Torque ripple reduction strategy of model based predictive torque control for doubly salient permanent magnet synchronous machines

The doubly salient permanent-magnet synchronous machine (DSPMSM) is an emerging type of brushless machine. It has been paid more attention by both academia and industry for some advantages of high power/torque density, simple /robust structure, good thermal dissipation ability, strong redundancy capability, and wide range for high speed cruising. Due to the nature of inherited salient poles in both stator and rotor, the DSPMSM suffers from severe torque and flux ripple for its various electromagnetic equivalent air gap lengths at different rotor positions. During the past couple of years, the conventional switching-table-based direct torque control (DTC) has demonstrated great potentiality due to its merits of quick dynamic response, strong robustness and simple control structure. However, during such DTC algorithm, there still exists large ripples of both torque and air gap flux linkage resulted from the Bang-Bang modification. This paper presents one improved strategy to reduce the torque ripple of DSPMSM drive system by help of model based predictive torque control (MPTC), which is a renewed algorithm for conventional DTC strategy. Different with that the traditional MPTC strategy with complete decoupling requirement, the new MPTC method in this work just needs a semi-decoupling control scheme. By adjusting the voltage vector online to best satisfy the demands of torque and flux linkage, the new MPTC algorithm can successfully reduce both torque and flux ripple obviously in DSPMSM drive system. Comprehensive simulation results are finally presented to validate the theoretical analysis. It gives good guidance or suggestion to increase stable and dynamic performance for PMSM, especially for those with double salient structures, which could extend their applications with requirement of high precision in the future.