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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.

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.

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.

Permanent magnet motors (PMMs) are widely used in electric vehicles because of their benefits. Based on the permanent magnet topologies on the rotor, PMMs are classified into three types: surface mounted PMM, inset PMM, and interior PMM. This paper discusses a comparison of the characteristics of interior and inset types of PMMs for electric vehicle applications. The study aims to find out the effect of the rotor construction on the magnetic characteristics, torque-speed characteristics, and cogging torque. Simulations were carried out analytically and numerically using the FEMM 4.2 software. The simulation results at the base speed show that the interior PMM generates a higher torque but with a lower rotation, namely 56.47 Nm and 3162 rpm, respectively, while the inset PMM produces higher rotation 4200 rpm but lower output torque of 46.01 Nm. However, with a higher saliency ratio, the interior PMM produces higher maximum torque and speed at both constant torque and field weakening regions than the PMM inset, which is 92.87 Nm and 6310 rpm, consecutively. In terms of cogging torque, the interior PMM raises it slightly higher (2.90 Nm) than the inset PMM (1.93 Nm). The results conclude that, in general, the interior PMM shows better performance in all studied regions and is preferable for electric vehicle applications.

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 paper analyzes the main techniques and technologies of oil fluid recovery in the context of energy consumption, significantly rising over the latest decade. It is recognized that the number of publications in the area of energy efficiency is growing steadily. Currently Russian oil and gas industry are facing the task of accelerating reduction of energy consumption while preserving, or even increasing, production rates. The task is complicated by the fact that the majority of deposits in Russia either have already entered (primarily, Volga-Ural region) or are now entering (West Siberia) their last stage of exploration, whereas new deposits in East Siberia are only being brought into production. Furthermore, a lot of new deposits, which provide for high recovery rates, are profitable a priori as at the first stage of exploration they do not need any artificial lift due to their free flow production without any oil well pumps. However, there is a significant share of new deposits with low-permeability reservoirs, which require either a system of reservoir pressure maintenance or periodic hydraulic fracturing. At the same time deposits at the late stages of exploration, apart from the use of pump units, systems of reservoir pressure maintenance and hydraulic fracturing, require regular repair and restoration, measures against salt and heavy oil sediments, mechanical impurities, flooding, etc., which all has a negative effect on well profitability. In order to solve these problems, the authors review existing methods and calculate specific energy consumption using various pump systems for hypothetical wells, varying in yield. According to the research results, it has been revealed that from the point of view of energy efficiency, it is desirable to equip low- and low-yield wells with sucker rod progressive cavity pump units, medium-yield ones – with electric progressive cavity pumps driven by permanent magnet motor, medium- and high-yield wells – with electric progressive cavity pumps or electric submersible pumps driven by permanent magnet motor, depending on the characteristics of the pumpedout oil fluid.

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.

This paper proposes a resolver offset calibration algorithm that can detect offset with high precision just by configuring a very simple experimental environment. This use of a simple experimental environment holds a great advantage for large-capacity permanent magnet synchronous motors (PMSMs) that require substantial resources to configure an experimental environment, such as EV traction motors. The proposed algorithm is designed based on the PMSM voltage equation. The algorithm is first verified for its validity through simulation with Simulink. Subsequently, it is implemented based on the C-language and installed on an inverter for verification experiments. The implemented algorithm is very simple and requires little execution time and memory. The error in the calibrated offset is experimentally found to converge within 3-bits based on 12-bits (the resolution of the commonly used RDC), and the results have very little deviation.

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.

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.

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.

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.

Given the problem that the drive system of the traditional mine transportation winch outputs a large traction force through the cooperation of an induction motor and reducer to meet the needs of a large traffic volume and heavy-load starting, this paper studies a low-speed and high-torque dual-stator permanent magnet direct drive motor with a separated magnetic circuit. The tinner motor is a torque motor, and the outer motor is a direct drive motor, which is characterized by no magnetic circuit coupling and independent control. The proposed motor has an excellent heavy load starting ability and operation efficiency, and it improves the output torque without increasing the motor volume, which belongs to a special application. According to the working characteristics of the inner and outer motors and the constraints between the overall dimensions, the size equation is derived, and the design principles of the electromagnetic parameters, pole-slot combination and winding structure are described. The torque characteristics and temperature rise characteristics of the motor are simulated using the finite element method and compared with the torque performance and electromagnetic materials cost of the single stator low-speed and high-torque permanent magnet motor with different rotor structures. The results show that the proposed motor has a high torque density and starting torque, and it greatly reduces the motor volume on the basis of a small cost difference.

This article proposes a torque optimization method that introduces the rotor magnetomotive force (MMF) harmonics, aiming to increase the average torque without increasing the cogging torque and torque ripple. A spoke type permanent magnet direct drive motor with fractional slot concentrated winding (FSCW) is designed. The FSCW can improve the utilization rate of the winding, but at the same time, it brings a wealth of MMF harmonics. First, the electromagnetic torque expression is derived using the principles of magnetic energy and virtual power. It means that the constant electromagnetic torque is generated when the stator and rotor MMF harmonics with the same space and time order are the same as the main wave speed. The analytical method is then used to analyze the influence of the stator and rotor MMF harmonics on the electromagnetic torque of the three-phase FSCW permanent magnet motor. On this basis, a rotor shape that introduces the third rotor MMF harmonics is proposed. Finally, the finite element software is used to compare and analyze the torque performance of motor before and after optimization. The finite element simulation and experiment results prove the correctness and effectiveness of the method.

Integrated on-board battery chargers (OBCs) have been recently introduced as an optimal/elegant solution to increase electric vehicle (EV) market penetration as well as minimize overall EV cost. Unlike conventional off-board and on-board battery chargers, integrated OBCs exploit the existing propulsion equipment for battery charging without extra bulky components and/or dedicated infrastructure. OBCs are broadly categorized into three-phase and single-phase types with unidirectional or bidirectional power flow. This paper starts with surveying the main topologies introduced in the recent literature employing either induction or permanent magnet motors to realize fully integrated slow (single-phase) and fast (three-phase) on-board EV battery charging systems, with emphasis on topologies that entail no or minimum hardware reconfiguration. Although, permanent magnet (PM) motors with conventional double-layer distributed winding layouts have been deployed in most commercial EV motors, the non-overlapped fractional slot concentrated winding (FSCW) has been the prevailing choice in the most recent permanent magnet motor designs due to its outstanding operational merits. Hence, a thorough investigation of the impact different FSCW stator winding designs have on machine performance under the charging process is presented in this paper. To this end, the induced magnet losses, which represent a challenging demerit of the FSCW, have been used to compare different topologies under both propulsion and charging operation modes. Based on the introduced comparative study, the optimal slot/pole combinations that correspond to the best compromise under both operational modes have been highlighted.

Linear induction motors (LIMs) have been extensively adopted in urban railway transportation given their nonadhesion thrust and simple stator structure. However, these LIMs undergo unfavorable power factor and efficiency considering their copper and eddy losses. Recently, linear flux-switching permanent-magnet motors (LFSPMs) have attracted the attention of researchers due to their high power density, simple structure, easy heat dissipation, high efficiency, and high power factor. However, so far, no quantitative comparison exists between LFSPMs and LIMs of the size 1:1 to prove the feasibility of LFSPMs to be used in railway transit systems. Therefore, a comparative analysis between the two motors is conducted in this paper. First, this paper investigates the LIMs for railway transit using the finite element method (FEM). Second, the LFSPMs for railway transit is designed and optimized. Third, the electromagnetic performance of the two motors is compared and analyzed through the FEM. Finally, a small-sized prototype of the LFSPMs is constructed to validate the FEM results. It is concluded that LFSPMs offer a favorable thrust force, have high efficiency, and high power factor but have large normal force and force ripple. Therefore, applying LFSPM requires a reliable supporting device and a shock absorber.

In engineering application, the hot press assembly technology is often used to improve the stability of the rotor structure, but the conventional design methods cannot effectively evaluate the influence of this process on the rotor strength, which easily causes the rotor strength to exceed its safety margin range, and seriously it will lead to the failure of the rotor structure. This paper takes the cylindrical magnet surface-mounted high-speed permanent magnet synchronous motor rotor as the research object. Firstly, the influence of the assembly pressing force on the rotor stresses and interference is analyzed; then, comprehensively considering the assembly pressing force, speed and temperature, the rotor strength’s design method with high structural stability is proposed. Finally, based on the proposed method, the rotor strength of a 100 kW/30,000 rpm high-speed motor is designed, and the feasibility of the design is verified by over-speed experiment.

This paper analyzes the impact of Soft Magnetic Composite (SMC) material properties on the losses and efficiency of electrical machines and presents a method for SMC grade selection. Three electric machines are simulated using 3D Finite Element Analysis (FEA): radial flux, axial flux and transverse flux Permanent Magnet (PM) machines. The core losses in SMC parts are calculated using a hybrid method that includes the joule loss of the induced 3D eddy currents in the SMC stator core as well as geometry-independent losses calculated by analytical equations based on toroid tester data. The results show that the selection of SMC material solely based on one given material property such as, permeability, core loss or resistivity results in suboptimal motor performance. On the other hand, the simulation results show that an SMC material with balanced properties achieved the highest efficiency and best overall performance. Finally, an SMC core with balanced properties was developed and tested in a toroidal measurement setup., 2021 IEEE Energy Conversion Congress and Exposition (ECCE), October 10-14, 2021, Vancouver, BC, Canada

This paper analyzes the losses of a high torque density toroidal permanent magnet motor has. The motor has a rotor wrapping around the stator in a circular shape in order to maximize the electromagnetic interaction with in the motor volume. The toroidal motor is simulated using 3D finite element analysis and the results show that the proposed configuration can achieve torque densities higher than radial and axial flux permanent magnet machines. However, it also has high magnet eddy current losses that could potentially limit the machine efficiency and reliability. Several techniques for magnet loss reduction are proposed including magnet orientation, material composition, position, and segmentation as well as winding configuration. These modifications led to a high efficiency - high torque density toroidal motor with only 1.3% of the magnet eddy current loss of the original design., 2021 IEEE Energy Conversion Congress and Exposition (ECCE), October 10-14, 2021, Vancouver, BC, Canada

Dual three-phase permanent magnet synchronous motors (DTPMSM) are used in the steer-by-wire system of electric vehicles that require high reliability. Multiple faults should be considered for the steering system, such as open-circuit faults and speed sensor faults. However, the current speed sensorless control methods of the dual three-phase motor are mainly derived from the promotion of the three-phase motor. They fail when an open-circuit fault occurs, leading to the failure of fault-tolerant control. Researchers have noticed this problem and proposed many methods, but they are very complicated and computationally intensive. This paper proposes one type of improved model reference adaptive system (MRAS). By adding certain fault-related restraints to the output of the adjustable model, speed sensorless control can automatically fit the open-circuit fault and estimate accurately even if an open-circuit fault occurs, which makes sure the whole system continues to operate. Simulation results are presented that contain normal operation, open-circuit fault operation, fault-tolerant control operation, and the whole process from start to fault-tolerant operation. The results show that no matter what period the motor is in, the improved speed sensor can accurately estimate the motor speed and position. The improved model reference adaptive system is significant for improving the reliability of the motor steering system and ensuring the safety of people and property.

In general, high-speed machines should be designed with high efficiency electromagnetic and mechanical characteristics. It is important to analyze the electromagnetic loss for a design with high efficiency. In this study, the effects of the magneto–motive force and time harmonics of the stator current according to the winding distribution of a high-speed permanent magnet motor on the electromagnetic characteristics were comparatively analyzed using analytical methods and FEM. In addition, the final model was proposed by analyzing the relationship between the magnet usage according to the rotor shape and the electromagnetic and mechanical properties according to the winding patterns. Finally, the optimal model was manufactured and the validity was experimentally verified.

The linear vernier permanent magnet (LVPM) motor incorporates the merits of high efficiency, simple mechanism, and low cost, which have a bright future in urban rail transportation. This paper proposes a new sensorless direct thrust force control (DTFC) for the LVPM motor. The novelty is the introduction of a modified flux linkage observer, which has strong robustness against the interferences, no phase lag, and no attenuation. Compared with conventional flux linkage calculation methods, the proposed observer can provide desirable flux linkages, which increases the robustness of the sensorless DTFC system. Simulation and experimental results based on an LVPM motor drive demonstrate the accuracy and robustness. The validations in the aspect of the robustness to parameter errors, measurement errors, and noise show the superiorities of the modified flux linkage observer.

This paper investigates the feasibility of novel data-driven deep learning (DL) models to predict the solution of Maxwell’s equations for low-frequency electromagnetic (EM) devices. With ground truth (empirical evidence) data being generated from a finite-element analysis solver, a deep convolutional neural network is trained in a supervised manner to learn a mapping for magnetic field distribution for topologies of different complexities of geometry, material, and excitation, including a simple coil, a transformer, and a permanent magnet motor. Preliminary experiments show DL model predictions in close agreement with the ground truth. A probabilistic model is introduced to improve the accuracy and to quantify the uncertainty in the prediction, based on Monte Carlo dropout. This paper establishes a basis for a fast and generalizable data-driven model used in the analysis, design, and optimization of EM devices.

This paper reveals a torque-angle approaching principle in a hybrid rotor permanent-magnet (HRPM) motor. The key is to obtain the relationship between angles of shifted surface-inserted PMs (SPMs) as well as assisted airspace barriers and the current angles of maximum PM torque as well as maximum reluctance torque. In order to find out this relationship, the PM torque and reluctance torque are separated accurately and effectively by the proposed torque separation method. In this method, the parameters in an abc reference frame are transformed to a d- - q reference frame via Park transformation, and then the model considering cross-coupling and magnetic saturation effect is used to calculate four torque components. Moreover, the shifting of SPMs has been confirmed to have both influence on the current angles of maximum PM torque and maximum reluctance torque, while the assisted airspace barriers only affect the current angle of maximum reluctance torque. Thus, the total torque can be enhanced by optimal angles of shifted SPMs and assisted airspace barriers because of higher utilization of both PM torque and reluctance torque. In order to evaluate the presented principle in the HRPM motor, a prototype is manufactured for experiments. Through theoretical analysis and experimental testing, it is verified that the proposed principle is feasible and effective.

During motor production processes, the influence of motor manufacturing tooling costs on motor prices is mostly negligible and considered to be insignificant. The manufacturing cost, particularly the molding cost, may not be a significant issue for mass production, but it would become a crucial issue for modern small-scale application-oriented design. When the total number of motors produced per motor manufacturing tool such as stator and rotor pressing tool is reduced, the effect of the motor manufacturing tool cost on the motor price can be greatly increased. To reduce the cost, we present a new design approach of a brushless AC (BLAC) motor that shares motor manufacturing tools, unlike many previous studies on low-cost designs. The design approach of a BLAC motor is applied to integrated electric brake (IEB) systems of various specifications. In addition, to analyze the motor performances in IEB systems, the BLAC vector control system, FEM, design of experiment, and moving least square method are used. Furthermore, to predict the available operating time of a motor, a heat compensation coefficient that uses the experimental data of an existing motor is proposed. By implementing this design approach, we have effectively designed motors that satisfy performance requirements such as speed response, available operating time, and total harmonics distortion (THD) of back EMF with minimum stator core volume, in the IEB systems, and achieve a 25.5% reduction in cost through sharing of motor manufacturing tools.

A Permanent Magnet Hysteresis Synchronous Motor (PMHSM) is designed and implemented in this paper. The designed motor is analyzed by using simulation and experimental studies. The torque, torque ripple, speed and flux density are also analyzed by using Finite Element Analysis (FEA) method. A standard commercial stator geometry is preferred for easy installation. A new rotor structure is designed for the motor. A submersible pump turbine is connected to the prototype motor in order to test under a real pump load condition by a pump test stand. The same pump used in the experiment was also tested with a commercial induction motor (IM) submersible pump motor with same power. Thus, the commercial and proposed motor are compared in terms of static head value, which is an important value in pump applications. The performance of the motor is better than the IM because it can operate at synchronous speed without slip. In addition, the proposed motor does not require any auxiliary system to achieve starting with grid. The proposed PMHSM can be used to obtain high performance and efficiency for pump applications.

This paper proposes a two-phase dual-stator axial-flux permanent magnet brushless dc motor with an ironless rotor for higher torque per magnet volume using the only-pull drive technique. The advantage of the ironless rotor is that it reduces magnet volume by providing an effective flux linkage, while the only-pull drive technique, which involves only the pull process, benefits from the use of thin magnets that do not experience the irreversible demagnetization. The axial-flux configuration of the proposed dual-stator motor was adopted because of its capability of achieving the desired trapezoidal back electromotive force that maximizes the advantages of the only-pull drive technique. The thin magnets were fixed on the ironless rotor using a non-magnetic structure, and the stator was particularly designed to implement the only-pull drive technique. The performance of the motor was analyzed in terms of torque per magnet volume using the finite element analysis and validated by the experimental results.

Linear switched reluctance motors (LSRMs) provide an alternative to linear induction motor and linear permanent magnet motor in both vertical and horizontal propulsion applications. This paper attempts to develop a unitized design method of a segmental secondary LSRM, which is characterized by a modular magnetic circuit structure and the independent operation of multimover units. The developed design method is directly performed in linear domain without transforming it to a rotary SRM, which complies with the essential natures of the segmental secondary LSRM, showing that it is capable of delivering more power at the same dimensions compared to the conventional tooth type LSRM. Further, the sensitivity analysis of the critical geometric parameters is performed, and the guidelines for selection of the best dimension parameters are given. Finally, the three-phase and four-phase LSRMs are designed and prototyped, respectively with a 1-m long stator. The experimental results validate the design procedures and analysis above.

© 1965-2012 IEEE. Soft magnetic composite (SMC) materials and SMC electromagnetic devices have attracted strong research interest in the past decades. However, SMC devices have large core loss that needs to be put into consideration even at the design stage. Effective and accurate prediction of the core loss becomes crucial for the design and optimization of high-performance motors with these materials. Equivalent circuit model is a widely used method for machine analysis, due to the advantages in the fast calculation with a clear physical mechanism. This paper presents an equivalent circuit model to predict the core loss of a claw-pole permanent magnet motor with SMC stator core. All the parameters including the equivalent core-loss resistance in the equivalent circuit model are identified based on the finite-element method to achieve high accuracy, and the effectiveness of the parameters identification methods is experimentally verified. The proposed equivalent circuit model can predict the core loss and motor's performance efficiently both under no-load and loading conditions.

Permanent magnet traction motor has the advantages of high efficiency, high power density, high torque density and quick dynamic response, which has been widely used in the traction field of electric vehicle. The high-performance control of permanent magnet traction motor depends on accurate rotor position information, which is usually obtained by using mechanical position sensors such as hall sensor, encoder and rotary transformer. However, the traditional mechanical sensor has the disadvantages of high cost, large volume and poor anti-interference ability, which limits the application of permanent magnet motor. The sensorless control technology is an effective way to solve the above-mentioned problem. Firstly, the sensorless control techniques of permanent magnet motor are classified. The sensorless control techniques of permanent magnet motor for rotor initial position, zero-low speed range, medium-high speed range and full speed range are deeply described and compared. Finally, the development trend of sensorless control technology of permanent magnet traction motor is prospected.

The paper compares the economic effect of using capacitors in fixed speed drives of a pumping station when using energy-efficient motors of various types. Induction motors of IE2 and IE3 energy efficiency classes, a direct-on-line synchronous motor with a permanent magnet in the rotor, and a direct-on-line synchronous reluctance motor are considered. The comparison takes into account not only the efficiency of the motors, but also their power factor, on which the losses in the cable and transformer depend. The possibility of using static capacitors to compensate for the reactive power of motors and reduce the losses is also considered. The feasibility analysis takes into account that the motors have different initial costs. The cost of capacitors is also taken into consideration. The analysis shows that the use of static capacitors can have a significant impact on the comparison between different motors in this application. Without considering capacitors, the permanent magnet motor has the shortest payback period, otherwise the synchronous reluctance motor has the shortest payback period. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. Funding: The work was partially supported by the Ministry of Science and Higher Education of the Russian Federation (through the basic part of the government mandate, Project No. FEUZ-2020-0060).

Double three-phase winding is one of the best solutions to improve the fault tolerance of an electric motor which is required to work continuously even under partial fault conditions. Actually, this type of machines is often preferred to custom and expensive multiphase drives, since it can be obtained by dividing the stator winding into two subsets connected to two standard, independent inverters of half the same total power. In the event of a fault, one of the two subsets is simply disconnected and the motor can continue to operate at a reduced power or with some overload of the remaining three-phase system.

This paper is focused on the transient thermal model of the Permanent Magnet Synchronous Motor (PMSM) and the airflow cooling model through the ribs in the stator lamination. The stator lamination has a new specialized designed shape. This type of lamination does not need a frame, and the lamination is directly cooled. It has reduced the thermal resistance between the cooling medium and stator lamination. The thermal model is loaded with variable Power, and the airflow speed of cooling air is variable. Thermal models are solved by software ANSYS CFX and Mechanical. The thermal model of PMSM is based on the traction motor. This machine is designed as enclosed. The modelled PMSM is used in the electric racing formula.

Different from the design of conventional permanent magnet (PM) motors, high-speed motors are primarily limited by rotor unbalanced radial forces, rotor power losses, and rotor mechanical strength. This paper aimed to propose a suitable PM motor with consideration of these design issues. First, the rotor radial force is minimized based on the selection of stator tooth numbers and windings. By designing a stator with even slots, the rotor radial force can be canceled, leading to better rotor strength at high speed. Second, rotor power losses proportional to rotor frequency are increased as motor speed increases. A two-dimensional sensitivity analysis is used to improve these losses. In addition, the rotor sleeve loss can be minimized to less than 8.3% of the total losses using slotless windings. Third, the trapezoidal drive can cause more than a 33% magnet loss due to additional armature flux harmonics. This drive reflected loss is also mitigated with slotless windings. In this paper, six PM motors with different tooth numbers, stator cores, and winding layouts are compared. All the design methods are verified based on nonlinear finite element analysis (FEA).

The permanent magnet spherical motor is simpler in structure and control and smaller in size than the general multi-DOF motors. This paper presents an 8-pole 12-slot, and the stator structure with three layers of multi-DOF spherical permanent magnet motor (MSPMM). The finite element software is used to build the motor model, and the electromagnetic density diagram of the motor is obtained through simulation. Cogging torque is a characteristic of permanent magnet motor, the cogging torque of MSPMM was analyzed by analytical method. The rotational and deflecting cogging torques obtained by analytical method are compared with the finite element method. The figures obtained by the two methods are similar with only a small error, which verifies that MSPMM conforms to the theoretical law of the motor.

Compared with the constant speed permanent magnet (PM) motor, the rotor strength and rotor dynamic characteristics of the high-speed PM motor(HSPMM) are particularly important. In this paper, a 100kW, 40000 rpm HSPMM rotors are used as an example, and the finite element method(FEM) is used to analyze the influence of different factors on the rotor strength and rotor dynamic of HSPMM. The analysis results show that the appropriate increase of the assembly interference and the use of a larger thickness of the protective sleeve can effectively reduce the effect of the centrifugal force on the permanent magnet, and increasing the support stiffness can effectively increase the critical speed, but its impact will no longer be obvious when the support stiffness exceeds 1 × 107N/mm. The results of this study will provide a reliable reference for the analysis of the mechanical characteristics of HSPMM.

A novel efficiency-shifting radial-axial hybrid permanent magnet synchronous motor that can realize two high-efficiency regions at low and high speeds is developed to extend the maximum driving distance and track the reference speed more accurately for electric vehicle application. The motor has two stators, which are radial and axial, to rotate one shared rotor. The rotor employs two combined topologies, i.e., inner surface-inset-mounted and outer V-shaped interior-mounted. For both outer and inner permanent magnets, Nd-Fe-B, having the remanent flux density of 1.23 T and coercivity of 890 kA/m, is used. The simulation result shows that the designed motor exhibits not only high maximum torque of 400 Nm and the maximum speed of 18,000 rpm but also two high-efficiency regions of 97.6 % and 92.0 % at low and high speed, respectively. Lastly, the developed motor shows better performance than corresponding separated radial and axial permanent magnet motor.

Interior permanent magnet synchronous motor (IPMSM) efficiency can be improved by using maximum torque per ampere control (MTPA). MTPA control utilizes both alignment and reluctance torques and usually requires information about the magnetization map of the electrical machine. This paper proposes an adaptive MTPA algorithm for sensorless control systems of IPMSM drives, which is applicable in industrial and commercial drives. This algorithm enhances conventional control schemes, where the output of the speed controller is the commanded stator current and the direct current is calculated using an MTPA equation; therefore, it can be easily implemented in the previously developed drives. The proposed algorithm does not use any motor parameters for the calculation of the MTPA trajectory, which is important for systems operating in changing environmental conditions, because motor inductances and flux linkage strongly depend on the stator current and the rotor temperature, respectively. The proposed algorithm continuously varies the current phase and in such a way it tries to minimize the magnitude of the stator current at the applied load torque. The main contribution of this paper is the development of a technique to overcome the main disadvantage of seeking algorithms–the necessity of a precision information about the rotor position. The proposed method was verified experimentally.

This paper investigates the influence of stator slot number on electromagnetic performance of 2-pole high speed permanent magnet (HSPM) slotted motors with toroidal windings. Four 2-pole slotted motors with different slot numbers, i.e. 3, 6, 9, and 12, are globally optimised for maximum torque, and their electromagnetic performance are compared, including winding factor, air-gap flux density, back-EMF, cogging torque, electromagnetic torque, winding inductances, unbalanced magnetic force (UMF), and various loss components. It shows that the 6-slot/2-pole HSPM motor with toroidal windings is eminently suitable for high speed application due to no UMF and easy to realise a modular structure. In addition, toroidal and tooth-coil windings are compared in the 3-slot/2-pole motors, and the results confirm that toroidal windings are not suitable for use in the 3-slot/2-pole HSPM slotted motor due to large airgap field harmonics. Finally, a 6-slot/2-pole prototype motor is manufactured and tested to validate the finite element (FE) predictions.