Optimized Allocation of Loads in MMC-based Electric Vehicle Charging Infrastructure

Utilization of the modular multilevel converter (MMC) topology can enable transformer-less interfacing between electric vehicle (EV) charging infrastructure and the power distribution grid. Such configurations are claimed to significantly reduce the system costs, space requirements and complexity for high-power charging facilities. On the other hand, ensuring the correct operation of such system is challenging under unevenly distributed loads in the MMC arms. Proper selection of the charging points to allocate the EVs can limit the loading unbalances between the arms and phases of the MMC system. This paper presents two load allocation strategies. The first strategy takes only the present loading into account, while the second one optimizes the decision according to the individual energy demands of the EVs over time. Simulations demonstrated that the optimized strategy minimizes loading unbalances between the MMC phases and arms during the charging operations. Furthermore, it can contribute to larger demand fulfillment.