Efficient Design Optimization of PMSM Drive Systems Using Improved Equivalent-Circuit-Based Loss Minimization Control

During the lifecycle of an electric drive system, the electricity cost usually constitutes a dominant portion, leading to extensive research on improving the efficiency of such systems. This article presents an efficient design optimization strategy for permanent magnet synchronous motor (PMSM) drive systems, cooperating with an improved loss minimization control, targeting to reduce the system power loss and improve the overall operating performances. Specifically, a generalized equivalent circuit model with a novel topology that considers rotating magnetization effects is first proposed to accurately predict the core loss of PMSMs under both no-load and load conditions. Moreover, after analyzing the copper and inverter losses, an integrated system-level loss model of the PMSM drive system is developed, based on which an improved loss minimization control is implemented through deriving the relationships among the electromagnetic torque, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i>-axis and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i>-axis currents. Then, the system-level optimization strategy that incorporates both the motor and control sides is presented, aiming to maximize the torque and efficiency and minimize the torque ripple and speed overshoot. Finally, a multilevel algorithm based on sensitivity analysis is employed to solve the multiobjective optimization models with reduced calculation costs. Extensive experimental and simulation verifications are demonstrated with a 20 kW interior PMSM drive system platform. Results show that the optimized drive system has promoted steady-state and dynamic behaviors, and the proposed loss minimization control can comprehensively reduce the system losses by about 3.25%.