多断条笼型转子感应电动机故障过程研究

Study on the faulty evolvement of squirrel cage induction motor with multi-broken rotor bars

针对多断条转子绕组非对称特点,采用拓展的综合矢量法建立了多断条感应电动机易于求解的数学模型.通过增大故障导条阻值,仿真了由单根断条演变为多根断条的故障过程.表明与断条相邻及相距一对极距的导条电流增大最多,其诱发断裂可能性最大;多断条故障使电机起动过程的电磁转矩/转速曲线呈现转矩脉动的故障特征,脉动幅度与断条位置密切相关;当2根断条间距π/2电角度,或3根及以上断条间距2π/Nf(Nf为断条数)电角度时,转子磁势保持对称,定子电流及电磁转矩不显故障特征.所得研究结果有助于对感应电机在线故障诊断作正确评估.

Owing to the multi-broken-bars rotor s winding asymmetry,an easy-solved mathematical model was established with the extended synthetic vector for multi-broken-rotor-bars squirrel-cage induction motors.By increasing the faulty bar s resistance,the model simulated the fault process from one-broken bar to multi-broken bars.The result shows that the highest bar current increment occurring on bars which is adjacent to the broken bar and spacing in one pair-pole from the adjacent bar,where it is the most likely to cause a breakdown. Further, fault on multi -broken bars causes a torque pulsation faulty feature on electromagnetic torque - speed characteristics curve during start - up. The torque pulsation magnitude closely relates to the broken- bars position. When two broken - bars or three and more than three broken - bars spacing in ,π/2 and 2π/Nf（Nf is broken - bar number） electrical angle respectively, the rotor mmf remains symmetrical, and no faulty feature shows up on the stator current and the electromagnetic torque. The study and investigation conclusions are directly applicable to induction motors online diatmosis and troubleshooting.