PERFORMANCE OF A CLOSED-LOOP INDUCTION MOTOR SPEED CONTROL SYSTEM WITH INTEGRAL-CYCLE-CONTROLLED SCR'S IN ROTOR CIRCUIT

Abstract

The closed--loop solid state resistance controller for a three phase slip ring induction motor has been designed fabricated and tasted, The contrtillcr consists of two banks of three phase resistors, in the rotor circuit, one of them connected in series with the thyristors and another one in parallel with thyristors. The speed variation is obtained by varying the rotor resistance between Rai and R0 by using integral cyclo control. The various fdnctional blocks which govern the behaviour of the system for small variations about the operating point are described. The responses For load and reference speed perturbations are obtained analytically. The analytical results are compared with the experimental values. The same solid-state resistance controller has been modified to obtain optimum dc dynamic braking. The braking with slip-ring shorted, optimum resistance In the rotor circuit and with solid_ state resistance controller are investigated. The braking perPor-mance characteristics have been obtained analytically for each of the above methods and compared with experimental results.