The More Electric Aircraft concepts aims at increasing the penetration of electric systems on aircrafts. In this framework, the electrical power distribution system (EPDS) is of high importance. In order to improve the utilization of the generators and face the peak power demand without disconnecting the loads, different technologies of storage are employed. This paper proposes the use of a quadruple active bridge converter, already employed in other fields, to interface a fuel cell, a battery, and a supercapacitor bank to the dc bus of the EPDS. This objective can be achieved by employing multiple dc/dc converters, which allow an individual control of the energy sources and a good efficiency. Obtaining the same power control and efficiency with a multiport power converter constitutes a challenge that is worth taking to reduce cost, volume, and weight and increase the system reliability. A novel control based on proportional integral (PI) controllers in conjunction with a decoupling system and current feedforward allow shaping the power request to each port. This, however, leads to an asymmetrical loading of each port, which could decrease the efficiency. A laboratory prototype is used to confirm that this asymmetrical kind of operation, where each port processes a different amount of power, does not imply a marked reduction of efficiency.

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A Quadruple Active Bridge Converter for the Storage Integration on the More Electric Aircraft

More electric aircraft (MEA) architectures consist of several subsystems, which must all comply with the settled safety requirements of aerospace applications. Thus, achieving reliability and fault-tolerance represents the main cornerstone when classifying different solutions. Hybrid electric aircraft (HEA) extends the MEA concept by electrifying the propulsive power as well as the auxiliary power, and thereby pushing the limits of electrification. This paper gives an overview of the high-power electrical machine families and their associated power electronic converter (PEC) interfaces that are currently competing for aircraft power conversion systems. Various functionalities and starter-generator (S/G) solutions are also covered. In order to highlight the latest advancements, the efficiency of the world’s most powerful aerospace generator (Mark 1) developed within the E-Fan X HEA project is graphically represented and assessed against other rivaling solutions. Motivated by the strict requirements on efficiency, power density, trustworthiness, as well as starting functionalities, supplementary considerations on the system-level design are paramount. In order to highlight the MEA goals and take advantage of all potential benefits, all subsystems must be treated as a whole. It is then shown that the combination of PECs, aircraft grid and electrical machines can be better adapted to benefit the overall system. This survey outlines the influence of these concerns and offers a view of the future technology outlook, as well as covering the present challenges and opportunities.

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High-Power Machines and Starter-Generator Topologies for More Electric Aircraft: A Technology Outlook

The idea of electric propulsion for transportation is not new; indeed, the first cars, nearly 200 years ago, were electric. However, our dependence on fossil fuels over the last 100 years is now being questioned, and as a global society, we are moving toward more-electric transportation solutions. Electric propulsion of aircraft is part of this trend, either all-electric or through a large variety of the proposed hybrid propulsion systems. This article considers some of these systems, their technological requirements, and the ongoing research and development in motors and drives necessary to make this technological change a feasible option for the future of passenger flight.

Electric/Hybrid-Electric Aircraft Propulsion Systems

A hybrid-electric propulsion system for an aircraft includes a propulsor and a turbomachine. The turbomachine includes a high pressure turbine drivingly coupled to a high pressure compressor through a high pressure spool. The hybrid electric propulsion system further includes an electrical system including a first electric machine, a second electric machine, and an electric energy storage unit electrically connectable to the first and second electric machines. The first electric machine is coupled to the high pressure spool of the turbomachine and the second electric machine is coupled to the propulsor for driving the propulsor to provide a propulsive benefit for the aircraft. The hybrid electric propulsion system also includes a controller configured to provide electrical power from an electric power source to the first electric machine to drive the first electric machine to start, or assist with starting, the turbomachine.

Propulsion system for an aircraft

In one aspect the present subject matter is directed to a gas-electric propulsion system for an aircraft. The system may include a turbofan jet engine, an electric powered boundary layer ingestion fan that is coupled to a fuselage portion of the aircraft aft of the turbofan jet engine, and an electric generator that is electronically coupled to the turbofan jet engine and to the boundary layer ingestion fan. The electric generator converts rotational energy from the turbofan jet engine to electrical energy and provides at least a portion of the electrical energy to the boundary layer ingestion fan. In another aspect of the present subject matter, a method for propelling an aircraft via the gas-electric propulsion system is disclosed.

Gas-electric propulsion system for an aircraft

More-electric aircraft (MEA) has become a dominant trend for modern aircraft. On-board MEA, many functions, which are conventionally driven by pneumatic and hydraulic power, are replaced with electrical subsystems. Starting aircraft engines with an electric motor instead of using pneumatic power from the auxiliary power unit is one of the major characteristics of future aircraft. This paper presents the development of a novel electric starter–generator system for aircraft applications. This paper describes the main achievements of the AEGART (EU CleanSky Project) project in the key areas, including electric machines, power electronic converters, thermal management, and overall system control design. The developed prototype has been tested successfully, and the test results are presented in this paper.

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Development of Aircraft Electric Starter–Generator System Based on Active Rectification Technology

The concept of “hybrid twin” (HT) has recently received a growing interest thanks to the availability of powerful machine learning techniques. This twin concept combines physics-based models within a model order reduction framework—to obtain real-time feedback rates—and data science. Thus, the main idea of the HT is to develop on-the-fly data-driven models to correct possible deviations between measurements and physics-based model predictions. This paper is focused on the computation of stable, fast, and accurate corrections in the HT framework. Furthermore, regarding the delicate and important problem of stability, a new approach is proposed, introducing several subvariants and guaranteeing a low computational cost as well as the achievement of a stable time-integration.

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Learning stable reduced-order models for hybrid twins

A protective method is provided against torque peaks between a motor adapted for setting a shaft of the motor into rotation and an electric source adapted for electrically powering an electric assembly and including a fixed section and a rotating adapted for rotating with the shaft. The method includes a step for controlling the operation of the electric source forcing the rotary movement of the rotating section with the shaft to observe an instruction relating to the torque of the rotating section applied to the shaft of the motor, the instruction being adapted depending on at least one element characterizing a current operating state of the motor.

Protective module and method against torque peaks between a motor and an electric machine

The paper presents a conceptual design approach for Energy Storage (ES) devices in advanced hybrid propulsion system for small aircrafts. The study targets operational improvement and reduction of fuel consumption for different flight missions. Power sharing strategies for ES and the engine are proposed for cruise flight phase aiming to maximise the range and/or endurance for the available amount of fuel in the tank. The ES size is designed against the engine performance and the proposed power sharing strategy by optimizing the flight altitude.

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Conceptual design of battery energy storage for aircraft hybrid propulsion system

Procede de protection contre les pics de couple entre un moteur (1) adapte pour mettre un arbre du moteur en rotation et une source electrique (31) adaptee pour alimenter electriquement un ensemble electrique et comportant une section fixe et une section tournante adaptee pour tourner avec l'arbre, comportant une etape de pilotage du fonctionnement de la source electrique contraignant le mouvement de rotation de la section tournante avec l'arbre a respecter une consigne relative au couple de la section tournante applique a l'arbre du moteur, ladite consigne etant adaptee en fonction d'au moins un element caracterisant un etat courant de fonctionnement du moteur

Jean-Marc Le Peuvedic

Papers

Development of Aircraft Electric Starter–Generator System Based on Active Rectification Technology

Learning stable reduced-order models for hybrid twins

Protective module and method against torque peaks between a motor and an electric machine

Conceptual design of battery energy storage for aircraft hybrid propulsion system

Procédé et module de protection contre les pics de couple entre un moteur et une machine électrique