基于机电耦合动力学的3K行星轮系裂纹故障电流信号研究

Stator current signal under gear crack fault mode of 3K planetary gear set based on electromechanical coupling dynamics model

考虑3K行星轮系内部时变啮合刚度、阻尼、齿侧间隙、综合啮合误差等非线性因素和电机-减速器系统内部机-电-磁耦合效应,建立了电驱动3K-Ⅱ型行星传动系统机电耦合动力学模型。并基于该模型,计算了5种裂纹故障情况下各齿轮副随转角变化的时变啮合刚度,得到了不同齿轮裂纹故障情况下的定子电流仿真信号。通过时移叠加去工频频谱和包络解调谱对电流信号进行了分析。结果表明:定子电流信号受故障特征的频域调制作用,且出现的边带成分中包含供电频率负值;定子电流信号受故障特征的幅值调制作用,在包络解调谱中,齿轮故障表现为在故障频率及其倍频处出现峰值;太阳轮故障在定子电流频谱边带和包络谱中虽能识别,但相较于其他齿轮故障,表现不够明显。通过机电耦合模型得到的分析结果与通过AM-FM(amplitude modulation-frequency modulation)数学模型分析结果吻合,表明提出的机电耦合模型的合理性,可为研究3K行星轮系各类齿轮故障情况下的电机定子电流信号提供理论指导。

Here,considering time-varying meshing stiffness,damping,backlash,comprehensive meshing error and other nonlinear factors inside 3 K planetary gear set and mechanical-electrical-magnetic coupled effect in motor-reducer system,the electromechanical coupling dynamics model of an electric drive 3 K-II planetary transmission system was established.Based on this model,time-varying meshing stiffnesses of various gear pairs with change of rotating angle under five kinds of gear crack faults were calculated,and stator current simulation signals under different gear crack faults were obtained.These current signals were analyzed using frequency spectra with current supply frequency removed by time-shift superposition and envelope demodulation spectra.The results showed that frequency domain modulation of fault characteristics is exerted on stator current signals,and appearing side-band components contain negative value of current supply frequency;stator current signalsare modulated by fault feature amplitude,in envelope demodulation spectra,gear faults reveal peaks at fault frequencies and their multiplication;although sun gear fault can be identified in sideband and envelope spectra of stator current spectra,it is not obvious compared with other gear faults;the analysis results obtained with the electro-mechanical coupled model agree well with those obtained with AM-FM mathematical model,so the proposed electro-mechanical coupled model is reasonable and can provide theoretical guidance for studying motor’s stator current signals under various gear faults of 3 K planetary gear set.