Detecting method for rotor broken bar fault of cage-type asynchronous motor

Abstract

The invention discloses a detecting method for a rotor broken bar fault of a cage-type asynchronous motor, comprising the following steps of: firstly, carrying out hilbert transformation on an instantaneous stator current signal acquired according to a certain frequency to obtain a Hilbert modulus; then, filtering a direct-current component out of the Hilbert modulus through subtracting an average value of the Hilbert modulus; next, carrying out spectral analysis by using ESPRIT to obtain an ESPRIT spectrogram; and finally, judging whether the rotor broken bar fault exists according to the fact whether spectrum peaks of a 2sf1 component and a 4sf1 component exist in the ESPRIT spectrogram, if the spectrum peaks of the 2sf1 component and the 4sf1 component exist simultaneously, judging that the rotor broken bar fault happens, otherwise, judging that a rotor normally runs. By using the method, the affect of load fluctuation is effectively overcome, the rotor broken bar fault of the asynchronous motor can be sensitively and reliably detected by only sampling a very short stator current signal, and therefore, the method is particularly suitable for a large asynchronous motor widely used in engineering.

Description

technical field [0001] The invention relates to a method capable of detecting broken bars of a cage-type asynchronous motor rotor, which belongs to the technical field of motors. Background technique [0002] During the operation of the cage-type asynchronous motor, the rotor guide bars are subjected to alternating stresses such as radial electromagnetic force, rotating electromagnetic force, centrifugal force, thermal bending deflection force, etc., coupled with rotor manufacturing defects, may lead to broken bars, such failures occur The probability is about 15%. [0003] Broken rotor bars are a typical progressive fault. Usually one or two guide bars break at the initial stage, and then gradually develop until the output of the motor drops or even stops. Therefore, it is necessary to implement fault detection for broken rotor bars. [0004] After the broken rotor bar of the cage-type asynchronous motor occurs, there will be (1±2 ks ) f 1 The frequency of the additiona...

AI Technical Summary

Problems solved by technology

[0026] In summary, it can be seen that the existing Hilbert transform method based on FFT spectrum analysis has a major defect - load fluctuations lead to fluctuations and leakage of the DC component in the Hilbert modulus, resulting in complex FFT spectrum and affecting rotor broken bars Reliability of fault detection; and, FFT spectrum analysis requires motor signals of sufficient duration to ensure frequency resolution, which means that load fluctuations are introduced with a higher probability, making this problem more prominent

Especially, for large-scale asynchronous motors widely used in engineering practice, the above-mentioned Hilbert transform method faces severe challenges and even fails

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