Inverter fault diagnosis method based on wavelet analysis and SVM

Abstract

The invention relates to an inverter fault diagnosis method based on wavelet analysis and SVM. The method comprises firstly establishing a diode NPC three-level inverter model and determining a principle of classification, respectively subtracting three phase voltages of an AC output side when an inverter breaks down from three phase voltages (Ua, Ub and Uc) of the AC output side when the inverter normally works to obtain [delta]Ua, [delta] Ub and [delta]Uc, carrying out d-q inversion on the [delta]Ua, the [delta] Ub and the [delta]Uc, changing three phases into two phases to obtain Ud and Uq, and analyzing the Ud and the Uq through wavelet transformation; secondly respectively extracting energy from each frequency band signal of the Ud and the Uq subjected through the wavelet transmission, determining a fault feature vector, and establishing a data sample based on the fault feature vector; and finally establishing a multi-valued classifier using the MATLAB and a LIBSVM tool box, so as to carry out fault diagnosis on a cross double-phase bridge of the diode NPC three-level inverter.

Description

Technical field [0001] The invention relates to the field of power electronic device fault diagnosis, in particular to an inverter fault diagnosis method based on wavelet analysis and SVM. Background technique [0002] Multi-level converter is a new type of converter that realizes high-voltage and high-power output by changing the topology of the converter itself. It does not require a buck-boost circuit and a voltage equalization circuit. Compared with two-level inverters, multi-level inverters have the advantages of low power switch voltage stress, series voltage equalization of power devices, low harmonic content of the output voltage waveform, small electromagnetic interference problems, low switching losses and high working efficiency. Therefore, inverters of this structure are widely used in high-voltage, high-current, and high-power fields, such as Shanghai maglev trains and Harmony CRH trains. The most typical in the multi-level converter is the diode NPC (NeutralPointCl...

AI Technical Summary

Problems solved by technology

[0003] However, the diode NPC three-level inverter uses more switching devices than the two-level inverter, and the circuit structure and control are more complicated, which increases the failure of power electronic equipment and greatly reduces the reliability of the system

Once a multi-level failure occurs, it will cause the enterprise factory to stop production, and cause a catastrophic accident, causing huge losses and impacts on the society.

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