Predictive Torque Control Based on Load Angle for an Induction Machine

Predictive control has been considered a suitable alternative for controlling electrical machines. This paper presents a predictive torque control (PTC) strategy that integrates the load angle into the control framework for three-phase induction motors. The predicted stator voltage components are obtained from the stator flux deviations and the estimated load angle (LA), which is computed from the slip speed derived from the torque error, and utilizes a voltage-based cost function, eliminating the need for weighting factor while achieving steady-state performance comparable to PTC schemes. The proposed approach minimises computational burden to 44.6% unlike PTC, and also was compared to the predictive current control (PCC). Experimental results at 1345 rpm and 60% load demonstrate that the proposed PTC-LA achieves a 19.44% torque ripple and steady-state speed error of 4.3 rpm, outperforming both conventional PTC and PCC. Under parameter mismatch conditions at low speed, the PTC-LA maintained a speed error below 5.9 rpm and a torque under 0.28 Nm. Furthermore, the proposed control exhibited superior dynamic performance, characterized by reduced settling times and enhanced robustness against inductance variations in terms of torque error, compared to PCC.