Rooted Tree Optimization Algorithm to Improve DTC Response of DFIM

Abstract

In this paper, an integral-proportional (IP) controller is employed in speed loop control in direct torque control (DTC) of a doubly fed induction motor (DFIM). Using IP parameters obtained from classical tuning methods, such as pole placement method, Ziegler–Nichols, etc., has disadvantages like high undershoot and overshoot, slow settling time, etc. To overcome the drawbacks of the classical methods, a new approach in which the IP controller parameters are tuned by rooted tree optimization (RTO) algorithm minimizing a multi-objective function is presented. The proposed algorithm has been verified and tested in control system with a PID controller. It presents improvement in performance response of various processes of different order compared with techniques such as Ziegler–Nichols, Kitamori’s, Fuzzy-PID and Iterative Feedback Tuning. In addition, simulation results of direct torque control response of a DFIM with an IP controller designed using the RTO algorithm minimizing a multi-objective function show its effectiveness and better performance in speed response. Robustness test against parameter sensitivity for the proposed DTC-DFIM-RTO is verified under stator resistance variation.