61 Megawatt charging | Deep insight “For stationary usage, you have no shock and vibration requirements, so there are some areas where you can specify down a little bit but the technique is the same. For a contactor that can handle up to 3 kA, there must be a lot of powerful busbars, and this means a lot of masses integrated which has an impact on the shock and vibration, as well as other severe environmental conditions such as high temperatures,” Rott continues. “The good thing is that in charging mode, the truck is not driving but the product has to survive in the nonactive use state when not charging, so it’s different from a traction contactor in a vehicle. “For other applications, in the vehicle we also have special contactors with integrated locking systems and this avoids moving to an uncontrolled position. But this is not used in the megawatt charger because it is not necessary. There is no additional mechanical interlock; it is software- and measurement-based by the battery management system.” The MCS specification details the position of the charger on a truck to make it accessible, but the positioning of the contactor is not yet decided. “Typically, the contactor will be close to the connector in the truck because you also have to take care of the losses in the battery system. Charging cables are 3 to 5 m, to give room to connect different trucks, but in the charging system, we have active cooling systems so it is possible to keep the temperature at the necessary level,” says Rott. The MCS standard is to be further tested in an extension of the NEFTON project. Charging currents of 3000 A will be tested, allowing an electric truck to be fully charged in 15 minutes. For NEFTON-3000, the Technical University of Munich, MAN Truck & Bus and the Deggendorf Institute of Technology are developing concepts with charging capacities in the range of 3 MW, which will also be tested on test rigs at Fraunhofer Institute for Solar Energy Systems. Multiport charging station In the US, the Oak Ridge National Laboratory (ORNL) is working on the requirements for charging stations that have to handle multiple trucks simultaneously. The researchers at ORNL have designed architecture, software and control strategies for a futuristic EV truck stop that can draw megawatts of power. The station’s design uses solar arrays and batteries, which generate and store enough power to handle the unpredictable load swings from recharging these large power plants on wheels. The software manages the system to draw a steady, predictable flow of power from the grid. The team fine-tuned the complex control hierarchy using real-time simulation, then verified their results with electronics in the lab. The developed megawatt-scale charging system/station supports power levels of 10–15 MW for vehicles ranging from heavy- to medium- and light-duty trucks. The multiport power conversion system is designed to interface and coordinate various assets and loads including grid, battery storage, solar cells and the vehicles themselves. Each multiport is designed to handle 1–5 MW with a charger dedicated to controlling the power delivery to the truck. Multiple multiports can be interconnected through the AC distribution network creating large networks of chargers for supporting the electrification of these higherpower vehicles. This will require station controllers that can optimise and dispatch the power to the multiports without significantly impacting the electric grid interconnection. The multiport charger was designed to support three high-power 1.2 MW chargers, each with a single MCS connector or three 400 kW CCS fast chargers running at 1000 V. The 400 kW charging ports are composed of dual-active bridge (DAB) converter systems that can control the DC link interconnection to the truck. However, this will require that each heavy-duty EV incorporates three different charging ports to increase charging capability and provide the ability to potentially sectionalise the battery system. The grid-tied interface is a 13.8 kV system consisting of cascaded H-bridge (CHB) modules tied to dualactive bridge (DAB) modules through a 12 kV DC link. Four of these CHB-DAB modules per phase are connected in series to meet the voltage requirements and the power handling capability of 1.2 MW per phase. Together, the 12 CHB–DAB modules are connected in parallel at the output E-Mobility Engineering | May/June 2025 Multiport charging architecture (Image courtesy of ORNL)
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