| 摘要 |
<p>665,319. Control of D.C. motors. METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. May 2, 1950. [May 12, 1949] No. 12728/49. Class 38 (iii). [Also in Group XXXV] The speed of the motor M1, supplied from the generator G of a Ward-Leonard set, is maintained constant at a value determined by the setting of a potentiometer P2, which, via transductors TD4, TD5, controls the voltage across resistor R8. This is compared with the output voltage of a tachometer generator TG, (or the back e.m.f. of the motor) and the resultant voltage is connected through rectifier ARX to control via transductors TD6, TD1, TD2, TD3, the output of a gried controlled rectifier R which supplies the field GF of the generator G. Contactors in all circuits ensure correct polarities when the motor is reversed. Rectifier ARX provides regenerative braking, since if the control voltage is reduced to a value below the tachometer voltage, the rectifier blocks and the rectifier R is cut off. The rates of acceleration and retardation are controlled by transductors TD9, TD10, which modify the reference voltage across resistor R8 by being energised via a condenser C according to the rate of change of reference voltage at P2. Additional limitation of the motor armature current is provided by transductors TD7, TD8, which are energised via rectifiers ARY, ARZ, according to the voltage drop across the series fields of the generator and motor, and which modify the output of transductor TD6. The input current to the AC motor M2 may be limited by a further transductor similar to TD7 energised from a current transformer in the A.C. supply line. In a modification, transductors TD7, TD8 have auxiliary control windings responsive to the rate of change of tachometer voltage and transductors TD5, TD9, TD10 are omitted. Specification 580,005, [Group XXXV], is referred to.</p> |
