Using Multi-physics System Simulation to Predict Battery Pack Thermal Performance and Risk of Thermal Runaway During eVTOL Aircraft Operations

Negative effects of greenhouse gas emissions from internal combustion engines has motivated a global trend towards electrification of transportation powertrains. Additionally, electrification of vehicle prime movers has enabled novel powertrain configurations such as electric distributed propulsion. Electric vertical take-off and landing (eVTOL) aircraft are a novel transportation mode developed at a confluence of emerging technologies including electric powertrains. eVTOLs are poised to institute a major change to urban mobility by increasing the speed and efficiency of urban travel. To facilitate safe and reliable operations, eVTOL battery packs must reliably provide adequate electrical power for mission requirements while sustaining pack health and cycle life over the course of hundreds of missions. These packs are under considerable thermal stress during flight, and must be designed to meet the challenges caused by these thermal stresses, including keeping individual battery cells below temperature limits. Using system simulation can be instrumental in providing optimal design of battery pack layouts and thermal management strategies. A multi-physics system simulation model has been constructed to predict the electrical-thermal-fluid performance of the A3 Vahana eVTOL battery pack with comparison to test data derived from a notional eVTOL mission profile. The model predicts outputs including individual cell currents, cell temperatures, cell voltage, environmental temperatures, and impact of different thermal management strategies on eVTOL battery pack design. The thermal profile predicted during flight is then passed to a predictive model for battery life using GT-SUITE simulation software. The model is then configured to simulate a thermal runaway event, where one cell is heated to the point of runaway, and response of the pack is predicted under different cooling strategies.