Fuzzy sliding mode controller for doubly fed induction motor speed control

Abstract

This paper, presents a Direct Field-Oriented Control (DFOC) of doubly fed induction motor (DFIM) with a fuzzy sliding mode controller (FSMC). Our aim is to make the speed control robust to parameter  variations. The variation of motor parameters during operation degrades the performance of the  controllers. The use of the nonlinear fuzzy sliding mode method provides very good performance for motor  operation and robustness of the control law despite the external/internal perturbations. The chattering effects is eliminated by a particular function "sat" that presents a serious problem to  applications of variable structure systems. The fuzzy sliding mode controller is designed in order to  improve the control performances and to reduce the chattering phenomenon. In this technique the  saturation function is replaced by a fuzzy inference system to smooth the control action. The proposed  scheme gives fast dynamic response with no overshoot and zero static error. To show the validity and the  effectiveness of the control method, simulation results are performed for the speed control of a doubly fed induction motor. Simulation results showed that improvement made by our approach  compared to conventional sliding mode control (SMC) with the presence of variations of the parameters of the motor, in particular the face of variation of moment of inertia and disturbances of load torque. The  results show that the FSMC and SMC are robust against internal and external perturbations, but the  FSMC is superior to SMC in eliminating chattering phenomena and response time.

Keywords: Direct Field-Oriented Control, sliding mode control, fuzzy sliding mode controller, doubly fed induction motor, fuzzy logic control.