Improved Operation of MMC Based Braking Choppers

This paper presents an improved operation method for MMC based braking chopper topologies with a centralized resistor. It reduces the hardware effort of the chopper submodules by over 15% and the needed amount of capacitors by over 65% without any impact on the operation performance. It provides an analytical description of the proposed modulation method and enables a proper system design by presenting relevant design criteria. The presented results are verified by full-scale simulations.