| 摘要 |
PURPOSE:To inhibit speed hunting resulting from the overshoot of speed by reducing currents only up to a value corresponding to motor voltage when the speed of a DC motor operated by a power conversion means, the direction of power of which is in one direction, is controlled by a speed control loop having a current control minor loop. CONSTITUTION:A DC motor 3 is operated by DC power output from a thyristor converter 2 as a power conversion means, a speed control loop having a current control minor loop is formed for controlling the speed of the DC motor 3, and a voltage detector 21, a cosine converter 22 and a second limiter 23 are installed. The cosine converter 22 generates the phase angle of ignition corresponding to motor voltage, gives it to the second limiter 23 and limits an ignition-angle limiting value alphamax to a value corresponding to the motor voltage. Accordingly, currents can be brought so as not to be reduced up to zero, thus inhibiting the overshoot of speed, then eliminating speed hunting. |
