This study presents the design of an electric motorisation for a landing gear. The concept of More Electric Aircraft is currently with one of the major concerns of all aircraft manufacturers and equipment suppliers throughout the world. The objective consists of eliminating, to the greatest extent possible, the use of any actuator containing fluid pressure and increasing the use of electric actuators. This applies to all airplane orders and accessories. The choice of this motorisation was to design synchronous machines with toothed coupling. When actuators of very high mass performance are required, the use of this type of actuator is an interesting solution, compared with conventional actuators with polar coupling. The principles used in our design method are based on two-dimensional finite-element simulations. The study and the calculation can be performed in two dimensions from a simple element called an elementary pattern, representing the interaction of magnets with stator teeth. Following a summary presentation of this type of actuator and its dimensioning, two prototypes are presented. To replace the hydraulic cylinders in the landing gear of an A320 aircraft, a vernier machine, and a multi-air gap linear motor has been dimensioned, manufactured and tested.

The high variable flux density in the air-gap of fault-tolerant flux-switching permanent-magnet (FT-FSPM) machine results in rich harmonics of the magnetic field, thus generating large vibration and noise. This study proposes two novel FT-FSPM machines which can effectively reduce the radial pressure, thus reducing the vibration and noise. First, the radial pressure of the initial FT-FSPM machine is analysed. Second, the novel proposed FT-FSPM machines are introduced and analysed. Third, the electromagnetic performance, including back electromotive force, output torque, inductance, and radial pressure harmonics, of the initial and the two proposed machines are compared by finite element method. Then, the vibration modes with corresponding natural frequencies are predicted. The vibration and noise are simulated by boundary element method. Finally, the effectiveness of the low-noise design is verified by measurement results.

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.

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.

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.

The brushless permanent magnet direct current (DC) machine with dual three-phase windings is proposed for critical drive systems. It is proposed to call such a solution with a dual stator winding as a dual-channel brushless permanent magnet DC motor (DCBLDC). The stator windings are supplied by two independent power converters under dual-channel operation (DCO) mode. After a fault of one channel, a further operation of the machine can be continued in the so-called single-channel operation mode (SCO). In this study, a mathematical model of DCBLDC machine which takes into account non-linearity of a magnetic circuit and all couplings between phases within a given channel as well as between channels is proposed. The results of experimental tests in static and dynamic states for SCO and DCO modes were presented.

In this paper, a novel overlap angle controlled Direct Torque Control (DTC) scheme is proposed which strikes the balance between commutation torque ripple and losses. The commutation torque ripple in a Brushless DC (BLDC) motor is mainly due to the effect of commutation on non-commutating phase current and it will be more severe in high power applications. DCT techniques are used to reduce the torque ripple. In comparison to the conventional two-phase conduction Six-Step DTC (SSDTC), the commutation torque ripple is considerably reduced by Twelve-Step DTC (TSDTC) but at the cost of increased inverter and winding losses. The proposed method offers commutation torque ripple minimisation and loss optimization simultaneously by controlling the motor operation in hybrid two- and three-phase conduction. The proposed method basically leads to motor operation in three phase conduction during overlap region and in two phase conduction during non-overlap region. The overlap and non-overlap regions are identified by calculating the commutation interval and suitably scaling it by a factor . The proposed method is validated through experimental results and the effect on commutation torque ripple and drive efficiency are compared with SSDTC and TSDTC experimentally.

A novel method based on contribution estimation for sound quality evaluation and improvement of electric powertrain is presented in this study. Firstly, the noise samples of an electric powertrain for electric vehicles are collected in a semi-anechoic chamber. Then the subjective evaluation of an electric powertrain is conducted. Through the correlation analysis between the acoustic energy of powertrain noise in each frequency band and subjective perception, the sensitive frequency ranges of electric powertrain noise which human hearing is susceptible to are determined. Subsequently, the acoustic harmonics of electric powertrain noise in sensitive frequency are distinguished by order tracking. After that, the contribution of sensitive harmonics to both psycho-acoustical parameters and subjective perception is estimated. Finally, the gear train model for optimisation of gear tooth micro-geometry is built to improve the sound quality of electric powertrain. The results of psycho-acoustical parameters and subjective rating of acoustic noise radiated by electric powertain after optimisation show that it is possible for the electric powertrain to improve the sound quality.

For permanent magnetic motors, the faults in inverter may cause serious mechanical vibration, winding overheating, and thermal demagnetisation for the magnets. Thus, this study addresses the problem of the electromagnetic field and temperature distributions for permanent magnet synchronous motor (PMSM) under open circuit fault (OCF) in the upper switch of one phase. Firstly, taking a 12.5 kW 2000 r/min PMSM as an example, the 2D transient electromagnetic field-circuit coupling calculation model is established. Then the flowing paths of the three-phase currents in inverter are analysed before and after the OCF in the upper switch of one phase. Next, by using the finite-element method, the current harmonics, the electromagnetic torque, the rotating speed, and the losses in PMSM are investigated. Simultaneously, direct current component and torque pulsation are also derived. Based on the 3D temperature field, the temperature distributions in different parts of PMSM also are comparatively studied before and after this fault. Moreover, the temperature of permanent magnets, which is the part most seriously affected by the temperature, are further analysed. Finally, calculation and experimental tests prove the accuracy of the theoretical analysis. The obtained conclusions may provide some references for the limit operation and effective diagnosis for inverter faults.

This study sets forth an equivalent electric circuit (EEC) model including core losses and phase interactions to obtain a more accurate steady and dynamic performance of the high speed switched reluctance motor (SRM) during the design, analysis, and control of the SRM drive system. The magnetic equivalent circuit (MEC) method is used to calculate the flux linkage and torque quickly and relative accurately. Based on the principle of transformation between the MEC and EEC, the EEC model is derived from the MEC model. To enhance the model precision, the dynamic core losses and phase interactions are analysed and added to the EEC model. The relationship between the phase current and virtual current corresponding to different parts is deduced. Then the simulation model of the whole SRM driver systems is established in MATLAB/Simulink to obtain the phase current and virtual current corresponding to a different portion. The experimental and simulated results of the static MEC model and the whole SRM drive system including the EEC model provide the conclusive evidence for validating their practicability.

This study proposes a novel inter-turn fault diagnosis method for a permanent magnet synchronous machine. Search coils are set on every stator tooth to measure the tooth fluxes. The high-order harmonics produced by the inverter are adopted to diagnose the inter-turn fault existence and locate the fault tooth. The fault severity coefficient is proposed on the basis of theoretical analysis and can identify the fault severity. A comparative analysis of a traditional method based on co-simulation shows that the proposed method is sensitive and that the fault severity coefficient is accurate, intuitive and independent of the operating condition of the motor. An experimental platform is set up, and it validates the effectiveness of the proposed method.

Most of the resolvers used in high precision servomechanism are two-pole, wound-rotor ones. The configuration of their stator winding is based on variable-turn, on-tooth method. However, there is different opportunity for their rotor: using distributed winding or on-tooth one. Furthermore, based on the operating principle of the resolver its rotor needs a single phase winding. While, in many practical cases a two-phase winding that one of them is short-circuited (damper winding) is employed for rotor. In this study, the effect of different configurations for rotor winding on the resolver performance in terms of the average of absolute position error, maximum position error, and total harmonic distortion of induced voltages envelopes is investigated. Then, the effect of damper winding on the performance of the resolver under static-, dynamic-, and mixed-eccentricities are studied. In this study, all simulations are performed using three-dimensional time stepping finite-element method and finally, the experimental tests on the studied sensor using a precision test setup are employed to approve the simulation results.

This study presents the evaluation of performance indexes of a novel synchronous reluctance motor (NSynRM) that has an axially sinusoidal rotor lamination shape. The stator of a 5.5 kW, 4-pole, 50 Hz conventional three-phase squirrel cage induction motor, with distributed and chorded by one slot, double-layer winding, is used for both standard and NSynRMs. Owing to the nature of the sinusoidal rotor structure, the three-dimensional finite element analysis (FEA) is utilised to study the electromagnetic parameters of interests. The NSynRM with sinusoidal rotor shape results is compared with the standard SynRM without cut-off on the q-axis. The FEA results are validated by means of practical measurements.

A novel 24 kW 12-slots/10-poles axial-flux permanent-magnet synchronous machine (AFPMSM) with external rotor motor applied to the large electric motorcycle is introduced in this study, which has the characteristics of the yokeless and segmented armature for power density improvement. The hierarchical method is used for calculation of stator iron core loss based on the analytical solution of air-gap flux density, which cuts the prototype into many equivalent linear motor slices in the circumferential direction. A major advantage of hierarchical methods over traditional iron core loss calculation is its higher accuracy and rapidity. Then a lumped parameter T-type thermal network model is presented for AFPMSM temperature rise calculation. A 3D liquid–solid coupling model is compared with the 2D T-type lumped parameter thermal network. Finally, a temperature rise measurement platform is established to verify the above-mentioned methods. Testing result shows that the hierarchical method and T-type thermal network have a higher accuracy to predict each part temperature.

Based on the back electromotive force (back-EMF) detection, a novel rotor position estimation strategy with adjustable turn on/off angle is proposed for the high-speed hybrid switched reluctance motor (SRM). The minimum back-EMF position is captured in every electrical cycle for rotor position estimation. The current comparator is employed to send out a turn-off signal for phase winding when the maximum inductance position is detected in the first electrical cycle. By providing sufficient current rise time to the phase winding, the proposed sensorless control system enables the motor to run in high-speed application. Besides the straightforward estimation principle, the proposed strategy has the implemental feasibility by eliminating extensive calculations and complicated look-up tables. The experimental results of a prototype are demonstrated to verify the proposed sensorless control system.

In a DC microgrid (DCMG), the DC bus voltage is vulnerable to the power fluctuations caused by the variations of intermittent renewable energy sources and local loads. A concept is developed to operate a bidirectional DC–DC converter as a DC machine to mimic the inertia characteristic of a DC machine and regulate the DC bus voltage fluctuations during power fluctuations of the DCMG. The concept of operating a bidirectional DC–DC converter as a DC machine can be termed as virtual DC machine (VDCM). The proposed concept of a VDCM is basically a control technique for a bidirectional DC–DC converter, which is derived from the theory of the DC machine operation and its speed control technique. The implementation, operation, controller design and dynamics of VDCM are also discussed. A VDCM can be easily operated in both generating and motoring mode also. Being free from comparatively slower mechanical devices, a VDCM can switch over from one mode to another very quickly. Hence, it provides a useful way to control the storage devices in microgrid applications.

The aim of this study is to present a new, accurate, and user-friendly software procedure for the analysis and rapid design of rotating induction machine windings, considering both the electric and the magnetic specifications of the machine itself. This procedure is a valid aid for quick first stage design without the necessity of using finite element method (FEM)-based design procedures. FEM can be used in a second design phase in order to refine the first stage results. The design procedure is hereafter outlined and some examples show its capability.