应用磁场摆角诊断异步电机转子断条故障

Induction Motors Broken-bar Fault Diagnosis Using the Rotor Magnetic Field Swing Angle

为及时发现电机故障,保证设备安全运行,介绍了一种新的基于异步电机转子合成磁场方向摇摆振动的断条故障诊断方法,并验证了在电机不同负载水平时该方法的有效性。异步电机转子发生断条故障时,断条会影响转子磁动势(MMF)波形,使转子合成磁场方向发生摇摆振动。通过检测磁场方向的摆角,即使是1根断条的轻微故障,也可以很容易诊断出来。与定子相电流的快速傅立叶变换频谱分析法相比,该方法几乎不受电机负载水平的影响,且不需要速度传感器。实验证明,该方法简单易行,能够准确地检测出转子断条故障,且能够根据摆角的大小来判断断条故障的严重程度,适宜做成在线状态监测系统。

A new method for diagnosing rotor broken bar fault is put forward, which is based on the orientation oscillation of asynchronous motor resultant magnetic field, and the validity of this method is verified at different load conditions. The pendulous oscillation phenomenon for the orientation of rotor resultant magnetic field is an electromagnetic phenomenon, which will take the shape of the rotor magneto motive waveform into consideration. Under the ideal condition, the magnetic field, of the asynchronous motor will rotate at motor＇s synchronous speed. Howev er, when rotor broken bar fault occurs in asynchronous motor, the rotor＇s MMF waveform will be affected. Through detecting swing angle of magnetic field orientation, even if one broken-bar light fault can be diagnosed easily. By comparing with the fast Fourier transform （FFT） spectrum of the phase current, it is found that this method can hardly be affected by the load level and do not need speed sensor. This method is proved to be simple and feasible by experiments and can detect the rotor broken-bar fault exactly. Furthermore, the severity degree of broken-bar can be estimated by the swing angle,so this method is suitable to an online state monitoring system.