Comparative performance analysis of PID and sliding mode controllers in speed control of permanent magnet synchronous motor

This paper presents the design and analysis of nonlinear controllers aimed at enhancing the performance of a Permanent Magnet Synchronous Motor (PMSM). A 3-phase, 900kW, 50Hz, 6-pole, 380 V, 756RPM PMSM with 48 rotor slots was modelled using MATLAB/Simulink and ANSYS. The study evaluates the motor transient and steady-state behavior in terms of torque, speed and current under different load conditions, with and without controller integration. Simulation result demonstrates that introducing controllers, particularly the Sliding Mode Controller (SMC), effectively reduces electromagnetic torque and output power ripple while achieving a faster response to steady state compared to the Proportional Integral Derivative (PID) controller. The SMC further enhances speed performance by increasing the load angle during rated operation, thus shifting the pull-out torque to power angle greater than 900. Maximum speed, torque, and current were achieved under 4Nm and 9Nm load conditions. The significance of this performance enhancement is underscored in applications such as robotics and conveyor systems, where variable speed operation is essential. Since PMSM speed is directly related to supply frequency and inversely to the number of poles, speed regulation is constrained by the number of pole-changing methods. Frequency variation remains the most effective approach for wide range speed control. The result obtained indicates that nonlinear control strategies offer superior performance over conventional methods, contributing to a more robust and responsive PMSM speed control system for industrial applications.