大功率盘式交流永磁同步电机电磁场分析

Electromagnetic Field Analysis on High-Power Disc-Type AC Permanent Magnet Synchronous Motor

针对应用于石油钻井平台的510kW盘式交流永磁同步电机进行了建模,并分别从空载、负载、电感角度进行了三维电磁场仿真。建模中考虑了模型的对称性和周期性,将整体模型简化成1/4模型,从而显著减少了仿真的计算量。在电机空载状态下,得到了空载磁通密度分布,分析了永磁体极弧系数、槽口宽度和极槽配合对齿槽转矩的影响,通过优化,在永磁体极弧系数取0.85、槽口宽度取5mm、极槽配合取18槽16极时,得到了最小的齿槽转矩30.64N·m,这将有利于降低转矩波动,从而减小电机的振动和噪声,提高系统的控制精度和品质。在电机负载状态下,分析了不同电流激励源和内功率因数角下的电磁转矩波形:在恒转矩区,当相电流为550A、内功率因数角为22°、额定转速为1 600r/min时的电磁转矩为3.115kN·m;在恒功率调速区,当相电流为550A、内功率因数角为41°、转速为2 000r/min时,电磁转矩为2.577kN·m;在过载工作区,当相电流为1 140A、内功率因数角为47°、额定转速为1 600r/min时,电磁转矩为4.756kN·m,电机达到1.5倍过载。与同体积的其他电机相比,该电机的电磁转矩密度有显著提高,内功率因数角调整裕度也较大,能满足过载能力要求。此外,结合电机空载和负载求得的参数,绘制了盘式电机矢量图,求得同步电感值为0.31mH。

A 3D electromagnetic field was modelled and simulated in the design of a 510 kW disk- type AC permanent magnet synchronous motor used on oil drilling platform. Considering the symmetry and periodicity of this model, the model was simplified into a one-fourth part hence the computing workload was greatly reduced. Under no-load condition, the no-load flux density distribution and the effects of pole arc-coefficient, slot opening width, and slot-pole combination on the cogging torque were analyzed. By optimization, the minimum value of cogging torque was 30.64 N · m when the pole arc-coefficient was set 0.85, the slot opening width was set 5 mm, and an 18 slot-16 pole combination was adopted. This significantly reduced motor torque fluctuation, hence reduced vibration and noise levels and improved the control accuracy andquality of the system. When the motor was working under loading condition, the waveforms of electromagnetic torque were analyzed under different exciting currents and inner power factor angles. The electromagnetic torques under different operation conditions were also obtained. Research shows that the electromagnetic torque density of this motor increases significantly compared with other motors with the same volume, and its adjustment margin of inner power factor angle is quite large, satisfying the requirement of overloading. Moreover, according to the obtained no-load and load parameters, the vectorgraph of this disk-type synchronous motor was drawn and the synchronous inductance value of 0. 31 mH was obtained.