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Due to the increasing demand for high-speed motors with high stability, bearingless motors have attracted much attention. Bearingless permanent magnet synchronous motors (BPMSMs) are a kind of motor, which uses suspension force to eliminate the motor bearings. This article proposes a five-phase BPMSM with 10 slots and 8 poles. Based on the principle of suspension force of BPMSM, an analytical expression of the suspension force is derived for the proposed BPMSM. To improve the suspension stability and torque, an optimization method consisting of a response surface model and a multiobjective optimization algorithm is employed. Not only the geometric parameters but also the winding distribution are considered in the optimization process. Finally, the effectiveness and superiority of the optimal design are verified by experiment.

In this study, we propose a fast topology optimization (TO) method based on a deep neural network (DNN) that predicts the current-dependent motor torque characteristics using its cross-sectional image. The trained DNN is shown to provide the current condition that provides the maximum torque under the assumed motor control method. The proposed method helps perform TO with a reduced number of field computations while maintaining a high search capability.

In this paper, a parallel-series magnetic circuit multi-permanent magnet motor is designed and optimized considering magnet characteristic variation effects, where two kinds of PMs are utilized as co-magnetic. Based on the equivalent magnetic circuit method, the detailed design method for the multi-permanent magnet motor is illustrated. And considering the various operation conditions in potential EV applications, the B-H curves of two PMs of different typical operation conditions are obtained. Then, a multi-objective optimization method is newly proposed which not only focuses on the magnet characteristics variation effect, but also considers output torque, toque ripple as well as anti-demagnetization capability under three typical operation conditions. And the performance of the initial motor and optimal motor are compared under typical operation conditions. Finally, a prototype machine is built and tested. Both theoretical analysis and experimental results verify the validity of the motor and the proposed design optimization method.

This paper deals with the finite element analysis of Hybrid Excitation Permanent Magnet Synchronous Motors, that is, synchronous motors characterised by a rotor including both permanent magnets and an excitation winding. Such a winding is adopted to modulate the rotor flux so that the motor exploits the maximum torque for any operating speed. The higher benefit is obtained at speeds higher than the nominal speed, i.e. during the flux weakening operations. Thus the focus is to determine the flux weakening performance of different topologies of hybrid excitation PM synchronous motors, considering different topologies. In addition, the performance parameters are compared to those achieved with a standard interior PM synchronous motors. The possibility to vary the rotor flux in the hybrid excitation PM motors allows to design the motor with a high no-load flux linkage, necessary to get high torque at low speeds, and to get high torque in a wide speed range.

Powered prosthesis actuation is a field where energy efficiency and mass are important characteristics. The motion requirements of high torque at low speed and low torque at high speed are difficult to effectively combine in a single electric motor. A possibility is to use an oversized direct–drive motor that can deliver the peak torque. However, this results in a heavy actuation system and low overall efficiency. A common practice is combining a smaller electric motor with a gear reduction system. In literature, novel redundant electric actuation systems have been presented with or without locking mechanisms to mitigate this problem. In this work, we provide a comparison of multiple electrical actuation systems composed of electric motors, gear reduction systems and locking mechanisms are compared to each other. This is done using the gait cycle of a human ankle as a case study. An electric motor with a double stator and a single rotor combined with a gearbox shows the most promising overall results when taking energy loss, total mass and complexity of the system into account.

In this article, based on flux modulation theory, an airgap-harmonic-based multilevel optimization design approach is proposed for a double-stator flux-modulated permanent-magnet (DS-FMPM) motor. The proposed DS-FMPM motor is purposefully designed, so as to realize the design requirements of driving cycle. In the proposed optimization approach, based on three fundamental elements of general flux modulation theory, motor optimization design is carried out from three levels. Furthermore, a response surface method, sensitivity analysis, and a genetic algorithm are purposely employed in different levels to obtain optimal motor design. In addition, electromagnetic performances of a DS-FMPM motor are demonstrated in detail. Finally, a prototype motor is manufactured and tested. Both simulation and experimental results verify the feasibility of the DS-FMPM motor and the effectiveness of the proposed airgap-harmonic-based multilevel optimization design approach.

With the large‐scale development of the ball mill, the direct‐drive gearless ball mill has emerged, eliminating the limitation of the transmission torque of large gear. However, it is difficult to process, transport, install and maintain the gearless ball mill because of its vast volume, and the coils cannot be decoupled freely. Therefore, this work proposes a module combined permanent magnet motor with wrapped type for mine ball mill (MBMWT‐MCPMM). Based on the principle of removing coils, the stator is modularized. Each module can be regarded as a small rotary motor, which improves the reliability and fault tolerance of the motor. In this work, the structure and general design process of the MBMWT‐MCPMM are described, and the electromagnetic performance is simulated and analysed. The influence of different factors on the cooling effect of the motor and the temperature rise of different modules during fault‐tolerant operation are analysed. An 80 kW prototype is developed, and its experiments are carried out. The experimental results verify the validity of the related design and analysis.

This work presents the comparative study of the linear tubular permanent magnet motor (LTPMM) for the active suspension system in vehicles. To analyse and design the LTPMM, a finite element‐based optimisation process is proposed. Since the proposed method reconstructs the entire field by storing the information of the air‐gap magnetic flux distribution in the form of a snapshot, it provides high accuracy and a reduced computation time. The magnetic fields are analysed in LTPMMs with external and internal permanent magnets that are classified according to the position of the permanent magnet. In the comparative analysis, an optimal model for the LTPMM is presented, taking into account characteristics such as thrust, detent force and THD. Especially, various magnetisation patterns are considered to accomplish high force density. The analytical model is verified by performing finite element analysis and experiments.

This article proposes the core loss reduction of a surface-mounted permanent magnet motor with a segmented stator core. First, it is shown that the core loss of a motor is decreased by the segmentation of a stator core made of a nonoriented electrical steel sheet. The nonoriented electrical steel sheet used as the segmented stator core has an anisotropy, which is easy to magnetize in the rolling direction. Therefore, it is important to investigate the core loss of the segmented stator core in consideration of the rolling direction of the electrical steel sheet. The rolling direction of the steel sheet can be taken into consideration in magnetic field analysis by using the Enokizono & Soda (E&S) model, which is one of the vector magnetic property utilization techniques. Accordingly, the finite-element method, which introduced the E&S model, is used to evaluate the core loss of the motor. Second, the core loss of the segmented stator core is further reduced by applying a corner radius to each tooth root. Finally, the relation between the core loss and the rolling direction in the segmented stator core applying corner radius is investigated.

Electrical machines are widely used in home appliances, the performance of which is mostly related to the quality function of the electrical machines. What has been used so far in home appliances brought with themselves a wide assortment of advantages and disadvantages. With the aim to overcome the drawbacks of the previously implemented electrical motors in washing machines, a new configuration of flux switching permanent magnet motor (FSPM) with the segmented outer rotor (SOR‐FSPM) is proposed benefitting from a direct driven drum. To reduce the cogging torque as well as torque ripple and to improve the total harmonic distortion, cutting the stator in a way to lower overlapping between the rotor and stator pole, inserting notches into the poles of the rotor to modify the air gap between the stator teeth and the rotor segments are proposed. The Taguchi method and sensitivity analysis are further applied to find the best combination set of changes in such a way to smoothen the chart showing reluctance between stator and rotor and fix the zero‐point crossing of the flux linkages in different rotor positions. Finally, the proposed SOR‐FSPM is prototyped, and experimental results along with the finite element method results are discussed and compared in order to verify the design process.

This paper proposes a novel torque measurement and control technique for cycling-assisted electric bikes (E-bikes) considering various external load conditions. For assisted E-bikes, the electromagnetic torque from the permanent magnet (PM) motor can be controlled to reduce the pedaling torque generated by the human rider. However, the overall cycling torque is affected by external loads, including the cyclist’s weight, wind resistance, rolling resistance, and the road slope. With knowledge of these external loads, the motor torque can be adaptively controlled for these riding conditions. In this paper, key E-bike riding parameters are analyzed to find a suitable assisted motor torque. Four different motor torque control methods are proposed to improve the E-bike’s dynamic response with minimal variation in acceleration. It is concluded that the wheel acceleration is important to determine the E-bike’s synergetic torque performance. A comprehensive E-bike simulation environment is developed with MATLAB/Simulink to evaluate these adaptive torque control methods. In this paper, an integrated E-bike sensor hardware system is built to verify the proposed adaptive torque control.

Low‐speed and high‐torque direct‐drive permanent‐magnet motors have found wide applications primarily due to their outstanding performance characteristics. The special applications of these motors demand high reliability against the motor drive system, that is, the power system should have a certain level of fault tolerance. Therefore, the fault‐tolerant motor drive system has been the focus of research all over the world. Many fault‐tolerant motors can only deal with the open‐circuit fault of the winding or drive, and their capability of fault tolerance is substantially limited. When in operation, the short‐circuit fault caused by the ageing of winding insulation may result in more serious hazards than the open circuit in the winding. Such serious faults should be tolerated by the fault‐tolerant system. Moreover, the simpler maintenance or shutdown repair upon completion of fault‐tolerant operation of large‐sized fault‐tolerant motors should also be considered. Therefore, a permanent‐magnet fault‐tolerant motor with module combination stator (MCS‐PMFTSM) and unequal span winding is proposed. By changing the winding structure of the conventional motor the modular operation of the whole motor is achieved, which not only provides the motor with a high fault tolerance capacity but also reduces the downtime during repair and maintenance. In this work, the structure and operating principles of the MCS‐PMFTSM are described followed by the evaluation of the operation performances of the MCS‐PMFTSM under different fault conditions and various control strategies. The fault‐tolerant capacity of this new machine is then analysed, and the prototype is tested with a power of 12 kW and a rated speed of 100 r/min. Both theoretical analysis and test results demonstrate the outstanding operation performance and high fault tolerance of the motor.

This paper investigates the electromagnetic and structural characteristics of a spoke type BLDC motor and provides a comparative study with respect to Interior Permanent Magnet motor (IPM).The electromagnetic analysis aims to determine the average torque and cogging torque of spoke type BLDC motor. The natural and induced vibration characteristics of the motor are evaluated by performing structural finite element analysis. The electromagnetic and vibration characteristics are assessed for different slot/pole combination to provide an insight on their influence on the performance of the motor. In addition, thermal analysis is performed to predict the temperature distribution and a comprehensive analysis of spoke type BLDC motor is presented.

To better address the requirements of integrated equipment, here, a multi‐branch modular permanent magnet motor using a toroidal winding with reverse turn coils is proposed. High‐speed motors have a large winding span, and the use of a toroidal winding with reverse turn coils in place of lap windings can effectively shorten the length of the motor end. Motor modularisation can improve production, assembly efficiency, and the maintenance economy. To innovate the windings from a basic toroidal winding, a modularised toroidal winding with reverse turn coil is proposed which enables the motor to be decoupled in electrical and mechanical structures. The inductance parameter calculation and finite element simulation verification are carried out on the new winding structure and the lap windings. The feasibility of the 60‐degree phase toroidal winding with a reverse turn coil structure with reverse turns is also assessed. The no‐load back electromotive force of the new winding structure is a square wave, which will bring certain torque fluctuations. To improve the performance of the motor, the method of radial magnetic pole segmentation is used, and the new magnetic pole is analysed and verified by the segmented magnetic circuit. Finally, the combination of magnetic pole segmentation is explored, and the effect of different segmentation methods on the performance of the motor is compared.

This paper develops an adaptive type-2 fuzzy logic controller for direct torque control of a permanent magnet synchronous motor. The type-2 fuzzy logic systems are used for modeling the unknown functions. The adaptive law proposed takes in consideration the compensation of reconstruction errors by adding a sliding mode term. This term ensures the stability and the robustness of the control system regardless the internal and external disturbances. The stability of closed-loop system was verified using Lyapunov’s stability theorem. Moreover, the proposed control scheme guarantees that all involved signals are bounded. The effectiveness and the feasibility of the proposed control method are demonstrated by extensive presentation and discussion of simulation results.

In order to optimize and analyze the cogging torque of hybrid stator motor, a hybrid stator motor is taken as the research project. The axial distribution of air gap magnetic flux density was analyzed, and the analytical formula of the cogging torque of the hybrid stator motor was derived. Combined with the cogging torque analytical formula, the superposition calculation method of cogging torque of hybrid stator motor was proposed, and the correctness of the superposition calculation method was verified by simulation analysis. The silicon steel segment and the amorphous alloy segment of hybrid stator core were optimized by using the uneven air gap structure, and the optimized results of the silicon steel segment and the amorphous alloy segment were obtained by two-dimensional simulation. Based on the results of two-dimensional simulation analysis, a three-dimensional model was built for simulation analysis. After optimization, the cogging torque of the motor was weakened by 48.1% and the torque ripple was reduced by 1.32%, while the loss and output torque remained basically unchanged.

The large current ripple caused by the limited switching frequency significantly degrades the control performance of the high-speed permanent magnet motor drive system. To mitigate the current ripple, the switching frequency of the inverter should be high enough. The purpose of this article is to reduce the current ripple of the HSPMSM drive system. First, a Silicon-Carbide/Silicon(SiC/Si) hybrid inverter is designed. The designed hybrid inverter consists of two SiC-MOSFETs and six Si-IGBTs, and the circuit modals of the SiC/Si hybrid inverter are analyzed. Second, based on the SiC/Si hybrid inverter, three improved space-vector-modulation (SVM) strategies are proposed. The core principle of the proposed SVM strategies is that most of the switching actions are transferred from the Si-IGBTs to the SiC-MOSFETs. The benefit from the low switching loss of the SiC device is that the total power loss can be significantly reduced. Besides, the SiC-MOSFETs can create the zero-voltage-switch condition for the Si-IGBTs, and then the switching loss of the Si-IGBTs can be almost eliminated. Finally, to verify the effectiveness of the proposed methods, sufficient simulations and experiments are implemented. The stator current ripple, total-harmonic-distortion, and the conversion efficiency of the inverter in the full power range are compared under the same condition based on the full-Si-IGBT inverter, the full-SiC-MOSFET inverter, and the SiC/Si hybrid inverter. The evaluated results sufficiently verify the superiority of the proposed SiC/Si hybrid inverter and the improved SVM strategies.

Due to the need for developing technology and comfort today, the use of electric motors increases in different fields such as pumps, household appliances, fans, aerospace and mixers. This affects energy consumption and production costs, and ultimately triggered the development of higher performance motors. Because of the multi-parameter designs and nonlinear structure of electric motor, it has become very important the use of multi-objective optimization algorithms in design studies on electric motors. At the same time, real-time simulations are provided by using finite element analysis programs to reduce test costs. This study purposes analysis and multi-objective design optimization of a direct drive permanent magnet synchronous motor with external rotor for low speed and high torque mixer applications. So, the third-generation algorithm NSGAIII was used and compared with the second-generation algorithm NSGAII. To examine both initial design result and optimization results Ansys/Maxwell program was used. According to the initial result, optimized motor geometries provided an efficiency increase of about 3.54% and a cost reduction of about 17%. In addition, the search strategies of both algorithms were compared on motor design parameters.

The rotor eddy current loss of high‐speed permanent magnet motor has an important influence on the temperature distribution of permanent magnet. In traditional method, the unbalanced distribution of eddy current in permanent magnet is ignored, and the eddy current loss is applied to the calculation of temperature field in the form of average heat density, which makes a certain error in the calculation of the temperature field in permanent magnet motors. This study proposes the 50 kW and 30,000 rpm high‐speed permanent magnet prototype and an eddy current loss segmentation model of permanent magnet. The unbalanced distribution of eddy current in permanent magnet is considered in this model, and the permanent magnet is divided into different regions. According to the eddy current loss segmentation model, the eddy current losses in different regions are obtained, then the heat density in different regions of permanent magnet is applied to the calculation of temperature field in the motor. The application of the proposed model is simple and convenient, and makes temperature simulation results closer to the actual situation. At the same time, in order to verify the accuracy of the model, the temperature calculation results using the proposed model are compared with the traditional method, and both the results are verified by relevant experiments.

This article aims to implement a fan motor design with an airfoil-shaped rotor via the newly developed 3-D printing method. This integrated design is originated from a flux-switching permanent magnet motor, in which the motor rotor can directly produce airflow without any external impellers. Such a design and manufacturing process can effectively enhance the robustness of the fan motor structure and increase its power density. This article adopts 3-D finite element analysis for electromagnetic and fluid field simulation. Moreover, a new metal 3-D printing method with a low core loss feature during high frequency operation is applied. Finally, the experimental results with a prototype are presented to verify the designed performance.

Many-objective problems, characterized by a high-dimensional objective space, are a source of challenge for standard methods of multi-objective optimization. An evolutionary algorithm based on the concept of least-conflict solutions is here presented; the shape design of a IPM motor is considered as the case study. In particular, optimization problems dealing with 3 and 4 objective functions have been solved, respectively.

Tubular permanent magnet motor (TPMM) can offer great thrust force density and high efficiency. To enhance its robustness against disturbances and solve the contradiction between response time and overshoot, a novel sliding mode control strategy based on disturbance observer (DOB-SMC) was proposed for a TPMM velocity drive system. The novelty of the proposed velocity control strategy lies in the incorporation of the mismatch disturbance observer in the sliding surface and the sliding mode control (SMC) law, and the introduction of internal model control (IMC) into the SMC law. The velocity control system is transformed to a first-order inertia model by IMC, thus the dynamic response performance is improved. The mismatched disturbances are estimated and the equivalent control voltage is employed, and then the effect of mismatched and matched disturbances can be restrained with little chattering. The simulated and experimental results are presented as validation for the proposed strategy.

This paper proposes an optimal design for a surface-mounted permanent magnet motor (SPMM) to reduce torque pulsations, including cogging torque and torque ripple, by using multi-grade ferrite magnets. Based on a conventional SPMM with single-grade ferrite magnets, the proposed SPMM is designed with four-grade ferrite magnets and then optimized to minimize torque pulsations by maintaining the required torque, utilizing the Kriging method and a genetic algorithm. The results obtained by the finite element analysis show that the optimized SPMM with multi-grade ferrite magnets exhibits improved airgap flux density distribution with highly reduced cogging torque and torque ripple by maintaining the same average torque, as compared to the conventional SPMM. Furthermore, the analysis of the working points for the multi-grade ferrite magnets reveals that the optimized SPMM has good durability against the irreversible demagnetization.

The multi-phase permanent-magnet motors are suitable choices for certain purposes like aircrafts, marine, and electric vehicles due to the fault tolerance and high-power density capabilities. The paper aims to design and prototype an optimized five-phase fractional slot concentrated windings surface mounted permanent magnet motor. To optimize the designed multi-phase motor, a multi-objective optimization technique based on the genetic algorithm method has been applied. The machine design objectives are to minimize mass and loss, subsequently, to determine the best choice of the designed machine parameters. Afterwards, 2-Dimensional Finite Element Method (2D-FEM) has been used to verify the performance of the optimized machine. Finally, the optimized machine has been prototyped. The results of the prototyped machine have validated the results of the theatrical analyses of the machine, and accurate consideration of the parameters improved the performance of the machine.

To enhance the steady-state performance of the virtual-vector-based model predictive current control (VV-MPCC) for a five-phase flux-switching permanent magnet motor, an improved multi-vector-based MPCC (MV-MPCC) method with geometric solution is proposed and investigated in this article. The desired voltage is employed to preselect voltage vector candidates and provide a guidance for the geometric division of a sector. According to the link between the reference voltage and the division, the optimal voltage vectors are determined and their duty ratios are obtained by projection method. Compared to the conventional MV-MPCC method using derivative method, the proposed geometric MV-MPCC method employs the desired voltage to quickly determine the voltage vectors and the corresponding duty ratio, which not only alleviates computational burden but also favors for more intuitive implementation. Finally, the effectiveness of the proposed method is verified by experiments.

One of the key challenges for the electric vehicle industry is to develop high-power-density electric motors. Achieving higher power density requires efficient heat removal from inside the motor. In order to improve thermal management, a multiphysics modeling framework that is able to accurately predict the behavior of the motor, while being computationally efficient, is essential. This paper first presents a detailed validation of a lumped parameter thermal network (LPTN) model of an Internal Permanent Magnet synchronous motor within the commercially available motor-cad modeling environment. The validation is based on temperature comparison with experimental data and with more detailed finite element analysis (FEA). All critical input parameters of the LPTN are considered in detail for each layer of the stator, especially the contact resistances between the impregnation, liner, laminations, and housing. Finally, a sensitivity analysis for each of the critical input parameters is provided. A maximum difference of 4%—for the highest temperature in the slot-winding and the end-winding—was found between the LPTN and the experimental data. Comparing the results from the LPTN and the FEA model, the maximum difference was 2% for the highest temperature in the slot-winding and end-winding. As for the LPTN sensitivity analysis, the thermal parameter with the highest sensitivity was found to be the liner-to-lamination contact resistance.

In the proposed work, a modified look-up table-based direct torque control (DTC) scheme is reported for a neutral point-clamped three-level inverter-fed interior permanent magnet synchronous motor ...

In order to reduce thrust force and stator flux ripples, this article proposes a simplified three-vector-based model predictive thrust force control method for a double-side linear vernier permanent magnet motor. First, a simplified control set is designed to select two active voltage vectors (VVs) in the prediction stage, instead of evaluating redundant VVs. Null VVs are applied to adjust the amplitude of the modified VV, which can realize a full-range modulation by the predefined cost function. To simplify the tuning work of the weighting factor, the variables in the cost function only consider the stator flux term. Then, the duration time of the selected VVs is distributed reasonably through a novel cascaded optimization process. Also, the deadbeat principle is adopted to calculate the duty cycle. With the proposed method, the thrust force and stator flux ripples can be considerably minimized. The simulated and experimental results are conducted to verify the proposed control method.

Demands of appropriate personal mobility-assistive devices for those needed persons have been increased considerably in recent years, with their specific operational requirements, developments of adequate motors to different device parts are the main concerns. For applications onto those knee joint parts of the exoskeleton system, three types of permanent-magnet (PM) motors, namely the surface-mounted PM motor, the Vernier motor, and the flux-switching motor were designed. Based on the operational and physical constraints of the particular exoskeleton parts, optimisations of these PM motors were provided along with their thorough performance comparisons. From emulated finite-element analyses along with hardware experimental validations, by following the standard test settings, selection guidance for the suitable motor structures at different operational objectives will thus be supplied.

Linear flux-switching permanent magnet (LFSPM) motors have drawn extensive concern for rail transit drive systems because permanent magnets and armature windings are all located on the short primary, whereas the long secondary is made up of iron only. Thus, the LFSPM motor with low cost and high efficiency is an excellent choice for urban rail transportation system. However, the installation of linear encoders that are expensive and unreliable along with the long stator will bring about increased costs and reduced reliability. To overcome the shortcomings and fully exert the advantages of LFSPM motors, extended Kalman filter (EKF) is adopted to achieve sensorless control of LFSPMs for its better stability, robustness, and low requirements for working environment in this article. An improving tracking performance can be obtained using EKF considering the end effects of LFSPMs and the presence of noise. Both simulation and experimental results indicate that the motor can run reliably from standstill without position sensors, which is advantageous compared with other sensorless control methods based on electromotive force.

The conventional five-phase finite-control-set model predictive control (FCS-MPC) suffers from heavy computational burden. Meanwhile, the control set with finite vectors inevitably leads to deteriorated operation performance. This article proposes a novel FCS model predictive current control (MPCC) with continued modulation. A cascaded optimization procedure is proposed, which includes main virtual voltage vector (VV) selection, determination of optimal combination of adjacent two VVs, and amplitude optimization. In this cascaded optimization procedure, the phase angle and the amplitude of the synthesized vector can be obtained in different steps. Also, there are two duty cycles calculated in different steps independently, which avoid overflow. By using this cascaded procedure, the continued modulation can be realized without using a modulator. Meanwhile, a vector selection method is introduced to reduce computational burden. This vector selection method avoids evaluation of all the candidate vectors without any negative effects. Moreover, the merits of conventional FCS-MPCC can be preserved. The experimental results verify the effectiveness and superiority of the proposed FCS-MPCC method.

This article proposes a new five-phase flux-intensifying fault-tolerant interior-permanent-magnet (FIFT-IPM) motor to realize high fault tolerance and sensroless operating capacity of the motor drive system for electric vehicles (EVs). By employing the new concept of flux intensifying, the proposed motor owns the outstanding characteristic of Ld > Lq , which can contribute the sensorless operation significantly. By integrating the special design of the stator tooth, using the masterly permanent-magnet (PM) placement and increasing the length of air gap in the q -axis, the high fault tolerance and high reliability can be obtained, which is essential for EV applications. The static performances of the proposed motor are investigated by using finite-element analysis. And the corresponding sensorless operation experiments are implemented based on the prototyped motor. Both theoretical analysis and the experimental results verify the validity of the proposed five-phase FIFT- IPM motor design.

This article proposes a robust observer and nonorthogonal phase-locked loop (PLL)-based sensorless control for the fault-tolerant permanent magnet synchronous motor (FTPMSM) in medium- and high-speed ranges to improve the position estimation reliability of the system, which can be applied for the sensorless control of the FTPMSM system in both normal and fault conditions. Due to the unsymmetric state of the FTPMSM under fault condition, a new sensorless control scheme based on the back electromotive force (EMF) of nonfault two-phase windings is proposed, in which the reference frame transformation is not necessary. The robust observer is proposed to accurately estimate the back EMF of the nonfault two-phase windings, which can guarantee the uniform boundedness and uniform ultimate boundedness of the system regardless of various uncertainties, including external disturbance, parameter variation, and phase winding fault. The nonorthogonal PLL is proposed to calculate the rotor position and speed of the FTPMSM by using the estimated two-phase back EMFs. The simulation and experimental results show that the FTPMSM system with the proposed sensorless control has excellent speed control performance, accurate rotor position/speed estimation, and great system robustness in the presence of various uncertainties, which is able to guarantee the system performance both in normal condition and in fault condition.

In this article, an airgap-harmonic-orientated design method is proposed, where the airgap harmonics are newly acted as the effective bridge between the three key elements of permanent magnet sources, modulators, or armature windings and the motor performances. In the proposed design method, the airgap harmonics play couple roles of design objectives and variables, which are not only served as the design variables for the motor performances, but also considered as the objectives for design parameters. For extensive investigation, a V-shape flux-modulated permanent-magnet (V-FMPM) motor is selected as a design example, which has a potential application for the electrical vehicles. In the optimization process, the sensitivity analysis of different airgap harmonics on the torque performance is conducted to select the leading airgap harmonics. Meanwhile, the sensitivity degrees of the design parameters on the leading harmonics are calculated to pick out the sensitive design parameters. Then, the performances of the V-FMPM motor are evaluated for validating airgap-harmonic-orientated design method. Finally, a prototype motor is built and tested. Both the theoretical analysis and experimental results verify the effectiveness and reasonability of the proposed design method and the V-FMPM motor.

Permanent-magnet motors are suitable choice for special applications such as aircrafts, marine, and electric vehicles Because of the fault tolerance and high power density capability. In this paper, an analytical design of a five-phase permanent-magnet motor is done and the advantages of multi phase motor over three phase motor are studied. Next Finite-element method is applied to verify and validate different machine designs. Finally thermal analysis of the designed machines is done. The results are shown multi phase motor has lower cogging torque and operation temperature, higher electromagnetic torque and back-emf in comparison with three phase motor.

A five-phase fault-tolerant permanent-magnet (FTPM) motor can offer high torque density, low torque ripple, and good fault-tolerance. To improve operational performance under open-circuit fault condition, this article proposes a novel direct torque control (DTC) based on virtual stator flux strategy for an FTPM motor drive. The novelty of the proposed strategy is the development of virtual stator flux, which is used to achieve circular trajectories of current and rotating magneto-motive force vectors, and to derive feedforward voltage. Additionally, optimal fault-tolerant current references get derived based on maximum torque criterion, and then combined with reduced-order orthogonal decomposition matrices deduced from them, the feedforward voltage is used to eliminate asymmetrical motor behavior under the fault condition. Hence, the DTC becomes applicable to the FTPM motor drive under open-circuit fault condition. This control strategy not only enhances the torque performance with smooth torque and high dynamic response but also allows minimal reconfiguration of the control structure from healthy operation to fault-tolerant operation. The simulation and experimental results are given to verify the feasibility of the proposed strategy.

This article proposes a method to extend the operating area of the surface permanent magnet motor by inserting the passive power networks between the motor and the voltage source inverter (VSI). In the conventional motor drive system, since the operating area is limited by the maximum voltage, which is synthesized by the inverter, the output torque capability is reduced in the high-speed region. In order to extend the operating area, two types of passive power networks are proposed in this article. The power networks supply the reactive power to the motor for amplifying the motor terminal voltage. Due to the actions, the proposed motor drive system can utilize a higher maximum motor terminal voltage than that in the conventional drive systems. Depending on the network types, the operating point at which the maximum power or torque is generated is shifted to a high speed. The design, control, and analysis methods of the proposed system are presented in this article. The effectiveness of the proposed system is verified through the experimental results.

This article proposes a fault-tolerant finite control set model predictive control for a five-phase permanent-magnet (PM) motor drive, which offers reduced computation burden and simplified control model. The virtual voltage vectors synthesized from two basic vectors are used to reduce the computation burden. Meanwhile, the steady-state performance is improved. Combining with a reduced decoupling matrix, the discrete model of the five-phase PM motor before and after fault remains unchanged. So, the reconfiguration of the control structure is minimal. Then, a control set and corresponding switching sequence are proposed, which are very suitable for the real-time system. Finally, the validity of the proposed fault-tolerant control is proved by experiments.

Linear vernier permanent-magnet (LVPM) motors have a bright future in long stroke applications, because of their merits of high efficiency, high force capability, and low cost. However, the position sensor for the LVPM motor costs huge. In this article, a sensorless control based on an improved mover flux observer is proposed. The proposed mover flux observer combines a disturbance observer and a feedback controller. It can be easily implemented, which results in low computation burden. Due to simple tuning parameters of this observer, the mover flux observer can have strong robustness to the dc bias and the initialization errors of integrators that are main weakness of flux model. This proposed observer also does not introduce error in either the estimated mover flux amplitude or phase. Then, a phase-locked loop is used to detected position information from the mover fluxes. Finally, the LVPM motor operates by using the estimated position and speed signals. Simulation and experimental results of the LVPM motor demonstrate the accuracy and dynamic performance of the proposed sensorless operation.

Permanent-magnet motors constitute a favored choice for electric drive applications in high-speed ranges due to their increased efficiency, compact rotor structure, and relative robustness. The respective design involves analysis of coupled electromagnetic, thermal, and mechanical phenomena imposing respective limitations. Direct coupling of such a multiphysics problem results in computational onerous optimization schemes; in order to tackle this difficulty, an innovative weak coupling design procedure is introduced considering the interdependence of the phenomena involved during both preliminary and final design stages foreseen. The proposed methodology has been applied in a surface-mounted permanent-magnet motor case.