Stator Structure Research Articles

A Novel Linear Resolver Proposal and Its Performance Analysis Under Healthy and Asymmetry Air-Gap Fault

A novel linear resolver (L-Resolver) is proposed in this article. The excitation and signals windings are placed on the mover, and the stator structure is designed by a certain number of teeth/slots per the mover length. Therefore, the proposed structure is more simple compared to other resolver types and causes a low price structure. A flexible magnetic equivalent circuit (MEC) is used for analysis due to its capability, introducing various structures. The resolver performance under healthy and faulty cases is evaluated, where the position error under asymmetry air-gap fault is obtained. The performed analysis shows that the proposed resolver has less than 100- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mathrm {\mu m}}$ </tex-math></inline-formula> position error. Hence, it can be a proper alternative as an accurate position sensor. The simple structure and high-accurate position estimation are the advantages of the proposed resolver compared to other types. Finally, the effectiveness of the proposed resolver is validated by experimental results.

Radial Force Density Calculation of Switched Reluctance Machines Using Reluctance Mesh-Based Magnetic Equivalent Circuit

Acoustic noise and vibration is one of the shortcomings of a switched reluctance machine (SRM). Harmonics of the radial force waveform in the airgap excite the stator structure at different vibration modes with specific frequencies. The radial force density in the airgap should be calculated before analyzing and mitigating acoustic noise and vibration. This paper proposes a reluctance mesh-based magnetic equivalent circuit (MEC) model to calculate the airgap radial force density. Reluctance mesh-based MEC models are developed for 3-phase 6/4, 6/16, 12/8 and 4-phase 8/6, 8/10, and 16/12 SRMs. A technique for the dynamic modeling of SRMs is proposed using the reluctance mesh-based MEC method. Dynamic currents are calculated using the proposed technique and, then, the radial and tangential flux density in the airgap are calculated. The radial force density in the airgap is calculated by applying the Maxwell Stress Tensor method. Fourier series is used to calculate the harmonics of the radial force density. The results obtained from the MEC model are verified using finite element method (FEM) models. The implemented MEC-based dynamic modeling method is validated using experimental results.

Magnetic suspension performance and energy consumption characteristics of a maglev pediatric VAD using an ultra-compact axial gap type self-bearing motor with different number of actively controlled axes

An ultra-compact ventricular assist device with an axial gap type self-bearing motor has been developed for use in pediatric circulatory support. The developed self-bearing motor has double stator structure to actively control five degrees of freedom (DOF) of levitated impeller postures and to enhance motor torque capacity with small device size which is 22 mm in outer diameter and 33.6 mm in total height, respectively. This study investigated magnetic suspension stability and energy consumption characteristics during pump operation with 3-DOF (z, θx, θy) control and 5-DOF (x, y, z, θx, θy) control. The axial position and inclination angles were sufficiently stabilized independently with the radial position control. The radial position control can be effective to suppress the radial whirling oscillation at resonance, however power consumption increased by up to 0.4-0.9 W compared to in the case of the motor utilizing 3-DOF control.

Sizing by optimization of line-start synchronous motor

PurposeThe purpose of this paper is to develop an algorithm and software for determining the size of a line-start permanent magnet synchronous motor (LSPMSMs) based on its optimization.Design/methodology/approachThe software consists of an optimization procedure that cooperates with a FEM model to provide the desired behavior of the motor under consideration. The proposed improved version of the genetic algorithm has modifications enabling efficient optimization of LSPMSMs. The objective function consists of three important functional parameters describing the designed machine. The 2-D field-circuit mathematical model of the dynamics operation of the LSPMSMs consists of transient electromagnetic field equations, equations describing electric windings and mechanical motion equations. The model has been developed in the ANSYS Maxwell environment.FindingsIn this proposed approach, the set of design variables contains the variables describing the stator and rotor structure. The improved procedure of the optimization algorithm makes it possible to find an optimal motor structure with correct synchronization properties. The proposed modifications make the optimization procedure faster and moreOriginality/valueThis proposed approach can be successfully applied to solve the design problems of LSPMSMs.

A comparative study on the performance of SSDR coreless AFPM generators with conventional and Halbach magnet arrays

An axial flux permanent magnet (AFPM) generator is known to be a good candidate for both low- and high-speed applications. In this paper, a comprehensive comparison of four coreless AFPM generators is presented with conventional and Halbach magnet arrangement combined with iron and ironless rotor (epoxy). With the same coreless stator structure, four different AFPM generators with different rotor magnet arrangement and materials are compared in terms of voltage, current, power, machine weight, and power density. The analytical design approach is first presented and is subsequently validated using ANSYS Maxwell electromagnetic finite element analysis (FEA) software. Results show that AFPM machine with fully coreless topology using Halbach array with epoxy rotor can deliver similar power density but has a lower cost compared to conventional magnet array with iron rotor. Hence, this topology is favorable for low power low cost applications.

Single stator‐single rotor permanent magnet Vernier machine topologies for direct‐drive applications: Review and case study

Stator and rotor structures, arrangement of permanent magnets (PMs), and type of coils of PM Vernier machines are reviewed and classified. Then, electromagnetic performance and the energy conversion process in the machine are described. Determination of magnetic field distribution and air-gap permeance of the machine is very complicated than that of other PM machines. Impacts of variations of dimensions in the machine such as the number of modulators on the modulus width and the rotor PMs thickness on the load characteristics (cogging torque, back-EMF, and power factor) are investigated. In addition, principles of flux modulation machines operation are presented and the shape and dimensions of the modulators are optimized. The two-phase and four-phase winding types are used to improve the output power of the machine. Finally, a 150 W PM Vernier generator is designed and prototyped to feed the road speed camera.

Performance verification of novel rotor line start PMSM

In this study, 5.5-kW 1500 rpm IEC-60034-30-1:2014-IE4 super premium efficiency class Line Start Permanent Magnet Synchronous Motor (LS-PMSM) was presented with an innovative rotor design utilizing two different slot types have been used. The slots offered in two different geometries make a significant contribution to the motor in the form of a high starting torque thus increasing the synchronization ability. The prototype was manufactured for the optimal model obtained via analytical methods and Finite Element Software. Torque ripples that pose an important issue for permanent magnet motors were tried to be reduced by way of a skewed stator structure. In addition, motor frame and stator main dimensions were acquired from a standard IE2 induction motor design during the manufacturing of the prototype. Experimental studies for the suggested LS-PMSM topology put forth a 6 % higher efficiency in comparison with low efficiency IE2 standard induction motors with the same shaft power. Results for the starting performance, torque ripples and back-EMF were presented for the prototype motor under a constant load of 0-1.25 p.u. It was verified as a result of the study that LS-PMSMs can be used as an alternative to induction motors in pump and fan industrial applications.

Design of the Six-Pole Hybrid Magnetic Bearing With Separated Magnetic Circuit to Generate Symmetrical Levitation Force

To solve the problem of generating the different two-degree-of-freedom (two-DOF) maximum levitation forces, a novel six-pole hybrid magnetic bearing (HMB), adopted combined stator and magnetic path structure, and its design method are proposed. Firstly, the configuration of the combined magnetic circuits and levitation principle are introduced. Then, the force-current relationships are derived. Furthermore, according to flux saturation, the permanent magnetic flux density is designed. Moreover, the combined magnetic circuit, force-current curves and design method are calculated and analyzed by Magnet 3D. Finally, the levitation forces are tested. The combined stator, levitation principle, force-current relationship and the design are proved to be correct.

Analysis of Influence of Stator and Rotor Pole Shape on Electromagnetic Performance of Flux Switching Motor With Segmental Rotor

According to the relationship between the stator and rotor structure and magnetic flux density of the traditional flux switching motor with segmental rotor (SFSM), the mathematical model of the SFSM was established. It was found that the height of the stator pole shoe has a great influence on the no-load electromagnetic characteristics of the motor. After the flux barrier was added on the segmental rotor, it can effectively solve the problem that the positive and negative half period of the no-load electromotive force (EMF) waveform of the motor with low pole shoe height. Using the method of finite element (FEM) parametric simulation, the optimal size of the flux barrier was obtained. Compared with the traditional SFSM, the even harmonics in the phase winding EMF waveform were greatly reduced, and the inductance waveform tends to be sinusoidal. Finally, a prototype was made, and the correctness of the new segmental rotor structure was verified by experiments.

Analytical Calculations of Magnetic Fields Induced by MMF Spatial Harmonics in Multiphase Cage Rotor Induction Motors

This article presents an improved analytical spatial harmonics subdomain (SHSD) model for analyzing the influence of individual spatial harmonics, in stator magneto-motive forces (MMFs), on the performance of multiphase cage rotor induction motors (CRIMs). The proposed SHSD model is an extension of conventional techniques that consider each MMF spatial harmonic, caused by stator slots with tooth-tips, to be individual excitations when quantitatively analyzing the resulting physical effects. The solution domain was divided into four subdomains (SDs) in 2-D polar coordinates, including 1) rotor bars described by the Helmholtz equation; 2) air gaps; 3) slot openings described by Laplace’s equation; 4) stator slots represented by pure forced vibration equations. Current density in the stator structure was decomposed in a Fourier series of position angles to obtain MMF spatial harmonics. This produced a set of pure forced vibration equations in the stator slots, which were first solved in 2-D polar coordinates rather than the typical Poisson’s equation. This approach establishes a relationship between electromagnetic performance and stator parameters, for further optimization of IMs and analysis of electromagnetic vibrations. The proposed analytical model was validated using a series of finite element simulations, which exhibited high accuracy and computational efficiency.

Analytical Model for Brushless Double Mechanical Port Flux-Switching Permanent Magnet Machines

In this article, a 2-D analytical model is presented for brushless double mechanical port flux-switching permanent magnet machines (BDMPFSPMMs). The BDMPFSPMM is an appropriate candidate to be employed as the electric motor in hybrid electric vehicles (HEVs) due to integrating two rotors and two stators into a compact structure. The radial and tangential components of the magnetic flux density are calculated due to permanent magnets and armature currents in each active region of the machine based on the subdomain method. The effects of the saliency on both the rotor and stator structures as well as their interactions are considered. The approach can be used for the magnetic field calculation in BDMPFSPMMs with any combination of rotor- and stator-pole numbers. Based on the computed magnetic flux density, electromagnetic torque, self and mutual inductances, flux linkage, induced voltage, local traction, and unbalanced magnetic force (UMF) are obtained. To validate the proposed model, the analytical results are compared with those obtained from the finite element method (FEM).

CFD analysis of flow field and power consumption of in-line high shear mixers with different stator structures

As a new type of process enhancement equipment, the high shear mixer (HSMs) has very complicated structure, high strain rate, and very complicated internal flow, makes it more difficult to understand the flow and mixing characteristics. Although the relationships between the power consumption and operating parameters of HSMs have been obtained, there are too many factors to be considered, and there is still a lack in how the model parameters depend on the design parameter size, such as the geometric structure sizes of the rotor and stator. In this study, Computational fluid dynamics (CFD) is used to study the effect of different number of stator slots and stator tooth thicknesses on the flow field and power characteristics of in-line HSMs under the same stator opening area. Through the CFD simulation of Newtonian fluid and shear thinning power-law fluid, the functional relationship between power consumption constant KP , strain rate constant Ks , stator tooth thickness and the number of stator slots is studied. The results show that with the decrease of the number of stator slots ns and the thickness of stator teeth Ts, the jet intensity from the outermost stator tooth slots increases, and the circulating flow behind the jet increases, so the influence of the jet on the tangential movement is more obvious. With the increase of stator tooth thickness, KP decreases and Ks increases. With the increase of the number of stator slots, KP and Ks increase. Based on the correlation between KP and Ks and stator structure parameters, a new correlation with tip-to-base clearance, shear gap width, stator thickness and the number of stator slots for the power number is established. A new correlation can be provided as a unified correlation for viscous fluid in the laminar regime.

The Magnetic Field Analytical Calculation in a Novel Double Air-Gaps Permanent Magnet Vernier Synchronous Motor

A novel double air-gaps permanent magnet vernier synchronous motor (PMVSM) is proposed in this article. Because of the unique slotted structure of the outer stator, the motor has the characteristics of low speed and large torque. The rotating magnetic field of the inner and outer double air gaps simultaneously drags the rotor to move. The parameterized outer stator slotted double air-gaps PMVSM has a 22.5% higher torque than the same structure single air-gap motor. Use a magnetic field analytical calculation to analyze the motor. By establishing the Laplace and Poisson equations, the general solution and the relevant coefficients in the analytical solution of each part of the motor are solved. The parametric study of the outer stator slot angle γ and the inner stator notch angle β increases the torque and reduces the torque ripple. The comparison between the analytical calculation results and the finite-element method (FEM) results confirms the effectiveness of the magnetic field analytical calculation and parametric study.

Design of a Low-Ripple Double-Modular-Stator Switched Reluctance Machine for Electric Vehicle Applications

To overcome the disadvantages of traditional switched reluctance machine (SRM) with moderate power/torque density and high torque ripple, this article proposes a novel double-stator SRM (DSSRM) with the inner and outer stators both adopting U-shaped segmental stator structure. By optimizing the polarity distribution of the inner and outer stator magnetic fields, the inner and outer stator magnetic fields are decoupled. Then, the relationships of torque ripple coefficient with the mechanical offset angles of the inner and outer rotor teeth are investigated. To optimize the mechanical offset angle and reduce the torque ripple of the motor, the initial design method is proposed, and five main parameters of the machine are optimized by the finite-element analysis. Then, the static magnetic characteristics and dynamic performance of this novel machine are simulated and analyzed. Finally, a 16/18/18/16 DSSRM is prototyped to validate the above simulation and theoretical analysis.

10kVA급 권선형 동기 발전기의 복합 전력 왜형률 개선을 위한 유전알고리즘 기반의 회전자 형상설계

This paper presents a rotor shape design using genetic algorithm to reduce the total harmonic distortion(THD) of a conventional 10kVA winding synchronous generator. The applied system uses a phase and line-to-line power together from the diesel engine generator. For the improved total power quality, the THDs of phase and line-to-line voltage have to be reduced together. According to the winding pitch, THD of phase and line-to-line voltage are analyzed to select the initial winding model of a conventional synchronous generator. Based on the initial stator winding model of a conventional synchronous generator, the rotor shape is re-designed using genetic algorithm to improve the output power quality and efficiency. Four important parameters of generator rotor shape are optimized by genetic algorithm. The fitness function is determined by the THD and core loss of generator.<BR> In the FEA(Finite Element Analysis) and the practical experiments of designed 10kVA generator, the THD of phase and line-to-line voltage are much decreased with similar operating efficiency in the designed rotor and the conventional stator structure.

Design and finite element analysis of modular C-Core stator tubular linear oscillating actuator for miniature compressor

PurposeFor compactness and ease in assembling, a novel miniature size tubular moving magnet linear oscillating actuator (MT-MMLOA) design for miniature linear compressor application is proposed in this paper.Design/methodology/approachThis MT-MMLOA design possesses a modular C-core stator structure having separation at the middle. Axially magnetized tubular permanent magnets are accommodated on the mover. To improve the output parameters of the linear oscillating actuators (LOA), all the design parameters are optimized using a parametric sweep. Finite element analysis of the proposed design is performed to examine the magnetic flux density as well as thrust force under both static and dynamic analysis within the intended stroke range.FindingsCompared to conventional LOA for miniature compressors, the motor constant of the proposed LOA is 37 N/A that is 85% greater while keeping the same size of LOA. Permanent magnet volume used in the investigated topology of LOA is 26% reduced. Additionally, the overall volume of the machine is 10.3% decreased. Furthermore, the proposed topology is simple, inexpensive and easy to manufacture.Originality/valueElectromagnetic performance comparison with different topologies proposed earlier in literature is carried out to prove the performance superiority of the proposed design.

Efficiency Model for Traveling Wave-Type Ultrasonic Motors Based on Contact Variables and Preload

The contact interface variables are difficult to measure for an ultrasonic motor. When the ultrasonic motor works under different preloads, the error between the traditional efficiency model and the real output is quite large. In order to solve these two problems, we propose a novel efficiency model. It takes measured preload and the feedback voltage data as the input, which may offer better accuracy and on-line ability. Firstly, the effect of the preload on the drive characteristics is investigated, and the relationship between preload and the change in motor energy input is analyzed. Secondly, a contact model based on measured preload and feedback voltage is built, providing a more accurate description of the contact variables. Finally, an efficiency model was developed with a new composite stator structure. A preload test rig for a 60 mm ultrasonic motor is built and real operating conditions are measured. The results show that the correlation coefficient of the present model is 0.991, larger than 0.925 of the conventional model. The proposed model is more consistent with the real working conditions for the motor.

Eksenel Akı Konseptindeki Senkron Relüktans ve İndüksiyon Motor'un Verim ve Performans Karşılaştırması

In this study, the Axial Flux Synchronous Reluctance Motor (AF-SynRM) with multiple barriers in its rotor is designed and it is aimed to compare the performance with the Axial Flux Induction Motor (AF-IM) with the same stator structure and dimensions. For an equal comparison, the motor dimensions and stator structure are chosen the same, only the rotor is changed. In the preliminary study of the designs, machine dimensions are calculated analytically and modeled with the 3D Finite Element Method (FEM). To optimize the saliency ratio, which is the most important factor affecting AF-SynRM performance, Genetic Algorithm (GA) based optimization is performed and the rotor geometry is changed. Thus, a suitable model is created for comparison. Torque, efficiency, input power, power factor, total loses and torque per amper parameters are analyzed. With the proposed comparison method, AF-SynRM obtains higher efficiency, power, torque per ampere and lower losses than AF-IM at the same power rating (2.2 kW). The AF-SynRM rotor will be a good alternative in applications where high efficiency and torque are required, with low cost-maintenance costs due to the absence of a squirrel cage and its structure without magnet.

Putative Spanner Function of the Vibrio PomB Plug Region in the Stator Rotation Model for Flagellar Motor.

Bacterial flagella are the best-known rotational organelles in the biological world. The spiral-shaped flagellar filaments that extend from the cell surface rotate like a screw to create a propulsive force. At the base of the flagellar filament lies a protein motor that consists of a stator and a rotor embedded in the membrane. The stator is composed of two types of membrane subunits, PomA (similar to MotA in Escherichia coli) and PomB (similar to MotB in E. coli), which are energy converters that assemble around the rotor to couple rotation with the ion flow. Recently, stator structures, where two MotB molecules are inserted into the center of a ring made of five MotA molecules, were reported. This structure inspired a model in which the MotA ring rotates around the MotB dimer in response to ion influx. Here, we focus on the Vibrio PomB plug region, which is involved in flagellar motor activation. We investigated the plug region using site-directed photo-cross-linking and disulfide cross-linking experiments. Our results demonstrated that the plug interacts with the extracellular short loop region of PomA, which is located between transmembrane helices 3 and 4. Although the motor stopped rotating after cross-linking, its function recovered after treatment with a reducing reagent that disrupted the disulfide bond. Our results support the hypothesis, which has been inferred from the stator structure, that the plug region terminates the ion influx by blocking the rotation of the rotor as a spanner. IMPORTANCE The biological flagellar motor resembles a mechanical motor. It is composed of a stator and a rotor. The force is transmitted to the rotor by the gear-like stator movements. It has been proposed that the pentamer of MotA subunits revolves around the axis of the B subunit dimer in response to ion flow. The plug region of the B subunit regulates the ion flow. Here, we demonstrated that the ion flow was terminated by cross-linking the plug region of PomB with PomA. These findings support the rotation hypothesis and explain the role of the plug region in blocking the rotation of the stator unit.

Effect of the leakage flow in runner on flow characteristics of a Francis turbine model

In the Francis turbine, there are gaps between the runner and the stator structure as the labyrinth seals. The flows inside gaps have the complicated flow phenomena; these complicated flows can affect the hydraulic performance and the downstream of the Francis turbine as the leakage flow. Therefore, it is important to investigate the flow characteristics induced by the runner gaps. However, normally the runner gap that has very complicated flow structure is often disregarded by considering the time and cost of the numerical analysis. But, it is necessary to apply all flow structures correctly to confirm the more accurate and reliable flow phenomena. In this study, the flow characteristics of gaps at the hub and shroud of the Francis turbine model runner were investigated with adding the leakage flow in the runner cone. In addition, the internal flow characteristics were compared by considering with and without the runner gaps application. For observing the influence of the leakage flow on the hydraulic performance and flow characteristics, the three-dimensional steady Reynolds-averaged Navier-Stokes analyses were performed using the shear stress transport turbulence model. The efficiency was decreased by applying the runner gaps; and the complicated flow phenomena were captured in the runner gaps.