Fault diagnosis method for cascaded H-bridge multi-level inverter

Abstract

The invention discloses a fault diagnosis method for a cascaded H-bridge multi-level inverter, and the method comprises the steps: firstly building a hybrid logic dynamic model for a cascaded H-bridge multi-level inverter system, and predicting an output side current value in a normal working state through a current sliding-mode observer; comparing the output of an actual system with the output of an observer to obtain a residual signal, analyzing the residual signal to obtain the category of a fault, then carrying out wavelet packet decomposition on the output current in a fault state to obtain a wavelet packet energy spectrum, carrying out principal component analysis dimension reduction to obtain a fault feature vector, and for a plurality of faults in each fault category, training the SVM corresponding to the fault category; and finally, carrying out fault identification by using the trained SVM in the category to which the fault belongs, so that fault diagnosis is completed.

Description

Technical field [0001] The present invention belongs to the field of power electronic converter fault diagnosis, and is specifically related to a fault diagnosis method of a cascaded H-bridge multi-level inverter. Background technique [0002] The traditional two-level inverter has a small capacity, and does not apply to high-power occasions, and there is a shortcoming of the DC bus voltage, the switch stress is equal. In order to overcome these disadvantages, the inverter can be applied to more, and some scholars have proposed a cascaded H-bridge inverter structure. [0003] The cascaded multi-level inverter has the advantages of modular and easy to expand. However, the multi-level circuit uses a large number of switching devices. Most of these switching devices are mostly high power, and the damage rate of switching devices is high. The most common is that one or two switching devices have an open failure. Once the failure can cause the entire circuit to stop working, it can ca...

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Problems solved by technology

[0005] The purpose of the present invention is to provide a fault diagnosis method for cascaded H-bridge multilevel inverters, which solves the problem that the efficiency and accuracy of existing fault diagnosis methods are often not high enough, and the identification of faults with similar fault characteristics low degree problem

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