Complex control system and method of modular multi-level converter

Abstract

The invention relates to a complex control system and method of a modular multi-level converter. The method is characterized in that each submodule capacitor voltage of an upper bridge arm and a lower bridge arm on the modular multi-level converter, currents of the upper and lower bridge arms and a power supply voltage of an alternating current (AC) side are detected, and a master controller carries out an operation on each submodule capacitor voltage, the currents of the upper and lower bridge arms and the power supply voltage of the AC side to obtain the public pulse-width modulation (PWM) duty ratio of the upper and lower bridge arms; an upper and lower bridge arm controller carries out an operation on each submodule capacitor voltage of the upper and lower bridge arms and the public PWM duty ratio of the upper and lower bridge arms to obtain the PWM duty ratio of each submodule of the upper and lower bridge arms; and the PWM duty ratio of each submodule is processed by a PWM signal generator so as to generate PWM control signals of each submodule, thus realizing balance control of each submodule capacitor voltage of the convertor and current and voltage control of the convertor. The complex control system is not required to use a special charge-discharge power circuit for a capacitor, can be applied to any PWM node, controls circulating flow flexibly, meets special demands, and is specific in physical significance and sufficient in theoretical foundation.

Description

technical field [0001] The invention relates to a comprehensive control system of a modular multilevel converter and a method thereof, and belongs to the technical field of control of multilevel power electronic power converters. Background technique [0002] Modular multi-level converter topology adopts cascaded and modular structure, and can obtain multi-level ladder voltage without direct series connection of power devices, with lower dU / dt and lower voltage harmonic content. / High-voltage large-capacity systems have broad application prospects. The converter topology is as figure 1 As shown in the figure, the upper bridge arm and the lower bridge arm are each formed by cascading N sub-modules, each sub-module is a half-bridge structure, and the sub-modules are connected in parallel with the same capacitor on the DC side. Since the DC-side capacitors of each sub-module of the modular multilevel converter are in a floating state, the capacitors of each sub-module will b...

AI Technical Summary

Problems solved by technology

However, the Chinese patent publication No. CN101546964A "Modular Combined Multilevel Converter" only discloses a combined multilevel converter topology, and does not solve the problem of the capacitance voltage of each sub-module of the modular multilevel converter. balance problem

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