Analytical sub-domain model for predicting open-circuit field of permanent magnet vernier machine accounting for tooth tips

2016 ◽  
Vol 35 (2) ◽  
pp. 624-640 ◽  
Author(s):  
Y. Oner ◽  
Z.Q. Zhu ◽  
L.J. Wu ◽  
X. Ge
Keyword(s):  
Magnetic Field ◽  
Permanent Magnet ◽  
Open Circuit ◽  
Air Gap ◽  
Domain Model ◽  
Direct Drive ◽  
Element Analysis ◽  
Cogging Torque ◽  
Content Type ◽  
Flux Modulation

Purpose – Due to high electromagnetic torque at low speed, vernier machines are suitable for direct-drive applications such as electric vehicles and wind power generators. The purpose of this paper is to present an exact sub-domain model for analytically predicting the open-circuit magnetic field of permanent magnet vernier machine (PMVM) including tooth tips. The entire field domain is divided into five regions, viz. magnets, air gap, slot openings, slots, and flux-modulation pole slots (FMPs). The model accounts for the influence of interaction between PMs, FMPs and slots, and radial/parallel magnetization. Design/methodology/approach – Magnetic field distributions for slot and air-gap, flux linkage, back-EMF and cogging torque waveforms are obtained from the analytical method and validated by finite element analysis (FEA). Findings – It is found that the developed sub-domain model including tooth tips is very accurate and is applicable to PMVM having any combination of slots/FMPs/PMs. Originality/value – The main contributions include: accurate sub-domain model for PMVM is proposed for open-circuit including tooth-tip which cannot be accounted for in literature; the model accounts the interaction between flux modulation pole (FMP) and slot; developed sub-domain model is accurate and applicable to any slot/FMP/PM combinations; and it has investigated the influence of FMP/slot opening width/height on cogging torque.

Sub-domain analytical model for armature reaction field of permanent magnet vernier machine

2016 ◽  
Vol 35 (2) ◽  
pp. 821-831
Author(s):  
Y. Oner ◽  
Z.Q. Zhu ◽  
L. J. Wu ◽  
X. Ge
Keyword(s):  
Permanent Magnet ◽  
Permanent Magnets ◽  
Air Gap ◽  
Domain Model ◽  
Polar Coordinates ◽  
Element Analysis ◽  
Content Type ◽  
Reaction Field ◽  
Armature Reaction ◽  
Flux Modulation

Purpose – An analytical sub-domain model is developed for predicting the armature magnetic field in permanent magnet vernier machine (PMVM) which has either non-overlapping or overlapping windings. The developed model accounts for tooth-tips and flux modulation pole slots (FMPs). The paper aims to discuss these issues. Design/methodology/approach – It is obtained by solving Poisson’s and Laplace’s equations in polar coordinates for each sub-domain, i.e. air gap, slots, slot openings at tooth-tips and FMP slots. Armature reaction field distributions in slots, slot openings FMPs, air-gap and magnet region and winding inductances are obtained from the analytical method and compared by finite element analysis. Findings – It is found that the developed model can be employed to accurately predict the armature field and winding inductance for any combination of slots/FMPs/permanent magnets. In addition, it is observed that the winding inductance is high which results in significant armature reaction and poor power factor in PMVM. Originality/value – The main contributions include: first, accurate sub-domain model for PMVM is proposed for armature reaction which is not addressed in literature; second, the model accounts the interaction between FMP and slot; and finally, developed sub-domain model is also used for inductance calculation.

A new optimal design of surface mounted permanent magnet synchronous motors with integral slot per pole

2018 ◽  
Vol 37 (1) ◽  
pp. 136-152
Author(s):  
Behrooz Rezaeealam ◽  
Farhad Rezaee-Alam
Keyword(s):  
Magnetic Field ◽  
Optimal Design ◽  
Permanent Magnet ◽  
Permanent Magnets ◽  
Air Gap ◽  
Permanent Magnet Synchronous Motors ◽  
Cogging Torque ◽  
Content Type ◽  
Synchronous Motors ◽  
Air Gap Magnetic Field

Purpose The purpose of this paper is to present a new optimal design for integral slot permanent magnet synchronous motors (PMSMs) to shape the air-gap magnetic field in sinusoidal and to reduce the cogging torque, simultaneously. Design/methodology/approach For obtaining this new optimal design, the influence of different magnetizations of permanent magnets (PMs), including radial, parallel and halbach magnetization is investigated on the performance of one typical PMSM by using the conformal mapping (CM) method. To reduce the cogging torque even more, the technique of slot opening shift is also implemented on the stator slots of analyzed PMSM without reduction in the main performance, including the air-gap magnetic field, the average torque and back-electromotive force (back-EMF). Findings Finally, an optimal configuration including the Hat-type magnet poles with halbach magnetization on the rotor and shifted slot openings on the stator is obtained through the CM method, which shows the main reduction in cogging torque and the harmonic content of air-gap magnetic field. Practical implications The obtained optimal design is completely practical and is validated by comparing with the corresponding results obtained through finite element method. Originality/value This paper presents a new optimal design for integral slot PMSMs, which can include different design considerations, such as the reduction of cogging torque and the total harmonic distortion of air-gap magnetic field by using the CM method.

Analytical calculation of magnetic field in surface-mounted permanent-magnet machines with air-gap eccentricity

2019 ◽  
Vol 38 (2) ◽  
pp. 893-914
Author(s):  
Jawad Faiz ◽  
Mohammadreza Hassanzadeh ◽  
Arash Kiyoumarsi
Keyword(s):  
Magnetic Field ◽  
Permanent Magnet ◽  
Field Distribution ◽  
Analytical Calculation ◽  
Air Gap ◽  
Magnetic Field Distribution ◽  
Magnetic Flux Density ◽  
Content Type ◽  
Air Gap Magnetic Field ◽  
The Magnetic Field

Purpose This paper aims to present an analytical method, which combines the complex permeance (CP) and the superposition concept, to predict the air-gap magnetic field distribution in surface-mounted permanent-magnet (SMPM) machines with eccentric air-gap. Design/methodology/approach The superposition concept is used twice; first, to predict the magnetic field distribution in slot-less machine with eccentric air-gap, the machine is divided into a number of sections. Then, for each section, an equivalent air-gap length is determined, and the magnetic field distribution is predicted as a concentric machine model. The air-gap field in the slot-less machine with eccentricity can be combined from these concentric models. Second, the superposition concept is used to find the CP under eccentricity fault. At this end, the original machine is divided into a number of sections which may be different from the one for slot-less magnetic field prediction, and for each section, the CP is obtained by equivalent air-gap length of that section. Finally, the air-gap magnetic field distribution is predicted by multiplying the slot-less magnetic field distribution and the obtained CP. Findings The radial and tangential components of the air-gap magnetic flux density are obtained using the proposed method analytically. The finite element analysis is used to validate the proposed method results, showing good agreements with the analytical results. Originality/value This paper addresses the eccentricity fault impact upon the air-gap magnetic field distribution of SMPM machines. This is done by a combined analysis of the complex permeance (CP) method and the superposition concept. This contrasts to previous studies which have instead focused on the subdomain method.

Novel linear switched-flux PM machine with 9/10 primary/secondary pole number combination

2015 ◽  
Vol 34 (6) ◽  
pp. 1656-1672 ◽  
Author(s):  
Qinfen Lu ◽  
Yanxin Li ◽  
Yunyue Ye ◽  
J.T. Chen ◽  
Z.Q. Zhu
Keyword(s):  
Permanent Magnet ◽  
Thrust Force ◽  
Load Condition ◽  
Design Parameters ◽  
Force Density ◽  
Direct Drive ◽  
Low Thrust ◽  
Element Analysis ◽  
Content Type ◽  
Force Ripple

Purpose – Due to linear structure, linear switched flux permanent magnet machines (LSFPMMs) also may have odd pole primary, such as 9, 15, 21, etc., without unbalanced magnetic force in equivalent rotary machines. The paper aims to discuss these issues. Design/methodology/approach – In order to increase the thrust force density, the influence of some major design parameters, including split ratio, PM thickness, primary slot width and secondary pole width, are investigated by finite element analysis. For reducing the thrust force ripple under on-load condition, the end auxiliary teeth are adopted and their positions are also optimized. Findings – This novel 9/10 primary/secondary poles LSFPMM has high average thrust force and low thrust force ripple by optimization. The results demonstrate that the odd pole primary may be a good candidate for long-stroke linear direct drive application. Originality/value – A novel 9/10 primary/secondary poles linear switched flux permanent magnet machine is developed in this paper. The similar conclusions could be obtained for other LSFPMMs with odd pole primary.

scholarly journals Design and Analysis of Outer Rotor Permanent-Magnet Vernier Machines with Overhang Structure for In-Wheel Direct-Drive Application

Energies ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1238 ◽  
Author(s):  
Dong Yu ◽  
Xiaoyan Huang ◽  
Lijian Wu ◽  
Youtong Fang
Keyword(s):  
Permanent Magnet ◽  
Magnetic Composite ◽  
Direct Drive ◽  
Soft Magnetic ◽  
Axial Flux ◽  
Element Analysis ◽  
Torque Density ◽  
Outer Rotor ◽  
Flux Modulation ◽  
Conventional Machine

This paper presents a novel outer rotor permanent-magnet vernier machine (PMVM) for in-wheel direct-drive application. The overhang structures of the rotor and flux modulation pole (FMP) are introduced. The soft magnetic composite (SMC) was adopted in the FMP overhang to allow more axial flux. The 3-D finite element analysis (FEA) was carried out to prove that the proposed machine can effectively utilize the end winding space to enhance the air-gap flux density. Hence the PMVM can offer 27.3% and 14.5% higher torque density than the conventional machine with no overhang structure and the machine with only rotor overhang structure, respectively. Nevertheless, the efficiency of the proposed machine is slightly lower than the conventional ones due to the extra losses from the overhang structures.

scholarly journals Analysis and Optimization of Axial Flux Permanent Magnet Machine for Cogging Torque Reduction

Mathematics ◽  
2021 ◽  
Vol 9 (15) ◽  
pp. 1738
Author(s):  
Hina Usman ◽  
Junaid Ikram ◽  
Khurram Saleem Alimgeer ◽  
Muhammad Yousuf ◽  
Syed Sabir Hussain Bukhari ◽  
...  
Keyword(s):  
Permanent Magnet ◽  
Three Dimensional ◽  
Latin Hypercube Sampling ◽  
Air Gap ◽  
Axial Flux ◽  
Element Analysis ◽  
Cogging Torque ◽  
Basic Source ◽  
Three Dimensional Finite Element ◽  
Torque Ripples

In this paper, a hexagonal magnet shape is proposed to have an arc profile capable of reducing torque ripples resulting from cogging torque in a single-sided axial flux permanent magnet (AFPM) machine. The arc-shaped permanent magnet increases the air-gap length effectively and makes the flux of the air-gap more sinusoidal, which decreases air-gap flux density and hence causes a reduction in cogging torque. Cogging torque is the basic source of vibration, along with the noise in PM machines, since it is the main cause of torque ripples. Cogging torque is independent of the load current and is proportional to the air-gap flux and the reluctance variation. Three-dimensional finite element analysis (FEA) is used in the JMAG-Designer to analyze the performance of the conventional and proposed hexagonal-shaped PM AFPM machines. The proposed shape is designed to reduce cogging torque, and the voltage remains the same as compared to the conventional hexagonal-shaped PM machine. Further, optimization is performed by utilizing an asymmetric overhang. Latin hypercube sampling (LHS) is used to create samples, the kriging method is applied to approximate the model, and a genetic algorithm is applied to obtain the optimum parameters of the machine.

Cogging Torque Reduction by Means of Pole Segmentation Optimization on the Permanent Magnet Synchronous Machine

2020 ◽  
Author(s):  
Hugo E. Santos ◽  
Khristian M. de Andrade Jr. ◽  
Wellington M. Vilela ◽  
Geyverson T. de Paula
Keyword(s):  
Permanent Magnet ◽  
Flux Density ◽  
Torque Ripple ◽  
Air Gap ◽  
Optimization Techniques ◽  
Machine Construction ◽  
Permanent Magnet Machines ◽  
Element Analysis ◽  
Cogging Torque ◽  
Main Component

One of the main obstacles during the design of permanent magnet machines consists in reducing the developed torque ripple characteristic of this type of machine. The main component of such ripples is a parasitic torque, called cogging torque. A technique present in the literature to reduce this parasitic torque considers the segmentation of the poles. This allows a decrease in the cogging torque, however reducing the air gap flux density too and thus the torque mean. Thus, in order to keep the torque mean reduction in reasonable levels, optimization techniques can be employed with the pole segmentation. The variables to be optimized are the number, distance and width of the segments. The present article proposes two methods to optimize these variables in order to minimize the cogging torque, but also maintain a satisfactory flux density value. Some constraints are added to account for the machine construction feasibility. The proposed methods were validated through a nite element analysis. The results proved the effectiveness of the proposed methods, with a reduction by up to 76% in the cogging torque and keeping, in the best case, about 95% of the reference machine air gap flux density and 78% in the worst one.

On the investigation of the magnetic forces of CWPMM

2014 ◽  
Vol 33 (5) ◽  
pp. 1502-1513
Author(s):  
Imen Abdennadher ◽  
Ahmed Masmoudi
Keyword(s):  
Permanent Magnet ◽  
Air Gap ◽  
Permanent Magnet Machines ◽  
Element Analysis ◽  
Content Type ◽  
Magnetic Forces ◽  
3D Fea ◽  
Ipm Machine ◽  
Mechanical Approach ◽  
Almost All

Purpose – The purpose of this paper is to investigate the magnetic forces generated by a 12 slot/10 pole concentrated winding PM machines, considering a comparative study between two topologies: a surface mounted permanent magnet (SPM) machine and an interior PM (IPM) machine. Design/methodology/approach – Following a description of the main characteristics of the concentrated winding permanent magnet machines (CWPMMs) under comparison, an investigation of the magnetic forces developed by both machines under study is carried out using finite element analysis (FEA). Findings – A 2D FEA-based investigation has highlighted that the SPM machine develops higher magnetic forces than the IPM one. However, and following a 3D FEA, it has been found that the distribution of the magnetic forces along the air gap of the SPM machine is almost homogenous while it is concentrated in two opposite positions in the air gap of the IPM machine. Research limitations/implications – This work has treated almost all features of the machines under comparison, except the power losses. These should be investigated with emphasis on the PM eddy current losses is so far as the harmonic content of the armature air gap MMF is high. Practical implications – The list of the selection criteria of CWPMMs should be extended to the magnetic force cancellation in order to fulfill the requirements of many applications such as the automotive ones. Originality/value – The paper proposes a combined electromagnetic-mechanical approach to investigate the magnetic forces generated by CWPMMs using 2D and 3D FEA.

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