Optimal Charging with Active Thermal Management for eVTOL Aircraft Battery Packs

Electric vertical takeoff and landing (eVTOL) aircraft operation often requires the battery packs to be charged and thermally conditioned to a given range of state-of-charge (SOC) and temperature for the next flight in minimum time to maximize aircraft utility. Where charging favors higher temperatures than what is required at launch, an optimal solution must trade-off faster charging times with the required thermal conditioning time. Here we develop a coupled electro- thermal battery, charger, and cooling system model, formulate an optimal control problem for fast charging, and solve it using a direct collocation approach. The resulting algorithm simultaneously provides the optimal current and thermal conditioning profiles that bring the pack from a starting temperature and SOC to their respective targets in minimum time, while ensuring degradation and safety constraints are satisfied. Insights from the results can be used to develop simple on-line control algorithms for charging with active thermal management that are critical for eVTOL applications.