Accelerated positioning method for IGBT open-circuit fault in modular multilevel converter

Abstract

The invention discloses an accelerated positioning method for an IGBT open-circuit fault in a modular multilevel converter. The method comprises: after an open-circuit fault is detected, performing enabling fault location, after entering a fault location link, firstly, calculating predicted values Ucpre of capacitor voltages of all sub-modules of a fault bridge arm, and a difference [delta]Uc between the predicted value and the measured value Ucma; after obtaining a measured value and a predicted value of the capacitor voltage of the sub-module, further calculating to obtain a virtual capacitor voltage value of each sub-module; finally, using virtual capacitor voltage as a sorting voltage value in the sorting link. According to the invention, it can be ensured that the capacitor of the fault sub-module is charged when the bridge arm current is greater than 0. When the bridge arm current is smaller than 0, the bridge arm current is kept unchanged, the rise of the capacitor voltage of the fault sub-module can be accelerated, the fault positioning time is obviously reduced, no extra hardware circuit needs to be added, the algorithm is simple and easy to implement, and both single-fault sub-module positioning and multi-fault sub-module positioning can be realized.

Description

technical field [0001] The invention belongs to the technical field of power electronic power converters, and relates to an accelerated positioning method for IGBT open-circuit faults in modular multilevel converters. Background technique [0002] In order to apply traditional low-level power electronic power converters to high-voltage and high-power applications, it is usually necessary to connect multiple switching devices in series and parallel. Since the switching characteristics of each device are different, multiple power devices connected in series and parallel will bring technical problems such as voltage equalization, current equalization, drive signal synchronization, and electromagnetic interference. In addition, the output voltage waveform quality of traditional low-level converters is poor, and a large-capacity AC filter needs to be installed at the output end to meet the output waveform quality requirements. [0003] Compared with traditional two-level and mul...

AI Technical Summary

Problems solved by technology

The open-circuit fault of the power switching device cannot be directly detected and isolated by the drive circuit. If the open-circuit fault cannot be cleared, it will affect the normal operation of the converter, deteriorate the output waveform quality of the converter, and even cause damage to other devices, eventually leading to system crash and shutdown

Although the bridge arm cascaded sub-module structure has brought many advantages to MMC, any open-circuit fault of a fully-controlled insulated gate bipolar transistor (Insulated Gate Bipolar Transistor, IGBT) in any sub-module will affect the normal operation of the system. run

Images