Optimum DC Dynamic Braking Control of an Induction Motor Using Thyristor Chopper Controlled Resistance

The optimum dc dynamic braking control here implies that, at all the speeds, the motor is operated at peak torque point. This can be achieved by controlling the rotor resistance of an induction motor such that the peak torque occurs at the speed at which the motor is running. The optimum control permits the stopping of a load in a minimum time with minimum heating of the motor and therefore is useful where very frequent and quick stops are needed. The present paper is concerned with the optimum dc dynamic braking control using rotor rectifier cascade feeding a resistance whose effective value is controlled by controlling the ON to OFF time ratio Of a thyristor chopper connected in parallel with it. It is shown that the use of this scheme permits the realization of a theoretically expected performance.