International Journal of Power Electronics and Drive Systems (IJPEDS) Vol. 13, No. 2, June 2022, pp. 733~743 ISSN: 2088-8694, DOI: 10.11591/ijpeds.v13.i2.pp733-743  733 Journal homepage: http://ijpeds.iaescore.com Switching function parameter variation analysis of a quasi- sliding mode controlled induction motor drive Shaija Palackappillil 1,2 , Asha Elizabeth Daniel 1 1 Division of Electrical & Electronics Engineering, School of Engineering, Cochin University of Science and Technology, Kochi, India 2 Department of Electrical & Electronics Engineering, Government Model Engineering College, Kochi, India Article Info ABSTRACT Article history: Received Sep 20, 2021 Revised Feb 23, 2022 Accepted Mar 16, 2022 Sliding mode control is a nonlinear, robust control that is having better load disturbance rejection capability, less parameter sensitivity and fast dynamic response. Conventional sliding mode control introduces high chattering that can degrade the induction motor (IM) drive system responses. Hence, a quasi-sliding mode controller (Q-SMC) using a hyperbolic tangent function coupled with equivalent control is designed for robust speed control of vector-controlled IM drive in this work. This work focuses on the effect of variation of the switching function parameters of the Q-SMC on the performance of the drive. Extensive simulations are performed using MATLAB/Simulink software, and the switching function parameters are adjusted across a wide range and its impact on motor performance is studied qualitatively and quantitatively, with accompanying graphical results and various transient parameters. It is observed that a Q-SMC controller with a larger boundary layer width has less overshoot, less steady-state error, and a lower current THD. It is also observed that even though a high gain Q-SMC controller responds quickly, the percentage overshoot for high gain systems is likewise large. Hence, if the boundary layer width and switching gain parameters are optimized, a Q-SMC speed controller is a promising choice for a high-performance IM drive. Keywords: Field oriented control Induction motor speed control Parameter tuning in SMC Quasi-sliding mode control Robust control Vector control This is an open access article under the CC BY-SA license. Corresponding Author: Shaija Palackappillil Division of Electrical & Electronics Engineering, School of Engineering CUSAT, Kochi, Kerala, India Email: shaijapj@gmail.com 1. INTRODUCTION Advances in power electronics, microcontrollers, processor-based systems, and nonlinear control theory have facilitated substantial research into advanced control approaches for induction motor (IM) drives during the last few decades. Despite the fact that induction motors are extremely complex, nonlinear, and tightly coupled [1], numerous researchers have developed various strategies for its dynamic control without compromising performance. Model predictive control (MPC) [2], Field oriented control (FOC), direct torque control (DTC) [3], feedback linearization (FL) [4] and observer-based nonlinear controllers [5] have all been presented in the literature to achieve quick dynamic responses in IM. Various sophisticated speed control approaches such as robust control, optimal control, adaptive control [6], sliding mode control (SMC) [7], and intelligent control techniques like fuzzy logic control [8], [9] and artificial neural network (ANN) are also being developed. In this work, an indirect field-oriented control (IFOC) or indirect vector control (IVC) is applied to the IM drive. There are two control loops in vector control. The inner loop controls current, whereas the outer loop controls speed [10]. Hysteresis controller is used in the inner current loop. Classical fixed gain