Comparative Analysis of Different Types of Membership Functions for Fuzzy Logic Controller in Direct Torque Control of Induction Motor

Abstract

AbstractFuzzy logic controller performance depends upon fuzzy rule base. The control strategy is represented by a set of rules which explain basic characteristics of the controller. The fuzzy logic controllers’ inputs and outputs are characterized by its membership function. Most of the researchers use triangular MFs for implementation of control algorithms. The basic objective of the paper is to evaluate the performance of fuzzy logic switching controller with different membership functions. The comparative analysis of different types of membership functions is carried out in direct torque control of induction motor. In DTC, speed control is achieved by selection of optimal voltage vector of voltage source inverter using switching logic table. Major disadvantages of DTC are high ripples in torque and flux and variable switching frequency due to hysteresis controllers. Use of fuzzy logic controller replaces the conventional switching table, and hysteresis controller exhibits reduction in torque and flux ripples. In this paper, fuzzy logic controllers are developed using different membership functions in MATLAB/Simulink Environment. Performance of speed control is evaluated and summarized.KeywordsDirect torque control (DTC)Induction motor (IM)Fuzzy logicMembership functionFuzzy logic controller