Base Speed Operation Point Study Of Wide Speed Range PMSM

High-speed motor has advantages of high power density, direct connection with high-speed load, and fast dynamic response. In recent years, high-speed motor has become a hot research topic in the field of electrical machines. In order to extend the speed range and increase the high-speed load capacity of the permanent magnet synchronous motor, flux-weakening control is widely adopted. The motor operates with constant torque when its speed is less than the base speed. Otherwise, it operates with constant power. Selection of the base speed is thus the one of the issues in designing a high-speed motor with high performance.The motor studied in this paper is a wide speed range permanent magnet synchronous motor with the rated speed of 12500 r/min and rated torque of 12.7 N-m. To deal with the higher requirements of speed range with flux-weakening control, four motors with the same size but different base speed are designed by changing the number of winding turns. Their finite element analysis models are established. Simulation results of each model with different base speed are obtained, under both ideal sinusoidal current excitation and PWM current excitation. And their load capacity and electromagnetic losses are compared. The calculation results show that, properly reducing the number of winding turns can not only improve the load capacity but also cut the electromagnetic losses provided that the power converter has sufficient current capacity though the supply voltage is limited.