Methodology of Cell Selection and Modeling of Cell Performance for Aerospace Application

Abstract

The electric vehicle industry has more than 20 years of experience in designing battery packs for automotive and small UAV (unmanned aerial vehicle) application. These battery packs consist of a combination of cells that are wired together in series and parallel to achieve the proper voltage and power/energy requirements for that vehicle. In general, the packs are designed to work at standard operating conditions of temperature (-30 – 60°C) and pressure (atmospheric). The aerospace industry is recently considering the on-board integration of energy storage elements (batteries) to improve fuel burn and carbon dioxide emission. The industry is looking at mainly a hybrid propulsion system, integrating the energy storage elements with the traditional turboshafts and generators. However, a battery back for aerospace application must be designed for use in temperatures reaching -60°C, a pack voltage of up to 2000 volts, and approximately 8 megawatts of power. One major obstacle that arises when creating a battery pack of this size and capability is that testing and building prototype battery packs is extremely inefficient regarding both cost and time. In order to bypass this obstacle, models are created to simulate the behavior of the battery pack. This research project will focus on the methodology of experimental testing methods to select the most fitting cell technology for aerospace application and the development of numerical models to characterize the cell’s behavior for a given power schedule the pack will be subject to during flight. Multiple tests are needed to be run on the battery cells, including Multi-Rate Capacity tests, HPPC (Hybrid Pulse Power Characterization) tests. The data from these tests needs to be analyzed to select which technology is most fitting, then a model needs to be created that characterizes the cell’s characteristics and simulates how the battery pack will perform during flight.