Application Research Of Hilbert Transform To Rotor Bar Broken Fault Diagnosis

Induction motors are widely used in the industrial and agricultural production because of its simple structure, low price, high reliability and convenient maintenance. A motor failure not only can result in damage to the motor, but also can result in unscheduled machine downtime and the shutdown of a production line, which will cause heavy financial losses and catastrophic failure. Statistical studies have shown that the rotor broken bar fault is the most familiar fault for induction motors. Consequently, researches on rotor broken bar fault diagnosis able to detect this kind of fault at an early stage and also to allow for carefully planed repair actions are of great theoretical significance and socioeconomic benefits.This paper discuss the principle of fault diagnosis of broken rotor bars and describes that there are some characteristics appear in the steady-state stator current when it has broken bars faults. The steady-state stator current as a study object, the Hilbert transform has been used in the rotor broken bar fault detection. The main research work is as follows:First of all, the stator current was processed with Hilbert transform to eliminate the DC component. This method has solved the problem of the fault characteristics extraction, because the characteristics are easy to be buried by fundamental frequency and hard to be detected.Secondly, the broken rotor bars fault was diagnosis by the Fourier spectrum method, the Hilbert envelope spectrum method, the wavelet coefficients method, after the Hilbert transform eliminated the DC component. By simulation and analysis, compared the results with the primary methods, the detection result was more directly and accurate.Finally, the combination of the Hilbert transform and wavelet packet energy, a novel way for detecting rotor bar broken fault is provided. Both of theoretical derivation and simulation results show that the Hilbert transform and wavelet packet energy combining method was best fit method.The fault diagnosis experimental system was builted for broken rotor bars by setting the sysytem simulation model and setting the Y100L1-4induction motor as the research object. Numerical and experimental results show that the approach is valid and effective.