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EV charging infrastructure could become a bottleneck for EVs growth. Nearly half of the U.S. consumers say that battery or charging issues are their top concerns about buying EVs, discouraging potential buyers [1].
Mass roll-out of EVs will challenge the local/regional grid infrastructure. One solution is to install energy storage at filling stations, storing energy at low-power from the grid and delivering it at high power (quickly) to vehicles. Governments have the potential to regulate the EV recharges at the filling stations and apply the same tax currently applied to gasoline and diesel [2].
Most EVs are equipped with both AC & DC charging inputs, giving to the driver the option of either charging method (DC for faster charges). Using a household AC outlet makes the process very slow: accustomed to filling their gas tank in less than 5 min, EV drivers will have to wait several hours to "fill the tank".
Fast charging
Fast charging will change the e-mobility game. But it is costly! In the European Union, a typical 350 kW charger can cost USD 150,000, including hardware, installation, and planning [3]. And, while most power grids in the U.S. can supply enough electricity to meet demand from EV charging, few can deliver large amounts of electricity to many EVs at high rates at the same time [4].
Tesla V3 Supercharging 1 MW power cabinet supports peak rates of up to 250 kW per car: as a result, Model 3 operating at peak efficiency can recover up to 75 miles of charge in 5 min and charge at rates of up to 1,000 miles per hour [5].
It is worth note, however, that the maximum charge rate is often limited by the EV acceptance rate (i.e., max. charge power, given in kW). While many EVs currently on the market charge at a maximum 50 kW, there are newer EV models capable of charging over 200 kW [6].
EVSE fast growing
EV charging stations (EVSEs - electric vehicle supply equipment) have become important loads in distribution networks, and the energy storage configuration of EV charging stations should satisfy the reliability of the station itself and fully consider the travel characteristics of vehicles and the uncertainties of charging behavior.
Nearly 500,000 chargers were installed in 2021, which is more than the total number of public chargers available in 2017. As in previous years, China is the global leader in number of publicly available chargers: the Dragon counts about 85% of the world’s fast chargers and 55% of slow chargers [7].
Perspectives
The increasingly higher currents during fast charging pose key challenges for both the power electronics and the contact system. The future Megawatt Charging System (MCS) is being designed for the development of existing fast-charging infrastructure and also for battery powered heavy traffic, with astonishing current & voltage upper limits (3,000 A - 1,250 V) [8].
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References
[2] https://www.carbon-ion.energy/ev-grid/
[3] https://energydigital.com/technology-and-ai/electric-vehicle-app-monta-partners-with-c
[5] https://www.tesla.com/blog/introducing-v3-supercharging
[6] https://www.iea.org/reports/global-ev-outlook-2022/trends-in-charging-infrastructure
[7] https://freewiretech.com/difference-between-ev-charging-levels/
[8] https://www.electrive.com/2023/01/17/hv-mela-bat-project-to-improve-high-voltage-charging-experience/