| 摘要 |
1,255,382. Control of D.C. motors. WESTINGHOUSE ELECTRIC CORP. 27 May, 1969 [19 June, 1968], No. 26740/69. Heading H2J. [Also in Division G3] In a system for preventing line voltage dips by limiting positive power peaks, a speed controller 42 for a hoist motor 18 receives a ramp signal from generator 40 and a feedback voltage representing motor speed, the controller being adapted to integrate the difference signal so that its output increases until a saturation, limit is reached in either direction The saturation limits are set by a current limiter 54 coupled to a power peak limiter 56 responsive to the output voltage from a tachometer generator 50. A current controller 60 receives the output from controller 42 as well as a feedbackcurrent from transducer 64. The controller 60 integrates the difference and its output is applied through thyristor circuit 16 to the field of generator 10 which supplies the motor. The power peak limiter 56 comprises an operational amplifier 62 associated with Zener diodes 64, 86, and rheostats P2, P4, each connected to a source of reference potential. Diodes 68, 70, connect the movable taps of the rheostats to a voltage divider Ra-Rd from which a signal representing the speed is derived. Resistors P1, P3, determine the maximum output of the speed controller. The power peak limiter has no effect until the speed of the motor reaches a set value whereupon the maximum output of the speed controller is reduced as the speed increases. The speed controller 42 comprises an operational amplifier 76 having an integrating feedback network 78, 79, 80. During regenerative conditions, signals applied to the limiter 80 from circuit 54 have no effect upon the control of the motor. The motor may be adapted for direct thyristor control, instead of through a generator. |
