Matlab-based simulations of a three-phase induction motor for dynamic studies

The aim of this paper is to develop a generalized MATLAB program to study the dynamic behavior of a three-phase induction motor. The d-q axis transformation theory is applied in rotor reference frame to study the motor dynamics. A general-purpose MATLAB program is developed and used for the dynamic simulation of a 5HP, 460V, 60Hz, 4-poles induction motor. The developed program is used to study the effect of variation of Stator Resistance (Rs), Moment of Inertia (J), and Load Torque (TL) at t=0.7sec during transient state. The results obtained show that, the torque-speed characteristic curve and mechanical rotor speed-time characteristics of induction motor depend upon the rotor resistance and the moment of inertia. Also, during the simulation of the motor under loaded torque at t=0.7sec, the results showed an increase in the initial starting torque and it reduces from 2000Nm – 0Nm as the operating time progressed. A sudden residual increase occurred in the torque from 0-1000Nm at the loaded time t=0.7sec, and the mechanical rotor speed increased at starting time from 0-1800rpm with respect to operating time and suddenly experienced a drop from 1800rpm to about 1700rpm at the loaded time of t=0.7 sec. The developed program is particularly useful for machine designers in the manufacture of various types of induction machines.