Patent attributes
A modular multi-level converter including modules each having switching elements and at least one electrical energy storage element, wherein a first number of modules are interconnected to form a closed ring, and at least two taps are arranged between respective adjacent individual modules of the closed ring. Wherein at at least two taps respectively a second number of modules are provided as a phase module branching off from the closed ring and forming a star string comprising at least two modules, the phase module connected to the respective tap on one end and forming a phase terminal at an other end. Wherein the switching elements enable interconnection of energy storage elements of adjacent modules, as a result of which between two adjacent phase terminals a voltage difference is provideable, which is regulatable by a control unit in accordance with a polyphase rotating field profile. Furthermore, the present invention relates to a polyphase system and a method for efficient power exchange between modules.