Full-bridge Modular Multilevel Converter with High Frequency Link for Photovoltaic applications

Abstract

This paper presents a novel “Modular Multilevel Converter” (MMC) topology. The topology takes advantage of the MMC characteristics by offering multilevel output voltage with low Total Harmonic Distortion (THD), increased reliability, and design flexibility due to the modular nature of the converter [1] and [2]. This topology is composed of a “full-bridge converter” (FBC) connected to multiple “High Frequency Link” (HFL) modules via high frequency transformers. Each module produces its own isolated DC voltage that keeps the capacitor charged to a specific level, removing the need of a voltage-balancing algorithm. Furthermore the module voltage can be controlled by changing the FBC duty cycle in order to obtain lower output voltages without decreasing the number of levels. This topology fits well in large scale Photovoltaic (PV) power plants due to its capability to produce a high voltage output. This topology's feasibility is validated by simulation results (Matlab/Simulink).