Redundancy fault-tolerant PWM method and modular series inverter based on the same

Abstract

The invention discloses a redundancy fault-tolerant PWM method. First, based on a modular series inverter control strategy, a modulating wave signal of each submodule is determined; then according to the number of redundancy submodules contained in modular series inverter topology, the amplitude of a triangular carrier of each submodule is determined; and finally, according to the modulating wave signals of the submodules and corresponding triangular carrier signals, control pulse signals of submodules are determined, thereby controlling the switching states of the submodules. The invention also discloses a modular series inverter based on the modulation method. In the method, the number of triangular carriers is equal to that of the submodules, when redundancy submodules exist, circulative allocation of carriers is not needed, thereby simplifying control difficulty of submodule switching devices, at the same time, reducing unnecessary switching states, and reducing the switching freuqnecy of submodules; and when a fault occurs in a submodule of the inverter, a traditional switching process of a normal submodule and a redundancy submodule is not needed, thereby reducing disturbance caused to a system.

Description

technical field [0001] The invention belongs to the field of power electronics, in particular to a redundant fault-tolerant PWM modulation method and a modular series inverter based on the method. Background technique [0002] In recent decades, with the rapid development of power electronics technology, voltage source converters (voltage source converters, VSCs) based on fully controlled power switching devices such as IGBTs have been widely used in power systems, among which multilevel converters have The output voltage has the characteristics of low harmonic content, small switching loss, and high applicable voltage level. It has obvious advantages in high-power occasions such as high-voltage direct current (high-voltage direct current, HVDC), medium and high voltage power quality management and other fields. [0003] Modular series inverters have become the mainstay of current multilevel converter applications due to their highly modular topology, easy system expansion a...

AI Technical Summary

Problems solved by technology

When the traditional carrier phase-shift PWM is applied to the modular series inverter with redundant sub-modules, since there are redundant sub-modules in each phase of the modular series inverter, and the redundant sub-modules participate in the whole operation process Switching, so the number of sub-modules and the number of carriers cannot be one-to-one correspondence

In order to ensure the normal output of the modular series inverter, it is necessary to distribute the carrier in a circular manner, resulting in some problems such as unnecessary switching actions of the switching devices in the sub-modules, increasing its switching loss, and increasing the The difficulty of controlling the switching devices in the module, etc.

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