| 摘要 |
PURPOSE:To prevent big delay time at the time of changing the current direction of a motor, by inputting a specified voltage value in place of a normal input value into the integral function of current PI control function, and by returning the integral function of this PI control function to its normal function after the current value of the circuit is detected. CONSTITUTION:The voltage of thyristors 2, 3 rises at a specified speed, since triggering phases outputted from a FOR/REV trigger pulse generator 17 are advanced, when an analog switch 20 is switched over on the side of (a) and a specified bias signal voltage C is inputted into an integral element 22. When a zero current detecting circuit 18 detects that a voltage value proportional to a current value obtained by a current transformer and a current detector 6 has become larger than a specified voltage, the output of a FOR/REV logic circuit 15 switches the analog switch 20 over on the side of (b). Accordingly, the output phases of the gate trigger pulses conform to the condition of the output signal of a differential circuit 14, as an operational amplifier 21 and the integral element 22 make PI control function useful. |
