Pulse width control method of modular multilevel converter

Abstract

The invention belongs to the power transmission and distribution field, and specifically relates to a pulse width control method of a modular multilevel converter. The method is characterized by determining the switched number of submodules at any time by carrier phase-shifting and then determining switching of the specific submodules by capacitance-voltage balance control, and comprising the steps of carrier comparison, signal acquisition, signal processing, PWM pulse signal generation and the like. The pulse width control method is simple, scientific and reasonable and easy for engineering realization, and has good dynamic property, thus being applicable to occasions with wider range of frequency variation in an AC system and free from restriction of the level number.

Description

Technical field: [0001] The invention belongs to the field of electric power transmission and distribution, and relates to a pulse width control method of a modular multilevel converter. Background technique: [0002] Multilevel converters have received extensive attention and research due to their unique advantages, especially in applications such as high power and high voltage. Traditional multilevel converters have various structures such as diode-clamped type, floating capacitor type and H-bridge cascaded type. Modular multilevel converter is a new converter topology, which has the characteristics of small voltage change rate, low harmonic content, high sine degree, and small switching loss of traditional multilevel converters. At the same time, it also has the advantages of high modularity and simple structure compared with diode-clamped converters and floating capacitor converters. Compared with H-bridge cascaded multi-level converters, it does not need to increase DC...

AI Technical Summary

Problems solved by technology

The modular converter adopts a modular structure design, and the modules are independent of each other, which is easy to realize the expansion of the number of levels, and does not need to provide an independent DC power supply; however, the sub-module capacitor voltage of the modular multi-level converter needs balance control

With the increase of the number of levels, the difference between the harmonic performance of the converter has been relegated to the secondary factor. How to use the fast and effective PWM modulation method to solve the practical engineering problem has become a problem that those skilled in the art have been eager to solve but have not yet succeeded. the puzzle

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