Operating Line of Battery-Driven Aerodynamic Rotor for Electric Aircraft Applications

Aviation electric propulsion has been increasingly used both in terms of its application scale and the weight of aircraft it drives. For the electric propulsion system composed of electrically driven rotary aerodynamic load, revealing the steady-state operating status subject to external flight conditions and internal matching constraints among components is beneficial to design and operating of electric aircraft. This article proposes a candidate operating line theory for aviation electric propulsion. By transforming aircraft and propulsive dynamics into algebraic equality constraints, the operating status of propulsion components are located on constraint hyperplanes of voltage and torque conservation with external flight conditions. The operating line is defined as the intersection of the two hyperplanes. The governing variables comprise battery current, shaft rotation speed, and motor duty cycle, which are solved sequentially using the trim equations between connecting components. The proposed method is applied to an electric aircraft with verified propulsive performance. The influence of external conditions is investigated by disturbing altitude, flight path angle, and battery capacity consumption. The resultant multiple operating lines further formulate higher order geometries. Applications to multiobjective optimization of electric propulsion bypass tedious numerical simulations and unnecessary infeasible points, implying the potential of the proposed theory in future design and performance analysis of electric aviation.