Model Matching and Controller Development for a Small-Scale Electric Aircraft Engine Testbed

Abstract Electric engines for commercial aircraft propulsion provide potentially significant efficiency and performance benefits over state-of-the-art turbomachinery due to the aerodynamic benefits provided by propulsion/airframe integration and the improved precision and bandwidth with which they can be controlled. This paper provides an overview of the SmartFan, a small-scale test rig constructed at NASA Glenn Research Center and designed to act as a representative electric engine for the purposes of Hardware-in-the-loop (HIL) testing, system identification, and control system development. The SmartFan is a small, single-stage axial ducted fan driven by a brushless DC (BLDC) motor, with a variable area nozzle controlled by a mass flow plug driven with a linear actuator. The flow path and electrical power system are instrumented to allow for detailed characterization of the test rig and investigations into the coupled dynamics of the components. Control and performance monitoring algorithms are implemented on a real-time computer with a field programmable gate array board. The paper describes the design of the test rig and documents the baseline performance of the fan and electrical power system. As an example use case, a digital twin model of the SmartFan electromechanical system is developed in MATLAB®/Simulink® using the Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS) and the Electrical Modeling and Thermal Analysis Toolbox (EMTAT). The model is presented and used to develop a simple closed-loop fan controller, which is then demonstrated on the test rig. The importance of low-cost, small-scale testbeds like the SmartFan for HIL testing for validating models, maturing control technologies, and reducing risk is discussed.