Synthesis of Multilevel Converters Based on Single-and/or Three-phase Converter Building Blocks

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