Aircraft Architecture Research Articles

Power Electronic Converters in Electric Aircraft: Current Status, Challenges, and Emerging Technologies

The electric revolution is underway in the transportation sector, and the aviation industry is poised to embrace fundamental disruption. Moving to electric aircraft brings undeniable benefits in terms of environmental impact, cost savings, maintenance, noise pollution, and safety. Nevertheless, several technical challenges are yet to be overcome to build electric airplanes that meet public needs while gaining acceptance and trust. From urban air mobility to long-haul flight applications, hundreds of projects are under research to push toward more electrification. At the heart of each aircraft architecture, power electronics plays a crucial role in the new era of transportation. This article aims to provide a comprehensive analysis of state-of-the-art power electronics in electric aircraft. A review of the current status of aircraft electrification will be provided, and technology surveys of power electronic converters will be detailed. Challenges for forthcoming power electronics in response to the future trends of the electrical network will be explained. Finally, emerging technologies regarding wide bandgap devices, advanced topologies and control, thermal management, passive components, and system integration will be discussed.

Head-up display architecture development for perspective civil aircraft

Nowadays the civil aircraft head-up displays available on the market could not be easily integrated onboard due to architectural aspects. Particularly, these systems usually contain a dedicated computer unit performing the data processing to generate the appropriate image. This leads to increases in the overall avionics weight and size and limits the scope of head-up displays application in general. However, the mentioned characteristics could be improved by the usage of the integrated modular avionics concept for architecture design. According to that approach, the common hardware platform is used by different functional consumers to share computation resources. Thus, the required data processing function could be performed by the equipment already available onboard (without the need in additional hardware). The paper proposes the head-up display architecture for civil aircraft based on integrated modular avionics which significantly reduces the system’s weight and size compared to characteristics of existing analogous. Also, this way allows reducing the time expenses for aircraft development, testing and certification, as well as the vehicle operational cost.

Design of hybrid electric heavy fuel MALE ISR UAV enabling technologies for military operations

PurposeThis paper aims to present the main results achieved in the frame of the TIVANO national-funded project which may anticipate, in a stepped approach, the evolution and the design of the enabling technologies needed for a hybrid/electric medium altitude long endurance (MALE) unmanned aerial vehicle (UAV) to perform persistent intelligence surveillance reconnaissance (ISR) military operations.Design/methodology/approachDifferent architectures of hybrid-propulsion system are analyzed pointing out their operating modes to select the more suitable architecture for the reference aircraft. The selected architecture is further analyzed together with its electric power plant branch focusing on electric system architecture and the selected electric machine. A final comparison between the hybrid and standard propulsion is given at aircraft level.FindingsThe use of hybrid propulsion may lead to a reduction of the total aircraft mass and an increase in safety level. However, this result comes together with a reduced performance in climb phase.Practical implicationsThis study can be used as a reference for similar studies and it provides a detailed description of propulsion operating modes, power management, electric system and machine architecture.Originality/valueThis study presents a novel application of hybrid propulsion focusing on a three tons class MALE UAV for ISR missions. It provides new operating modes of the propulsion system and a detailed electric architecture of its powertrain branch and machine. Some considerations on noise emissions and infra-red traceability of this propulsion, at aircraft level.

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

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.

Feasibility study of an induction motor rim drive for an aircraft boundary‐layer‐ingestion fan

This study presents a feasibility study for an induction motor rim drive to power aircraft boundary-layer-ingestion (BLI) fans. The design is developed from a BLI-fan specification for traditional aircraft architecture: the rotor is fastened to the rim of the blade shroud, not to obstruct the fan duct and interfere with the air flow. The main objective of this study is the identification of achievable power density and efficiency levels with an induction motor rim drive configuration considering the structural requirements for the integrity of the rotor operating with high tip speeds. The proposed 250 kW, 14,000 rpm design example achieves an efficiency in excess of 97% with an active mass around 20 kg.

Advanced low-noise aircraft configurations and their assessment: past, present, and future

Aircraft noise remains the key inhibitor of the growth of air transportation, but the focus of the noise mitigation strategies has changed. As the propulsor fan pressure ratio is decreased for improved fuel burn and lessened environmental impact, the propulsion system noise can be reduced near or even below the noise level of the airframe. Jet noise has become less of a concern, and during approach and landing, the acoustic signature is predominantly set by the airframe. Novel aircraft concepts and architectures, enabled by distributed, more integrated, and boundary-layer ingesting propulsion systems, pose new aeroacoustic problems which require innovative approaches and call for teaming and collaboration as the technological challenges cut across disciplines. One past example of such a collaborative research effort was the Silent Aircraft Initiative (SAI), aimed at the conceptual design of an aircraft imperceptible to the human ear outside the airport perimeter. The initiative brought together researchers from academia, industry, and government agencies. This chapter gives a brief summary of the Silent Aircraft Initiative, the SAX-40 aircraft design, and the noise reduction technologies which were pursued. A decade past SAI, novel aircraft architectures such as the D8 double bubble aircraft, the outcome of a joint effort between MIT, Aurora Flight Sciences and Pratt and Whitney, are being pursued in the quest of reducing the climate impact of aviation. With regulations continuing to reduce the allowable aviation noise emission levels, both new challenges and new opportunities are emerging. Electric, hybrid, and turbo-electric aircraft concepts are currently being investigated as potential game changers. Independent of the level of electrification, noise will remain a major issue as air transportation is growing and mobility might become a key driver. The chapter discusses a selection of enabling technologies and their implications on acoustics and noise and gives a perspective on future trends and new directions in aeroacoustics required to address the challenges.

FeCo soft magnetic, electrically insulated nanopowders

Abstract The concept of more electrical aircraft architecture requires new magnetic materials, with improved magnetic and electrical properties. The paper investigates the soft magnetic materials based on FeCo/Al2O3 core-shell nanoparticles, synthesized by sol-gel technique. These nanomaterials combines the high saturation magnetisation of FeCo compound with the increased resistivity of Al2O3 and allow the decreasing of time-dependent magnetic losses for the bulk sized components, compared with the currently available Fe-Si alloys, used as metallic punched sheets for the building of the magnetic cores in electrical machines. The main physical characteristics of the FeCo/Al2O3 prepared nanomaterials are: saturation magnetisation in the range of 136–213 emu/g, coercivity around 24.5 kA/m (320 Oe) and electrical resistivities of order of 1014 Ω·m.

Navigation architecture for hypersonic aircraft

This paper aims at presenting an integrated navigation algorithm designed for estimating the navigation state of the STRATOFLY vehicle (LAPCAT–MR3). STRATOFLY project has been funded by the European Commission, under the framework of Horizon 2020 plan, with the aim of assessing the potential of high–speed transport vehicle. The complex interaction between elements of an air-breathing hypersonic vehicle represents a new paradigm in aircraft design. In particular, one of the needs for early GNC analysis in the case of LAPCAT–MR3 vehicle is the assessment of navigation performance over the reference trajectory. The navigation algorithm presented in this paper is based on an augmented state EKF data fusion algorithm exploiting inertial measurements provided by gyroscopes and accelerometers, heading estimates provided by a magnetometer and satellite-based measurements provided by a spaceborne GNSS receiver, considering GPS, GLONASS and GALILEO constellations.

Parallel hybrid electric propulsion architecture for single aisle aircraft - powertrain investigation

This paper presents an investigation of the fuel- and energy-saving potential through the introduction of several hybrid electric propulsion (HEP) and more electric aircraft (MEA) systems on single aisle aircraft. More specifically, for an A320NEO the following main electric systems are considered: electric motors, batteries and power electronics for parallel HEP, electric components for replacement of the main pneumatic and hydraulic non-propulsive systems like environmental control system and actuators, and electric power transport and supply. The power sizing of the electric components, as well as their mass effects on overall aircraft mission performance are evaluated by system modelling of the aircraft, turbofan and the considered electric components. It is found for the considered aircraft and missions that the fuel saving potential of parallel HEP systems alone is very limited or absent. Typically the combination of HEP and MEA technologies shows potential for improved energy efficiency due to synergies of the involved systems and their operation.

Investigation on the Selection of Electric Power System Architecture for Future More Electric Aircraft

This paper identifies the most promising electric power system (EPS) architecture for a future more electric aircraft based on reviews and evaluations of both system weight and stability feature of the existing EPS architectures. When comparing the overall system weight of different architectures, various aspects, including voltage generation, wiring system, ground operation, power conversion, and complexity of integrating alternative energy sources, are considered. After choosing the possible candidates among all the possible architectures by using weight-saving criterion, stability features for the initially selected candidates are further evaluated. Necessary simulation studies are carried out in MATLAB/Simulink to prove the correctness of stability study. Finally, the one both good at weight saving and with the highest stability region is deemed as the most promising EPS architecture for future MEAs.

Preliminary Design Investigation of Dual Stator HE FSM using Segmental Rotor

To drop the effect of air transportation on the atmosphere as well as to advance fuel productivity more-electric aircraft (MEA) architectures is a well-known approach. As the electrical machines are competent to deliver higher torque densities and are foremost for the viability of electrical driving force for aircraft applications. For these reasons a new category of machine has been familiar and published in last decade known as flux switching machine (FSM). FSMs comprises all excitation sources on stator side without winding robust rotor structure. Additionally, FSMs are classified into three types such as permanent magnet (PM) FSMs, field excitation (FE) FSMs and hybrid excitation (HE) FSMs. PM FSM and FE FSM use PM and FE coil for their excitation sources respectively, whereas both PM and FE coil are used in HE-FSM for excitation. Afterwards, HE FSMs have shown higher torque to weight ratios with higher efficiency during research in the last decade. Yet, in existing structures of HE FSMs, there is flux cancellation between the fluxes of PMs and FE coil which causes to reduce the performance of machines. Hence, in this paper, a novel structure of dual stator (DS) HE FSM with segmented rotor has been proposed and analyzed. The main reason of dual stator is to make the separate flow fluxes in HE machines to avoid cancellations. The proposed novel DS HE FSM has a simple structure using dual stators to endorse separate dual excitations to be used in fault conditions. The proposed structure has been analyzed using commercial 2D FEA package, JMAG-designer. Initially, this paper presents the coil test analysis of proposed DS HE FSM to confirm the working principle. Besides, performance analysis has been carried out at no load and load conditions.

Exploiting the synergy between aircraft architecture and electric power system in unmanned aerial vehicle through many-objective optimisation

This study addresses the preliminary design of a fixed-wing, tailsitter electric unmanned aerial vehicle (with vertical take-off and landing capability) by optimising the size of the powertrain components together with the main aircraft design specification. To this scope, different optimisation problems are considered, with two, three and four objective functions, respectively. The results of the optimisation are used not only to compare the performance of different optimisation algorithms when increasing the number of goals, but also to discuss the synergy between architecture and power systems optimisation.

Exploiting the synergy between aircraft architecture and electric power system in unmanned aerial vehicle through many-objective optimisation

This study addresses the preliminary design of a fixed-wing, tailsitter electric unmanned aerial vehicle (with vertical take-off and landing capability) by optimising the size of the powertrain components together with the main aircraft design specification. To this scope, different optimisation problems are considered, with two, three and four objective functions, respectively. The results of the optimisation are used not only to compare the performance of different optimisation algorithms when increasing the number of goals, but also to discuss the synergy between architecture and power systems optimisation.

Behavioural modelling and power quality simulation of a HVDC electric power system for MEA

High-voltage direct current (HVDC) electric power system (EPS) is a promising architecture for more electric aircraft (MEA). With more electric power used, a higher voltage is necessary to make aircrafts more efficient and less weighted. However, there are no standards can be followed to evaluate the power quality of HVDC EPS, especially for 540 VDC system. In this study, a potential HVDC EPS is proposed and power quality is studied by simulation. Behavioural models of the system are established in detail from source to load. Three kinds of typical loads of MEA are defined and their impacts on power quality are analysed including resistances, power electronic converters, and motors. Some suggestions are provided for design and integration of the EPS for MEA.

Architectural Decisions in Commercial Aircraft from the DC-3 to the 787

The volume of passenger air travel has increased rapidly since the first commercially viable passenger aircraft, the DC-3. Over this period, commercial aircraft increasingly appear to have consolidated around a dominant architecture. That is to say, aircraft designers have increasingly made the same architectural decisions (categorical choices such as high wing or low wing), while realizing performance gains in component technologies rather than from major architectural innovations. To quantify the assertion that a dominant architecture has emerged, in this paper, architectural decisions over time are analyzed, finding a decrease in variation of these decisions in a data set of 157 historical aircraft architectures. An architectural performance metric is defined based on passenger-carrying efficiency, technical performance, and market value, observing that, in parallel with architectural consolidation, there has been a twofold increase in average performance since the inception of the DC-3. However, the performance trend is shown to follow a trajectory similar to that of a technology S curve, implying that current improvements in performance with this dominant architecture may be reaching the stage of diminishing returns. Given current levels of activity in engine technology and potential architectural implications of large fan diameters, among other trends, this paper forms the basis for an evaluation of limits to the dominant design.

A Module-Based Approach for Stability Analysis of Complex More-Electric Aircraft Power System

Moving toward more-electric aircraft (MEA) architecture, future aircraft power system will consist of a large number of power converters and motor drive loads which behave as constant power load and may cause stability issues. It is essential to ensure stable operation of the MEA power system, even though the complexity of the system hinders the comprehensive analysis of system stability. This paper presents a framework for stability analysis of a complex MEA power system. A module-based approach is proposed to provide a general and flexible solution for modeling and integrating complex systems, even under situations of system extension and reconfiguration. Using the proposed technique, a complex system model is conveniently formulated and overall system stability can be evaluated. Then, the critical stability points can be investigated. Impacts of parameters and their damping effects are identified by eigenvalue analysis and sensitivity analysis. The hybrid ac/dc MEA power system adopted by Boeing 787 is analyzed using the proposed technique. Simulations in MATLAB/Simulink are conducted to validate the effectiveness of the proposed modeling technique and the analytical results.

VTOL 타입의 복합형 비행체에 적용가능한 다수 프로펠러 기반 자세제어기법의 개발

In recent decades, many researchers have been struggling to developing the compound aircraft that is capable high speed and VTOL flight. And in recent years, multi-copters are very popular because of having advantages of VTOL and easy handling, but they are lack of doing long-range mission. Therefore, we presents simple aircraft architecture which is equipped fixed wing, multi propellers and no control surfaces. In this paper, we designed the attitude control for the compound aircraft prototype and measured the attitude control performance with flight test for validating prototype’s performance. We analysed the attitude control test result comparing with similar size of a fixed wing aircraft. The performance was almost same as fixed wing aircraft.

Influence of Technology Trends on Future Aircraft Architecture

In the last 30 years, aircraft performance has experienced diminishing returns in terms of efficiency, on the order of 1% reduction in fuel consumption annually since 2010. Meanwhile, according to projections by Airbus and Boeing, air passenger traffic is expected to increase 3.5–4.6% per annum. International Civil Aviation Organization has recommended that overall energy efficiency be improved by 2% annually. The rate of increase in demand and decrease in fuel consumption raises the question of how this goal can be met. In this paper, engine technology advances are identified as the most significant contributing trend to aircraft performance. These trends are extrapolated in order to analyze the conditions that could lead to a potential break in the dominant aircraft architecture. A hybrid analytical/empirical model for aircraft optimization is used to predict the effects of these technological trends on aircraft design. Four technology scenarios are used to analyze the expected performance increase and expected year of break in architecture, for existing airframes and unconstrained airframe geometry. It is found that for existing airframes performance is expected to increase by 6–38% relative to the 737MAX and A320neo within the next 10–14 years and 17–40% for an unconstrained airframe within the next 20–30 years.

A new aircraft architecture based on the ACHEON Coanda effect nozzle: flight model and energy evaluation

Aeronautic transport has an effective necessity of reducing fuel consumption and emissions to deliver efficiency and competitiveness driven by today commercial and legislative requirements. Actual aircraft configurations scenario allows envisaging the signs of a diffused technological maturity and they seem very near their limits. This scenario clearly shows the necessity of radical innovations with particular reference to propulsion systems and to aircraftarchitecture consequently. This paper presents analyses and discusses a promising propulsive architecture based on an innovative nozzle, which allows realizing the selective adhesion of two impinging streams to two facing jets to two facing Coanda surfaces. This propulsion system is known with the acronym ACHEON (Aerial Coanda High Efficiency Orienting Nozzle). This paper investigates how the application of an all-electric ACHEONs propulsion system to a very traditional commuter aircraft can improve its relevant performances. This paper considers the constraints imposed by current state-of-the-art electric motors, drives, storage and conversion systems in terms of both power/energy density and performance and considers two different aircraft configurations: one using battery only and one adopting a more sophisticated hybrid cogeneration. The necessity of producing a very solid analysis has forced to limit the deflection of the jet in a very conservative range (±15°) with respect to the horizontal. This range can be surely produced also by not optimal configurations and allow minimizing the use of DBD. From the study of general flight dynamics equations of the aircraft in two-dimensional form it has been possible to determine with a high level of accuracy the advantages that ACHEON brings in terms of reduced stall speed and of reduced take-off and landing distances. Additionally, it includes an effective energy analysis focusing on the efficiency and environmental advantages of the electric ACHEON based propulsion by assuming the today industrial grade high capacity batteries with a power density of 207 Wh/kg. It has been clearly demonstrated that a short flight could be possible adopting battery energy storage, and longer duration could be possible by adopting a more sophisticated cogeneration system, which is based on cogeneration from a well-known turboprop, which is mostly used in helicopter propulsion. This electric generation system can be empowered by recovering the heat and using it to increase the temperature of the jet. It is possible to transfer this considerable amount of heat to the jet by convection and direct fluid mixing. In this way, it is possible to increase the energy of the jets of an amount that allows more than recover the pressure losses in the straitening section. In this case, it is then possible to demonstrate an adequate autonomy of flight and operative range of the aircraft. The proposed architecture, which is within the limits of the most conservative results obtained, demonstrates significant additional benefits for aircraft manoeuvrability. In conclusion, this paper has presented the implantation of ACHEON on well-known traditional aircraft, verifying the suitability and effectiveness of the proposed system both in terms of endurance with a cogeneration architecture and in terms of manoeuvrability. It has demonstrated the potential of the system in terms of both takeoff and landing space requirements. This innovation opens interesting perspectives for the future implementation of this new vector and thrust propulsion system, especially in the area of greening the aeronautic sector. It has also demonstrated that ACHEON has the potential of renovating completely a classic old aircraft configuration such as the one of Cessna 402.

Selecting the Best Electric Machines for Electrical Power-Generation Systems: High-performance solutions for aerospace More electric architectures

The electric machines (EMs) for high-performance electrical power-generation systems (EPGSs) play a significant role in the modern aerospace and military industries. This is particularly true in the area of More Electric Architecture (MEA) for aircraft, spacecraft, and military ground vehicles. The commercial aircraft business is moving toward no-bleed air environmental control systems, variable-frequency and dc power-distribution buses, and electrical actuation. A typical example is the Boeing 787 platform. The next-generation Boeing narrow-body airplane (the replacement for the 737) and the Airbus replacement for the A320 will most likely use MEA. Some ?military ?aircraft already use MEA for both primary and secondary flight control. Military ground vehicles have migrated toward hybrid electric technology. In those cases, the main propulsion is performed by electric drives. This demonstrates that substantial demand has arisen for improved electric power-generation performance. Future space vehicles will require electric drives for thrust-vector and flight-control actuation, demanding more high-quality electric power. These systems must be more robust and will offer greatly reduced operating costs and improved safety compared with Space Shuttle hardware.