By analysing the structure and working principle of hybrid actuation system (HAS) which consists of a servo-hydraulic actuator (SHA) and an electro-hydrostatic actuator (EHA), the overall mathematical model with dissimilar redundancy conforms is established, which considers various influencing factors, such as air load and attachment stiffness. Furthermore, the mechanism of dynamic force fighting is expounded. In addition, a new control strategy which uses the trajectory generator and weight coefficient theory is proposed to restrain the force fighting. The modelling and simulation analysis between the new control strategy and a conventional proportional–integral–derivative control strategy is carried out as well. Based on the above researches, quantitative analysis is carried out on the procedure of operating mode switching, which is from active/active mode to active/passive mode. The results indicate that the position/velocity trade-off control strategy has a good control performance, and effectively restrains the static force fighting as well as dynamic force fighting. Besides that, it can also shorten the system response time. The HAS can still meet the actuating requirements after the operating mode switches to active/passive mode. The actuator in passive state generates a certain static error by the reason of tracking the position of the control surface.

Since the lower carbon emission and lower direct operating cost, MEA has drawn great attention worldwide. Considering and validating the flight control requirements under all engine failure conditions for MEA is the minimum design requirement, which is widely associated with aircraft characteristics, controllability and manoeuvrability, and system specialities such as electrical system, power plant system, hydraulic system, and avionics. Therefore, taking this topic as an example to illustrate a requirement validation process will be great interest to the aircraft design and integration, where the correctness and completeness of the requirements would be satisfied, the method and evidences of validation would be proposed, the requirement assumption validation and management should be presented, and scenario analysis and typical timeline analysis would be analysed. This paper presents the above processes from configuration, requirement definition and validation, to scenario analysis in compliance with SAE 4754A, which will be a fundamental process to the further verification and integration tasks.

Hydraulic system is an important part in aircraft secondary energy-resource system, its pumping source contains engine-driven pump (EDP) and electrical-motor-driven pump, and it is in charge of safe and reliable power transmission for flight control actuation in the aircraft. The power losses in hydraulic system will inevitably result in the temperature rise of hydraulic system, and which will seriously affect the performances of hydraulic system. Therefore, to cool thermal load and control hydraulic oil temperature in allowable range is necessary. This survey paper reviews the present status of thermal load analysis and thermal management of the aircraft hydraulic system, especially more electric aircraft (MEA), and proposes fuel/hydraulic oil heat exchanger is the more effective heat dissipation component for fuel oil as heat sink be directly burned in burner without the extra cooling cost. Moreover, this paper provides some considerations and thorough analysis on thermal management schemes and actuators in power by wire transmission system of MEA. The main summarised conclusions and proposed considerations have the important practical significances to design and high efficient operation of airborne hydraulic system.

As a power electronic converter, DC/DC converter plays a pivotal role in power electronic system. By measuring G-parameter frequency data, people can extract information to identify the converter, building two-port ‘black-box’ model, thereby improving system-level simulation and analysis. Paper takes the 270–28 V DC/DC phase-shifted full-bridge converter of multi-electric aircraft distributed power supply system as study object, implements hardware design of the converter with high performance of loop and respond, and verificating the design by Saber simulation. Paper analysis ways of measuring converter's frequency response, considering injection strength of disturbance signal and interaction of subsystem, paper gives advices that experimenter should add input filter and use constant current source load. Base on Levy method, paper calculates corresponding G-parameter transfer function of converter by Matlab, builds ‘black-box’ model, then verifies the result by Matlab time domain simulation. Paper's research results will have great impact on the integration and optimisation of power electronic systems.

Matrix converter (MC) is a typical high-power-density converter used in more electric aircraft, in which MC can be used as electric de-icer converter and generation starter converter; this study proposes an analytical spectral calculation method based on three-dimensional (3D) Fourier integral to obtain accurate spectra of both output voltage and input current of a space vector pulse width modulation (SVPWM) MC. The MC is a direct AC–AC power converter without an intermediate DC link; three-phase output is synthesised by three-phase input through nine bidirectional switches. At present, there is no such research on spectral analysis for MC space vector modulation. This study focuses on spectral calculation, by the adoption of 3D Fourier integral, spectral of bidirectional switch duty cycle function, output voltage and input current can be achieved. When analytic spectral solution is obtained, the correspondence between SVPWM and harmonic components is established. Simulation and experimental results are given to demonstrate the theoretical work.

Based on the disturbance-observer (DOB)-based disturbance attenuation, this study proposed three disturbance feed-forward compensation methods in more electric aircraft DC power system. This study compares the observation performance of three DOBs, including traditional linear DOB, improved non-linear DOB and DOB based on extended Kalman filter. Theoretical and simulation results verify the stability promotion and sensitivity effects of the disturbance feed-forward compensators.

Five-level active neutral point clamped (ANPC) converter has become one of the most attractive topologies in industry applications, especially in the field of the motor drive. A novel common-mode voltage (CMV) reduction strategy for five-level ANPC is presented, which is based on the phase-shifted pulse-width modulation (PS-PWM). A basic PS-PWM method is presented, which can realise the NP voltage and the flying capacitor (FC) voltages balance. Moreover, a general CMV reduction method is summarised. The proposed CMV reduction strategy can minimise the CMV by injecting zero-sequence voltage to the modulation wave and it does not affect the ability of NP voltage and FC voltages balance. The validity of the proposed CMV reduction method based on PS-PWM strategy is verified by simulation.

A speed-sensorless direct torque control (DTC) system and control means of AC motor based on matrix converter (MC) fed was proposed, for reducing harmonic pollution and advancing control accuracy. At the base of expounding MC and speed-sensorless DTC means, both the fusion technology and model reference of rotational speed are discussed with emphasis, and the latter has adaptive parameters. Experimental results show that accuracy of parameter identification is higher than the measurable accuracy of measure module, and dynamic response is also fast, the predominance of MC and DTC are exerted at the same time. The system not only can realise the control request of torque and flux linkage as speed accelerates or loaded torque of AC motor changes, but also can run steadily, furthermore actualise energy bi-directional flow and input unity power factor.

The transient behaviour of electric heating and de-icing of the wing is studied by numerical method. The thermal convection coupling method based on the equivalent heat transfer coefficient and the boundary condition iteration is developed for the two designed schemes of the electric heating system. According to the surface temperature, the internal temperature, and the icing condition, the system transient performance is investigated. The purpose of this study is to establish the de-icing transient model of the wing ice protection system, simulate the transient de-icing process and form the method of performance estimation. The results under different working conditions show that the temperature distribution of the skin surface is not uniform, rather presents certain regularity. The rising rate of temperature decreases with the increase of the temperature. The trend is more obvious at lower ambient temperature, when the ambient temperature rises, the surface temperature rises rapidly in a short period. Scheme 2 has certain advantages in heating capability, while the hot knives structure of scheme 1 can narrow and split the icing area.

Real-time test platform based on hardware-in-the-loop (HIL) simulation technology, troubleshooting for real-time problems such as interrupt latency and interface communication before physical testing, can effectively improve the traditional development process, shorten the research and development cycle, and reduce the cost and risk of test. Based on the technologies of virtual instrument, mathematical modelling, and HIL simulation, a real-time simulation framework combining the discrete-time converter system and the continuous-time motor system is proposed. Combined MATLAB/Simulink, dSPACE, and real-time hardware, an HIL real-time test platform is designed for the prototype and proper testing of the electrical control unit of more electric aircraft. The results and design principles of a three-stage brushless synchronous starter/generator system emulation using HIL simulation are presented.

In order to accurately obtain the switching characteristics of SiC MOSFET in practical application, a dual pulse test circuit is used to test the SiC MOSFET in this subject. By analysing the double pulse test circuit and taking into account the parasitic parameters, the effects of different gate resistances (R _g) and the capacitance between gate and source (C _gs) on the switching characteristics of the SiC MOSFET are summarised. Also, a phase-shifted full-bridge power supply based on SiC device is designed, which can be changed from 270 V direct current (DC) to 220 V alternating current (AC)/50 Hz, which consists of two stages. The first stage is the phase shifted full bridge ZVS DC/DC converter, which will boost the 270 V DC to the 350 V DC; the latter is a single-phase full bridge inverter, and the 350 V DC will be converted to the 220 V AC/50 Hz. The power supply uses the SiC MOSFET as the switch tube, which can reduce the switching loss, improve the switching frequency and reduce the volume of the transformer. A rectifier circuit using a SiC Schottky diode, with almost no reverse recovery process, greatly reduced the transformer side parasitic oscillation and improved the efficiency of the power supply. In this study, the design method of the parameters of the power supply is described in detail. Finally, the rationality of the design of the power supply parameters is verified by MATLAB/Simulink simulation and experimental prototypes.

For safety critical applications, electrical machines need to satisfy several constraints, in order to be considered fault-tolerant. In fact, if specific design choices and appropriate control strategies are adopted, fault-tolerant machines can operate safely even in faulty conditions. However, particular care must be taken for avoiding uncontrolled thermal overload, which can cause severe failures. This study describes the thermal modelling of a three-phase, synchronous machine for aerospace applications, analysing the machine's thermal behaviour under open-circuit fault conditions. A particular winding's layout is chosen with the purpose of satisfying fault-tolerance constraints. The winding temperature is evaluated by using a simplified thermal model, which was experimentally validated. Copper and iron losses, necessary for the thermal simulations, are calculated analytically and through electromagnetic finite element analysis, respectively. Finally, an aerospace study case is presented and the machine's thermal behaviour is analysed during both healthy and open-circuit conditions.

Silicon carbide (SiC)-based junction field-effect transistor (JFET) bi-directional switches (BDSs) have great potential in the construction of many power electronic circuits, including matrix converters, multi-level converters, solid-state breakers, and cycloconverters. However, the oscillations of BDSs during turn-on and turn-off transition have great impacts on the stability and reliability of power electronic systems. Two methods are proposed to improve the switching performance, namely using a snubber capacitor and using a ferrite ring. It is found that the use of a snubber capacitor mainly improves the turn-off transition, and the use of a ferrite ring not only damps the oscillation of current waveform during turn-on transition but also makes the waveforms cleaner and less noisy. Besides, both methods can cut down settling time significantly. The effects have been demonstrated by theoretical analysis and verified by experimental results.

This study presents a novel on-line rotor position estimation method of an aviation brushless synchronous motor in the low-speed region using high-frequency voltage signal injection. Square wave voltage signals are imposed on the stator windings of the main generator, and the response current signals extracted on the stator windings of the main exciter are used to estimate position information. The mutual inductance characteristics between stator windings and filed winding of the main generator are utilised. The proposed method eliminates the dependency on the magnetic saliency. Experimental results verify the feasibility and effectiveness of the proposed method.

The growing economical and environmental pressures have accelerated the research and development of hybrid electric power technology in order to increase aircraft performance and reduce the operating and maintenance costs. There has been a big increase in the electrical power rating on new aircraft entering into service. This study gives an overview of the design and development of a hybrid electric propulsion system for light General Aviation aircraft. The theoretical and practical challenges are reviewed and elaborated firstly. The system architecture design is based on a parallel configuration. The ground test of the developed hardware-in-the-loop system is presented based on a test flight mission.

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.

The high fault-tolerance ability is one important application characteristic of multiphase motors. At present, researches on fault-tolerant control of multiphase motors are focused on open-phase faults. When an open-phase fault occurs for the dual three-phase machine, the α–β subspace and z1–z2 subspace currents are no longer decoupled, so the mathematical model with open phases should be set up. In this study, the mathematical model of the dual three-phase permanent-magnet synchronous motor (PMSM) with one open phase is set up by the vector space decomposition modelling method, and two optimal current control modes of minimum stator loss and maximum torque output are achieved by vector control strategy. The experimental results demonstrate the effectiveness and feasibility of the proposed strategy.

This study introduces three methods for building an auto-transformer rectifier units (ATRU) real-time model based on different application scenarios. Real-time models run on an advanced real-time simulator that has the capability to leverage central processing units and field programming gate arrays. In the first section, the disadvantages of the off-line simulation are explained and the solution is offered through real-time simulation. In the second section, applications of real-time simulation in a more electric aircraft (MEA) electric power system will be presented. In the third section, methods to build the ATRU real-time model are illustrated based on requirements and different scenarios. Simulations are conducted to demonstrate the agreement between the results and analysis.

The most important characteristics of aircraft power system are power density, reliability, availability and power quality. The traditional more electric aircraft (MEA) 28 VDC network is used to power the core electronic system. However, the 28 VDC network in modern MEAs such as B787 or A380 is a centralised power network obtained by transformer rectifier unit (TRU), battery charge and rectifier unit (BCRU) or two-stage power conversion (AC/DC + DC/DC) from 230 VAC, 400–800 Hz variable frequency input. The traditional centralised architecture is of low-power density and low fault tolerance. Furthermore, compared to distributed power network, the centralised architecture is of less availability inherently, therefore a single-stage, isolated, low-power and high-power density power supply is required to achieve the distributed 28 VDC network. In this study, a three-phase single-switch discontinuous mode AC–DC flyback converter is proposed. The converter directly rectifies a three-phase, 400–800 Hz, 230 VAC network into a 28 VDC network. The operation modes of the converter are analysed. A prototype is carefully designed and implemented using high-frequency planner transformer and SiC MOSFET techniques, aiming at higher performance. Experimental results demonstrate the practicability and high performance of the proposed power supply system.

This study deals with the development of new control logic for more electric aircraft (MEA) electrical power systems (EPSs). A key aspect of the MEA concept is that traditional pneumatic and hydraulic loads are replaced by electrical equivalents. These new electrical systems are more reliable, highly efficient, and easier to replace or maintain. However, as the number of on-board electrical loads increases the electrical distribution systems on-board are becoming more and more complex. As a result, the control system needs to be adapted and improved in order to allow better manage the overall electrical energy flow, provide faster computational operations, and ensure operation of safety-critical loads under all fault scenarios. This study first gives a brief analysis of the different electrical system topologies before outlining potential control strategies which may be applicable to future MEA EPSs. A new control concept for MEA EPSs is then investigated and considered as a potential substitute of the classical control systems. Finally, a model of the newly proposed logic is implemented and simulated showing how it is able to select and apply a correct reconfiguration of the electrical system under different operating conditions.

In this study, according to zero-sequence current modelling of fourth leg, the control strategy for suppressing circulating current is proposed. Meanwhile, a control method based on average current loops and third harmonic injection loop has been applied in the parallel 3p4l inverter system, consequently, the peak value of circulating current is improved by third harmonic signals. In order to suppress circulating current and minimise the number of interconnecting wires between inverters, output impedance modelling is established, and feed-forward loop of zero-sequence circulating current is added upon current loop accordingly. The proposed control method could be implemented by using analogue design and related to 400 Hz paralleled inverter systems. Both simulation and experimental results indeed show the effectiveness of the proposed control.

Bidirectional DC/DC converter is an important part of the more electric aircraft (MEA). A high-performance bidirectional DC/DC converter with high efficiency and power density reduces the both volume and power loss of the converter. There are mainly two kinds of basic topologies applied to bidirectional DC/DC converter. One is a dual active bridge (DAB) and the other is symmetrical CLLC resonant topology. Both topologies can realise zero-voltage switch (ZVS). The DAB has been widely researched and applied to many fields including the MEA as DAB is easy to design and control. However the ZVS region of the DAB is limited. What is worse, the DAB always switches when the current is at the peak. Symmetrical CLLC resonant topology has also been widely researched in recent years. Compared with the DAB, the symmetrical CLLC resonant converter can reach ZVS in a wider region. In this study both the topologies are discussed and the design of the better one is demonstrated. A 3 kW symmetrical CLLC resonant converter is designed to verify the conclusion.

This study focuses on the rotating rectifier fault detection method of the wound-rotor synchronous starter-generator (WSSG) with the three-phase exciter. Due to the difference in the topography between the traditional DC filed excitation system and the three-phase exciter, the existing method for rotating rectifier fault detection of DC filed excitation system is not effective in WSSG. To solve this problem, this study points out that the ratio of the second to fourth harmonic's amplitude and the fundamental amplitude can be used as the signature after having analysed harmonic components of the exciter rotor current which is estimated by stator flux under the healthy and fault condition. The novel method puts forward that the ratio's Euclidean distance can determine whether the rotating rectifier is faulty or not, and discriminate which phase becomes a fault. By comparing the sum of the maximum and minimum faulty phase current within one cycle with a set threshold value, the location of failure diode is confirmed. The simulation results verify the effectiveness of the proposed method.

In this study, a new three-phase four-leg matrix converter (TFMC) topology is proposed, and the three-dimensional space vector modulation (3DSVM) strategy is used to realise the output with the three-phase unbalanced load. Aiming at the situation that the icing area of the more electric aircraft on the wing is larger than the icing area in the belly, wing ice protection system is constructed by using the TFMC. Through the real-time detection of the heating element temperature and icing condition by the sensor installed in the wing and belly position, working temperature and three-phase output power of TFMC can be set reasonably. In order to save fuel consumption and reduce operating costs, the key point is to reduce the power transmission in belly position. Finally, simulation and experiment verify the correctness of the proposed 3DSVM strategy and realise the TFMC output with unbalanced three-phase load.

This study presents the design and implementation of a starting control system with an LC filter for an aircraft start generator (SG). Based on the optimal design of the filter, a small-signal model is built to account for improved stable and dynamic performance. The transfer function is deduced to tune the control parameters of the whole system. The design of the controller aims at a 75 kVA SG drive system and is verified in a digital signal processor. Finally, simulation results are obtained to predict the behaviour of the starting control system during a transient duty and experimental results show characteristics of the starting process.

An initial rotor position estimation method which is independent of the magnetic saliency is proposed for the main generator (MG) of aircraft three-stage wound-rotor synchronous starter/generators. Voltage signals are injected into the stator of the MG and the field current response of the MG is evaluated in this method. Owing to the brushless excitation structure, the field current of the MG cannot be measured directly. Thus, estimation of the field current of the MG is performed first. Then, high-frequency sinusoidal and pulse voltages are injected into the stator windings of the MG separately and the induced field current of the MG, estimated from the main exciter side, is regarded as the indicator for the initial rotor position of the MG. Simulation tests are carried out to verify the method and the results are presented and analysed.

Switched reluctance motors (SRMs) are considered a competitive technology for more electric aircraft and automotive applications due to their excellent fault-tolerant capabilities and robust configuration. In such applications, system reliability is a crucial feature. Therefore, here, a new fault-tolerant control strategy with real-time fault diagnosis for power transistor faults in SRM drives is proposed. The developed fault-tolerant topology is composed of four additional power switches and a relay network based on the conventional asymmetric converter. Moreover, an online fault diagnostic algorithm based on high-frequency (HF) signal injection is proposed. In contrast to the existing strategies that use additional sensors, this diagnostic algorithm extracts the fault signatures from the fundamental current by injecting an HF voltage signal into the upper switches of the asymmetric converter. Open- and short-circuit faults of the power switches are analysed by monitoring the variation in frequency and amplitude of the resulting HF current along with the amplitude variation in fundamental current with the occurrence of fault. Simulations performed on a three-phase 12/8 SRM drive and results are presented to validate the effectiveness of the proposed strategy.

This study proposes an approach for the fault-tolerant control of an interior permanent magnet synchronous motor (IPMSM) drive when a power switch open-circuit fault occurs without addition of any extra hardware or reconfiguration to the inverter. With this approach, the IPMSM's operation effectively alternates between the three-phase mode and the two-phase mode. Thus, the electric power is evenly distributed between three-phase windings as much as possible, and the remaining healthy power devices are all utilised. The post-fault drive performance is analysed. A simulation model has been built to verify the proposed principle. Finally, the approach has been implemented on an IPMSM test rig. Both the simulation and experimental results confirm the feasibility of the method.

Four-leg matrix converter (MC) is an AC–AC converter which has the ability to drive the unbalanced load. It can be used in many fields such as the ice protection system of More Electrical Aircraft to reach a considerably high power density. Detailed space-vector modulation algorithm and circuit modelling are discussed in this study. Analysis, modelling, and characteristics of common-mode voltage (CMV) are presented. The relationship between the peak value of CMV and circuit parameters is studied and quantitative results are provided. Simulation of a four-leg MC driving system is built and an experimental platform based on DSP/CPLD control system is set up.

A high-voltage direct current (HVDC) electric power system (EPS) has become an attractive power distribution architecture for the more electric aircraft. The structure of a typical HVDC parallel EPS based on the permanent magnet synchronous machine (PMSM) starter/generators (S/Gs) is proposed in this study. On the basis of this structure, the control strategy for a single PMSM S/G system is presented, which is suitable for wide-speed operation and high-power application. It can not only achieve both starter and generator functions but also achieve the stability of DC bus voltage. A master–slave current sharing method is derived and can be applied in the HVDC parallel system, compared with the droop-control strategy. The validity of the proposed strategies is verified by simulation studies in a Matlab/Simulation environment.

For the three-stage synchronous starter/generator, the pole ratio studied here is defined as the pole number of the main generator (MG) to that of the main exciter (ME) ratio and the operation mode means the operation mode of the rectifier at rated load in the generating mode. In this study, the pole ratio and the operation mode influence on the excitation system (consisting of the ME and the rotating rectifier) when the MG is short-circuited has been analysed. Simulation results show that, instead of pole ratio, the operation mode of the rectifier has much more to do with minimising current shock to the excitation system when the MG is short-circuited in the generation mode. Further, it's better to design the ME and MG to make the rectifier operate at mode 2 or 3 to reduce current shock.

This study proposes a novel rotor position estimation method for wound-rotor synchronous starter/generator (WSSG). At starting stage, WSSG needs a resolver to obtain main generator (MG)'s rotor position. However, the use of resolver increases starting system's complexity, volume, weight and cost. In order to solve this problem, a new kind of MG's rotor position estimation method is proposed, which considers the structure of WSSG as a resolver. This method injects a rotating voltage into MG's stator, detects main exciter's stator currents and subsequently processes the current signals to estimate MG's rotor position. Experiment results show that this method has high estimation accuracy, which are in good agreement with the theoretical analyses and simulation results. Compared to the traditional saliency tracking rotor position estimation method, this method does not rely on WSSG's parameters (including MG's saliency), and the signal processing procedures are more simple.

The main generator (MG) and main exciter (ME) of the aircraft wound-rotor synchronous starter-generator (WRSSG) are electromechanically coupled seriously, which makes the start control for the WRSSG complex in the starting mode. A decoupling control method for the MG and ME of the WRSSG is proposed in this study based on the estimation of the MG field current. In the proposed decoupling method, the MG field current is estimated first and used in the closed-loop excitation control for the ME to make the MG field current meet the MG demand. With the desired field current, the MG is decoupled with the ME and is controlled by using a traditional synchronous motor to start the aircraft engine at maximum torque per ampere. The feasibility and effectiveness of the proposed decoupling control method are verified by experimental results.

Isolation distance is an important consideration in aircraft wiring for coupling effect. according to electrical wiring interconnect system (EWIS) isolation requirements specified in SAE 50881D and airworthiness regulations CCAR 25.1707, explicit isolation distances are not specified. Aircraft wiring is complex or diverse. In order to evaluate coupling effects between the main feeder and signal wire, the three-phase-seven-wire main feeder with 230 VAC, 250 kVA was chosen as the simulation object. The impedance model of three-phase feeder is given with which the coupling effects can be analysed in theory at first. The coupling voltage amplitude is the main evaluation index. In the simulation process, the following cases are chosen: different distances between signal wire and main feeder; signal wire lies in the different phase of the main feeder; isolation distance analysis with types of loads; there exits arc faults on main feeder. Based on the analysis of the simulation results, proposed methods to reduce the coupling effects between wires are given. Through the work in this study, it has some guiding significance for wire or cable laying.

It is an important trend to develop the more electric aircraft (MEA) ±270 V high-voltage direct current (HVDC) power system because of its better reliability, power quality and power density. However, there also exists the low-voltage 28 V DC system in HVDC power system, for the aviation battery and some equipment still rely on it. In traditional MEA power systems, battery is only used as a backup power supply, hardly participating in the adjustment of the power system. On the other hand, the function of turbine engine is unidirectional. Hence, it's necessary to add an energy storage port. In this research, the authors put forward the problems of power coupling and strong non-linearity in traditional three-port triple active bridge (TAB) converters, and propose a decoupled TAB topology, which has the feature of decoupled power flow. The topology is compatible with ±270 V DC, 28 V DC and energy storage system with high-power density and efficiency. In addition, the authors unify the efficiency optimisation problem of dual active bridge topology mathematically and provide an optimal parameter design approach for inductance and turns ratio. Simulation results show the power flow control strategy is appropriate for the topology.

More electric aircraft (MEA) is a developing trend in modern aerospace engineering aiming for a reduction of the aircraft weight, operation cost and environmental impact through putting more emphasis on the utilisation of electrical power. It has many advantages, but also increases the complexity of the aircraft. Therefore, the requirements of prognostic and health management for MEA are needed. The method that using sequential importance re-sampling (SIR) particle filtering state estimation and smoothed residual to diagnose fault for typical components is discussed. The simulation results show that this method can locate faults accurately and quickly.

The matrix converter (MC) is a kind of universal power transformation topology. It merits in unit power factor operation; no intermediate storage link, bidirectional power conversion etc. Compared to traditional MC, three-level MC can achieve multilevel high-voltage output, high-power conversion, improved power quality etc. An interesting space vector modulation (SVM) of the MCs has been reported for the common mode voltage (CMV) suppression recently. However, the CMV suppression method on three-level MCs is seldom mentioned due to its complicated SVM. The CMV suppression of a capacitor clamped three-level MC is introduced in this paper. Aiming at reduce the CMV on three-level MC, the contribution of this article is determined an improved SVM with minimised CMV on the proposed three-level MC, this SVM chooses the different modulation strategy based on the different modulation index.

This paper discusses the effects of different space vector modulation (SVM) hexagon partition on common mode voltage suppression at high modulation index and presents an improved capacitor voltage balance strategy for multilevel matrix converter. Matrix converter is a compact designed converter which allows direct AC–AC power transfer without an intermediate DC link. Multilevel matrix converters, which utilises a multilevel structure on a traditional matrix converter, expand these characters to high-voltage and high-power situations. This paper is concerned with SVM of three-level matrix converter and concentrates on the comparison between different hexagon partitions; the improved balancing strategy is employed to improve the performance of flying capacitor voltage control. Simulation from Matlab/Simulink and results from a small-scale experimental prototype are presented to validate the theoretical results.

This study presents a static method for measuring torque ripple of the high power starter generator (SG), which has an advantage over the traditional dynamic method. The method proposed accurately measures the torque ripple of the SG during the start mode. The results can be applied to analyse the harmonics of the torque ripple. The accuracy of the method is verified by the experiments.

The multiphase synchronous generator–rectifier system could provide an ideal DC power source for more electric aircraft (MEA). When the inter-turn short-circuit fault occurs in phase windings of the generator, a large short-circuit current would be introduced inside the armature windings, which could cause severe damages to the system for overheat in the windings and irons as well as huge electromagnetic forces on the end coils. To improve the reliability of the MEA, this study researches on the inter-turn fault of the multiphase generator–rectifier system, including the theoretical analysis, numerical simulation and experimental verification. A 12-phase system is taken for example, and a multi-loop mathematical model is built up to calculate all voltages and currents in the multiphase synchronous generator–rectifier system with armature inter-turn fault. Many factors are thoroughly considered in the model, including the location and short-turns of fault, space harmonics of air-gap magnetic field and the changing circuit topology of the system. The mathematical model is verified by fault experiment results. Moreover, the electric characteristics of the fault are summarised, which could provide a quantitative basis for early detection of the inter-turn faults in the multiphase generator–rectifier system.

This study presents a kind of feedback between smooth and discontinuous feedback control method for electromechanical servo system. First, the construction and working principle of electromechanical servo systems was introduced on the basis of their structure characteristic. Then with the building of the electromechanical servo system structure, some research on the control strategy of permanent-magnet synchronous motors has been developed control in the light of their control characteristics. Combined with the theory of the field oriented control and the structure features and performance metrics of the mechanical and electrical servo system, a simulation model for the mechanical and electrical servo system was built. The simulation result shows the reliability of this method.

A multi-objective optimisation design method for passive power filter devices is proposed to solve the input current harmonic suppression problem of the aircraft starter/generator system. The parameters of the filter device are optimised by using the particle swarm optimisation algorithm. The proposed algorithm takes harmonic parameters, DC voltage drop, total volume and weight as the optimisation target. With these optimisations, the filter has the minimal volume and weight, while the current harmonic and the DC side voltage drop are able to meet the power quality requirements. This approach improves the filter design procedure with advantages of the reduced amount of calculation. Finally, theoretical analysis and computer simulation validate the effectiveness and viability of the presented algorithm.

This study presents a model predictive control (MPC) considering transformer DC magnetic bias for a reduced matrix converter (RMC). The control scheme selects the switching state that minimises the error in the output current and input instantaneous reactive according to their reference values; furthermore, the pulse sequence in MPC has been re-distributed to suppress the DC magnetic bias in transformer for RMC. MPC also presents stronger immunity to the influence of abnormal input voltage than bipolar space vector modulation strategy. Moreover, the simple performance comparison between RMC and pulse-width modulated rectifier + dual active bridge was provided. The feasibility and validity of the proposed control scheme in an RMC has been verified by simulation results.

GaN devices used to drive a three-phase inverter drive motor can greatly improve the switching frequency and increase the power density. However, the traditional microcontroller unit (MCU) controller cannot achieve high switching frequency single-cycle control. This paper describes the use of GaN devices in the design of a three-phase motor drive system to drive a permanent magnet synchronous motor and vector control algorithm, that is completely implemented in a field programmable gate array. The system achieves 200-kHz switching frequency single-cycle precise control, as verified by the experimental results.

This study presents two neutral-point balance control methods for a hybrid VIENNA rectifier, which is composed of a parallel system of a single-switch three-phase Boost rectifier and a VIENNA rectifier. Each rectifier in this topology processes part of the output power, therefore, a highly efficient and reliable performance is achieved in this rectifier system. However, the unbalance voltage of two DC-link capacitors in the VIENNA-type three level rectifier is also reflected in this hybrid rectifier. The fluctuation reason in neutral-point has been analysed using a mathematical model, meanwhile, the two methods with a hybrid algorithm and a simplified method based on zero-sequence component injection are proposed to control neutral-point fluctuation in this hybrid rectifier system. Furthermore, the performance comparison between these two methods is provided. The effectiveness of the two control methods has been verified using experimental results.

More electric aircraft (MEA) becomes a trend for next generation aircraft to respond to the global wide energy shortage. The technological advancement in power electronics makes MEA possible. Airbus and Boeing have advanced their research and application 30 years or earlier than China does. As a major civil aircraft manufacturer in China, COMAC can play an important role in applying and promoting new technologies for next generation aircraft. Based on authors' practice in recent years MEA development project, in this study, the challenge for MEA design is identified and the key technologies for MEA are elaborated from the aircraft, system and component level, and an attempt is made to address the challenge encountered. The method for MEA system integration is given in lieu of ARP 4754A. Finally, an innovative collaboration between original equipment manufacturer (OEM) and suppliers is suggested to achieve win–win situation in developing next generation aircraft.