Electrochemical Cell Loss Minimization in Modular Multilevel Converters Based on Half-Bridge Modules

In the developing context of distributed generation and flexible smart grids, in order to realize electrochemical storage systems, Modular Multilevel Converters (MMCs) represent an interesting alternative more traditional Voltage Source Inverters (VSIs). This paper presents a novel analytical investigation cell power losses MMCs their dependence on injected common mode voltage. Steady-state are calculated under Nearest Level Control (NLC) modulation for equipped with large number half-bridge modules, each directly connected elementary cell. The total both Single Star MMC (SS-MMC) Double (DS MMC) derived compared loss VSI working same conditions. An optimum voltage injection law is developed, leading minimum possible. worst case, it achieves 17.5% reduction conventional laws. analysis experimentally validated using laboratory prototype set-up based two-arm SS-MMC 12 modules per arm. experimental results within 2.5% models all cases considered.