Search

Due 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. [ABSTRACT FROM AUTHOR]

In order to enhance the dynamic performance of aircraft high‐voltage direct current wound rotor synchronous generator (WRSG) system under load variations, a dual internal model control (DIMC) method utilising improved load current feedback (ILCF) is proposed. It employs internal model controllers in both voltage and current loops, thereby significantly augmenting the system's disturbance rejection capabilities. Improved load current feedback is incorporated between the DC voltage loop and the field current loop. Additionally, a method for designing a feedback fitting function is established, enhancing the system's adaptability to changes in operational speed and load. The authors outline parameter design methods for voltage and current loops in DIMC, based on the internal model control principle. Adjustments to these parameters can further enhance the system's disturbance rejection capabilities. Finally, comparative experiments between the PI method with ILCF and the DIMC method with ILCF are conducted on a 15 kW WRSG experimental platform. These experiments demonstrate that the proposed DIMC method with ILCF optimises dynamic performance across the entire speed range, enhancing the competitiveness of WRSG systems in aircraft applications. [ABSTRACT FROM AUTHOR]

A systematic definition of an aircraft generator's "available power" (used to supply loads on its DC bus) is given, which is defined in the context of constraints on transient and steady‐state performance. Using a geometric, data‐driven approach, such a characterisation has been achieved, and a new method, called Power availablE Estimation Tool (PEET), has been developed to determine in real‐time whether a given load can be fulfilled at a given time while maintaining power quality. This is an important problem, especially for safety critical electrical systems such as more electric aircraft, for which it is imperative to know a priori whether an added load will result in voltage variations outside of allowed values. PEET is introduced and its conceptual framework is formalised. Lastly, it provides simulation results that illustrate its performance. The results show that the PEET method produces reliable a priori estimates of power availability, and that this can be achieved within time frames that make it applicable in a real‐time implementation. [ABSTRACT FROM AUTHOR]

This article presents a dual‐winding permanent magnet generator (PMG) system with integrated dual‐channel controller to meet the requirements of high power density, high reliability, and high output performance of aircraft electric power system. The dual‐winding of the PMG are designed to have the same phase spatially, with which the same rotor position can be applied in independent vector control. In addition, a dual‐channel controller is applied to control the two sets of windings, which achieves high‐performance control under normal state and fault‐tolerant control under fault state. The integrated dual‐channel controller integrates two sets of main power circuits into one controller and uses a main control unit, which simplifies the PMG system leading to reduction in the overall volume and weight. Reliability analysis of dual‐winding PMG system is proposed to be compared with that of the single‐winding PMG system. A dual‐winding cooperative control strategy and a fault‐tolerant control strategy are proposed to achieve high‐performance control of DC‐link voltage under normal condition and redundant functions under fault condition. As a result, the reliability of the PMG system is improved. The experimental results validate the effectiveness of the proposed PMG system and the control strategy. [ABSTRACT FROM AUTHOR]

Brushless power generation sets are a technology of choice for on‐board power generation in aerospace and marine applications, emergency and backup power systems, etc. Efficient modelling of these systems is necessary for various purposes such as design, analysis, control and specially condition monitoring. An accurate and efficient model of a diesel‐engine generator‐rectifier system consisting of a three stage brushless synchronous generator is presented. The constant parameter voltage‐behind‐reactance model of the pilot exciter (PE), main exciter (ME) and main generator are derived and integrated to form a unified model suitable for efficient simulation of a diesel‐engine brushless generation system. Simulation studies are carried out in MATLAB using PLECS toolbox and the results are compared to experimental results to verify the performance of the proposed integrated model. [ABSTRACT FROM AUTHOR]

Magnetic‐geared double‐rotor machines are recognized as a promising power‐splitting component in hybrid electric aircrafts (HEAs). However, the high fuel efficiency speed of the turbine engine in HEAs is about 10,000 rpm, whereas conventional topologies suffer from low efficiency at high speed due to its specific operation principle—the magnetic field modulating principle. A coreless stator magnetic‐geared double‐rotor machine (CS‐MGDRM) is proposed to enhance high‐speed efficiency and thus comply with the operation condition of HEAs. First, the machine structure and hybrid propulsion system configuration are introduced, and power‐flow analysis of three basic operation modes is presented. Second, the operation principle of the machine is illustrated, and investigation of electromagnetic performances is carried out by finite element analysis. Third, an analytical model of the machine is developed, based on which the design optimization towards the maximum torque capacity is investigated. Furthermore, the loss distribution law and transmission efficiency are analysed and compared with conventional scheme, and the power factor characteristic is investigated as well. Finally, the overall performance of the proposed machine is evaluated. [ABSTRACT FROM AUTHOR]

To improve the performance and reduce the total harmonic distortion (THD) of the autotransformer 12‐pulse rectifier, a novel pulse multiplication circuit (PMC) based on two tapped inter‐phase reactors (TIPRs) is proposed to improve performance and reduce the THD of the autotransformer 12‐pulse rectifier. The proposed rectifier includes a phase‐shifting autotransformer based on a polygon connection, two 6‐pulse diode bridge rectifiers (DBRs), and a PMC. The novel PMC consists of two TIPRs (TIPR1 and TIPR2), an auxiliary single‐phase diode bridge (including four diodes D1 to D4), and two auxiliary diodes D21 and D22, which are connected directly to the output terminal of the DBRs (DBR1 and DBR2). The simulation and experimental results confirm the high capability of the proposed PMC to reduce the harmonic distortion of the input current, so that by using the proposed PMC, the input current is almost sinusoidal and the THD of the input current is less than 3%. Also, the results show that the proposed 12‐pulse rectifier meets the standard requirements of aircraft electrical systems (DO‐160G) without the need for any input and output filters.To improve the performance and reduce the total harmonic distortion (THD) of the autotransformer 12‐pulse rectifier, a novel pulse multiplication circuit (PMC) based on two tapped inter‐phase reactors (TIPRs) is proposed to improve performance and reduce the THD of the autotransformer 12‐pulse rectifier. According to the results, the total harmonic distortion of the input current in the proposed rectifier is less than 3% and meets the requirements of the DO‐160G standard in aircraft electrical power systems without the need for filters. [ABSTRACT FROM AUTHOR]

The More‐Electric Engine (MEE), with its electrified engine auxiliary systems and increased multi‐shaft power offtake, is likely to become an increasingly central aspect of future More‐Electric Aircraft. Consequently, lightweight but resilient electrical power architectures are needed for these future MEE applications. However, whilst a range of MEE architectures exist in the research literature, no effective baseline architecture or standardised feature identification has been proposed to specifically address their unique design requirements. Accordingly, any underpinning technology‐focused research for critical MEE subsystems may ultimately have a reduced effectiveness without this credible baseline. Based on comprehensive design analyses, preliminary design requirements and anticipated operational modes, this article proposes key design rules for the formation of the first generic baseline MEE electrical power system architecture concept. Guidance is provided on features such as the number of power generation systems, the number and topologies of distribution channels, type of power conversion, essential load redundancy, and the location of emergency power supply. This article also provides full transparency of the design process so that key decision points can be revisited to capture application‐ specific requirements and updates to certification requirements. [ABSTRACT FROM AUTHOR]

Great efforts are devoted for integrating Renewable Energy Sources (RES) on the propulsion system of Unmanned Air Vehicles (UAVs). This is applicable to small UAVs, having a horizon to expand to large UAVs within the next decades. For the conventional propulsion systems to be replaced, the required power needs of the aircraft should first be examined. The required power depends on the UAV's flight stage from takeoff to landing, whereas its calculation varies with regard to the propulsion system type, which is separated into two main categories, the propelled‐driven engines and the jet engines. Two obstacles are arising. First, the parameters needed for the power estimation are commercially sensitive and second the analysis alters with respect to the engine's type. This paper focuses on the mathematical analysis of the required power for both the main propulsion systems, presented extensively for each flight phase, proposing, at the same time, a parameter estimation method which is applicable to any UAV type. The main purpose of this paper is to act as a guide for the calculation of any type UAV's required power at any flight stage. To validate the analysis, the MQ‐9 Reaper/Predator B, a High Altitude Long Endurance (HALE) turboprop UAV produced by General Atomics is analysed. Its unknown parameters are estimated and based on a selected flight profile, the required power in terms of horsepower from takeoff to landing is assessed, for two scenarios regarding the aircraft's initial weight. In the first scenario the UAV has the maximum gross takeoff weight, whereas in the second scenario it does not carry any payload. The estimated required shaft power per flight phase for each scenario is then marked into the TPE331‐10 turboprop engine characteristic curves. [ABSTRACT FROM AUTHOR]

In this paper, an H‐type electric/hybrid electric aircraft propulsion architecture is proposed to address the issues associated with the radial electric propulsion architecture. In a radial architecture, a fault on the main bus or failure of the generator leads to shut down of all the propulsion motors in that channel, thus increasing the burden on the remaining motors to maintain the power required by the aeroplane. As a result, it is necessary to oversize the motors for the purpose of compensating for the loss of other motors. To mitigate these issues, a new H‐type architecture is introduced to isolate the particular faulty section while still maintaining power flow to the remaining healthy motors. The proposed architecture minimises the oversizing of various components in the system as compared to radial propulsion architecture. The sizing of components and the amount of overall mass reduction is discussed by using the proposed architecture. Typhoon Hardware in the Loop platform is used to validate the performance of both the architectures for faults at different locations, and the results are presented. [ABSTRACT FROM AUTHOR]

The design of electrical power subsystem of a satellite is challenging since it involves many components and depends on multiple parameters including mission duration, satellite orbit, eclipse times and etc. In contrast to the existing mission specific designs, we propose a generalized and comprehensive method to design and size key EPS elements: PV array and battery, which are integral for mission success. For battery, the proposed design incorporates battery cell characteristics, round trip efficiency, degradation, eclipse load profile and operating modes. The proposed design of PV array takes into account orbit inclination and altitude. In addition, structure and geometry of PV array are also considered and used for irradiance forecasting. Reliability, power margins and power fraction for summer solstice are also factored in the design. For the planning and development of operational strategy, parameter limits are determined for depth of discharge, initial state‐of‐charge, final state‐of‐charge and end‐of‐charge voltage of the battery. The controller design is also presented for the EPS. The effectiveness of the proposed design methodology is verified by a case study of Mysat‐1, an imaging nanosatellite developed and launched by Khalifa University. [ABSTRACT FROM AUTHOR]

The traditional Monte Carlo sampling method has several deficiencies in evaluating the reliability of more‐electric aircraft (MEA), such as more sampling times and longer simulation time, due to the complex topology and low probability of failure of the aircraft. In this Letter, the optimal probability distribution of multi‐component systems is introduced by cross‐entropy, which theoretically makes the variance of reliability evaluation zero. Based on this, an evaluation method for the power‐supply reliability of MEA is presented. For further analysis of the system vulnerabilities, the sensitivity of MEA is modelled based on reliability calculation. Finally, the hybrid MEA and high‐voltage direct current MEA power systems are used as application scenarios to calculate the reliability and sensitivity. The results show that the proposed method has advantages in evaluating small probability events, and it is useful for the optimisation of MEA's power‐supply system structure. [ABSTRACT FROM AUTHOR]

In this study, an efficient multi‐orbital simulation model is presented for satellite Electrical Power Subsystem (EPS) which is integral to the success of the mission. The model integrates converter models, PV array model, DC bus model, and a numerical battery model according to a generalised EPS architecture to form one unified model of the entire EPS. The proposed model reduces simulation complexity, enhances speed, and enables multi‐orbit analysis capability. Dynamic interaction among the elements is modelled through a coordinated control containing maximum power point tracking (MPPT), voltage regulation, battery charge/discharge control and management. Practical concerns of digital control implementation for PI controllers and MPPT are also incorporated in the model. Anti‐windup is implemented to avoid latency in controller action after the eclipse. Additionally, a robust MPPT algorithm ensures fast immediate action after eclipse. Efficient component models and practical attention‐to‐detail enable the developed model to simulate multiple orbits with eclipse periods. The superior speed of the model, ability to simulate multiple orbits, and test different control strategies are demonstrated with a practical case study of Mysat‐1, an imaging satellite launched by the Khalifa University. The model can be used as a proof‐of‐concept tool for predicting the operational behaviour of EPS during the development of a satellite. [ABSTRACT FROM AUTHOR]

With the move to more electric aircraft (MEA), a key area of investigation is the development of commercially viable systems which are reliable, efficient, low mass, and are compatible and commensurate with the power and multiplex requirements of current and future aircraft. In rotorcraft, the pace of adopting more electric systems, to replace conventional mechanical and hydraulic ones, say, is perceived as being much lower than in fixed wing aircraft. However, recently there has been growing evidence to suggest that a quadruplex electric tail rotor (ETR) is a technically viable solution. This paper shows the methodology to support the most reliable configuration of the four independent generators required to power such a quadruplex tail rotor drive, and takes account of the failure severity due to power loss in each independent channel, target reliability setting, and supporting reliability analyses. The conclusions drawn support a particular hybrid series-parallel configuration of generators, with identification of further work related to the gearbox reliabilities which support the reliability attainment for the configuration. [ABSTRACT FROM AUTHOR]

This study describes the design, construction, and testing of an aero-engine starter-generator and its associated power electronic converter. A high-speed, permanent magnet machine and a dual-channel machine-facing converter with an electrical power offtake rating of 95 kW have been developed for a small civil turbofan application. The study also describes the more-electric architecture into which the machine and converter are integrated and reviews the multi-faceted performance specification, which is a common feature of machines of this type. [ABSTRACT FROM AUTHOR]

This paper discusses the design route followed in the development of a permanent magnet (PM) machine for electrical power generation on board a rotorcraft (helicopter). The focus of the machine design is to optimise system power density, efficiency, and robustness – all of which are crucial considerations in aerospace applications. A matrix of designs was created consisting of two stators with different winding conductors – copper and aluminium – and three rotors, each using different containment sleeve materials. These include two semi-permeable metallic sleeves, which act to decrease the effective air gap. Combinations of the different materials will yield different system-level power densities and efficiencies. Here, all the designs are presented along with the initial test results for the baseline machine combination validating the design predictions. [ABSTRACT FROM AUTHOR]

A design procedure for the dual active bridge (DAB) converter is presented, which aims to optimised power density and computational effort. When designing a DAB, the selection of circuit design parameters such as switching frequency, leakage inductance and semiconductor technologies is a complex question when targeting losses and weight minimisation of the final design. In this study, analytical models of the operating waveforms, the losses and the weight of all DAB components are developed. The proposed design algorithm is used for designing a 3 kW high-frequency DAB for an aircraft DC power system. [ABSTRACT FROM AUTHOR]

Wound‐rotor synchronous starter‐generator (WRSSG) has the advantages of less volume and weight, high safety and low cost in maintenance, so it is becoming increasingly popular in modern aircraft, especially for more‐electric aircraft. The main machine (MM) and main exciter (ME) of the aircraft WRSSG are electromechanically coupled seriously, which makes the start control for the WRSSG complex in the starting mode. In this study, a decoupling start control method for aircraft WRSSG based on main field current estimation is proposed to solve the serious coupling problem and improve start control performance. In the proposed decoupling control method, the main field current is estimated first and used in the closed‐loop excitation control for the ME to make the main field current meet the MM demand. With the desired field current, the MM is decoupled with the ME and controlled like a traditional synchronous motor to start the aircraft engine under maximum torque per ampere. The feasibility and effectiveness of the proposed decoupling control method is verified by experimental results. [ABSTRACT FROM AUTHOR]

Energy system as a key component of stratospheric airship plays an important role in the success or failure of the whole flight mission. Here, the topology of HE-boost SBC converter for airship energy system is deeply studied. Based on the original HE-boost converter, a new HE-boost converter is proposed. By analysing its state space equation and small signal model, it is concluded that the stability of the new HE-boost converter is better than that of the original HE-boost converter. Based on this analysis, the optimal design of compensation network of the new HE-Boost converter is studied to ensure that the converter satisfies the condition of minimum phase system, so as to improve the stability of converter. Here, the theoretical analysis is verified and optimised by means of simulation. The paper builds: circuit, verify the correctness of the theoretical analysis and test, the frequency characteristics of the new HE-boost converter under different input and output conditions, technical index of converter can meet the requirements. [ABSTRACT FROM AUTHOR]

This study proposes a new three‐phase dual‐rotor middle‐stator brushless flux switching generator for 400Hz diesel‐driven aircraft ground power units. For the proposed machine, both field and armature windings are hosted in the stator in such a way that not only fulfils brushless structure, but also realises the flux switching function. Moreover, both windings have non‐overlapping concentrated windings to shorten the end‐windings and reduce the copper losses. In the meantime, the rotor has only slots without any active parts. First, the machine detailed design is provided, and its performance is analysed using finite element method. Also, a selection topology of both stator and rotor pole arcs is carried out, targeting maximum generated electromotive force, minimum harmonic content, and minimum cogging torque. Then, a prototype is implemented and experimented to confirm the feasibility of the proposed machine. [ABSTRACT FROM AUTHOR]

To adapt to the single power supply system of the aircraft, this study proposes and investigates a novel fault‐tolerant drive system based on the redundancy bridge arm for aerospace applications. The proposed fault‐tolerant drive system adopts a dual‐winding fault‐tolerant (DF) motor; the DF motor offers the advantages of magnetic isolation, physical isolation, thermal isolation, small cogging torque ripple, inhibiting the short‐circuit current and high fault tolerance. The proposed fault‐tolerant drive can adapt to the single power supply system of the aircraft, reduce the drive cost, and cut down the number of independent power sources and power switches. In addition, it can improve the power density, reliability, and the utilisation rate of the drive system. To realise the open‐circuit fault diagnosis performance, the diagnosis and processing method of the open‐circuit fault has been investigated. Then, to realise the fault‐tolerant performance, a novel space‐vector pulse‐width modulation (SVPWM) fault‐tolerant control strategy is proposed. Finally, the performances of the fault‐tolerant drive have been verified by simulations and experiments. The research results verify the reliability and effectiveness of the proposed fault‐tolerant drive system based on the redundancy bridge arm and SVPWM fault‐tolerant control strategy. [ABSTRACT FROM AUTHOR]

Here, a reduced‐order model for stand‐alone cascaded doubly fed induction generator (CDFG) is presented for aircraft application, which is capable of operating in both starting and generating modes. This generator has lower maintenance cost and higher reliability, in comparison with traditional variable speed constant frequency system, based on a doubly fed induction generator (DFIG). These features make the CDFG appropriate for embedded aircraft applications. The main drawback of this generator is its inherent complexity; therefore, its analysis and control design is difficult. This complexity is due to the existence of resistances and voltage sources in the rotor loop of the full‐order model. To overcome this difficulty, this study proposes a reduced‐order model for the CDFG, which is similar to that of the DFIG in the synchronous reference frame. To demonstrate the efficiency of the proposed model, a field‐oriented controller for CDFG is designed based on this model and compared to the full‐order model. The performance and accuracy of the proposed model is validated through simulation and experimental results subject to balanced and unbalanced load change, and rotor speed variations test scenarios. [ABSTRACT FROM AUTHOR]

To achieve benefits similar to those seen in hybrid‐/all‐electric ground‐based and marine vehicles, electric propulsion has been proposed for large commercial aircraft. Among the main drivers of this are improved fuel economy, reduced harmful emissions, and lower audible noise. In converting to electric propulsion, the added electrical components' masses must be minimised so that the benefits that the components enable – improved turbine efficiency, distributed propulsion and propulsion‐airframe integration – are not cancelled out by their weight penalty. This puts stringent requirements on the large electric machines used in the system, both those that generate electric power from the turbine shaft and those that drive propellers or ducted fans, because they are among the heaviest of the added electric components. A key machine design metric in this application is the specific power (SP), or the power‐to‐mass ratio. This study gives a comprehensive overview of large electric machines for aircraft electric propulsion applications, with a focus on methods for mass reduction and SP improvement. [ABSTRACT FROM AUTHOR]

Fractional‐slot concentrated‐winding (FSCW) permanent magnet synchronous machines, which are characterised with high power density, fault tolerance and wide constant‐power speed range, are gaining more and more attention in the aircraft starter generator (SG) systems. Nevertheless, the short‐circuit (SC) fault, especially the turn‐to‐turn SC fault, is the obstruct crux in aviation applications. This study is aimed to demonstrate the feasibility of FSCW permanent magnet SG (PMSG) in dealing with turn‐to‐turn SC fault. The law of FSCW‐PMSG SC fault is analysed and verified by finite‐element analysis (FEA), including the influence on turn‐to‐turn SC current by the number of the shorted turns and the coil position in the slot. The three‐phase current injection control is employed to mitigate the SC fault in PMSG when a turn‐to‐turn SC fault occurs. A 24‐slot, 16‐pole FSCW‐PMSG with spoke‐type rotor topology is designed to confirm the ability of inhibiting turn‐to‐turn SC current without the risk of irreversible demagnetisation. Both FEA and experimental results are presented, verifying the effectiveness of the three‐phase current injection control in restraining the turn‐to‐turn SC current for FSCW PMSG in an acceptable range. [ABSTRACT FROM AUTHOR]

Competition in the aircraft industry market and global warming has driven the industry to think along economic and environmental lines. This has resulted in the emergence of more electric aircraft (MEA). The increase in the power demand of aircraft, especially in the last two decades, coupled with advancement in battery materials and technology has led to the development of many high energy density batteries. This study presents an overview of the battery systems for MEA. In this paper, a study on the battery technologies used in aircraft in the last five decades is being done. A general background of the battery system is presented and the performance of the batteries based on energy densities and low temperature capabilities are evaluated and discussed. Evolution of MEA with its power system architecture and load profile is presented to understand the requirements of the battery system. Weight saving and cost analysis is done for the Li‐ion and Ni–Cd batteries with respect to the requirement of an MEA 'Aircraft X'. Battery management system (BMS) for Li‐ion batteries is also explored and discussed. Based on the analysis, Li‐ion battery is selected and integrated with the power distribution DC network for future MEA. [ABSTRACT FROM AUTHOR]

Distributed propulsion concepts are promising in terms of improved fuel burn, better aerodynamic performance, and greater control. Superconducting networks are being considered for their superior power density and efficiency. This study discusses the design of cryogenic cooling systems which are essential for normal operation of superconducting materials. This research project has identified six key requirements such as maintain temperature and low weight, with two critical components that dramatically affect mass identified as the heat exchanger and compressors. Qualitatively, the most viable concept for cryocooling was found to be the reverse‐Brayton cycle (RBC) for its superior reliability and flexibility. Single‐ and two‐stage reverse‐Brayton systems were modelled, highlighting that double stage concepts are preferable in specific mass and future development terms in all cases except when using liquid hydrogen as the heat sink. Finally, the component‐level design space was considered with the most critical components affecting mass being identified as the reverse‐Brayton compressor and turbine. [ABSTRACT FROM AUTHOR]

This study proposes a novel mathematical model based on excitation system output equations (ESOEs) to evaluate the steady‐state performance of the three‐phase brushless asynchronous excitation system (BAES) of a wound‐field synchronous aircraft starter–generator system. The steady‐state performance could be used to evaluate the field current output capabilities of the BAES and provide a reference for the control schema of the BAES. However, the BAES has unknown multivariable non‐linear characteristics, which give rise to difficulty in modelling the steady‐state performance. Meanwhile, without closed‐loop control of the main exciter stator current, the traditional methods fail to efficiently calculate the required excitation voltage and frequency for a desired field current. Steady‐state performances are achieved for numerous discrete states with tedious simulations. This study develops the mathematical model of the ESOEs, which can be used to express the non‐linear relationships among the main generator field current, main exciter (ME) rotor speed, ME excitation voltage, and frequency. The field current output capabilities could be evaluated in a time‐efficient manner by solving these ESOEs. The proposed mathematical model and theoretical findings are verified by experimental results. [ABSTRACT FROM AUTHOR]

The More Electric Aircraft concept is a fast-developing trend in modern aircraft industry. With this new concept, the performance of the aircraft can be further optimized and meanwhile the operating and maintenance cost will be decreased effectively. In order to optimize the power system integrity and have the ability to investigate the performance of the overall system in any possible situations, one accurate simulation model of the aircraft power system will be very helpful and necessary. This paper mainly introduces a method to build a simulation model for the power distribution system, which is based on detailed component models. The power distribution system model consists of power generation unit, transformer rectifier unit, DC-DC converter unit, and DC-AC inverter unit. In order to optimize the performance of the power distribution system and improve the quality of the distributed power, a feedback control network is designed based on the characteristics of the power distribution system. The simulation result indicates that this new simulation model is well designed and it works accurately. Moreover, steady state performance and transient state performance of the model can fulfill the requirements of aircraft power distribution system in the realistic application. [ABSTRACT FROM AUTHOR]

In recent years there has been an increase in the number of unmanned aerial vehicle (UAV) applications intended for various missions in a variety of environments. The adoption of the more‐electric aircraft has led to a greater emphasis on electrical power systems (EPS) for safe flight through an increased number of critical loads being sourced with electrical power. Despite extensive literature detailing the development of systems to detect UAV failures and enhance overall system reliability, few have focussed directly on the increasingly complex and dynamic EPS. This study outlines the development of a novel UAV EPS fault classification and diagnostic (FCD) system based on hidden Markov models (HMM) that will assist and improve EPS health management and control. The ability of the proposed FCD system to autonomously detect, classify and diagnose the severity of diverse EPS faults is validated with development of the system for NASA's advanced diagnostic and prognostic testbed (ADAPT), a representative UAV EPS system. EPS data from the ADAPT network was used to develop the FCD system and results described within this study show that a high classification and diagnostic accuracy can be achieved using the proposed system. [ABSTRACT FROM AUTHOR]

The more‐electric aircraft (MEA) has become a dominant trend for next‐generation aircraft. The electrical power system (EPS) on‐board may take many forms: AC, DC, hybrid, frequency‐wild, variable voltage, together with the possibility of novel connectivity topologies. To address the stability, availability and capability issues as well as to assess the performance of the power quality and transient behaviour, extensive simulation work is required to develop the EPS architectures. The study develops a fast‐simulation model of active front‐end rectifiers based on the dynamic phasor concept. The model is suitable for accelerated simulation studies of EPS under normal, unbalanced and line fault conditions. The performance and effectiveness of the developed model have been demonstrated by comparison against time‐domain models in three‐phase and synchronous space‐vector representations. The experimental verification of the dynamic phasor model is also reported. The prime purpose of the model is for the simulation studies of MEA power architectures at system level; however it can be directly applied for simulation study of any other EPS interfacing with active front‐end rectifiers. [ABSTRACT FROM AUTHOR]

Aeronautical ground lighting (AGL) systems provide visual reference to aircraft during airport operations. In AGL systems, constant current regulators feed a series circuit composed of luminaires supplied through transformers. Component modelling is necessary to simulate AGL systems, and thus characterise and predict their behaviour. This paper presents an AGL transformer model including transformer core saturation. Moreover, a procedure to estimate transformer model parameters is proposed. Both the model and the estimation method are validated with extensive measurements on more than 20 AGL transformers of different power ratings and trade names. [ABSTRACT FROM AUTHOR]

A system‐level behavioural modelling technique is described for a switched reluctance motor drive. The model enables simple and efficient analysis or simulation of multiple drive systems such as pumps, actuators and engine starters within a more‐electric network, for example, on‐board an aircraft. The behavioural model is based on a power balance analysis. The transfer functions in the model are parameterised from experimental tests on the drive system, resulting in a simple model that only reproduces the average behaviour of the input–output variables necessary for system‐level analysis. No data from the manufacturer is required to develop the model. The technique is discussed and validated using an engine starter in an aircraft test facility. [ABSTRACT FROM AUTHOR]

This study proposes a novel and compact AC/DC electrical distribution system for new generation aircraft. In these new aircraft power systems, all loads are fed by two DC bus systems: at 28 V and at ±270 V. The electrical distribution system, whose design and implementation are described in this study, has only one primary AC source (360–900 Hz at 230 V) with all the required DC voltage levels being derived from this source. This solution enables elimination of the complex mechanical coupling apparatus currently used, for fixed frequency AC systems, to maintain the generator speed at constant level while the engines operate at variable speed. Under the proposed solution, all the conversion stages needed to generate various output voltage levels are implemented by using power converters assembled in one unit. Each converter has a current control loop in order to regulate the output current even during output line short circuits and also to limit the inrush current to the circuit at turn‐on. To prove the concept, a 5 kW prototype was designed and tested, and demonstrated to meet all the specifications within the relevant standards regarding input and output power quality. [ABSTRACT FROM AUTHOR]

In the aircraft power systems with 360-800 Hz line frequency or medium- and high-power three-phase pulse-width modulation (PWM) rectifier applications operating at the utility line frequency (50/60 Hz), the ratio of switching frequency to power line frequency will be reduced because of the increased line frequency or low switching frequency. Therefore the assumptions that the average voltage drop across the input inductor of the PWM rectifiers can be neglected if the conventional one-cycle controlled (OCC) method had been adopted can no longer be true anymore, which will deteriorate the system power factor (PF) dramatically. To solve this issue, a modified OCC scheme is proposed in this study. The proposed control method can improve the input PF of three-phase PWM rectifier without sacrificing the advantages of the conventional OCC scheme, such as no phase-locked loop and constant switching frequency. The control equation of the modified OCC method, which considered the voltage drop across the input inductor, is first derived. The theoretic analysis is supported by the experimental verification performed by a 2.5 kW modified OCC-based three-phase three-switch Vienna rectifier. [ABSTRACT FROM AUTHOR]

To fulfill the high reliability of the aeronautical application, a novel three-phase four-wire shunt active power filter (APF) is proposed in this study. In this proposed configuration, traditional phase-leg which is composed of two power switches is replaced by the novel leg composed of one power switch and one diode. The annoying 'shoot-through' phenomenon is eliminated by using this novel configuration. Meanwhile, better efficiency and better performance brought by this novel configuration benefit the improvement of the compensation performance. Moreover, operation principle of the APF is analysed in detail; current control strategy and the voltage balance control strategy for the split-capacitor topology are studied as well. Finally, a prototype with the compensating capacity of 3 kVA is designed. Simulation and experimental results are shown to confirm the validity and feasibility of the novel aeronautical APF. [ABSTRACT FROM AUTHOR]

The proposals for the 'More Electric Aircraft' place a significant, increased demand on the electrical power distribution system. To increase safety and reduce aircraft maintenance times on the ground, there is a greater need to quickly identify and locate electrical faults within the electrical distribution system. The work presented in this study provides the mathematical basis for the use of power system harmonic impedance measurement for identifying and locating faults within power cables. The method is passive – that is, it does not require the injection of any test signals – and can potentially be embedded into a centralised equipment controller to provide intelligent, real time diagnostics. The method monitors the harmonic line–line self‐impedance at strategic points in the distribution system; this is obtained by measuring load voltage and current. Faults can be identified and located within a few fundamental cycles, and therefore provides a 'backup protection' system which does not require measurement of the line current. It also can provide details of the fault location and could therefore be a significant aid to aircraft maintenance. This study derives the theoretical basis of the scheme and provides simulation results for a proposed aircraft power system to demonstrate the validity of this approach to detect and locate faults within the system. [ABSTRACT FROM AUTHOR]

This study deals with pre‐sizing methodology of embedded static converters using optimisation for which high performances of weight, volume and efficiency are required. Moreover, in the automotive and aircraft domains, power‐sharing architectures should be an other investigation path to reach such performances. The idea of power sharing is suitable and judicious if the actuators are in the same power range. In this study, the authors consider three electrical machines sequentially driven. The first solution is to use three independent inverters without power sharing, the second one is an inverter with a power‐sharing system. A non‐conventional DC–AC matrix converter is proposed to replace classical inverters. So as to overcome a priori power designers habits, a general modelling and optimisation is performed to provide a virtual prototyping tool to avoid physical prototyping because of their exhaustive cost. The objective function is the overall volume (mainly the heatsink's volume). The optimisation results are presented and discussed. These preliminary results, under a three‐AC drive assumption, show clearly that {inverter + power sharing system} and even the DC–AC matrix converter have an overall volume lower than the three‐inverter solution. [ABSTRACT FROM AUTHOR]