Variable switching point predictive torque control

In this paper an approach to include a variable switching time point into predictive torque control (PTC) is introduced. In PTC the switching frequency is limited by the sampling frequency; its theoretical maximum value is half the sampling frequency. In reality, however, the switching frequency is lower than this value, resulting in high current and torque ripples compared to modulator-based control methods. In order to overcome this an optimization problem is formulated and solved in real-time. The goal is to find the time point at which the switches of the inverter should change state in order to not only achieve the regulation of the torque and the flux magnitude to their references, but also the minimization of the torque ripple. Further advantages of the proposed method include the design flexibility and great performance during transients. Experimental results that verify the performance of the presented control strategy are included.