三电平逆变器多故障模式识别方法

Multiple Faults Identification of Three-level Inverter

以二极管中点钳位型三电平逆变器为例,分析了三电平逆变器单管开路和多管同时开路故障状态下的相电流和桥臂电压信号,提出了基于相空间重构和小波包分析的三电平逆变器故障识别方法。利用相空间重构技术,对相电流进行重构,得到表征系统故障特征的不同形状、大小和方向的电流轨迹图形,借助图像处理技术识别出相电流不同的各类故障;对相电流相同的不同故障模式辅以小波包分析,提取出桥臂电压的特征频谱,识别出三电平逆变器的所有典型故障。仿真与实验结果表明该方法可以精确提取出各故障状态的特征向量,实现多种故障模式的识别。

A three-level neutral point clamped（NPC） inverter was taken as an example, phase current and bridge voltage in the fault states of single switch open and several switches open at the same time were analyzed, and a method based on reconstructive phase space（RPS） and wavelet packet analysis was proposed to identify three-level inverter faults. Based on RPS method, totally different reconstructed current trajectories were obtained, which showed the features of the inverter under different fault conditions. With the help of image processing technology, all kinds of faults with different phase currents were identified. The wavelet packet analysis was adopted to extract the features of frequency-spectrum for different faults with the same phase currents and all typical faults were identified. Simulations and experiments show that the method can accurately extract the feature vectors for each fault condition and various failure modes can be identified.