The variation of stator winding turns will directly affect the key parameters of a motor, such as winding resistance and winding reactance, which further affect the steady-state performance of the motor. In order to get excellent steady-state performance from line-start permanent magnet synchronous motors (LSPMSMs) under different load powers, taking an 11 kW LSPMSM as an example, the finite element method (FEM), combined with the steady-state phasor diagram and torque angle characteristic, are used in this paper for the optimal design of the stator winding turns of the prototype. The correctness of the model is verified by comparing the experimental data with the calculated data. First, the influences of different stator winding turns on the no-load, back-induced electromotive force (EMF), as well as on inductance and overload ability are studied, and the variation mechanism is obtained. In addition, from the perspective of the torque angle characteristic, the influence of the change in synchronous inductance caused by the number of turns on the steady-state power angle is studied. Second, the variation of the current and power factors with turn number is obtained by studying the steady-state power angle and end voltage. Based on the coupling relationship between the no-load back EMF and the power angle, the mechanism of non-linear variation of current and power factor is revealed. Finally, the variation of the number of turns on the core loss and eddy current loss is analyzed under various operating conditions, and the variation mechanism is revealed, based on the armature reaction theory.

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The line start permanent magnet synchronous motor (LSPMSM) can be used for direct-on-line (DOL) starting, so it is easily affected by voltage unbalance. Based on the finite element method (FEM) and analytical method, the influence of voltage unbalance on the steady-state performance of LSPMSM is studied in this paper. A two-dimensional finite element model is built, and the armature current, losses and torque ripple as a function of the phase voltage unbalance rate (PVUR) are obtained. The influence mechanism of voltage unbalance on the steady-state performance of a motor is demonstrated. Finally, a prototype of LSPMSM is manufactured and tested. By comparing the experimental data with the simulation data, the accuracy of the calculation model is verified, and the correctness of the research is proved. Hongbo Qiu(Non-member) received his graduation degree from the Harbin University of Science and Technology, Harbin, China, and a Ph.D. in electrical engineering from the same university in 2014. He has been with the Zhengzhou University of Light Industry, Zhengzhou, China, since 2014. His research interests include electromagnetic and thermal analysis on electrical machines, especially in permanent magnetic machines.