基于变频器供电侧电流Hilbert解调制方法的空载电机转子断条故障诊断

Fault diagnosis of broken rotor bars of inverter-fed squirrel-cage induction motor at no-load using supply-side current based on Hilbert demodulation technique

变频器供电侧电流比电机定子电流易于获取且较少受到噪声干扰。然而,由于基频频谱泄露的影响,基于变频器供电侧电流的电机电流信号特征分析方法无法诊断低负载或空载运行条件下的鼠笼电机转子断条故障。首先基于转移函数和调制理论建立了变频器供电侧电流谐波分析简化模型。在此基础上,提出了基于Hilbert解调制的空载电机转子断条故障诊断方法。该方法的核心是采用Hilbert变换提取电机稳态运行时的变频器供电侧电流信号包络线、构造基于包络线平方的解析信号并对该信号作FFT频谱分析。在3 kW电机实验台上对所提出的方法进行实验验证,实验结果表明了该方法的有效性。

In comparison with stator current, supply-side current of invert-fed squirrel-cage induction motor is conven- ient to acquire and immune to noise. However, when a motor operates under light load or no-load conditions, the motor current signature analysis （MCSA） method based on supply-side current can not diagnose the broken rotor bar faults of inverter-fed squirrel-cage induction motor due to the spectrum leakage submerging other spectral response in its vicinity. In this paper, a simplified model of supply-side current harmonic signal for squirrel-cage induction motor is firstly established using the transfer function concept and frequency modulation theory. A diagnosis method of broken rotor bar faults of inverter-fed squirrel-cage induction motor at no-load based on Hilbert demodulation technique is proposed. The core of the method is to extract the envelope of the supply-side current signal under the motor steady operation condition using Hilbert transform, construct the analytic signal based on the square of the envelope and per- form the FFT spectrum analysis of the signal. The experiment verification was performed on a 3 kW motor experiment test bench;the experiment results prove the effectiveness of the proposed method.