A Comparison of Sensorless MTPA and Quasi-MPF Control for VSD-PMaSynRM

Permanent Magnet Assisted Synchronous Reluctance Motor (PMaSynRM) is one of the most popular motors in variable speed drive (VSD) systems nowadays due to their comparable cost, maintenance requirement, efficiency and power density in contrast with other popular motors such as Induction Motor (IM) and Permanent Magnet Synchronous Motor (PMSM). Further improvements in cost and reliability are achieved with the sensorless control of PMaSynRMs while overall performance of the machine strongly depends on the control type. This study presents an experimental comparison of two control types; the Maximum Torque per Ampere (MTPA) Control and Maximum Power Factor Control (MPFC) which are the sensorless control implementations in the constant torque region. Both control methods are modelled in a simulation environment and the proposed approaches are experimentally evaluated and compared. In the case of MTPA, up to 5.15% and 13.99% increase for the efficiency and torque per ampere respectively are observed at base speed compared to those of MPFC. On the other hand, with MPFC, up to 0.1 increase in power factor and nearly 20% decrease in the base speed voltage are obtained in contrast to MTPA.