T-type three-phase four-wire rectifier fault real-time detection and positioning method and system

Abstract

The invention discloses a T-type three-phase four-wire rectifier fault real-time detection and positioning method and system, and belongs to the technical field of online fault diagnosis. The method comprises the following steps: firstly, carrying out fault detection by utilizing a zero-domain current threshold and a fault detection judgment threshold; and after detecting that the power tube has afault, obtaining an accurate fault positioning result by utilizing the polarity of the three-phase current after the time delay delta T and the polarity change of the three-phase modulation voltage during the occurrence of the open-circuit fault. Higher real-time performance is achieved. During fault detection, the characteristic that the influence of the bus capacitor voltage on the current in the fault interval can be quickly reduced to be close to zero is utilized, the zero-domain current threshold value is set for fault detection, and high real-time performance is achieved; during fault positioning, only current and modulation voltage signals need to be analyzed, system parameters such as system inductance values are not needed, and the method is insensitive to changes of the system parameters, good in robustness and high in disturbance rejection capacity.

Description

technical field [0001] The invention belongs to the technical field of online fault diagnosis, and more specifically relates to a method and system for real-time fault detection and location of a T-type three-phase four-wire rectifier. Background technique [0002] In recent years, with the rapid development of new energy technology, more and more new energy vehicles have appeared one after another. As an important charging module of the new energy vehicle charging pile, the stability of the rectifier is an important indicator to consider the quality of the system. In the rectifier, the power tube is easily turned on and off due to high frequency to cause an open circuit fault, which directly affects the normal operation of the system. T-type three-phase four-wire rectifiers are widely used in rectifier modules of charging piles due to their superior performance. Researching real-time and effective diagnostic methods for open-circuit faults of T-type three-phase four-wire ...

AI Technical Summary

Problems solved by technology

[0003] At present, most of the real-time diagnosis methods for open-circuit faults of three-phase three-level rectifiers are based on signal processing methods such as Fourier transform and wavelet transform, and then optimize the combination of feature quantities to realize fault diagnosis. These signal processing methods require complex mathematical calculations. Increases the CPU calculation burden; for three-phase three-level rectifiers, additional filtering operations will lose fault information, resulting in indistinct features; selecting the threshold value based on experience or fixing the threshold value will cause problems such as low robustness of the diagnostic algorithm

Existing methods such as signal-based residuals need to add capacitive voltage sensors to improve accuracy, which increases the cost of diagnosis

Images