Branch energy control for the modular multilevel direct converter Hexverter

Abstract

Modular multilevel converters offer many advantages for high-voltage and high-power applications. A recently proposed modular multilevel direct AC/AC converter is the so-called Hexverter. This paper presents a method to control the energy stored in the branches of the Hexverter topology. The control concept is described and possible degrees of freedom for the branch energy control are analysed analytically for different operating points. The findings are verified using a simulation and a laboratory test setup.