Design of Fractional Order Terminal Sliding Mode Control for Robust Speed Tracking in Sensorless Multiphase Drive Systems

Multiphase induction motor drives are an emerging research are in electric machines. This paper presents a sliding mode control (SMC) and fractional calculus assisted terminal sliding mode control scheme (FOTSMC) for encoder-less operation of 5-phase induction motor speed control. Model predictive control scheme is used to generate switching signals using the reference torque generated through the FOTSMC. The shortcomings of speed sensors are eliminated using a robust sliding mode based speed observer. The proportional integral (PI), SMC and FOTSMC are compared using simulation based analysis carried out in MATLAB/SIMULINK. The PI, SMC and FOTSMC are tested under variable speed reference, speed reversal, and constant load. The PI, SMC and FOTSMC controllers are also evaluated for stator flux trajectories. The results indicates that the FOTSMC has improved performance as compared to SMC in terms of chattering elimination for encoderless predictive torque control of IM whereas the SMC and FOTSMC are robust as compared to PI controller.