异步电机定子叠频法温升试验及效率研究综述

摘要

Large power vertical asynchronous motor is hard to find a proper coupler or load. So, temperature rise test should be simulated by equivalent loading using stator mixed⁃frequency method, i. e. , to superpose the primary and the secondary power supply vectors with similar frequency thus to form a new beat frequency power supply which should be applied at the terminal of the motor. The air⁃gap magnetic field generates pulse oscillation near the synchronous speed making the rotor of the asynchronous motor have a frequent status switching at generator and mo⁃tor. The moment of inertia of the rotor is changed, which excites electrical current flowing to the motor winding, and from the viewpoint of motor loss, it corresponds to introducing an equivalent mechanical loading. In this paper, the variation rules for the loss of the asynchronous motor, the estimated error for the efficiency and temperature rise at mixed⁃frequency are discussed, at mixed frequency, the temperature rise increases by 2~6K, and the efficiency decreases by 0�5 to 1 percent. With a deepening understanding of mixed⁃frequency, this will give a hint to the e⁃lectromagnetism design, ventilation calculation and lubrication calculation of sliding bearing. The feasibility of the mixed⁃frequency test of water lubricated thrust bearing is put forward. At present, our mixed⁃frequency technology is still at the developing period, and the aim is by referring to latest motor standard from IEEE112⁃B of the U. S. , the JEC⁃2137 of Japan, AS/NS1359�5 of Australia and IEC34⁃2 of EU, to improve related part of the mixed fre⁃quency test of our GB/T1032 in detail. Finally, the existing problems in the mixed⁃frequency method and the fu⁃ture study aspects are discussed in the paper.%大功率及立式异步电机难以找到恰当的对拖机组或负载，需要通过定子叠频等效负载法来模拟温升试验，即将两种相近频率主、副电源矢量叠加形成新的拍频电源，将其加载在电机的接线端。合成的气隙旋转磁场在同步转速附近产生脉动振荡，使得异步电机转子在发电和电动两个状态频繁切换，改变转子转动惯量，从而在电机绕组中引入电流，从电机损耗的观点考虑相当于引入了一个等效的机械负载。本文探讨了叠频时异步电机各种损耗的变化规律，以及效率、温升的估算误差，即叠频时温升增加2～6K，效率降低0�5％～1％。叠频理论对电磁、通风计算和滑动轴承润滑计算具有指导作用，本文提出了水润滑推力轴承叠频试验可行性。目前，我国叠频技术应用尚处于发展阶段，借鉴美国IEEE112⁃B、日本JEC⁃2137、澳大利亚AS／NZS1359�5、欧盟IEC34⁃2的最新电机标准，对国标GB／T1032中有关叠频试验部分要求进一步细化。最后，探讨了叠频方法当前存在的问题及未来仍需深入研究的方向。