A Closed-Loop Rotor Resistance Control Method for Improved DC Dynamic Braking of Wound Rotor Induction Motor

A closed-loop rotor resistance control method using thyristors in the rotor circuit is presented which considerably improves the dc dynamic bracking performances of the wound rotor induction motor (WRIM). This method uses four thyristors in back-to-back fashion in any two of the rotor phases, and a bank of three-phase resistances is connected in parallel with them. The effective value of rotor resistances are controlled by controlling the firing of the thyristors. The experimental results show good agreement with the theoretical ones.