System-level thermal and electrical modeling of battery systems for electric aircraft design

TL;DR

This paper presents a comprehensive simulation framework for electric aircraft batteries, including thermal and electrical modeling, and optimizes thermal management to improve range and safety.

Contribution

It introduces an equivalent circuit model for battery behavior and evaluates BTMS design impacts on aircraft performance and safety.

Findings

Water cooling outperforms air cooling in BTMS efficiency.

Adding water-cooled BTMS increases weight and reduces range.

The battery design effectively prevents thermal runaway.

Abstract

This work introduces a framework for simulating the electrical power consumption of an 8-seater electric aircraft equipped with high-energy-density NMC Lithium-ion cells. We propose an equivalent circuit model (ECM) to capture the thermal and electrical battery behavior. Furthermore, we assess the need for a battery thermal management system (BTMS) by determining heat generation at the cell level and optimize BTMS design to minimize energy consumption over a predefined flight regime. The proposed baseline battery design includes a 304-kWh battery system with BTMS, ensuring failure redundancy through two parallel switched battery banks. Simulation results explore the theoretical flight range without BTMS and reveal advantages in increasing battery capacity under specific conditions. Optimization efforts focus on BTMS design, highlighting the superior performance of water cooling over air cooling. However, the addition of a 9.9 kW water-cooled BTMS results in a 16.5% weight increase (387 kg) compared to no BTMS, reducing the simulated range of the aircraft from 480 km to 410 km. Lastly, we address a heating-induced thermal runaway scenario, demonstrating the robustness of the proposed battery design in preventing thermal runaway.