Comparative Performance Analysis of PID and Sliding Mode Controllers in Speed Control of Induction Motor Drives with Intermittent Loading

Abstract

Induction motor (IM) is the most used AC machine, and it is a constant speed device. If induction motion must be used in variable speed applications, its speed must be controlled.  Speed control of a squirrel cage induction motor (SCIM) using a control algorithm with proportional integral derivative (PID) and sliding mode controller (SMC) was designed, simulated, and analyzed in this paper. Three-phase SCIM was considered, MATLAB software was used for both design and simulation and decoupling of the flux and torque-producing components for separate control was done for the actual control of the SCIM drive. The motor drive was used in driving a constant load of 0% (0 Nm), 28% (4 Nm), and 62% (12 Nm) of the rated torque with a variable speed of 0 rad/s, 10 rad/s, and 25 rad/s. It is observed that SMC gave the best speed performance compared to other controllers. The steady-state error, rise time, settling time, and overshoot of the SMC model were 0.1%, 0.01 sec, 0.05 sec, and 4%, respectively while that if PID were respectively 2 %, 0.02 sec, 0.2 sec, and 16 %,  when driving 4Nm under intermittent speed.  The improved speed performance of the proposed SM controller can be used in robotics where high precision speed performance is required.