Electronic Science and Technology ›› 2022, Vol. 35 ›› Issue (5): 81-86.doi: 10.16180/j.cnki.issn1007-7820.2022.05.013

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Parametric Fault Characteristics Analysis of Electrolytic Capacitor in NPC Three Level Inverter

WANG Xin,HUANG Chong,XU Xiang   

  1. School of Physics and Electronic Information Engineering,Henan Polytechnic University,Jiaozuo 454000,China
  • Received:2020-12-06 Online:2022-05-25 Published:2022-05-27
  • Supported by:
    National Key R&D Program(2016YFC060906)


In view of the problem that it is difficult to extract the fault features of electrolytic capacitor in NPC three-level inverter, a fault feature extraction method based on variational mode decomposition and modal energy is proposed. By collecting the output current signal of NPC three-level inverter and combining with the reference current signal, the current deviation signal is obtained. According to the characteristics of frequency distribution of current deviation signal, the decomposition scale of VMD is optimized by modal repetition rate. The VMD is employed to decompose the current deviation signal to obtain the limited bandwidth modal component with the center frequency. According to the information entropy of the modal component, the characteristic component which can represent the capacitor fault is determined. Then the modal energy of the characteristic component is calculated, the characteristic vector is constructed, and the characteristic variation rule is sought and classified. The results show that this method can accurately reflect the working state of electrolytic capacitor.

Key words: NPC three level inverter, variational mode decomposition, electrolytic capacitor, modal energy, modal repetition rate, information entropy, deviation signal, center frequency

CLC Number: 

  • TP29