The invention discloses a fault diagnosis method for an AC / DC charging equipment power device based on
wavelet packet analysis, and the method comprises the steps: analyzing a charging equipment powermodule, and determining a
fault class; obtaining output signals of the charging equipment
power module under the normal condition and various fault conditions; carrying out the high-
low frequency decomposition of the output signals, carrying out the multilayer
wavelet packet
decomposition of the high-
low frequency signals obtained through
decomposition, and carrying out the reconstruction of a
wavelet packet decomposition coefficient; calculating the extracted
signal energy at all frequency bands, carrying out the normalized calculation of the
signal energy, and finally determining a centralized
frequency band range of the
signal energy; carrying out the power
spectrum analysis of the reconstructed
wavelet packet decomposition coefficient, determining the feature frequency and power spectrum value of a
frequency band signal, comparing the comparison with the
fault analysis, and determining the type of a fault; and carrying out the fault type coding of the type of the fault. The methodimproves the time-
frequency resolution of a signal, achieves the precise fault positioning through the spectrum features, and improves the precision of the fault diagnosis of the AC / DC charging equipment power device.