A Framework to Analyze the Requirements of a Multiport Megawatt-Level Charging Station for Heavy-Duty Electric Vehicles

Abstract

Widespread adoption of heavy-duty (HD) electric vehicles (EVs) will soon necessitate the use of megawatt (MW)-scale charging stations to charge high-capacity HD EV battery packs. Such a station design needs to anticipate possible station traffic, average and peak power demand, and charging/wait time targets to improve throughput and maximize revenue-generating operations. High-power direct current charging is an attractive candidate for MW-scale charging stations at the time of this study, but there are no precedents for such a station design for HD vehicles. We present a modeling and data analysis framework to elucidate the dependencies of a MW-scale station operation on vehicle traffic data and station design parameters and how that impacts vehicle electrification. This framework integrates an agent-based charging station model with vehicle schedules obtained through real-world vehicle telemetry data analysis to explore the station design and operation space. A case study applies this framework to a Class 8 vehicle telemetry dataset and uses Monte Carlo simulations to explore various design considerations for MW-scale charging stations and EV battery technologies. The results show a direct correlation between optimal charging station placement and major traffic corridors such as cities with ports, e.g., Los Angeles and Oakland. Corresponding parametric sweeps reveal that while good quality of service can be achieved with a mix of 1.2-megawatt and 100-kilowatt chargers, the resultant fast charging time of 35–40 min will need higher charging power to reach parity with refueling times.

Grid Impact Analysis and Mitigation of En-Route Charging Stations for Heavy-Duty Electric Vehicles

“…In this work, we use an in-house agent-based charging station modeling and analysis tool named Electric Vehicle Infrastructure, Energy Estimation, and Site Optimization (EVI-EnSite) tool to develop the station load profiles [13], [14]. A flowchart of the vehicle charging operation in the EVI-EnSite tool and generation of station load profiles through a Monte Carlo simulation is shown in Fig.…”

“…The EVI-EnSite tool can be found here [15]. The heavy-duty vehicles charging schedules are obtained by combining and analyzing real-world vehicle telemetry data analytics with EV system modeling [14]. Vehicle agents in this tool are defined using battery capacity, arrival time, initial state of charge (SOC), final desired SOC or energy demand, final stop time, and a charge acceptance curve.…”

Estimating the Breakeven Cost of Delivered Electricity to Charge Class 8 Electric Tractors

“…Like depots, travel centers in this study serve the charging need of vehicles with long dwell times during driver rest periods, and therefore provide EVSE with a similarly low charging power. However, some drivers will require stations designed to serve shorter dwell periods to immediately complete their trip, thus requiring the use of EVSE with up to 3 MW of power (Mishra et al 2020).…”

“…High-power charging at the megawatt level enables the electrification of Class 8 regional and long-haul tractors by ensuring that drivers can complete their existing routes without excessive delay (Mishra et al 2020). Through the use of high power levels, such as 3 MW, electric tractor batteries can be fully charged at a duration approaching the time it takes to refuel a typical diesel tractor.…”

“…In this problem, each vehicle can only be converted from diesel to electric if, over the course of its existing route, a set of charging stations exist so that it never needs to exceed the range of its onboard battery without having the opportunity to charge. This constraint is central to the underlying linear program, whose details can be found in Mishra et al (2022) but are omitted here for brevity. Note that this approach does not consider modification to the travel route or alternate freight movement strategies.…”