Online Maximum Power Factor Searching Control for Synchronous Reluctance Motor Based on Current Angle Control

To develop a high-efficiency synchronous reluctance motor (SynRM) drive system, a novel maximum power factor control (MPFC), which is based on current angle control with stator flux and stator resistance estimators, is proposed in this study. First, a conventional maximum power factor control (CMPFC) system using a saliency ratio of the SynRM to generate a fixed current angle command is introduced. Since the saliency ratio needs offline pre-preparation and can't be adjusted automatically, it is difficult to improve the performance of the MPFC in different operating region owing to the increasing of manufacturing cost and time-consuming. Therefore, an online maximum power factor searching control (MPFSC) based on current angle control is designed for the speed control of a SynRM. Moreover, a proportional-integral (PI) speed controller is adopted to generate the stator current command, and the proposed online MPFSC is employed to produce the current angle command. Finally, from the experimental results, the current angles of the optimal power factor (PF) can be effectively obtained online at different speed and load torque conditions.