Electric Control System For A Winding Engine Electric Driving Motor

摘要

1,158,144. Automatic speed control. ENGLISH ELECTRIC CO. Ltd. July 22, 1966 [July 22, 1965], No.31334/65. Heading G3R. In a closed loop system for regulating the speed of an electric motor, the speed reference signal 17A is modified to provide a signal 14A whose variation with respect to time is controlled to avoid high rates of change of motor torque in response to abrupt changes in the signal 17A, the modified signal 14A being supplied to the closed loop regulator for comparison with a speed feedback signal. The signal modifier comprises stages 23-26, the signal 17A being applied to transistor amplifier 28 which also receives the signal 14A as a negative feedback signal. Feedback circuits 29 comprise non-linear and linear resistors 30, 31, arranged so that the signal 23A is constant when a change in the resultant input signal to the amplifier 28 is above a given value, and is proportional to the square root of the amplitude of the resultant signal when the change falls below that value. The signal 23A is applied to transistor amplifier 33 which has a linear feedback circuit 34 and a non- linear negative feedback circuit 35 associated with bias circuit 39. The rate of increase of signal 24A is thus limited to the value determined by the current through bridge rectifier 43. Stage 25 limits signal 25A to potentials determined by tappings 46, 47, according to the sense of the signal 24A. Stage 26 acts as an integrator whereby, for step changes of the signal 17A of small magnitude, the motor is accelerated uniformly from zero followed by a uniform deceleration back to zero. An abrupt change of large value in the speed reference signal causes the motor to accelerate for a period at a uniform rate, followed by a period of constant acceleration, and then by one in which the motor decelerates at a uniform rate. In a modification, the amplifier 28 has only a linear negative feedback circuit, whilst amplifier 33 has additionally a feedback circuit arranged so that signal 24A varies as the square root of signal 23A when the latter falls below a predetermined value. The amplifier 33 also has a further feedback circuit which serves the same function as the limiting stage 25.