Loss Minimization Control for Interior Permanent Magnet Synchronous Motor in a Wide Speed Range

Abstract

To achieve the loss minimization control of the interior permanent magnet synchronous motors (IPMSMs) in a wide speed range, the loss model for IPMSMs is established considering the dynamic working conditions. The implicit expression of the direct-axis (d-axis) current that minimizes the loss is derived, and the numerical method is used to solve the optimal d-axis current. Furthermore, the equivalent iron loss resistance is estimated to update the loss model with an extended Kalman filter (EKF). The proposed strategy combined with the field-oriented control method is compared with the traditional control strategy where the maximum torque per ampere (MTPA) strategy is used below the rated speed and the flux weakening control (FW) or maximum torque per voltage (MTPV) strategy is adopted above the rated speed. The research results show that compared with the traditional strategy the proposed strategy can minimize the total electrical losses in the full speed range and obtain higher efficiency under both dynamic and steady state. Moreover, the dynamic response below the rated speed is faster. The proposed loss minimization control strategy achieves a unified solution in a wide speed range and has the advantages of fast and concise calculation, which is suitable for both the dynamic and steady working conditions and more efficient.