A switching cell based on Hybrid Switched Capacitor and Modular Multilevel Converters is presented. Automatic arms voltages clamping are achieved, while the current spikes and the efficiency dependence on duty cycle can be reduced by a proper design. A Buck type topology simulation and experimental results are presented and an example of cell application as a single-phase inverter is shown.

Abstract—Aiming to address the growth and the integration of renewable sources and electronic loads, different types of dc-dc topologies with specific features have been proposed, going from medium frequency isolated Modular Multilevel Converter to Switched Capacitor and Hybrid Switched Capacitor topologies. In this paper, a bidirectional Modular Multilevel Converter based Hybrid Switched Capacitor dc-dc converter is presented, featuring transformerless structure, automatic total arm voltages clamping/balancing, voltage static gain independent of the submodules quantity and efficiency with reduced duty cycle influence. The topology operates with a Quasi-Two-Level modulation, which provides passive components volume/weight reduction, a degree of freedom regarding the dv/dt applied on the magnetic windings and basis to perform the submodule capacitor voltages equalization within each arm. The topology operating principles are approached by an average value static analysis while an instant value static analysis is used to estimate the operating current spike worst case. A 1.17 kW, 350/200 V laboratory scale prototype using IGBTs is implemented to experimentally confirm the theoretical approaches.