Modelling and control of a hybrid electric propulsion system for unmanned aerial vehicles

Abstract

This paper presents the modelling and control of a hybrid electric propulsion system designed for unmanned aerial vehicles. The work is carried out as part of the AIRSTART project in collaboration with Rotron Power Ltd. Firstly, the entire parallel hybrid powertrain is divided into two powertrains to facilitate the modelling and control. Following this, an engine model is built to predict the dynamics between the throttle request and the resulting output. It is then validated by comparing with experimental data. On the basis of d-q model of the motor/generator, a good estimation of torque loss at steady state is achieved using the efficiency map. Next, a rule-based controller is designed to achieve the best fuel consumption by regulating the engine to operating around its ideal operating line. Following the integration of the models and controller, the component behaviour and control logic are verified via the final simulation. By enabling the engine to operate at its best fuel economy condition, the hybrid propulsion system developed in this research can save at least 7% on fuel consumption when compared with an internal combustion engine powered aircraft.

Fuzzy logic based equivalent consumption optimization of a hybrid electric propulsion system for unmanned aerial vehicles

“…This section also validates the established relationship between the equivalence factor of ECMS and the co-state variable of Hamiltonian function. Please note that all simulations are carried out on the basis of the HEPS model developed in the previous study [15].…”

“…The rotation speed following a power value via @ indicates that this is the power reached at the stated speed. More details of system information and parameters can be acquired in the previous study [15].…”

“…The Adaptive-ECMS (A-ECMS) [12,13], has been adopted as a charge-sustaining strategy to maintain the battery SoC at a specific value (such as 30%), which is typical of hybrid ground vehicles [14]. However, the charge-sustaining strategy is not ideal for aerial vehicle applications [15]. If the SoC is sustained at a very low level, the residual battery capacity cannot guarantee a safe landing if there is a failure of the engine; on the other hand, maintaining a high-level SoC means full use cannot be made of the electrical energy in the battery.…”

Control and optimisation of hybrid electric propulsion system for light aircraft

“…It can retain the feature of lossless relaxation from previous studies but also lead to a more straightforward and clear form of convexified problem. Further technical and theoretical details can be found in [26].…”

Indirect engine sizing via distributed hybrid-electric unmanned aerial vehicle state-of-charge-based parametrisation criteria

“…University of Colorado Boulder [1], Queensland University of Technology [2], and U.S. Airforce Research Laboratory [3] all have researched this area. The other ongoing small hybrid aircraft project is AIRSTART, project in the UK, which is aiming to develop a parallel hybrid propulsion system to support routine small UAV operations beyond visual line of sight [4].…”