A CLOSED LOOP PULSE WIDTH MODULATED VSI-BASED CONTROL OF SQUIRREL CAGE INDUCTION MOTOR

ABSTRACT

This project presents a quality model of induction motor showing steady state and dynamic analysis using Volt/Hertz open loop, Volt/Hertz closed loop, Slip differences and constant flux methods. The main objective is to maintain the speed at constant rotor flux and to investigate the control schemes for controlling induction machine, particularly the scalar control method and to evaluate their performance under variable input-output conditions. Analysis of the steady state equivalent circuit model of the induction motor is established showing equations that justify the use of constant Volt/Hertz speed control of both open and closed loop techniques. The induction motor is fed from three phase bridge inverter which is operated with sinusoidal pulse width modulation (SPWM) technique and these are used to evaluate the developed models.  With the help of a powerful tool called MATLAB SIMULINK it is observed that the induction motor control performance is improved by adopting the conrstant flux method, the simulation results have shown the efficiency of the proposed models, the performance of volt/hertz technique and constant flux technique are also compared.