Capacitor voltage balancing in back-to-back modular multilevel converter

Modular Multilevel Converter is a widely accepted technology for HVDC applications. It consists of several sub-modules or cells connected in cascade. These are bidirectional chopper cells and each one of them has a floating capacitor. This paper discusses the modulation and voltage balancing strategies which are essential for the converter to work as rectifier or inverter. The discussion is followed by the simulations of the Back-to-Back Modular Multilevel Converter (MMC) topology employed in a model HVDC power system using MATLAB/SIMULINK.