MMC sub-module IGBT open-circuit fault ride-through method based on fault sub-module independent control

Abstract

The invention discloses an MMC sub-module IGBT open-circuit fault ride-through method based on fault sub-module independent control, and the method comprises the steps: judging whether a fault sub-module is in a controllable region or an uncontrollable region through a bridge arm current iarm when a lower switching tube Q2 in the sub-module is in an open circuit, and determining whether to start a fault ride-through method or not according to the judgment result; according to the fault ride-through method, an optimal duty ratio Dopt is selected through a model prediction algorithm, and then a driving signal of a switching tube Q1 on a fault sub-module is determined; and according to the current iarm state of the bridge arm and the driving signal of the fault sub-module Q1 in the step S2, determining a sub-module which is specifically put into the fault bridge arm. According to the invention, fault sub-module capacitor voltage independent control based on model prediction control is provided for the first time, and on the basis of completing fault sub-module capacitor voltage suppression, a corresponding fault bridge arm sub-module voltage-sharing method is provided at the same time, so that independent voltage control of the fault sub-module and bridge arm sub-module voltage-sharing control are realized; and a stable transition condition is created for MMC fault tolerance.

Description

technical field [0001] The invention relates to the field of fault tolerance of power electronic converters, in particular to an open-circuit fault ride-through method of an MMC sub-module IGBT based on the independent control of a fault sub-module. Background technique [0002] Since the switch tube of the half-bridge sub-module in the MMC bridge arm has an open-circuit fault, when the lower switch tube Q in the half-bridge sub-module 2 In the event of an open-circuit fault, the sub-module capacitor voltage will absorb more energy than it releases. Therefore, the capacitor voltage of the faulty sub-module will rise in waves. By analyzing the current path of the faulty sub-module, it can be seen that when the half-bridge sub-module Q 2 When an open-circuit fault occurs, the faulty sub-module is greater than zero (i arm (t)>0) shows an uncontrollable mode. Therefore, the working mode of the sub-module in this state is called the uncontrollable area. When the bridge ar...

AI Technical Summary

Problems solved by technology

[0003] However, existing MMC fault-tolerant control methods have not yet 2 Independent fault ride-through control in the event of an open circuit fault, so a new technical solution is needed to solve these problems

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