Speed Control of a Three Phase Induction Motor using a PI Controller

Three-phase Induction motors are typically used in an increasing variety of applications such as fans, milling machines, transportation, etc. This paper discusses the speed control of the three-phase induction motor and an associated PI controller. A model of the three-phase induction motor is presented, analyzed and used to demonstrate the effectiveness of the speed controller. The performance of the motor system is carefully examined and compared with and without the PI controller. The unit step response of the speed control loop is characterized by rise time, peak overshoot, settling time and steady state error of 0.0815s, 6.97%, 0.82 and 0.11% respectively. Simulation results show that the speed of the uncontrolled motor changed whereas that of the controlled motor returned quickly to its initial value after the motor is subjected to load changes from 1 pu to 0.5 pu and subsequently to 0.25 pu.