GB1165008A - Speed Control Arrangement for Electric Motors. - Google Patents

Abstract

1,165,008. Electric correspondence control. BRITISH IRON & STEEL RESEARCH ASSOCIATION. Dec. 4, 1967 [Nov. 8, 1966], No.50016/66. Heading G1N. The output torque G of motor is sensed, e.g. by strain gauges on the motor output shaft and compared with a reference signal Gm, the error signal being supplied to a function generator producing a signal dependent on its input according to the characteristics. This signal is compounded with a reference speed signal Nm and the resultant signal N is supplied to control the motor. In one embodiment the characteristic is represented by the equation:- N = Nm - #K (G - Gm), where # = 0 for G# Gx and # = 1 for G > Gx, see Fig. 2 (not shown). In the computing circuitry, the sliders of potentiometers, Fig. 3, connected to a constant voltage source, are set according to the constants Nm, Gm and Gx. The signal representative of Gm is then subtracted from the signal representative of the actual torque and fed via a relay controlled switch and potentiometer st at K to a subtraction unit whose other input is provided by the signal representative of Nm. The above switch is opened or closed to connect or disconnect the signal representative of (G - Gm) from the subtraction unit according to whether G is greater or less than Gx with which it is compared in a circuit whose output is connected to the relay. In a second embodiment in which the function generator includes non-linear elements, the characteristic is represented by the equation:- N = Nm - 8Nm Gm/G + 1