中文摘要：

异步起动永磁同步电动机起动过程中,定转子电流产生的强退磁磁场可能导致永磁体发生不可逆退磁。该文采用二维有限元法,深入研究了W形转子结构异步起动永磁同步电动机起动过程中永磁体的退磁特点,分析了定转子基波磁动势对永磁体工作点的影响,以及永磁体最大退磁点出现的规律。结果表明：电机以不同负载条件及转子初始位置起动时,每个起动过程中永磁体退磁最明显的时刻可能出现在任意转速;随着负载转矩和转动惯量的增大,永磁体退磁最明显时刻的电机转速接近同步速的概率增大,永磁体遇到最严重退磁磁场的概率也将增大。电机正常起动过程中,很可能在永磁体边角位置发生不可逆退磁,位置比较固定且区域面积很小,不会对电机性能产生显著的影响。

英文摘要：

During the starting process of line-start permanent magnet synchronous motor（LSPMSM）, the severe demagnetization field produced by stator and rotor currents may cause irreversible demagnetization of permanent magnets. This paper further analyzed demagnetization characteristics of LSPMSM with W type rotor during starting process, using two-dimensional finite-element method. Effect of fundamental magnetomotive forces produced by currents in stator windings and rotor bars on permanent magnets＇ operating point was studied. The rule that magnets＇ largest demagnetization point occurs during starting process was also analyzed. Results show that when LSPMSM with W type rotor starts with different load conditions and initial rotor positions, the moment that demagnetization of magnets is the most obvious during one starting process may occur at any speed; as load torque and moment of inertia increase, the speed at the moment that demagnetization of magnets is the most obvious is more likely close to synchronous speed, and the probability that permanent magnets encounter the severest demagnetization field will increase. Irreversible demagnetization probably appears in the corners of magnets during normal starting process, and the position is fixed. The area is small, and no significant impact on motor performance will be caused.