基于改进HHT的一体化电液作动器故障诊断

介绍了机载变排量变转速一体化电动静液作动器(EHA-VPVM,Electro-Hydrostatic Actuator with Variable Pump displacement and Variable Motor speed)的系统结构,根据EHA-VPVM早期故障信号非平稳、时变等特点,采用一种新的时频分析方法希尔伯特黄变换(HHT,Hilbert-Huang Transform)进行信号分析.针对HHT方法的模态混叠和虚假本征模态函数问题,提出两点改进:通过集合经验模式分解算法抑制模态混叠的发生;采用相关系数法保留真实本征模态函数.对EHA-VPVM工程样机进行早期故障诊断实验,用Hilbert边际谱和HHT谱分析永磁无刷直流电机两种工作状态下的振动信号.实验结果表明:改进HHT方法较好解决了HHT的模态混叠和虚假本征模态函数问题,能准确提取研究对象的早期故障特征,对EHA-VPVM早期故障具有良好的诊断效果.

Fault diagnosis of EHA-VPVM based on improved HHT

The system composition of the electro-hydrostatic actuator with variable pump displacement and variable motor speed(EHA-VPVM) was introduced. According to early fault signal features of EHA-VPVM, a new time-frequency analysis method Hilbert-Huang transform(HHT) was used. Two improved methods were introduced to solve problems of HHT, these problems were mode confusion and false intrinsic mode functions(IMF). The ensemble empirical mode decomposition(EEMD) was used to solve the mode confusion, and the correlation coefficient method was used to identify the effective IMF. In the early fault diagnosis experiment of EHA-VPVM prototype, Hilbert marginal spectrum and HHT spectrum were used to analyze the vibration signals of the permanent magnet brushless DC motor in different work conditions. The experiment results show the improved HHT well solved the problems of mode confusion and false IMF, and extracted the early fault features of the rolling bearing accurately. Moreover, the improved HHT method has good effect on the early fault diagnosis of EHA-VPVM.