A power traction converter based on Modular Multilevel architecture integrated with energy storage devices

In this paper a power converter based on a modular multilevel topology integrated with energy storage devices for directly supplying of traction motors is discussed. The Modular Multilevel Converter (MMC) is one of the emerging technology for high- or medium- voltage transformerless power conversion. The possibility to directly control the traction motors by means of a dc/ac MMC topology, using also integrated energy storage systems (ESS) for recovering the kinetic energy, is exploited. Furthermore, a simplified mathematical model of the MMC with integrated ESS has been developed in order to evaluate the behavior of the traction unit during a typical load-cycle. The control law of the traction motor, integrated with energy storage flow management, has been introduced. The numerical results reported in the paper permit to confirm the feasibility of the proposed design and control strategy for light travel vehicle.