Slow and Fast Charging Solutions for Li-Ion Batteries of Electric Heavy-Duty Vehicles with Fleet Management Strategies

Abstract

This work presents a real-life demonstration of 23 heavy-duty (HD) public electric buses (e-buses) in Jaworzno, Poland, with three lengths: 8.9 m, 12 m, and 18 m. The e-bus demo is based on the development of baseline e-buses to optimize the operational cost based on technical optimization. The demo aims to switch public transportation from internal combustion engine vehicles (ICEVs) to electric ones to minimize CO2 emissions. The e-buses are equipped with standard charging solutions, which are plug-in charging with Combined Charging System Type 2 (CCS2, Combo 2) and pantograph-up (Type B). The CCS2 solution is used for overnight slow/normal charging (NC) in the depot of the e-bus operator, whereas the pantograph charging solutions are installed along the e-buses routes and used for fast charging (FC) when the e-buses are stopped for a short time. In Jaworzno, there are 20 chargers with CCS2 in the depot of the e-bus operator and 12 pantograph-up (Type B solution) fast-charging stations. This work studies the technical operations and operational costs of the e-bus fleet, and the impact of the NC and FC solutions on the Li-ion battery packs and on the grid. The uncoordinated/standard and coordinated charging (smart charging) based on load shifting were investigated to study the impact of e-bus fleet integration on the distribution grid. The exploited data in this study were collected from the data logger devices, which are installed on the e-buses and record over 46 signals. Data from over one year were collected, and some sample data were processed and analyzed to study the technical and economic operations of the e-bus fleet.

Real-Time Charging Scheduling and Optimization of Electric Buses in a Depot

“…Finally, and most importantly, an off-board charger, which directly provides DC current to the battery of the EV, is used for the experimental testing. This is the dedicated charging technology for BEBs, since they are not equipped with an on-board AC charger such as conventional EVs [37]. The off-board charger has a CCS Combo 2 connector which needs to be plugged in into the EV and which is also the standard charging connector for BEBs in depots.…”

Smart Charging: A Comprehensive Review

“…The depot happens when the EBs parked for several hours, usually at night. Pantograph charging usually happens when the EBs are stopped for short time, 5-7 min to collect the passenger or a bit longer according to their working schedule [79], [80]. EV integration has risen considerably over the past few years.…”

“…14. the standard charging has notorious impact on the busbars' voltage, which could be increased as more EBs' integrated unlike the smart charging, which support the voltages on the busbars [80]. The charging cost optimization based on DAM was simulated according to CCS2 in depot charging (see Fig.…”

Optimization and Analysis of Electric Vehicle Operation with Fast-Charging Technologies

“…There are two types of charger infrastructures, i.e., CSS2 in depot (40-150 kW) and opportunity charging on route lines, bus stops, or at terminals. The opportunity charging systems usually have various rated power levels: 150 kW, 300 kW, 450 kW up to 600 kW with the main feature being that charging can take place during the service along the EB route line [11].…”