A new high power density modular multilevel DC-DC converter with localized voltage balancing control for arbitrary number of levels

A new modular multilevel DC-DC converter with high power density and simplified localized voltage balancing control is proposed. In the proposed configuration, converter building blocks with the same power handling capability are connected in parallel in each row. Converter building block consists of an H-bridge and mutually coupled inductors whose total current is nearly ripple free. These features are shown to reduce the voltage ripple of DC-link capacitors significantly, leading to a smaller capacitance and size. An optimized control algorithm with voltage feedback PI loop is proposed resulting in the elimination of current sensors. This, reduces overall system complexity and increases cost-effectiveness. Significant ripple reduction of the inductor current and capacitor voltages is observed based on the simulation and prototype of multi-level systems. With a fully modular power stage module and localized control module, a system of arbitrary number of level can be built by stacking modules thereby contributing to enhanced system redundancy.