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This paper presents an energy management strategy for a hybrid electric propulsion system designed for unmanned aerial vehicles. The proposed method combines the Equivalent Consumption Minimization Strategy (ECMS) and fuzzy logic control, thereby being named Fuzzy based ECMS (F-ECMS). F-ECMS can solve the issue that the conventional ECMS cannot sustain the battery state-of-charge for on-line applications. Furthermore, F-ECMS considers the aircraft safety and guarantees the aircraft landing using the remaining electrical energy if the engine fails. The main contribution of the paper is to solve the deficiencies of ECMS and take into consideration the aircraft safely landing, by implementing F-ECMS. Compared with the combustion propulsion system, the hybrid propulsion system with F-ECMS at least reduces 11% fuel consumption for designed flight missions. The advantages of F-ECMS are further investigated by comparison with the conventional ECMS, dynamic programming and adaptive ECMS. In contrast with ECMS and dynamic programming, F-ECMS can accomplish a balance between sustaining the battery state-of-charge and electric energy consumption. F-ECMS is also superior to the adaptive ECMS because there are less fuel consumption and lower computational cost.

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.

This paper describes the design and development of a hybrid fuel cell/battery propulsion system for a long endurance small UAV. The high level system architecture is presented, followed by the hardware-in-the-loop testing and performance analysis. A high fidelity 6-DoF simulation model of the complete system was developed and used to test the system under different battery state-of-charge. The simulation model included the power manager for the hybrid propulsion system configuration, which is based on rule-based control. The simulation results are compared with the experimental results obtained from the Hardware-in-the-Loop testing.