Synthesis of multilevel converters based on single- and/or three-phase converter building blocks

This paper synthesized a family of multilevel converters that is constructed by using multiple well-developed single- and/or three-phase converter building blocks. The resulting advantages include a modular structure that leads to convenient construction and maintenance as well as easy extension to higher voltage levels. One successful example from this family A is the cascaded H-bridge converter, which is now widely used for volt-amperes reactive (VAR) compensation and motor drive applications due to its many advantages. Another emerging member is the Hexagram converter, composed of six interconnected C three-phase converter modules, which has many eminent features such as lowered component count and lowered dc energy storage requirement compared to the cascaded H-bridge converter, and thus, is a promising candidate for high-power applications.