More Electric Aircraft Research Articles

Dual‐port network‐based impedance modelling and AC‐port characteristic analysis of wound rotor synchronous machine for more electric aircraft

AbstractDue to the increasing variety of converters in more electric aircraft (MEA), the stability of the MEA power system has become a critical issue that receives wide concerns. As the primary power source for MEA, the wound rotor synchronous machine (WRSM) greatly affects the stability of the whole power system, and therefore accurate modelling of the WRSM serves as the basis for the analysis of system characteristics and even stability. Nevertheless, the complex structure and coupling of WRSM bring great challenges to small‐signal modelling methods. This paper introduces a novel method to model the WRSM in a modular and cascaded manner. Instead of deriving the complex transfer function, the proposed method uses a dual port to model each component. By connecting the dual port of each component from the rear stage to the front stage in a cascaded way, a dual‐port network can be built to describe the external impedance characteristics of the WRSM. Kirchhoff law can be applied to calculate the impedance by circumventing the complicated decoupling process. The proposed dual‐port network model has been validated on a hardware‐in‐loop platform. Furthermore, the output impedance characteristics of the AC port has also been analysed with the proposed model.

An Analysis of a Complete Aircraft Electrical Power System Simulation Based on a Constant Speed Constant Frequency Configuration

Recent developments in aircraft electrical technology, such as the design and production of more electric aircraft (MEA) and major steps in the development of all-electric aircraft (AEA), have had a significant impact on aircraft’ electrical power systems (EPSs). However, the EPSs of the latest aircraft produced by the main players in the market, Airbus with the Neo series and Boeing with the NG and MAX series are still completely traditional and based on the constant speed constant frequency (CSCF) configuration. For alternating current ones, the EPS is composed of the following: prime movers, namely the aircraft turbofan engine (TE); the electrical power source, i.e., the integrated drive generator (IDG); the command and control system, the generator control unit (GCU); the transmission and the system distribution system; the protection system, i.e., the CBs (circuit breakers); and the electrical loads. This paper presents the analysis of this system using the Simscape package from Simulink v 8.7, a MATLAB v 9.0 program, which is actually the development of some systems designed in two previous personal papers. For the first time in the literature, a complete MATLAB modelled EPS system was presented, i.e., the aircraft turbofan engine model, driven by the constant speed drive system (CSD) (model presented in the first reference as a standalone type and with different parameters), linked to the synchronous generator (SG) (model presented in second reference for lower power and rotational speed) in the so-called integrated drive generator (IDG) and electrical loads.

Comparison of Effects of Partial Discharge Echo in Various High-Voltage Insulation Systems

In this article, an extension of a conventional partial discharge (PD) approach called partial discharge echo (PDE), which is applied to different classes of electrical insulation systems of power devices, is presented. Currently, high-voltage (HV) electrical insulation is attributed not only to transmission and distribution grids but also to the industrial environment and emerging segments such as transportation electrification, i.e., electric vehicles, more-electric aircraft, and propulsion in maritime vehicles. This novel PDE methodology extends the conventional and established PD-based assessment, which is perceived to be one of the crucial indicators of HV electrical insulation integrity. PD echo may provide additional insight into the surface conditions and charge transport phenomena in a non-invasive way. It offers new diagnostic attributes that expand the evaluation of insulation conditions that are not possible by conventional PD measurements. The effects of partial discharge echo in various segments of insulation systems (such as cross-linked polyethylene [XLPE] power cable sections that contain defects and a twisted-pair helical coil that represents motor-winding insulation) are shown in this paper. The aim is to demonstrate the echo response on representative electrical insulating materials; for example, polyethylene, insulating paper, and Nomex. Comparisons of the PD echo decay times among various insulation systems are depicted, reflecting dielectric surface phenomena. The presented approach offers extended quantitative assessments of the conditions of HV electrical insulation, including its detection, measurement methodology, and interpretation.

Partial abrasion modeling and variable load characteristics analysis for high-speed load sensing electro-hydrostatic actuator pump of aircraft

The load-sensing electro-hydrostatic actuator (LS-EHA) allows to reduce the thermal output and enhance the dynamic characteristics of the more electric aircraft (MEA). In addition, the forecasting of the LS-EHA is crucial for its efficient functioning. This study proposes a novel model for the analysis of overturning and wear characterization of the slipper, while focusing on the partial abrasion. The transient thermoelastic hydrodynamic (TEHD) lubricating analysis of the slipper pair is solved by an analytical model along with the finite difference method. In the proposed partial abrasion model, the non-uniformity of the oil film thickness and the partial abrasion contour for the slipper bottom surface are considered through the discrete friction area approach in order to reach a higher precision. Afterward, the overturning behavior characteristics of the slipper and the variation law in its overturning behavior under different rotation speeds, load delivery pressures, and swashplate angles are analyzed. The obtained results demonstrate that the lubricating oil film field is unevenly distributed, and the overturning behavior of the slipper has certain variable load characteristics. Finally, the effectiveness and precision of the proposed partial abrasion model are validated through comparative simulation experiments and analysis.

Characteristic investigation of digital control four quadrant electro-hydrostatic actuator with separated hydraulic motor.

The asymmetric electro-hydrostatic actuator (EHA) is a promising distributed hydraulic actuation solution for the more-electric aircraft (MEA). However, the flow asymmetry is a common problem causing the poor position control accuracy and dynamics of EHA. To achieve good flow control in all quadrants and save energy in the assistive quadrants, a digital control four quadrant electro-hydrostatic actuator with a separated hydraulic motor using a novel four-quadrant division principle was proposed in this article. The theoretical model of the proposed EHA has been developed in MATLAB/Simulink and validated in the experiments. The theoretical results indicated that the increased external force allows the proposed EHA to have a constantly and partly linearly and varied motion velocity of the cylinder piston in the resistive and assistive quadrants, and the latter is determined by the specific external forces of 0.5 and 2.8kN, respectively, in the extension and retraction quadrants. Compared with EHA without SHM, in the second and fourth quadrants, the energy dissipation is reduced by 104% and 36.7%, respectively, while the motion velocity of the cylinder piston is reduced by 12.9% and 25.6%, respectively. The theoretical and experimental results indicated that the proposed four quadrants division method effectively corrects the misjudgment of quadrants by using the existing four quadrants division method under the lower external force.

Research on Classification Maintenance Strategy for More Electric Aircraft Actuation Systems Based on Importance Measure

In this paper, a practical maintenance algorithm is proposed to improve the reliability of actuation systems and their components, specifically addressing the consistency degradation caused by faults in the symmetric actuation system components of more electric aircraft (MEA). By integrating important measures with traditional genetic algorithms, the accuracy of the algorithm is improved. Prior to maintenance, a reasonable classification of components is built to mitigate the adverse effects of extreme fault conditions on the algorithm. This approach improves both the effectiveness and efficiency of the algorithm, rendering the overall maintenance strategy better suited for real-world needs. Finally, comparative simulations confirm the algorithm’s superior performance in reliability improvement, demonstrating its substantial contribution to the field of MEA maintenance and reliability.

Meeting the challenge of mitigating Li-ion battery fires for aviation

The aviation industry faces a pressing challenge in reducing its environmental footprint, especially with the projected growth in global passenger traffic. Electrification and more-electric aircraft, particularly through Lithium-ion Battery (LiB) systems, offers a promising pathway to reduce emissions but introduces significant safety concerns, particularly regarding thermal runaway (TR) events. This prospective paper examines the unique challenges posed by aviation environments for developing safe LiB systems. It discusses multifaceted mitigation approaches, integrating fire containment structures with advanced thermal management and fire protection technologies. Various cooling technologies and fire suppression agents are explored for their effectiveness in extinguishing LiB fires and mitigating thermal runaway propagation. Integrated LiB suppression systems are proposed to combine fire containment, suppression, and thermal management functionalities for achieving the demanding specific energy density levels that will be required. Scaling safe LiB pack solutions for commercial aviation requires coordinated efforts among regulators, original equipment manufacturers (OEMs), engineers, and researchers to establish standardized design criteria, develop validated modeling tools, and establish rigorous certification testing requirements. In conclusion, addressing the safety concerns of large LiB packs in aircraft applications requires a holistic, integrated approach. This paper provides insights into current research, identifies key challenges, and outlines future directions for advancing LiB safety in aviation.

Comprehensive Experimental Database and Model Fitting for Electric Arc Behavior in Aircraft Environments

The More Electric Aircraft (MEA) paradigm advocates weight reduction by transitioning to electrical components, resulting in increased system voltage and higher arc fault risk. This paper presents a methodology for creating a database of nearly one thousand tests simulating parallel arc faults, using Andrea's arc model for accurate representation. Objectives include the creation of a robust experimental database and the use of a simplified model to analyze arcing behavior. The setup follows the UL 746A standard and considers various pressure and electrode separation conditions. The database includes 960 experiments with PVC and PTFE materials, and model fitting ensures accurate representation of arc currents and voltages. Error analysis shows consistent model performance across materials and highlights sensitivity to electrode spacing, pressure, and source voltage. The paper concludes with a clear 30% error threshold for model validity, enhancing the understanding of the applicability of Andrea's model under various experimental scenarios in aircraft environments.

Improved Reference Current Extraction Method for Electric Aircraft Active Power Filter Application

This paper proposes a robust reference current extraction method useful for active power filters (APFs) connected to the More Electric Aircraft (MEA) grid for addressing power quality issues. Hence, it is essential to investigate and develop better APF harmonic compensating control algorithms that can eliminate the impact of harmonics emerging from the nonlinear loads connected to the MEA grid. The proposed method envisages a half-cycle moving window discrete Fourier transform filter approach to rapidly extract the fundamental positive sequence (FPS) from a polluted three-phase grid voltage. Thus, allowing the harmonic cancelation method to generate desired clean reference current which is in phase with FPS component of the grid voltage. This reference current is used in conjunction with the hysteresis current controller to generate appropriate gate pulses for the current-controlled voltage source APF. The employment of the digital filter in the control structure of the APF ensures improved power quality for the MEA grid as compared to traditional filtering algorithms. The numerical and experimental results demonstrate that the proposed control solution helps to reduce the total harmonic distortion under abnormal grid disturbances, thus, indicating the potential benefits of the proposed work for addressing power quality issues in MEA applications.

Integrated Power and Thermal Management Systems for Civil Aircraft: Review, Challenges, and Future Opportunities

Projects related to green aviation designed to achieve fuel savings and emission reductions are increasingly being established in response to growing concerns over climate change. Within the aviation industry, there is a growing trend towards the electrification of aircraft, with more-electric aircraft (MEA) and all-electric aircraft (AEA) being proposed. However, increasing electrification causes challenges with conventional thermal management system (TMS) and power management system (PMS) designs in aircraft. As a result, the integrated power and thermal management system (IPTMS) has been developed for energy-optimised aircraft projects. This review paper aims to review recent IPTMS progress and explore potential design solutions for civil aircraft. Firstly, the paper reviews the IPTMS in electrified propulsion aircraft (EPA), presenting the architectures and challenges of the propulsion systems, the TMS cooling strategies, and the power management optimisation. Then, several research topics in IPTMS are reviewed in detail: architecture design, power management optimisation, modelling, and analysis method development. Through the review of state-of-the-art IPTMS research, the challenges and future opportunities and requirements of IPTMS design are discussed. Based on the discussions, two potential solutions for IPTMS to address the challenges of civil EPA are proposed, including the combination of architecture design and power management optimisation and the combination of modelling and analysis methods.

Derivation of Ambient Enhancement Factors of Impregnated Twisted Pairs for Partial Discharge Risk Evaluation

Partial discharge (PD) is the main issue challenging the electrical machine (EM) insulation system for more electric aircraft (MEA) applications. Indeed, the trend of adopting higher DC link voltage and fast switching device further boost the risk of PD. Partial discharge inception voltage (PDIV) is mostly dominated by ambient conditions (i.e., temperature, pressure, and humidity), and their influence is accounted for through experimentally determined ambient enhancement factors. For non-impregnated windings, ambient enhancement factors are suggested by both IEC 60034-18-41 and recent literature. However, in many applications, EMs’ windings are often impregnated with resin to improve thermal performance, mechanical resistance, and electrical insulation. In this case, no indications of the enhancement factors for PD risk assessment are given. The ambient enhancement factors are experimentally determined in this paper to enable the PD risk evaluation for impregnated windings. These factors are obtained relying on an extensive PD investigation, where PDIV and partial discharge extinction voltage are measured under variable temperature, pressure, and humidity conditions. Finally, the tests are performed on different wire types and motorette samples to validate the applicability of the derived factors.

More Electric Aircraft Conversion to All-Electric During Ground Operations: Battery-Powered Landing Gear Drive System

Raising awareness about environmental issues moves the aerospace industry towards electrification and the corresponding solutions are already present at some airports. However, commercial aircraft are the missing links in claiming the all-electric ground operations. They rely on fossil fuels without any electric alternative due to the technological inability to store large amounts of energy while maintaining low weight of batteries. The issue diminishes if an electric system uses only a fraction of energy normally consumed by the engines and comprises kinetic energy recovery. Accordingly, this paper demonstrates the landing gear drive system for a narrowbody air-plane which has the sustainable and economic means to replace all onboard engines throughout ground operations. The system is simulated in MATLAB/Simulink and leads to the kinematic results which are based on the real drive cycles. The kinematics are subsequently used to estimate the overall on-ground power and energy demand of a more electric aircraft (MEA). The impact is maximized with the components scaled according to performance metrics and two-speed gear ratio optimization. The net fuel advantage is demonstrated for different ground operation modes, taxi times and flight path lengths.

Airport Microgrid and Its Incorporated Operations

This paper presents the development of an airport bipolar DC microgrid and its interconnected operations with the utility grid, electric vehicle (EV), and more electric aircraft (MEA). The microgrid DC-bus voltage is established by the main sources, photovoltaic (PV) and fuel cell (FC), via unidirectional three-level (3L) boost converters. The proposed one-cycle control (OCC)-based current control scheme and quantitative and robust voltage control scheme are proposed to yield satisfactory responses. Moreover, the PV maximum power point tracking (MPPT) with FC energy-supporting approach is developed to have improved renewable energy extraction characteristics. The equipped hybrid energy storage system (HESS) consists of an energy-type battery and a power-type flywheel; each device is interfaced to the common DC bus via its own 3L bidirectional interface converter. The energy-coordinated operation is achieved by the proposed droop control. A dump load leg is added to avoid overvoltage due to an energy surplus. The grid-connected energy complementary operation is conducted using a neutral point clamped (NPC) 3L three-phase inverter. In addition to the energy support from grid-to-microgrid (G2M), the reverse mcrogrid-to-grid (M2G) operation is also conductible. Moreover, microgrid-to-vehicle (M2V) and vehicle-to-microgrid (V2M) bidirectional operations can also be applicable. The droop control is also applied to perform these interconnected operations. For the grounded aircraft, bidirectional microgrid-to-aircraft (M2A)/aircraft-to-microgrid (A2M) operations can be performed. The aircraft ground power unit (GPU) function can be preserved by the developed microgrid. The MEA on-board facilities can be powered by the microgrid, including the 115 V/400 Hz AC bus, the 270 V DC bus, the switched-reluctance motor (SRM) drive, etc.

More Electric Planes Analyses of the Difficulties and Possibilities for Business Transport Aircraft Using WSM Method

More electric aircraft (MEA) and the transition to electric vehicles has been the subject of extensive study. The objectives of this research include lowering emissions and fuel consumption, which are comparable to those for automobiles. Many components in traditional airplanes may make use of one or more types of power, such as electrical, hydraulic, mechanical, or pneumatic power. However, each form of energy has its own disadvantages, such as sacrificing overall mechanical efficiency when capturing a particular energy, as in the case of hydraulic and pneumatic systems.The majority of the primary non-electric systems, like environmental controls, Old electrical systems will be replaced with new electrical systems in future aircraft to improve "a variety of aerospace characteristics such as engine start, efficiency, emissions, reliability, and maintenance". This essay offers a thorough examination of how systems alter or will alter. Future aviation innovations like gas-electric propulsion for planes and electric taxis are also discussed. Modern state-of-the-art electric aircraft technology is used in the most recent commercial transport planes. Test results on the WSM method show results with a classification of the best and worst aircraft alternatives.

BOEING 787 Model Daha Elektrikli Uçak Sistem Yenilikleri ve Araştırılan Sorunları

In recent years, MEA technology has brought about developments in the field of power electronics, fault-tolerant architecture, electro-hydrostatic actuators, flight control systems, high-density electric motors, power generation and conversion systems. Non-propulsive systems in traditional aircraft systems, ıt is powered by a combination of different secondary power sources such as hydraulic, pneumatic, mechanical and electrical while the more electric aircraft (MEA) concept ensures the use of optimum electrical power for all non-propellant systems. 
 The goal of future aircraft technology is to replace the majority of non-electrical power-using systems, such as environmental control and engine starting, with electrical systems to improve various aircraft characteristics such as efficiency, emissions, reliability and maintenance costs. B787 series aircraft, the first civil aircraft with more electric aircraft features of modern times, ıt features composite fuselage and wing profiles, fly-by-wire flight controls, advanced cockpit and General Electric or Rolls-Royce engines. Different from previous designs, Boeing has minimized the use of air from the engines in the B787 technology and makes extensive use of electrically powered systems instead of traditional pneumatically powered systems. B787 new generation passenger aircraft, ıt is anticipated that significant improvements such as aircraft weight, fuel consumption, total life cycle costs, carbon neutrality, ease of maintenance and aircraft reliability will reduce the effects of adverse environmental conditions.
 In this study, the system innovations of the B787 aircraft model, which is a more electric aircraft concept and introduces different testing and working methods throughout the design process, and the problems caused by the new systems were investigated.

Promising electric aviation industry and its bright future

There have been rising concerns about the amount of greenhouse gas emissions that commercial aviation produces each year. Greenhouse gases generated by aircraft trap the sunlight in the ozone layer, causing the planet's temperature to rise yearly. Thus, developing more electric aircraft (MEA) and all-electric aircraft (AEA) is crucial to serve as alternatives to traditional fossil-fuel airplanes to avert climate change. Although electric aircraft theoretically provide numerous benefits in improving efficiency, reducing noise levels, and cutting emissions, numerous challenges exist, such as energy density, cost, and power distribution. This paper aims to analyze these challenges and looks for potential technologies or systems, including electromechanical actuators, high energy-density lithium batteries, and superconducting motors, to resolve these challenges. Overall, the electric aviation industry is promising with further improved new technologies. While MEA will become common shortly, there will still be at least two to three decades before AEA establishes ground and become prevalent in the commercial aviation industry.

A Review of EMI Research of High Power Density Motor Drive Systems for Electric Actuator

With the global attention given to energy issues, the electrification of aviation and the development of more electric aircraft (MEA) have become important trends in the modern aviation industry. The electric actuator plays multiple roles in aircraft such as flight control, making it a crucial technology for MEA. Given the limited space available inside an aircraft, the power density of electric actuators has become a critical design factor. However, the pursuit of high power density results in the need for larger rated power and higher switching frequency, which can lead to severe electromagnetic interference (EMI) issues. This, in turn, poses significant challenges to the overall reliability of the electric actuator. This paper provides a comprehensive review of EMI in high power density motor drive systems for electric actuator systems. Firstly, the state of the art of electric actuator systems are surveyed, pointing out the contradictory relationship between high power density and EMI. Subsequently, various EMI modeling approaches of motor control systems are reviewed. Additionally, the main EMI suppression methods are summarized. Active EMI mitigation methods are emphasized in this paper due to their advantages of higher power density compared with passive EMI filters. Finally, the paper concludes by summarizing the EMI research in motor drive systems and offering the prospects of electric actuators.

Design of High Power Density MVDC Cables for Wide-Body All Electric Aircraft

Aircraft electrification yields the next generation of aircraft such as more electric aircraft (MEA) and all electric aircraft (AEA). These aircraft require high-power-density and low-system-mass electric power systems (EPS). To this end, the voltage of the system must be enhanced to reach medium voltage levels in a few kV ranges. However, using medium voltage (MV) EPS for aircraft exacerbates the challenges of designing aircraft cables such as arc and arc tracking, partial discharges (PD), and thermal management. In this paper, several novel multi-layer based insulation systems for MVDC power cables are proposed to resolve aircraft cables’ challenges while maintaining low weight and size. The proposed cables are thermally and electrically analyzed and compared to cable systems designed based on IEC60502 and AS50881 standards. We use a coupled electrical-thermal-fluid flow dynamic model, for simulations where all possible heat transfer approaches, including conduction, convection, and radiation, to transfer mainly the joule heating generated in the core conductor to ambient with a low pressure of 18.8 kPa which is the air pressure at cruising height of wide-body aircraft (12.2 km) are considered and modeled. To compare the proposed cables to the designs based on IEC 60502 and AS50881, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">J</i> is introduced, which is the product of cables’ overall mass in a unit length and diameter. The results show that besides benefiting multi-layer, multi-function insulation systems to resolve aircraft cables’ challenges, the overall diameter and weight of the designed cables are lower than single-layer insulation system designs based on AS50881 and IEC60502.

An Improved Model-Free Active Disturbance Rejection Deadbeat Predictive Current Control Method of PMSM Based on Data-Driven

This article proposes an improved model-free active disturbance rejection deadbeat predictive current control(ADRDPCC) method for permanent magnet synchronous motor (PMSM) used in more electric aircraft (MEA) based on the data driven method, which is used to solve the parameter mismatch problem of deadbeat predictive current control (DPCC) and improve the performance of PMSM control system. DPCC model applied to the current loop of the MEA motor is established as the main control strategy of the system. The principle of active disturbance rejection control is combined with DPCC, and the ADRDPCC structure is formed to optimize the control strategy. A specific extended state observer (ESO) of ADRDPCC is designed to track the internal disturbance caused by parameter mismatch and the external disturbance in real time. DPCC is used as the control law of the ADRDPCC structure to predict the current and output the reference voltage based on the observation of ESO. A deep reinforcement learning model based on ADRDPCC is designed and trained based on the data-driven method. The trained model can compensate and optimize ADRDPCC based on the disturbance observed by ESO and the observed control state of PMSM. The simulated and experimental results show the superiority of the proposed method.

Robust performance comparison of PMSM for flight control applications in more electric aircraft.

This paper describes a robust performance comparison of flight control actuation controllers based on a permanent magnet synchronous motor (PMSM) in more electric aircraft (MEA). Recently, the PMSM has become a favorite for the flight control applications of more electric aircraft (MEA) due to their improved efficiency, higher torque, less noise, and higher reliability as compared to their counterparts. Thus, advanced nonlinear control techniques offer even better performance for the control of PMSM as noticed in this research. In this paper, three nonlinear approaches i.e. Feedback Linearization Control (FBL) through the cancellation of the non-linearity of the system, the stabilization of the system via Backstepping Control (BSC) using the Lyapunov candidate function as well as the robust performance with chattering minimization by applying the continuous approximation based Sliding Mode Control (SMC) are compared with generalized Field-Oriented Controller (FOC). The comparison of FOC, FBL, BSC and SMC shows that the nonlinear controllers perform well under varying aerodynamic loads during flight. However, the performance of the sliding mode control is found superior as compared to the other three controllers in terms of better performance characteristics e.g. response time, steady-state error etc. as well as the control robustness in the presence of the uncertain parameters of the PMSM model and variable load torque acting as a disturbance. In essence, the peak of the tolerance band is less than 20% for all nonlinear and FOC controller, while it is less than 5% for SMC. Steady state error for the SMC is least (0.01%) as compared to other three controllers. Moreover, the SMC controller is able to withstand 50% parameter variation and loading torque of 10 N.m without significant changes in performance. Six simulation scenarios are used to analyze the performance and robustness which depict that the sliding mode controller performs well in terms of the desired performance for MEA application.