Conception of a modular multilevel converter for high-scale photovoltaic generation based on efficiency criteria

This work presents the design of a modular multilevel converter for high-scale grid-connected photovoltaic generation. Converter modules are used in order to divide between them the power to deliver, giving more advantages in comparison with using only one total converter. Losses and efficiencies are derived for each stage of a modular component, in order to select the most adequate number of converter modules according to efficiency criteria. First, a modular multilevel converter topology is proposed, rising its advantages over other reported topologies. Second, the calculation of losses of each stage of the converter module is performed. Then, the design of the modular multilevel converter is developed for two practical examples, one for a 10 kW-1.32 kV generation system, and another one for a 1 MW-13.2 kV medium-voltage generation system. These designs are developed considering different number of converter modules, and an analysis to select the most adequate number of them is made for both cases. One of the intentions of this work is to draw the highest efficiency possible when implementing a multilevel power converter for interconnecting photovoltaic generation to the grid. (C) 2015 Elsevier Ltd. All rights reserved.