GB637544A - Improvements in or relating to speed-regulating arrangements for electric motors - Google Patents

Abstract

637,544. Automatic speed control systems. SPERRY GYROSCOPE CO., Inc. Aug. 8, 1947, No. 22128. Convention date, Dec. 4, 1943. [Class 38 (iv)] In a system for controlling the speed of a constant speed motor, the motor 11 drives a permanent magnet generator 12 having twophase windings 23, 24, the winding 23 of which is connected through a non-resonant impedancereactance network 13 to the grid of an amplifier 14 which supplies a phase-detector 15 connected to an auxiliary field winding on the motor 11. The second winding 24 of the generator is connected to the split secondary winding 48 of the transformer 46 feeding the phase-detector. The arrangement is such that at correct frequency the network 13 delivers zero output, but at frequencies above or below that value, the network produces voltages which are of opposite phase and proportional to the speed difference and the rate of change of speed (i.e. acceleration). Accordingly, the amplifier 14 supplies a control voltage which together with the reference voltage produced in the winding 24 is detected by 15 and supplies a voltage to the compensating winding 62 to correct any departure from constant speed. In a modification, the speed of a repulsion motor is maintained constant by a similar system wherein the output from the phase-detector is modulated by a voltage of the supply frequency to the motor and the modulated voltage is supplied direct to the commutator brushes of the motor. The generator 12 may also act as a source of constant voltage supply; also the resistances of the network may be adjustable so that the system may be adapted for operation at different constant speeds. Specification 612,426 is referred to.