM inverter is not switched excessively. By such arrangement, power loss can be suppressed and the switching element can be protected. |
