56 September/October 2025 | E-Mobility Engineering Nick Flaherty looks at the development of ultrafast-charging stations around the world The fast and the furious Drivers of EVs are often frustrated by the speed of charging. While home chargers use AC at power rates to 22 kW, fast charging covers direct current (DC) charging at a power of 30 kW. Above that, up to 200 kW, ultrafast charging, also called extreme fast charging, is a less standardised term for a type of fast charging. It refers to speeds of EV charging comparable with those of traditional cars, generally understood to be 10 minutes or less. This ultrafast charging, which depends on two factors – whether it can accept high charging current rates and whether the charging facilities can provide the high-power input – is driving a new class of power conversion topologies. The implementation of fast chargers needs a combination of high-power technologies. Inside the vehicle, the high-power level 3 (L3) DC charger bypasses the onboard charger of the EV and directly charges the battery via the EV Battery Management System. Level 4 is typically for trucks and off-road equipment with megawatt charging levels. Outside the vehicle, the high-power charging unit has to provide power at up to 1000 V with high currents. This has to take into consideration the cooling of the charger and the connecting cable, and also the infrastructure of the wider charging station. The Tesla Supercharger V3 for example reaches 250 kW for the Model 3 and is planned to be upgraded further to 500 kW. The Porsche Taycan achieves a maximum fast-charging power of 270 kW such that the 93 kWh battery can be recharged from 10% to 80% in 19 minutes. GAC AION EVs offered a 6C fast-charging option with a maximum power of 480 kW, sufficient to raise the battery state of charge from 30% to 80% in 5 minutes. Across the charging station, the demand for high-power charging can place significant pressure on the electricity grid, and there are studies now showing how to address this (see below). Higher power DC chargers are typically built with a modular architecture, stacking power blocks of 15 to 75 kW (and above) in a single cabinet. Level 3 DC fast charger Because L3 DC fast chargers must convert a three-phase alternating current (AC) input voltage to DC, they therefore include an AC-DC Power Factor Correction (PFC) front-end with an isolated DC-DC converter to interface the PFC output to the EV’s battery. Multiple power modules are often paralleled to achieve higher output power. Digital power control architectures and silicon carbide (SiC) MOSFET power transistors and diodes enable designs that offer higher system efficiency and integration, high power density, advanced control loops and increased flexibility in various power topologies that are optimised for DC fast-charger applications. Ultrafast-charging systems are being rolled out (Image courtesy of Atlante Energy)
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