This paper proposes a novel architecture for plug-in electric vehicles (PEVs) dc charging station at the megawatt level, through the use of a grid-tied neutral point clamped (NPC) converter. The proposed bipolar dc structure reduces the step-down effort on the dc-dc fast chargers. In addition, this paper proposes a balancing mechanism that allows handling any difference on the dc loads while keeping the midpoint voltage accurately regulated. By formally defining the unbalance operation limit, the proposed control scheme is able to provide complementary balancing capabilities by the use of an additional NPC leg acting as a bidirectional dc-dc stage, simulating the minimal load condition and allowing the modulator to keep the control on the dc voltages under any load scenario. The proposed solution enables fast charging for PEVs concentrating several charging units into a central grid-tied converter. In this paper, simulation and experimental results are presented to validate the proposed charging station architecture.@en

The automotive industry is making important changes towards the electrified transportation. Several Electric Vehicles (EVs) and Plug-in Hybrid EVs are currently on the market offering a clean and environment friendly alternative to conventional vehicles. However, limited mileage capacity and long refueling times have lead to a lukewarm reception from the consumers. In order to reduce the charging time fast charging architectures are being developed, usually as off-board solutions located in public installations. This paper presents a centralized charging station architecture, using a bipolar dc grid to power off-board chargers and integrate of DGs and storage systems. The central converter topology is an NPC and a novel balancing technique is implemented to extend the operating range of the power converter.@en