基于电磁转矩复解析小波变换的感应电机转子故障检测

Rotor Fault Detection for Induction Motors Based on Complex Analytical Wavelet Transform of Electromagnetic Torque

提出一种运用电磁转矩信号对感应电机转子断条故障进行检测的新方法。当感应电机转子发生断条故障时,转子绕组的不对称将会使电磁转矩中引入2s同步速的脉动转矩(s为转差率)。对电机起动电磁转矩信号进行复值小波变换,根据分析小波在特定中心频率条件时信号瞬时频率与其对应小波脊线的关系,提取出故障特征转矩频率变化规律,实现转子故障的可靠检测。同时,对应尺度上小波系数的模值还能够反映该故障特征转矩在电机起动过程中的幅值变化规律,将其作为故障严重程度指标则可以进一步判断转子断条根数。实验结果证明了该方法的有效性。

A new method based on the electromagnetic torque signal analysis to detect the rotor broken bar fault for the induction motors is presented. Researches show the asymmetry of the rotor caused by broken bar fault will give rise to the appearance of additional frequency component of 2sfs (s is slip and fs is supply frequency) in the electromagnetic torque spectrum. When the center frequency of the mother wavelet is selected, the signal instantaneous frequency and its wavelet ridge have certain relationship. The rotor fault characteristic torque frequency which can be used to identify the rotor broken bar fault can be extracted based on the wavelet ridge of the fault characteristic torque. Moreover, the wavelet coefficients modulus can give the amplitude variation of the fault characteristic torque during the startup process of the induction motors and it can be used as the rotor fault severity factor to analysis the number of rotor broken bars. Experimental results verify the effectiveness of the proposed rotor fault diagnosis method.