Proximate Maximum Efficiency Control for Synchronous Reluctance Motor via AMRCT and MTPA Control

To develop a high-efficiency synchronous reluctance motor (SynRM) drive system, a proximate maximum efficiency (PME) control is proposed in this study. First, a SynRM drive based on a traditional vector control with a constant d-axis current command is developed. However, the constant command is not suitable for the high-efficiency applications of SynRM. Therefore, a three-control-mode system including the adjustable maximum rate of change of torque (AMRCT) control, finite element analysis (FEA)-type maximum torque per ampere (MTPA) control, and PME control is proposed to enhance the efficiency of the SynRM drive system. Moreover, the PME control is a combination of an AMRCT control and an FEA-type MTPA control. As a result, the d-axis current command is flexible and depends on the minimizing loss target chosen by the end-user. In addition, a novel adaptive computed q-axis current speed control with d-axis current regulation is proposed to further increase the robustness of speed control. Finally, the proposed three-control-mode system is implemented in a 32-bit floating-point digital signal processor and some experimental results are provided to verify its effectiveness.