| 摘要 |
PURPOSE:To prevent a circuit element from damaging by detecting the rising rate of a current which flows through a smoothing condenser, thereby rapidly detecting the current of a trouble. CONSTITUTION:A current which flows through a smoothing condenser 2 is detected by a detector 5, is differentiated by a differentiating circuit 6a, and is compared with a reference level which is determined in advance by a comparator 6b. Then, the compared result is fed through a timer 6c, is removed at a signal which is lower than the prescribed width, only the signal which continues for longer than the prescribed period of time like a trouble current is produced, is led to an inverter base controller 7, and the base of the inverter 3 is interrupted. Then, the trouble can be detected at the early stage wherein the overcurrent is not sufficiently raised and breaking of the converter can be performed. |
