Preliminary Design and PIL Testing of a Battery Monitoring System for eVTOL UAVs Based on an Extended Kalman Filter and Electro-Thermal Model

The performance of electric Unmanned Aerial Vehicles depends heavily on their onboard energy storage system. In battery-based propulsion, optimizing battery utilization and extending both cycle life and flight time are the primary objectives of the Battery Management System (BMS). In particular, monitoring the states of charge and temperature with a limited number of sensors plays a key role in battery management and flight mission planning, especially for energy storage systems based on distributed multiple batteries connected in series and parallel. In this work, the battery pack’s state of charge and temperature are estimated based on an experimentally validated electro-thermal model of the battery pack, coupled with an Extended Kalman Filter, leveraging voltage measurements, current, and the surface temperature of the battery pack. The proposed approach is first tested in Model-in-the-Loop (MiL) and then validated through Processor-in-the-Loop (PiL) on a target board. The case study refers to a 6-cell, $22.2 \mathrm{~V}, 2000 \mathrm{mAh} \mathrm{Li}$-Po battery pack used in a $\mathbf{2 5 ~ k g}$ dual electric Vertical Take-Off and Landing (eVTOL) UAV.