Human-robot-collaboration requires robot to proactively and intelligently recognize the intention of human operator. Despite deep learning approaches have achieved certain results in performing feature learning and long-term temporal dependencies modeling, the motion prediction is still not desirable enough, which unavoidably compromises the accomplishment of tasks. Therefore, a hybrid recurrent neural network architecture is proposed for intention recognition to conduct the assembly tasks cooperatively. Specifically, the improved LSTM (ILSTM) and improved Bi-LSTM (IBi-LSTM) networks are first explored with state activation function and gate activation function to improve the network performance. The employment of the IBi-LSTM unit in the first layers of the hybrid architecture helps to learn the features effectively and fully from complex sequential data, and the LSTM-based cell in the last layer contributes to capturing the forward dependency. This hybrid network architecture can improve the prediction performance of intention recognition effectively. One experimental platform with the UR5 collaborative robot and human motion capture device is set up to test the performance of the proposed method. One filter, that is, the quartile-based amplitude limiting algorithm in sliding window, is designed to deal with the abnormal data of the spatiotemporal data, and thus, to improve the accuracy of network training and testing. The experimental results show that the hybrid network can predict the motion of human operator more precisely in collaborative workspace, compared with some representative deep learning methods.

In this paper, the AC copper losses are investigated and mitigated for different permanent magnet synchronous motor designs. AC copper losses can represent a substantial share of the total loss in electrical machines. In an application such as aerospace, it is more demanding to optimise all aspects of the motor design. Recently, different approaches to modelling the AC copper losses have been proposed. This paper utilises simulation software to quantify the expected AC losses from six different propulsion motor designs. The motor designs are then modified to reduce the AC winding losses. Using two-dimensional finite element analysis, the motor slot openings are modified such that an optimum design with reduced losses is achieved. The paper considers distributed, fractional slot and concentrated windings, and the results show promising reductions across these different winding configurations.

In the last decade, the trend toward higher efficiency and higher torque density electrical machines (EMs) without permanent magnets (PMs) for the industrial sector has rapidly increased. This work discusses the latest research and industrial advancements in synchronous reluctance machines (SynRMs), being the emergent motor topology gaining wide acceptance by many industries. This article presents an extensive literature review covering the background and evolvement of SynRM, including the most recent developments. Nowadays, SynRM has found its niche in the EM market, and the reasons for that are highlighted in this work together with its advantages and disadvantages. The key journal publications in SynRM topics are discussed presenting the biggest challenges and the latest advancements with particular regards to the design methodology. This article aims to provide a thorough overview to the research community and industry about SynRM. There is a clear potential for SynRM to take over a significant portion of the EM market in the near future to meet efficiency standards in industrial applications without the use of rare-Earth PM technology.

Synchronous reluctance machines are becoming a widespread solution in many engineering areas thanks to their simple rotor structure, the absence of rare-earth permanent magnets and high efficiency. The design of such machines is a widely investigated research topic, given the challenge of analytically estimating their electromagnetic performance, especially when a high-speed scenario is considered. The design choices and assumptions, which include the selection of the magnetic load and the stator and rotor lamination materials, play an important role in the machine performance. Consequently, it is of paramount importance to assess their validity. This paper, after a brief re-call of a general design methodology able to consider all the magnetic non-linearities and structural and thermal limitations occurring at high-speed, presents a sensitivity analysis against the magnetic load when a Cobalt-based alloy is adopted for both stator and rotor laminations. The analysis is carried out for different speeds up to 90 krpm, in order to draw general design guidelines for a given outer envelope and cooling system.

This work discusses the modelling approach adopted for the estimation of the voltage distribution within hairpin windings of electrical machines. The physical phenomena and the major contributors to the occurrence of the uneven voltage distribution are first described. Then, the equivalent circuit used to predict the voltage distribution is presented in detail. The circuital parameters employed in the equivalent circuit are estimated via finite element electrostatic and electromagnetic analyses. Finally, a numerical tool is used to solve the differential equations describing the equivalent circuit above mentioned. Simulation results are illustrated and discussed. The phenomena under investigation are applied to a pre-defined reference system, consisting of slot motorettes.

This paper describes the conjugate thermal analysis performed on an traction electric motor for electric vehicle (EV). The machine considered adopts hairpin windings and the cooling is achieved by combining an external water jacket and internal oil spray on the end-windings which is delivered by high pressure nozzles. The thermal characterization was performed in two stages; in the first stage the thermal performance of the original design was investigated whilst in the second stage some solutions were proposed to enhance the cooling effectiveness. Due to the heavy computational cost of the analyses, performed by the means of Computational Fluid Dynamics (CFD), fluid flow and conduction heat transfer were investigated separately. The results produced have shown that despite the good overall cooling capabilities of the spray, some issues may arise when the motor operates at low speed-high torque condition as the number pin layers increases. In this scenario droplets might struggle to penetrate through the conductors, leading to localized hotspots. It is also found that minor adjustments of the position of the nozzles may considerably improve the heat transfer rate. The realistic 3D representation of the conductors has allowed to further improve the accuracy of the analyses carried out.

Synchronous reluctance machines (SynRel) are becoming very attractive for different applications because of their reluctance nature, easy manufacturability and low cost. Their design still represents a challange because of the many degrees of freedom that their rotor structure presents. Furthermore, in order to obtain a design with defined electromagnetic characteristics and low torque ripple machine geometry is needed to be optimised. In this paper, three different optimisations are performed on 6 poles SynRel motor with three flux barriers per pole. The aim of the work is to show the effect of the objective selection on the optimization process. An automatic procedure has been applied coupling finite element analysis with an optimization algorithm that is working towards the competitive targets of maximazing the torque, while minimizing the torque ripple and losses. The effects of these objectives on the geometrical variables are investigated in detail. The outcome of the analysis show how the problem definition heavily affects the obtained results. This gives useful insights on how to approach SynRel rotor design.

This paper presents a comparison between hairpin and random distributed winding in electrical machines for automotive applications. Indeed, the overall performance of an electrical drive system is seriously affected by its winding design. The considered electrical machine has a peak power of 115kW and a maximum operating speed of 12000 rpm. Both cost and manufacturing aspects are here discussed in detail. Two different machine topologies have been investigated and Finite Element Analysis (FEA) results are presented and discussed. Then, the comparison between hairpin and random winding configuration in terms of AC copper losses are presented for the selected geometry. The accurate AC losses estimation can be done by modelling each single conductor. In order to significantly reduce the simulation time, a domain model reduction has been adopted. Based on two different driving cycles, Urban Dynamometer Driving Schedule (UDDS) and Highway Fuel Economy Test (HWFET), the AC losses have been evaluated. It is shown that horizontal pin segmentation can contribute to considerable AC loss reduction.

One of the challenges brought forward by the gradual electrification undertaken by the aviation sector is the requirement of fault tolerance for machine drive systems to be used for critical on-board tasks such as propulsion or primary flight surface actuation. Their inherent advantages in both volumetric and gravimetric power density makes integrated drives the prime candidates for these applications. Despite the large advances in this field, few key area still need work. Key among which is fault tolerant current control strategies. This paper studies the application of resonant control techniques to achieve a scalable and fault tolerant current control strategy for multiphase machine.

Nowadays, Interior Permanent Magnet Synchronous Machines (IPMSM) are widely adopted in various sectors such as automotive, railway or public transportation (e- buses, trams, etc.). Among the benefits that these machines present, they offer a number of design degrees of freedom. Furthermore, they can operate over a wide speed range, with a good flux weakening capability. One of the main challenges is to define a complete geometrical parametrization, in order to identify an optimal structure that satisfies the design requirements. In this paper, a detailed analysis of the rotor structure is carried out looking at understanding the effects of the geometrical parameters on key performance indexes (e.g. flux density harmonic content, torque capability, torque ripple, etc.). Based on the preliminary analysis, an optimization procedure is implemented for the design of a Nabla-shaped rotor to satisfy the electromechanical performance of a case study traction motor. The results are showing how an optimal machine can be designed with a reduced amount of permanent magnet, by optimizing the rotor structure.

Health monitoring has gained a massive interest in power systems engineering, as it has the advantage to reduce operating costs, improve reliability of power supply and provide a better service to customers. This paper presents surrogate methods to predict the electrical insulation lifetime using the neural network approach and three curve fitting models. These can be used for the health monitoring of insulating systems in electrical equipment, such as motors, generators, and transformers. The curve fit models and the supervised backpropagation neural network are employed to predict the insulation resistance trend of enameled copper wires, when stressed with a temperature of 290 °C. After selecting a suitable end of life criterion, the specimens' mean time-to-failure is estimated, and the performance of each of the analyzed models is apprised through a comparison with the standard method for thermal life evaluation of enameled wires. Amongst all, the best prediction accuracy is achieved by a Backpropagation neural network approach, which gives an error of just 3.29% when compared with the conventional life evaluation method, whereas, the error is above 10% for all the three investigated curve fit models.

Recently, the synchronous reluctance machine limits have been pushed toward meeting the requirements of traction applications. A skilled electromagnetic architecture of a synchronous reluctance machine with the help of permanent magnets can push the limits of power density and speed range to that of traction applications, however, the mechanical integrity of the rotor can still be in question. A traction application means large rotor diameter and high rotational speed, two criteria that makes a challenging design, in particular, mechanically. In this paper, the multi-physics design steps of a permanent magnets assisted synchronous reluctance motor for automotive application, have been presented. Firstly, the electromagnetic design following the size and thermal aspects and constrains has been conducted. Secondly, methods to reduce the mechanical stress has been explored and a bridged mechanical design has been adapted. Finally, thermal analysis of the machine has been conducted to ensure the thermal limits have been satisfied.

Mechanically-driven actuators, compressors and pumps are being replaced by the aircraft manufacturers that shift the trend towards “More Electric Aircraft” and hence reducing the mechanical linkages within the aircraft system. This elevates the dependence of the electrical power on the main engine, deicing and cabin environmental system which originates from the starter-generator. This paper presents a trade-off study for the design of high-performance starter-generator, surface-mounted permanent magnet machines, considering slot-pole combination, winding configuration and geometrical layout as degrees of freedom while satisfying the output power and strict volume requirements. 18S/12P combination seems a promising candidate for starter generator application which satisfy all the given requirements, giving the output power of 32kW at 14kRPM within the volume of 1407cm3.

This paper presents an analytical tool to generate torque vs speed characteristics of the surface-mounted permanent magnet machines to minimize the computation time and efforts. The paper also derives an expression of d-axis current in the field weakening region while the stator resistance effect takes into account in order to evaluate the phase advance angles for the motor control. Finally, the results of the analytical tool have been compared with the MotorCAD software which gives less than 1% discrepancies in the results.

Electrical machines with high torque density are required for traction application. Availability of bonded magnets with complex shapes and magnetization pattern can significantly extend the design space of electrical machines. This paper introduces a hybrid flux barriers design to improve the torque density of permanent magnet assisted synchronous reluctance (PM -SynRel) machine using ferrite magnets. The torque density with hybrid flux barriers is found to improve along the entire range of speed compared to the conventional flux barriers. The hybrid barrier design achieves similar performance to that of curved barrier with relatively flat shaped magnets in the last flux barrier. Thus, the hybrid barrier is able to enhance the torque density at a potentially reduced cost of manufacturing. The hybrid flux barrier design is validated for both electromagnetic and mechanical performance using commercial finite element analysis (FEA) packages.

High power density and high torque density are the fundamental requirements for electric machines used in traction application. The former is obtained by potentially increasing the speed of the machine while the latter by using high energy density rare earth magnets. Ferrite magnets are explored as a viable alternative to rare earth magnets which are relatively expensive and geographically concentrated. The paper is intended to bring out the current trend of electric machines used in electric vehicles (EVs) with due focus on permanent magnet assisted synchronous reluctance (PM-SynRel) machine. High power and high speed PM-SynRel machine with rare earth and ferrite magnets are designed and compared based on the requirements for a future electric commercial vehicles. The ratio of stack length, mass of magnet, total mass and inertia of rare earth machine in comparison to ferrite PM-SynRel is found to be 0.72, 0.42, 0.72 and 0.32, respectively. Based on these, the rare earth based machine is found to have high power density, torque density and also utilizes lesser volume of magnets but PM-SynRel with ferrite is getting closer.

Typically, electrical machines feature rotor and stator winding configurations and core structures which comply with both simplicity and cost requirements. Such constraints limit the design search space and degrees of freedom, thus leading to exploit and implement only standard symmetrical layouts which therefore represent by far the most common choice. In this paper, the potential of adopting non-symmetrical windings and geometries in electrical machines is discussed. The perceived benefits are first detailed and then proven by applying the concepts to two case studies, namely a squirrel-cage induction machine and a salient-pole synchronous machine.

In Electric Vehicle (EV) application, the in-wheel motors are driven by the same dc-link voltage. To reduce the space, the Voltage Source Inverters (VSIs) can share one dc-link capacitor. Long-term experiences and experimental data demonstrate that the capacitors are one of the major failures in the motor drive system. The current profile of the dc-link capacitors is the main factor for this degradation, therefore, by reducing the current harmonic components of the dc-link capacitors can increase the lifetime. In this paper, a dc-link capacitor current harmonic reduction method for dual Permanent Magnet Synchronous Motor (PMSM) drive system in EV application is proposed. The Phase Shift Pulse Width Modulation (PSPWM) is employed in the dual inverters to reduce the harmonic components of dc-link capacitor. To verify the proposed method, a experimental platform is established and the experimental results are presented.

In the More Electric Aircraft framework, the objective is to increase the efficiency and the reliability of the aircraft by gradually substituting the existing subsystems with electrical ones. Newer aircrafts already incorporate a great share of electric power, making the on-board electrical power distribution system (EPDS) a complex structure composed of generators, actuators and storage. Because of the importance of power electronics in this scenario, the control system is critical to ensure the stability of the EPDS. This paper analyzes the sensitivity to the control parameters of the EPDS stabiltiy. A state-space model is derived and the root loci are used to show in a graphical way the effects of the design parameters.

The more-electric aircraft initiative represents an important technology step-change for the aircraft industry. The reduction of both fuel consumption and environmental impact are leading to alternative solutions for actuating the flight control surfaces. The traditional hydraulic systems, are progressively being replaced with electrically powered actuators. In this scenario, electromechanical actuators are gaining an ever-increasing importance as enabling technology for next generation aircraft. This paper presents the design and testing of a permanent magnet synchronous motor driving a linear geared electromechanical actuator for commercial aircraft. The experimental results are discussed throughout the paper and compared to the finite element ones obtained at the design stage. Finally, the machine is integrated into the mechanical drivetrain and the electromechanical actuator performance is evaluated through experimental tests carried out on a purpose-built mechanical demonstrator for achieving a high technology readiness level.

The on-going electrification transportation system revolution has already started and the continuous evolution of power electronics allows new and more reliable system layouts and control strategies to be investigated. Mainly, this revolution is driven by increased reliability levels. Since multi-three phase motors are fault tolerant by definition, they are a very good candidate for more reliable transportation systems. In this work, load sharing in multi-three phase synchronous motors is presented. For better explaining the new possibilities introduced in transportation systems by multi-three phase motors, few examples relative to a DC micro-grid for aerospace applications are provided. Analytical equations and experimental validation of speed control with load sharing capabilities are given by means of Matlab/Simulink simulations and by experimental on a 22kW test rig.

Bearingless motors combine in the same structure the characteristics of conventional motors and magnetic bearings. Traditional bearingless machines rely on two independent sets of winding for suspension force and torque production, respectively. The proposed Multi-Sector Permanent Magnet (MSPM) motor exploits the spatial distribution of the multi-three-phase windings within the stator circumference in order to produce a controllable suspension force. Therefore, force and torque generation are embedded in the same winding setting. In this paper the force and torque generation principles are investigated and a mathematical model is presented considering the rotor displacement. A two Degree of freedom (DOF) position controller is designed taking into consideration the rotor overall dynamic system and a controller gains selection strategy is suggested. A simulation study of the bearingless system in different operating conditions is presented and the suspension force and torque produced are validated through Finite Element Analysis (FEA).

This paper proposes a semi-flooded cooling concept for a high speed machine design. The electrical machine considered is for an aircraft starter-generator system where power density and efficiency are crucial. In order to achieve the high power density permanent magnet machine, a direct oil cooling strategy for the machine stator is adopted. A stator oil sleeve is designed to separate the machine into an oil-flooded stator chamber and an oil-free rotor chamber to avoid windage loss due to the high rotor speed. Different materials, Carbon Fiber (CF) and E-glass fiber (GF) are considered for the oil-sleeve design. Implications of the aforementioned materials on the structural design are investigated and optimized accordingly using finite element methods. It is shown that the oil sleeve made of CF provides structural capability with a minimum sleeve thickness. However the sleeve made from GF has the benefit of having no electrical conductivity. Both oil sleeves are made and the GF sleeve is successfully applied to the machine and tested.

The development of new power electronic device and high performance magnetic materials are the main technological factors that have led both industries and research community to focus their attention on high speed electrical drives. Several papers have already outlined the electrical machine and/or converter topology choice for certain high speed application. This choice obviously depends on the applications under study. This paper aims to identify the most important high speed applications. For each of them, the main design challenges are highlighted and an overview of the already available product on the market is presented.

This paper presents the trade-off analysis and design of a high power-density machine for industrial pump applications. The developed permanent magnet synchronous machine drives an electric, oil flooded pump. Different slot/pole combination and winding configuration have been investigated in order to identify the optimal combination that satisfies the electromagnetic and thermal constraint while keeping the losses as small as possible. Several strategies such as the use of the Cobalt iron material for the stator core lamination and the adoption of Halbach array have been investigated in this work to improve the performance capabilities of the designed machine. The electromagnetic performances have been evaluated by using a finite element method. Thermal behaviour has been determined using a lumped parameter network. The outcome of the thermal analysis helped to identify the optimal cooling configurations. The final results are presented highlighting the achieved design targets.

This paper proposes an analytical model that considers the torque characteristics and results in an optimum geometry for dual-stator synchronous machines with permanent magnets. The distribution of the magnetic field in the air gap is obtained by solving Neumann's problem by using Green's function. The results of the study shows that the dual-stator topology of synchronous machine with permanent magnets can achieve up to 1.7 times more torque when compared to conventional machine with radially magnetized magnets. This effect is achieved due to more efficient using of the volume of the machine. The analytical model presented in the paper allows fast but accurate optimization of the machine's geometry and is used to achieve an optimal design for the considered application.

This paper presents novel integration options for passive inductor which include: motor-shaped rotational and motor-shaped rotor-less inductor for high speed motor drive system. The novel options have been designed and their performance is compared with the conventional EE core inductor using finite element analysis. It is observed that there is a significant reduction in total losses at fundamental frequency along with substantial reduction in the AC copper loss at 10, 15 and 20 kHz switching frequencies, when the proposed integrated options are utilized. For the motor-shaped rotational inductor, the total losses at fundamental frequency and AC copper loss at different switching frequencies are reduced by 26.1% and 73.8% (at different switching frequencies) respectively. There is a reduction in overall volume by 3.6%, but this comes with 11.7% increase in weight. For the motor-shaped rotor-less inductor, the total losses at fundamental frequency and AC copper loss at different switching frequencies are reduced by 10.4% and 73.8% (at different switching frequencies) respectively. There is a reduction in overall volume by 3.6% but this comes with 6.1% increase in weight. The proposed designs can share the cooling system of the motor thus, eliminating the requirement of separate cooling system.

This paper presents a novel approach to integrate the output filter inductor in permanent magnet synchronous motor (PMSM) drive system. The integrated output filter inductor is based on utilizing the motor magnetics as a filter inductance instead of introducing a separate filter inductor. Thus, eliminating added filter inductor losses and associated weight and volume. The vector controlled model, taking modulation and switching effect in to account, has been developed using MATLAB/Simulink tool for the proposed integrated output filter inductor. The currents obtained from MATLAB/Simulink model are then injected into the Finite Element model to validate the concept. The performance of the proposed and conventional system is analyzed in terms of mean electromagnetic torque, torque ripple, motor losses, inductor losses, weight and volume.

Active Magnetic Bearing (AMB) technology is becoming attractive for several reasons such as high speed operations, high reliability and vibrations exemption. Moreover, AMB can behave as active vibration dampers and provide a real-time control of the shaft. For all these advantages, AMBs are particularly attractive for high power - high speed applications. These desirable features come at the cost of an increased complexity of the system, which now includes a power electronic converter and a control system dedicated to the AMBs. This paper focus on the overall system design, from the AMB design, to the power electronic converter design and control, for an AMB featuring Wheatstone bridge winding configuration. The magnetic design has been developed analytically and validated by means of Finite Elements simulation, to generate up to 2kN of axial forces. The power conversion system is based on three full bridges, one to magnetize the bearing and two to control the axial forces independently on the x and y axes. In order to achieve high bandwidth current control able to generate the desired orthogonal forces, a predictive control strategy has been proposed, for the several advantages it can provides such as fast dynamic response, no need of modulation, easy inclusion of nonlinearities and constraints of the system, possibility of incorporating nested control loops in only one loop and the flexibility to include other system requirements in the controller. The control system has been validated in Matlab/PLECS simulation, including the effect of parameters mismatches in the coils.

In this paper, the work has been developed aiming at reduction of inverter non-linear influences on high frequency carrier voltage injection sensorless control algorithm. For this method, inverter non-linear errors introduce distortions of the motor stator voltage that degrade the estimation performance. The main cause is the deviation of the high frequency voltage vector angle used for the demodulation process of extracting the rotor position from negative sequence of high frequency current response. For sensorless applications where the injection frequency becomes comparable to Pulse Width Modulation (PWM) switching frequency, the command voltage compensation method is prone to fail. In this work, the injected high frequency voltage vector angle for current demodulation is calculated with estimated voltage error Look-up-table (LUT), sensorless position estimation accuracy is enhanced compared to feed-forward compensation technique validated by experiment.

Potential benefits of Integrated Motor Drives (IMD) include increase in power density, reliability and efficiency. These benefits are particularly valuable in Aerospace and Automotive applications. However, close physical integration of the drives and the machine may also lead to an increase in component temperature. This requires careful thermal analysis and coupled design of the IMD system. This paper reviews different integration topologies and compares them using FEA based thermal analysis. The effects of the power electronics (PE) position on the IMD system as well as thermal management concepts and cooling systems are also investigated. Thermal models of these IMDs are created using ANSYS and the temperature distributions of these models are analysed.

This paper proposes solid rotor Interior Permanent Magnet (IPM) machine for an aircraft starter-generator. The key challenge in the design is to satisfy two operating conditions which are high starting torque and high speed continuous operation. A Surface mounted PM machine designed for such an application is used as a benchmark. Then, the IPM machine is designed adopting a solid rotor to have a maximum mechanical stress level well below the material Ultimate Tension Strength (UTS) and minimal rotor eddy current losses. A detailed design is carried out through Finite Element (FE) electromagnetic and structural analysis. The static and dynamic structural analyses are presented. Several novel approaches to minimize the rotor eddy current losses are investigated. It is shown that the proposed solid rotor concept for IPM fulfils both high torque and high speed design requirements whilst satisfying the structural and magnetic limitations.

New emission standards are progressively moving transportation systems toward an electrification process that must provide high reliability, fault tolerance and high integration levels. Integrated Modular Motor Drives (IMMD) are an interesting candidate for these applications. Focusing on reliability and fault tolerance, this paper proposes a simple speed droop controller for IMMDs. Extending the concept of droop control to the speed loop of an IMMD, inherent power sharing among the modules and regulated speed are achieved without communication. The paper proposes a simplified design procedure, validated with experimental results from a 3KW rig, showing good agreement with the expected performances.

This paper presents an extensive study on the electromagnetic and structural influences of the end barrier shape of a Synchronous Reluctance Machine (SynRel). One of the most challenging tasks in designing these machines is to achieve a smooth torque and a mechanically robust structure, especially when high operating speed range is required. Several papers have already addressed the electromagnetic design problem related to the choice of the flux barriers thicknesses and positions. However a comprehensive work on the influence of the end part of the flux barrier on the electromagnetic and structural performance has not been yet presented. In this work two end barrier shapes are considered and optimized using the same methodology. Then the optimized machines have been deeply analyzed in terms of torque, torque ripple and rotor von Mises stress distribution. Furthermore, with the aim to further investigate the influence of such end barrier shape, a detailed sensitivity analysis is presented. In conclusion, general guidelines for the structural and electromagnetic design of such end barrier shape are drawn.

This paper is focused on the electromagnetic and structural design of high-speed synchronous reluctance (HS-SyR) machines. Both design aspects are equally taken into account due to high speed requirements. Two design procedures, both based on multi-objectives stochastic optimization algorithms (OA) and Finite Element Analysis (FEA), are presented and compared in terms of computational time and quality of the final result. The first design procedure combines an electromagnetic FEA with an analytical rotor structural design. The second procedure evaluates both electromagnetic and structural performance using FEA simulations within the optimization. The former approach needs a structural refinement stage of the rotor geometry. The latter gives rotor designs ready for manufacturing at the cost of increased computational resources. The two approaches have been investigated considering the rotor design of an 80.000 rpm SyR motor for aeronautical applications. Finally, a sensitivity analysis has been performed to identify which variables most affect structural performance and which parameters need tighter manufacturing tolerances.

In this paper, the optimization process of a rotational Electro-Mechanical Actuator (EMA) for an Aerospace application is presented. Specifically, the EMA is designed for the extension and retraction of a landing gear. The main aim of the optimization process is the minimization of the overall weight of the system whilst maintaining the system dependability. Since the EMA is composed of different, interacting subcomponents, it is necessary to adopt a system level, design approach. The work reported here will show how the motor weight is influenced by the gear ratio and the DC-Link voltage in such an EMA. The result of this analysis is the optimum configuration of the drive-train gear ratio, which minimizes the EMA's weight. This paper pays particular attention to the motor design approach.

Wide-bandgap devices are under the spotlight of scientific research as they exhibit great performance in terms of efficiency and temperature operation. However, to fully exploit their characteristics, dedicated driving circuits are needed. High-power gate-insulated switching devices exhibit important input capacitance; when fast switching speeds are demanded, high-current pulses are needed to drive the gate terminal. This is particularly true for wide-bandgap devices, capable of lower transition times than conventional silicon devices. The proposed circuit is a voltage controlled resistor, which output can drive wide-bandgap devices. Design criteria, as well as simulation results, are presented.

This paper investigates two winding concepts for Permanent Magnet (PM) machines used for more electric aircraft systems where reliability is a concern. Analysis is carried out using two different surface mounted PM machines designed for low and high speed applications: a 12 slot, 10 pole machine with concentrated windings for rotorcraft swashplate actuation and a 36-slot 6-pole machine with distributed winding arrangement for an aircraft starter-generator. The impact of the winding arrangement for the low speed machine is investigated with a focus on turn-turn Short-Circuit (SC) faults. Implications of the SC fault and methods to restrain the resulting SC current are discussed. A prognostics method for potential turn-turn SC faults for the high speed application is then investigated. It is shown that potential winding faults can be detected at an early stage of fault inception and thus measures can be taken to limit propagation.

In safety critical applications, such as for the aerospace industry, where fault tolerant systems are mandatory, the ability of an electric actuator to detect a malfunctioning and eventually operate in faulty conditions is of paramount importance. This paper is concerned with the fault tolerance operation of a linear actuation drive, consisting of a tubular, linear motor controlled and driven by a high performance matrix converter for an aerospace application. The aim of this work is thus to propose and validate techniques addressing specific faulty operation conditions. The main points of interest addressed in this paper are the operation of the position sensor and operation during a fault on one of the phases of the motor. An Extended Kalman Filter is adopted for the double goal of improving the measured data of the position sensor and to continuously monitor its condition. On the other hand, the TLPM motor is operated under the assumption of a total fault of a single phase. In this work the modification to the Field Oriented Control (FOC) with only two phases is described, and the results are compared to those of the healthy machine. Theoretical analysis, simulations and experiments confirms the feasibility of the described strategies.

This paper deals with the performance assessment of different permanent magnet motor drives topologies for Starter/Generator systems in aircraft applications. The comparison focuses on power electronics topologies, evaluating, by means of simulations performed with Matlab/Simulink and Plexim Plecs, some relevant key points such as efficiency, losses and motor current harmonic distortion. For all the topologies, simulations have been carried out considering both 2-Levels and 3-Levels converter structures, and different machine arrangements. All the power electronics systems data are obtained from off-the-shelf power modules characteristics, both Silicon and Silicon Carbide technology based.

Early detection of incipient faults in AC drives is one of the most difficult challenges for condition monitoring, especially for faults related to insulation degradation of the windings. This is because insulation degradation is very difficult to be detected on-line, so these faults may pass unnoticed before turning into a major faults. This paper looks at the feasibility of using coaxially insulated windings not only to increase reliability against winding insulation problems, but as an alternative to advance condition monitoring that may be suitable for the detection of insulation degradation, and other faults not easily detected by conventional schemes such as demagnetization issues, and the presence of inter-turn short circuits. The concept of insulation degradation for the case of coaxially insulated windings is analytically considered in this work and a novel condition monitoring alternative proposed. The proposed scheme and winding topology are extensively evaluated numerical to determine their feasibility to drive condition monitoring.

We describe a single sided matrix converter (SSMC) designed for safety critical applications like flight control actuation systems. Dynamic simulations of multi-phase SSMC using Matlab Simulink are carried out to evaluate the fault tolerance capabilities. Investigation into different numbers of phases and power converter topologies under single phase open circuit, single switch open circuit, and single switch short circuit has been executed. The simulation results confirm 5-phase SSMC design as a compromise between fault tolerance and converter size/volume. A 5-phase SSMC prototype was built. Experimental results verify the effectiveness of our design.