| 摘要 |
PURPOSE:To arrest a detection delay time and keep a capacity of a main circuit capacitor minimum by a method wherein a drive stop signal is output when a terminal voltage of the main circuit capacitor becomes lower than a prescribed value. CONSTITUTION:Pulse signals A, B are fed from a control circuit 38 to transistors 33A, 33B respectively, and as a result, a voltage V2 is fed to a secondary winding of a transformer 34 against a voltage V1 of the main circuit capacitor 32. On the other hand, signals C are made output from the control circuit 38 and pulses F are fed as outputs from a delay trigger pulse output circuit 42. In addition, the set voltage and the voltage V2 are compared in a comparator 41, and the outputs E and the pulses F of the comparator feed signals G through AND circuit. Thereby, the voltage V2 is also decreased as the voltage V1 of the main circuit capacitor. Accordingly, since the operating frequencies are generally of the order of 20- 50kHz, the detected abnormal delay times are approximately 50-20mus, which are so small as being ignored, so that the capacity with the minimum capacity can be selected. |
