| 摘要 |
PURPOSE:To perform the weakened field drive of a DC motor with a high power- factor without the failure in commutation, by detecting that the control delay angle is minimum in power running and that the armature voltage of the motor is constant in regenerative braking. CONSTITUTION:In the power running, a running/braking discriminator 11 energizes a relay 84 to close a contact 86 and open a contact 87. The motor is then accelerated. When the control delay angle of an armature thyristor 1 falls below a minimum advancement angle, a minimum control delay angle detector 10 supplies an output signal to a limiter 83 to start the weakened field drive to raise the power-factor. In the regenerative braking, the running/braking discriminator 11 deenergizes a relay 84 to open the contact 86 and close the contact 87. The armature voltage is compared with a reference voltage -E by a subtracter 82, whose output is applied to the limiter 83 to perform the weakened field drive as well as in the power running. The reference voltage for the armature voltage is set near the minimum value of the voltage of power to prevent the failure in commutation. |
