Hysteresis based predictive torque control without weighting factors for induction motor drives

Abstract

This work proposes a weighting-factor-free finite control set predictive torque control (FCS-PTC) for induction motor drives by incorporating a hysteresis controller to eliminate stator flux error from the cost function. The tuning of the weighting factor coefficient in FCS-PTC is critical for improved drive performance. Conventionally, the tuning is based on an intuitive understanding of the dynamical system and empirical methods, which may not yield optimal results. The proposed method regulates the flux by incorporating a separate two-level hysteresis controller and torque by the conventional cost function-based PTC. The cost function uses torque error only and employs a reduced number of voltage vectors. The reduction of voltage vectors is obtained through the flux hysteresis output and sector determination. The proposed work is implemented experimentally on the dSpace DS1104 controller board for a two-level three, three-phase voltage source inverter-fed induction motor drive. The experimental results validate the effectiveness of the proposed work under different drive tests compared to conventional PTC and direct torque control (DTC). The obtained results show comparable dynamic performance of the drive with $43\%$ lower computational burden than conventional PTC. Along with computational benefit, the proposed work demonstrates improved total harmonic distortion (THD) at low-speed regions due to the absence of a weighting factor in the cost function.