Validation of Analytical Model for Turboelectric Power System for Preliminary Design Purposes

Abstract

Small, electrically powered, unmanned aircraft are limited in the range and endurance due to inherently low energy density of batteries, prompting the development of hybrid gaselectric power systems. Turbo-electric power systems fill this gap by leveraging the high power density of electric flight in conjunction with the high energy density of hydrocarbon fuels, while mitigating some issues encountered with piston-based hybrid systems. Previous studies have evaluated the electrical system for a 7.3 kW turbo-electric system for small Unmanned Aerial Systems (sUAS) and suggest that power system electrical efficiencies range between 60% and 70%; however, the driving system parameters which dictate this efficiency are not discussed in detail. Thus, there is a critical need to develop a design tool which can be used to estimate electrical efficiency and show how different parameters affect the system. An overall system transfer function must be developed and evaluated thoroughly to determine the reliability and accuracy of modeling methods. Classical methods are used in developing the models, making models general and not specific to one system. Measurements included generator shaft speed, as well as rectified power, voltage, and current. Results of the steady-state behavior form a basis for developing an analytical model that includes both empirical and theoretical power system behavior. This model will pave the way for design down-selection when designing and realizing a turbo-electric powertrain.