Fuzzy-PID speed controller for an induction motor

Abstract

The main objective of vector control or field-oriented control (FOC) control is to have decoupled control of flux and torque in three phase induction motors. FOC rotates the stationary stator reference frame into rotating reference frame attached to the rotor flux linkage space phasor which results in a decomposition of stator currents into torque and flux producing components under orthogonality. This will give fast dynamic response as compares to other scalar drives i.e. variable frequency drive (V/F). This project presents a Fuzzy-PID control system for the speed control of a three-phase squirrel cage induction motor. The proposed method uses both Fuzzy logic and conventional controllers along with vector control technique. This method combines the advantages of the fuzzy logic controller and conventional controllers to improve the speed response of the induction motor. The FLC observes the closed loop error signal and then controls the PID input error signal so that the actual speed matches the reference speed with reduced rise time, settling time, and peak over shoot. Implementation and simulation results using MATLAB of multiple controllers such as (PID, Fuzzy, and Fuzzy-PID) are compared along with conventional PI controller in terms of some performance measurements such as rise time (tr), maximum percent overshoot (Mp), settling time (ts), and steady state error (Ess) at various load conditions. The results of the simulation verified the effectiveness of the proposed speed controller model under different operating conditions and demonstrated improvements in performance in speed tracking and system's stability.