This article presents a preliminary suitable sizing methodology for the design process of the powertrain architecture for a hybrid-electric propulsion system for ultra-light and general aviation aircraft. The main objective of this activity is to design and realize a prototype of a hybrid-electric propulsion system for Cessna 337 aircraft with a maximum take-off power of 134 kW. At the same mission, two operating strategies have been chosen, max recharge and max efficiency. The first one consists of the engine running at wide-open throttle to quickly charge the battery, while the second runs at minimum specific consumption to reduce consumption. The primary energy assessment has been conducted in all proposed propulsion configurations with the same aircraft, mission, and maximum take-off weight. The results also indicated that parallel hybrid propulsion shows a better compromise in terms of 10% energy saving, 4% CO ₂ reduction, and mission duration.

The present work proposes a new torque/speed equilibrium point monitoring technique for an aircraft Hybrid Electric Propulsion System (HEPS) through an accelerometric-signal-based approach. Sampled signals were processed using statistical indexes, filtering, and a feature reduction and selection algorithm to train a classification Feedforward Neural Network. A supervised Machine Learning model was developed to classify the HEPS operating modes characterized by an Internal Combustion Engine as a single propulsor or by combining the latter with an Electric Machine used as a motor or a generator. The abnormal changes in the torque/speed equilibrium point were detected by the monitoring index built by computing the Root Mean Square on the value identified by the classifier. The procedure was validated through experimental tests that demonstrated its validity.

This article presents a numerical model of an aeronautical hybrid electric propulsion system (HEPS) based on an energy method. This model is designed for HEPS with a total power of 100 kW in a parallel configuration intended for ultralight aircraft and unmanned aerial vehicles (UAV). The model involves the interaction between the internal combustion engine (ICE), the electric motor (EM), the lithium battery and the aircraft propeller. This paper also describes an experimental setup that can reproduce some flight phases, or entire missions, for the reference aircraft class. The experimental data, obtained by reproducing two different take-offs, were used for model validation. The model can also simulate anomalous operating conditions. Therefore, the tests chosen for the model validation are characterized by the EM flux weakening (“de-fluxing”). This model is particularly suitable for preliminary stages of design when it is necessary to characterize the hybrid system architecture. Moreover, this model helps with the choice of the main components (e.g., ICE, EM, and transmission gear ratio). The results of the investigation conducted for different battery voltages and EM transmission ratios are shown for the same mission. Despite the highly simplified model, the average margin of error between the experimental and simulated results was generally under 5%.

This paper deals with an upgrade of an existing test bench for medium size (about 100 kW) Internal Combustion Engine (ICE). The redevelopment was needed to adapt the system to new challenges and scopes. Hybrid Electric Propulsion Systems (HEPS) are widely spread in the automotive field. Moreover, the interest in other fields (e.g., aeronautical) is increasing. The enhanced test bench is flexible enough to be adapted to the main different HEPS configurations (series and parallel). Both the hardware and software parts are open and re-configurable for future development. The current upgraded bench can acquire all the physical quantities needed for a full characterization of both the ICE and the Electric Motor (EM).

The hybrid-electric propulsion control system plays a fundamental role to ensure the correct function of all components and to operate a performing energy management. Several control strategies have been proposed in the literature, but the challenge is to keep these techniques methodologically simple and easy to implement. In this paper, an analytical derivation of the Equivalent Consumption Minimization Strategy (ECMS) for energy management of hybrid-electric aircraft is presented, based on Pontryagin’s Minimum Principle (PMP). Simulation results obtained for a parallel hybrid electric configuration with a maximum take-off power of 134 kW are also presented.

Worldwide mopeds and motorcycles are taking on a growing main role in private mobility with a direct impact on air pollution, particularly in urban contexts of many Asian and European countries. In a preceding experimental investigation, HC and CO emissions were measured in the exhaust of a last-generation motorcycle belonging to the Euro-3 legislative category. Since exhaust emissions and fuel consumption are very sensitive to variations in vehicles instantaneous speed and acceleration, in this research new experimental results are used to recognize the kinematic parameters that cause higher engine-out emissions. In this paper, the hybrid electric propulsion is proposed for motorcycle application to reduce exhaust emissions in particular driving conditions which include high levels of acceleration with resultant rapid steep increase in engine speed. In such operating conditions, an enrichment of the air/fuel mixture is required, which affects the catalyst conversion efficiency. Subsequently, the power requirements and the grade of electrical assistance in such driving situations are calculated by a procedure based on both the measured exhaust emissions and the kinematic parameters of the driving dynamics collected during the experimental tests. Lastly, the share of CO and HC emissions that could be saved utilizing a hybrid motorcycle instead of a conventional thermal motorcycle is estimated through a specific environmental analysis.