Fuzzy logic control of induction motor drive for performance improvement

Abstract

This thesis paper portrays the way of implementing fuzzy logic in improving the performance of induction motor drive. Here a rule-based fuzzy logic based controller is designed and simulated with the help of MATLAB. A PI controller is also designed in SIMULINK. Then performances of both the controller are simulated and compared. For controlling speed here scalar control method is employed, where magnitude of the stator voltage and frequency is changed proportionately. For this V/F control, a reference speed is chosen and controller is designed as such, it can provide that desired (reference) speed in case of frequent load changes. The major merit of Fuzzy controller over PI controller is use of linguistic variable and user defined rule base that makes it possible to incorporate human intelligence in the controller. Fuzzy logic based controller also has the capability to control both linear and nonlinear system. Inputs given to the fuzzy logic based controller are speed error (e) and change in speed error (Äe). And output is the change of control (ùsl) , which is the frequency correction. So the inputs error and change in error are processed according to the rule base, which is user defined and output correction is provided to the inverter. The membership functions and the rules are defined in FIS editor window. Based on rules, control surface is also generated. The system or model for speed controlling of induction drive is simulated both with PI and Fuzzy controller and results are analysed and compared and Fuzzy controller is found to perform better than the conventional PI controller.