Capacitor voltage ripple and capacitance evaluation in a direct three-phase to single-phase ac/ac MMC

This paper introduces the capacitor current and voltage ripple evaluation of a direct three-phase to single-phase ac/ac modular multilevel converter with full-bridge sub-modules. Based on a desired sub-module capacitor voltage ripple, the required capacitance is calculated, which is valuable to dimension sub-modules’ energy storage in many applications. Simulations and measurements using a scaled-down prototype validate the analysis.