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This article explores enhancing spoke-type flux-intensifying permanent magnet (SFI-PM) motor performance by strategically placing flux barriers (FBs) in the asymmetric rotor. Integrating multi-FBs into the conventional spoke-type PM (CSPM) rotor topology elevates the d-axis inductance ( $L_{d} \gt L_{q}$ ), intensifying flux density and improving output torque while posing challenges like increased cogging torque, torque ripple, and harmonic distortion. An asymmetric rotor design is proposed to mitigate these issues by strategically placing a higher number of FBs along the forward direction (FD) of the spoke magnet axis (q-axis). Analysis reveals that this configuration reduces torque ripple and enhances output torque. A multi-objective genetic algorithm (MOGA) is applied to optimize this asymmetric design considering mechanical constraints. The analyses are validated by manufacturing and testing a 5-kW asymmetric SFI-PM machine with a higher number of FBs along the FD of the spoke magnet axis.

This contribution elucidates the impact of the fillet radius (FR), a geometric feature of rectangular insulated wires not commonly considered, on the partial discharge inception voltage (PDIV) in low-voltage machine turn-to-turn winding insulation. Initial PDIV tests involve edgewise-insulated wire samples with a reference FR. These measurements are performed under constant conditions: 30 °C temperature, 35% relative humidity (RH), and atmospheric pressure (1000 mbar). These tests are carried out under ac 50-Hz excitations, following IEC 60034-18-41 guidelines for inverter-fed motor insulation system qualification. Subsequently, a probabilistic PDIV predictive model is developed based on Schumann’s streamer inception criterion (SCSIC). This expanded model then analyzes and forecasts the impact of the FR on PDIV and its associated dispersion level, within the context of the two-parameter Weibull distribution and the given environmental conditions. Furthermore, a novel method is presented to understand partial discharge (PD) phenomenology and its destructive potential in rectangular insulated wires with varying fillet radii. This approach employs SCSIC-derived streamer inception parameters (SIPs): critical field line length (CFLL), air effective ionization coefficient ( $\alpha _{\text {eff}}$ ), PD inception field ( ${E}_{\text {inc}}$ ), and firing voltage ( ${V}_{\text {firing}}$ ). The developed probabilistic predictive model enables the selection of an optimal FR value, facilitating the creation of a reliable insulation system with maximum PDIV and minimal PD-related damage.

This contribution develops the partial discharge inception voltage (PDIV)-finite-element method (FEM)-based model based on Schumann’s streamer inception criterion (SCSIC) with respect to thermal aging time (TAGT) or the insulation lifetime for the turn-to-turn insulation of coil winding made by rectangular insulated wires. The accelerated thermal aging is performed at 250 °C, which is 50 °C higher than the thermal class, with aging intervals of 156 and 312 h. PDIV measurements are conducted at a constant temperature of 25 °C, 40% relative humidity, and atmospheric pressure (1013 mbar). The measurements are done under ac 50-Hz excitations, following IEC 60034-18-41 guidelines for inverter fed motor insulation system qualification. Furthermore, this study analyzes streamer inception parameters such as critical field line length (CFLL), effective ionization coefficient ( $\alpha _{\text {eff}}{)}$ , partial discharge (PD) inception field ( ${E}_{\text {discharge}}{)}$ , firing voltage ( ${V}_{\text {firing}}{)}$ , and its correlation with PD charge amplitude as a function of TAGT or the insulation lifetime.

Most industrial applications concern output torque, rotor mass, and utilization of rare Earth permanent-magnet (PM) material of electrical machines. Generally, it is challenging to improve these aspects simultaneously. The objective of this article is to propose a novel concentrated-flux-type PM machine with irregular magnets and iron poles (CPMIP). The configuration has following advantages. First, the employment of quasitrapezoid magnets with opposite magnetization direction and large cross-section helps to enhance the flux-focusing effect and thus the torque generation. Second, the quasitriangular iron poles can improve the magnetic self-shielding effect well, and thus the rotor yoke can be removed completely and the rotor mass could be reduced significantly. Third, due to the reduction of PM volume and the improvement of torque output, the PM utilization ratio of electrical machine can be increased greatly. The schematic structure and pole patterns of the proposed electric machine are presented. Subsequently, the equivalent magnet circuit is established to validate the performance improvement of the CPMIP machine. Then, the design improvement with offset iron-pole arc is proposed to suppress torque ripple and balance torque output and PM utilization ratio capability well. Following that, an electrical machine with the irregular magnets and iron poles is designed. Then, the electromagnetic characteristics of the proposed pole designs are compared with those of the electric machines with conventional radial, Halbach, and consequent-pole patterns. Finally, the research prototype is developed, and experiments are conducted to verify the design concept and analysis of CPMIP machine.

For a five-phase permanent magnet synchronous machine (PMSM), the third-order harmonic back EMF is increased by changing the shape of the permanent magnet for increasing average torque in healthy operation. Additionally, in the open-circuit (OC) and short-circuit (SC) faults, the effect of injected third-order harmonic back EMF also needs to be considered. Therefore, this paper proposes a fault-tolerant control method with original transformation matrixes and coefficients reconfiguration in fundamental and third-order harmonic subspaces for both single-phase OC and SC faults. Fault tolerance can be applied by reconfiguring the relative coefficients after an OC or SC fault occurs, depending on the type of fault. Besides, the proposed method aims to optimize the OC fault tolerance strategies and effectively solve the single-phase SC fault, considering the influence in the third-order harmonic back EMF. According to experimental results, the torque fluctuation after applying the proposed method is similar to that in the healthy stage and much lower than that using most fault-tolerant control methods without considering the third-order harmonic back EMF.

This article proposes a novel method to estimate the parameters of isotropic PMSMs which uses only steady-state measurements of load conditions commonly available during the regular operations of off-the-shelf industrial drives. Differently from existing online and offline approaches, the proposed method is designed considering real-world scenarios where ad-hoc tests, additional sensors and the implementation of custom software procedures, such as signal injection, are highly discouraged. The rotor flux linkage, the stator resistance and inductance are estimated with the aid of Adaline neural networks using two operating conditions of the motor. Considering parameter variations according to the actual operating conditions as well as the influence of the inverter nonlinearity and actuation delay, the estimation errors are minimized by proper selecting these two optimal conditions. The accuracy of the proposed method is validated by simulation and experimental studies considering scenarios with different number of motor operating conditions.

Purpose: This study provides a detailed investigation on the prediction and diagnosis of unsteady electromagnetic vibroacoustic performance of IPMSMs for electric vehicles under typical unsteady operating conditions with consideration of rotor step skewing and current harmonics. Methods: Firstly, the control model considering the influence of PWM carrier modulation and rotor step skewing is established. Based on this, the currents of the IPMSM under unsteady operating conditions (driving condition and feedback braking condition) are obtained. Accordingly, the currents calculated through the control model are used as the excitation source of electromagnetic finite element. Then, the electromagnetic vibroacoustic performance under unsteady operating conditions is calculated through electromagnetic force subsection mapping and acoustic transfer vector (ATV) method. Moreover, the conditions where resonance vibroacoustic occurs are diagnosed. Finally, the results of prediction and diagnosis are fully verified by experiments of multiple physical fields. Results and Conclusions: The amplitude errors between prediction results and test results are less than 3.2$\%$\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\%$$\end{document}. The influence of current harmonics on electromagnetic vibroacoustic can be predicted. The frequency range and speed range of predicted peak vibroacoustic are consistent with the experimental results. The rotor step skewing can be used to weaken the vibroacoustic amplitude of IPMSMs under typical unsteady conditions in the full speed range. This study provides guidance for prediction and diagnosis for electromagnetic vibroacoustic performance of IPMSMs under typical unsteady operating conditions.

The automotive intelligence and electrification require the braking system to cooperate with the controller to achieve regenerative and active braking functions. Hence, the range and driving safety of the electric vehicles are improved. Electromechanical brake (EMB) systems completely abandon the fluid and hydraulic elements and replace the traditional hydraulic braking system with a wire harness and electromechanical parts. The braking torque adjustment is achieved entirely by controlling the four-wheel EMBs. At present, reliability and fault tolerance are the key technical issues associated with EMBs. To eliminate the need of any clamping-force sensor due to its vulnerability and high cost, in this article, a switching extended state observer (SESO) is presented to provide rapid force estimation with higher precision. The substrates of the internal linear and nonlinear structures have been unified into a single form by using an equivalent gain method. The SESO is effective to detect the initial contact between the braking disk and pad by estimating the load torque. It is experimentally verified that the developed force sensorless control strategy is accurate and superior to the existing techniques.

This paper presents a systematic comparative design study of permanent magnet assisted synchronous reluctance (PMaSyR) machines for a light traction application aimed at considering an holistic approach for a given outer envelope and cooling system specification. Electromagnetic, structural and thermal aspects are all accurately considered in a computationally efficient manner using a hybrid analytical-finite element (FE) design approach. The SyR machine geometries providing the maximum torque with increasing number of poles are identified and their performance deeply investigated with full FE analysis. The study has been carried out considering several requirements in terms of base and maximum speeds with the aim of drawing general design considerations. Results reveal that the optimal pole number from a torque perspective depends on the considered maximum speed. The reasons behind this behavior are fully investigated as well as how and why the optimal geometries change. The optimal SyR machines are then compared also considering the insertion of permanent magnets within the rotor slots with the aim of maximizing the constant power speed range. The rationales behind the selection of the machine to manufacture are then outlined including aspects related to efficiency and demagnetization under the worst short circuit condition in the entire torque-speed range. The optimized machine (after a FE-based design refinement) has been manufactured and tested on an instrumented test bench validating the proposed design approach and the deduced design insights.

Due to the different design optimization, five-phase electrical machines can have a nonnegligible distortion in their back electromotive force (EMF) waveform. Most fault-tolerant control methods for this machine used extra fundamental and third-order harmonic currents to eliminate the torque fluctuation due to the nonsinusoidal back EMF, bringing high copper loss. An open-circuit fault tolerant control using the original transformation matrix is proposed in this article with the objective of converting the parts of torque fluctuations into useful output for copper loss reduction by harmonic current injection. Compared with the previous methods, the proposed method has not only low torque fluctuations, but also the copper loss is reduced by 29% further. Copper loss reduction and the dynamic response of the proposed method are experimentally verified, confirming the advantage of the proposed method.

Five-phase machines represent a widely adopted choice for fault-tolerant applications due to their extra degrees of freedom. This article deals with the single-phase short-circuit fault tolerant control using original transformation matrix for five-phase permanent-magnet machines. The proposed method first follows the fundamental phase current injection (FCI) method based on the calculated SC current. Moreover, third-order harmonic phase current injection (THCI) method is presented to reduce copper loss. The computational method of derating factor is also adopted for industrial applications. The fault tolerance and dynamic performance are also verified by the experimental results. A reduction of copper loss in THCI method by about 15% is achieved, compared with general and FCI methods.

This article proposes a nonintrusive parameter identification procedure suitable for Internet-of-Things (IoT)-embedded isotropic permanent magnet synchronous machines (PMSMs). The method is designed for scenarios where only measurements collected without additional sensors, dedicated tests, or signal injection from in- service off-the-shelves motor drives are available. After automatic detection of the steady-state operating conditions (OCs) defined by the triplet current–speed–temperature, the rotor flux linkage, the stator resistance, the inductance, and the inverter distorted voltage term are estimated using two operating points. Particular emphasis is placed in defining the criteria of selecting these two optimal OCs to minimize the estimation errors. The latter are due to the inevitable difference between the parameters in different operating points. As a vessel to investigate the effectiveness of the proposed parameter identification, experimental and simulation tests carried out on a high-speed PMSM drive have been used for validation purpose. The proposed method is also compared with the existing methods from the literature to demonstrate its superiority in the considered scenario.

Motor drives form an essential part of the electric compressors, pumps, braking and actuation systems in the More-Electric Aircraft (MEA). In this paper, the application of Machine Learning (ML) in motor-drive design and optimization process is investigated. The general idea of using ML is to train surrogate models for the optimization. This training process is based on sample data collected from detailed simulation or experiment of motor drives. However, the Surrogate Role (SR) of ML may vary for different applications. This paper first introduces the principles of ML and then proposes two SRs (direct mapping approach and correction approach) of the ML in a motor-drive optimization process. Two different cases are given for the method comparison and validation of ML SRs. The first case is using the sample data from experiments to train the ML surrogate models. For the second case, the joint-simulation data is utilized for a multi-objective motor-drive optimization problem. It is found that both surrogate roles of ML can provide a good mapping model for the cases and in the second case, three feasible design schemes of ML are proposed and validated for the two SRs. Regarding the time consumption in optimizaiton, the proposed ML models can give one motor-drive design point up to 0.044 s while it takes more than 1.5 mins for the used simulation-based models.

Surface permanent magnet synchronous machines are one of the most widely adopted machine topologies in high-speed applications where efficiency and power factor cannot be compromised. Although the design of such machine type has been extensively investigated in both industry and academia, this work aims at addressing its limitations when applied in high-speed applications. First, this paper proposes an accurate design methodology for continuous-duty high-speed surface-mounted permanent magnets synchronous machines, capable of accounting for the rise of the speed-dependent losses and structural needs with a limited impact on the computational burden. The outlined approach can be used to speed-up the initial design stage as it allows to reduce the number of solutions to evaluate before commencing the refinement stages required before the definition of the final design. Indeed, the introduced design approach is used to systematically assess the maximum power capability as function of the maximum speed and the airgap thickness for a given outer envelope and cooling system. The influence of the high-speed limiting factors is deeply investigated also considering their effects on the machine geometries providing the highest torque. The selection of the final design is discussed and justified. Experimental results of the 4.2 kW-80 kprm prototype validate the design methodology.

This article proposes a modulated model predictive torque and flux control (M2PTFC) method with low complexity for a two-level voltage source inverter (2L-VSI)-fed permanent magnet synchronous motor (PMSM). The proposed strategy aims to reduce the computation burden and simplify the control implementation of the conventional M2PTFC scheme by reducing the number of candidate voltage vectors at every control sample to the minimum (i.e., only two candidates) and eliminating the weighting factor of the cost function and its corresponding tuning procedures. For these purposes, the proposed method devotes different control objectives to the duty modulation and the cost function evaluation processes while executing them sequentially. First, aiming at torque ripple reduction, a duty modulation strategy is proposed based on the analysis of torque deviations produced by different voltage vectors, which ensures proper selection of the two candidates and restricts active voltage vectors (AVVs) that cause high deviations. Then, these candidates are evaluated based on a cost function assigned to achieve the stator flux control objective. The effectiveness of the proposed control scheme is verified through comparative assessment with the conventional M2PTFC and two existing simplified methods by means of simulation and experimental results.

Implementation of proportional–integral (PI) controllers in the synchronous reference frame (SRF) is a well-established current control solution for electric drives. It is a general and effective method in digital control as long as the ratio of sampling-to-fundamental (S2F) frequency ratio, $r_{\mathrm {S2F}}$ , remains sufficiently large. When the aforesaid condition is violated, such as operations in high-speed or high-power drives, the performance of the closed-loop system becomes incrementally poor or even unstable. This is due to the cross-coupling of the signal flow between $d$ - and $q$ -axes, which is introduced by the SRF. In this article, an accurate model of current dynamics, which captures the computational delay and PWM characteristics in the discrete-time domain, is developed. This motivates the investigation of eliminating cross-coupling effects in permanent magnet synchronous motor (PMSM) drive systems. A new current control structure in the discrete-time domain is proposed targeting full compensation of cross-coupling effects of SRF while improving dynamic stiffness at low S2F ratios. The matching simulation and experimental results carried out on a 5-kW high-speed drive corroborate the theoretical analysis.

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.

Synchronous reluctance (Syn-Rel) machines with embedded permanent magnets (PMs) are research hotspots in variable speed motor drives due to their robust rotor structure and wide constant power speed range (CPSR). In this article, the potential of PM-assisted Syn-Rel machine to be next generation heavy duty traction motor solution has been investigated, with special attention put on one key geometric parameter, i.e., airgap length. Careful machine design and optimization has been conducted based on geometric parametrization including airgap length variation, for 15000 rpm peak speed and 350 kW peak power output. In low speed operations, the influence of airgap length on different torque components has been analyzed in detail based on the frozen permeability method. In field weakening region, the variation trend of several key parameters such as output power, torque ripple, and power losses have been investigated along with airgap length. It is found that with high electric and magnetic loading, reducing the electromagnetic airgap length is not always beneficial. There exists a suitable airgap length value to comprehensively balance torque/power density, cooling capability, efficiency and reliability. Numerical FEA and experimental tests of the prototype are combined to verify the conclusions.

Advances in electrical machines and power electronics (PEs) are helping to achieve the power density and efficiency required by the transportation sector. However, the reliability of components and production processes is a challenge. This is especially true for electrical machines, whose winding processes are far from the high levels of automation, programmability, and repeatability that are required. This article looks into hairpin windings and outlines a number of future actions to address challenges and eventually enable the complete penetration of hairpin windings in transportation.

The insertion of permanent magnets (PMs) within the rotor slots of Synchronous Reluctance Machines (SyRM) is the most common design strategy used to increase significantly their performance. In this paper it is shown how a permanent magnet assisted synchronous reluctance machine (PMaSyRM) can be optimized to satisfy all the electromagnetic and structural constraints arising as the maximum operating speed increases. This is done considering a variety PMs material. This work, the second of two companion papers, briefly recalls the novel systematic design approach proposed in Part I, and then describes the characteristics of the optimal machines achieved considering a maximum speed ranging from 1 to 140 krpm with and without the assistance of ferrite and neodymium based PMs. The reasons behind the performance deterioration as the speed increases are all investigated along with the geometrical variations of the optimal designs. The selection of the design solution to be manufactured is justified as well as the final structural and electromagnetic refinement stages leading to the prototype. All the reported considerations are experimentally validated testing an 8.5 kW at 80 krpm PMaSyRM, comparing the measured and expected performance in terms of torque and internal power factor.

The design of synchronous reluctance machines with and without permanent magnets assistance constitutes a challenging engineering task due to the numerous design variables and performance indexes to be considered. The design complexity increases even further when the application requires high speed operation, with consequent rotor structural constraints and related effects on the electromagnetic performance. Structured as two-parts companion papers, this work proposes a comprehensive design procedure able to consider all the non-linear aspects of the machine behaviour, greatly reducing the number of independent design variables, without worsening the computational burden. In particular, the non linear behaviour of the rotor iron ribs and the effect of the permanent magnets on the structural design are all taken into account with the proposed iterative design procedure targeting the achievement of a desired power factor. The proposed method will be then used to draw some preliminary design considerations highlighting the several trade-offs involved in the design of high speed permanent magnet assisted synchronous reluctance machine. Part I is setting the theoretical bricks that will be further expanded and experimentally validated in the companion paper Part II.

Control of interior permanent magnet synchronous motors (IPMSMs) has been extensively attempted without any position sensor. At extremely low speeds, sensorless operation would not rely on the fundamental model-based sensorless methods since the situation becomes more sophisticated. The existing high-frequency (HF) injection techniques predominantly concentrate on current or voltage excitations. Whereas, compromises are made between the signal strength and inevitably generated current fluctuations and torque ripples. Noise and disturbances could also deteriorate the performance. To accomplish the low speed sensorless operation successfully, this paper presents a position error observer and a current injection scheme for the extremely low speed sensorless operation. A discrete-time super twisting extended-state observer (STESO) extracts the estimated position and speed considering the disturbances. The design of the HF observer is carried out. The lowest speed is extended down to 2% rated value in the experimental tests.

This study uses the Neural Network (NN) technique to optimize design of surface-mounted Permanent Magnet Synchronous Motors (PMSMs) for More-Electric Aircraft (MEA) applications. The key role of NN is to provide dedicated correction factors for the analytical PMSM mass and loss estimation within the entire design space. Based on that, a globally optimal design can be quickly obtained. Matching the analytical estimation with Finite-Element Analysis (FEA) is the main research target of training the NN. Conventional analytical formulae serve as the basis of this study, but they are prone to loss accuracy (especially for a large design space) due to their assumptions and simplifications. With the help of the trained NNs, the analytical motor model can give an estimation as accurate as the FEA but with super less time during the optimization process. The Average Correction Factor (ACF) approach is regarded as the comparison method to demonstrate the excellent performance of the proposed NN model. Furthermore, a NN aided three-stage-seven-step optimization methodology is proposed. Finally, a Pole-10-Slot-12 PMSM case study is given to demonstrate the feasibility and gain of the NN aided multi-objective optimization approach. In this case, the NN aided analytical model can generate one motor design in 0.04 s while it takes more than 1 min for the used FEA model.

Recently, active disturbance rejection control (ADRC) scheme has been widely used for current regulation in ac drive systems owing to its robustness to system uncertainties and its high disturbance-rejection capability. However, it has not been considered as an option for high-speed drives usually operated at limited switching and sampling frequencies. Therefore, this article thoroughly analyzes and discusses the effects of high operating speed, modulation, and computational delays on the conventional ADRC. Based on this analysis, an enhanced ADRC for the current control is proposed to operate the drive system at low sampling time ratio with high robustness to the internal and external disturbances. Effect of model uncertainties on the proposed scheme has also been analytically analyzed and reported. Comprehensive simulation and experimental results have been presented to demonstrate the improved performance of the proposed ADRC scheme and to support the analytical studies.

The influence of hub motor unbalanced magnetic force (UMF) on the vibration of electric vehicle under steady state conditions has been known, but under unsteady conditions, the hub motor UMF will change with the vehicle operation condition, and there would exist complex coupling vibration for the hub motors driven electric vehicle. Here, the longitudinal-vertical coupling dynamics of the four hub motors driven electric vehicle under unsteady condition is studied. Integrating the motor electromagnetic excitation and electric vehicle dynamics, a longitudinal-vertical coupling dynamics model of the four hub motors driven electric vehicle is established. Based on the variable switching frequency field-oriented control model, analytical model of the UMFs acting on the motor stator and rotor parts under unsteady condition are developed. For model validation, a four hub motors driven electric vehicle has been tested, the accuracy of the longitudinal-vertical coupling dynamics model established in this paper was verified. Then, longitudinal-vertical coupling vibration characteristics of the four hub motors driven electric vehicle under road excitation and coupling excitation are analyzed. The results show that the longitudinal and vertical movement of the four hub motors driven electric vehicle is coupled by hub motor. In addition, under unsteady condition, the motor UMFs will cause vertical vibration of the electric vehicle body and hub motor stator, the vibration shows order characteristics including low order harmonic hfcand inverter switching frequency sideband harmonic k1fs±k2fc(fc= pn/60, fsis inverter switching frequency, k1and k2are positive integers, pis the number of pole pairs and nis motor speed.). The motor electromagnetic torque will cause longitudinal vibration of the electric vehicle body, the vibration shows order characteristics including harmonics fs±3fcand 2fs. The main harmonic of vehicle body pitch angle acceleration is 2fs.

This article proposes a four-degree-of-freedom overmodulation strategy for five-phase space vector pulsewidth modulation (SVPWM) in order to reduce the low-order harmonics of the output voltage during overmodulation. Based on the nearest-four-vector SVPWM algorithm, this overmodulation strategy calculates the corresponding third harmonic injection rate according to the modulation ratio in the overmodulation region. What is more, this strategy optimizes and controls the third harmonic so that basic voltage vectors of the fundamental wave subspace and the third harmonic subspace can be controlled simultaneously, thus effectively decreasing the low-order harmonic contents without reducing control degrees of freedom. The whole overmodulation region is divided into three subregions with linearized approximation to reduce the complexity of computation. Simulation and experimental results demonstrate that under the same modulation ratio during overmodulation, the proposed overmodulation strategy can improve the dc bus voltage utilization of a five-phase inverter, make the third harmonic controllable with four control degrees of freedom, and also reduce the low-order harmonic contents of the output voltage.

Modular parallel-connected dc–dc converters with interleaved operation are a well-known solution for a wide-application range in order to achieve high-quality waveforms with reduced rate power devices. Usually, modular parallel-connected converters share equally the power achieving ideally an inherent aging equalization. However, hardware asymmetries or replacement of damaged modules after maintenance operations create an unavoidable aging mismatch between the power modules. In this article, a method to equalize the aging of the power modules of parallel-connected dc–dc converters is presented. The method is particularized for boost converters. It is based on the power routing concept forcing a nonequalized power sharing among the modules of the modular converter. The power routing technique improves the remaining useful lifetime of the converter reducing the maintenance costs. Experimental results are shown in order to show the good performance of the proposed method. The results are also supported by a statistical analysis based on a Monte Carlo approach to evaluate the robustness of the proposed solution.

In this paper the important impact of high temperature withstand on performance of electromagnetic actuators for aerospace applications is illustrated. Particular materials enabling high performance and increased reliability in such applications are analysed both through numerical simulations and experimental validation. Specific examples outline advancements in electrical machine technologies for this class of problems.

Six-phase permanent magnet synchronous machine and the control system are also widely used in industry, precision instruments and aerospace. However, most PMSMs employ magnet patterns either in alternatively radial magnetization or Halbach array, which may constrain the performance improvement in a certain degree. Therefore, a novel six-phase trapezoidal Halbach magnet array (THMA) is proposed in this paper. Six-phase permanent magnet synchronous machines (PMSMs) can reduce the harmonic components of magnetic flux in air gap, and decrease the iron loss and electromagnetic vibration caused by harmonic torque. Thus, it helps to improve the working efficiency and depress the torque ripple of the electrical machine. Dual three-phase windings are employed for the stator design to further improve the power density and reliability of the machine. Six-phase vector model of the machine is built based on dual dqcontrol. It can minimize the electric coupling, magnetic coupling and thermal coupling. The radial electromagnetic force of the machine under load or no load is extracted, then the harmonic decomposition of the radial electromagnetic force for the spatial with time Fourier decomposition is carried out to obtain the force amplitude of different orders which is conducive to analyze the vibration characteristics of the machine.

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.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.