Analytical calculation of air gap magnetic field in permanent magnet linear motors

2017 ◽  
Author(s):  
Feiran Wang ◽  
Youyong Liao ◽  
Jinhua Chen ◽  
Chi Zhang ◽  
Jun Luo ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Permanent Magnet ◽  
Analytical Calculation ◽  
Air Gap ◽  
Linear Motors ◽  
Air Gap Magnetic Field

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.

A novel analytical calculation of magnetic field in the slotted air gap of spoke-type permanent-magnet machines using conformal mapping

2020 ◽  
pp. 1-15
Author(s):  
Jianqi Li ◽  
Yu Zhou ◽  
Jianying Li
Keyword(s):  
Magnetic Field ◽  
Conformal Mapping ◽  
Permanent Magnet ◽  
Flux Density ◽  
Analytical Method ◽  
Electromotive Force ◽  
Analytical Calculation ◽  
Air Gap ◽  
Permanent Magnet Machines ◽  
Peak Value

This paper presented a novel analytical method for calculating magnetic field in the slotted air gap of spoke-type permanent-magnet machines using conformal mapping. Firstly, flux density without slots and complex relative air-gap permeance of slotted air gap are derived from conformal transformation separately. Secondly, they are combined in order to obtain normalized flux density taking account into the slots effect. The finite element (FE) results confirmed the validity of the analytical method for predicting magnetic field and back electromotive force (BEMF) in the slotted air gap of spoke-type permanent-magnet machines. In comparison with FE result, the analytical solution yields higher peak value of cogging torque.

Torque ripple optimization for synchronous reluctance motors based on a virtual permanent magnet harmonic machine model

2021 ◽  
Vol 67 (3) ◽  
pp. 327-338
Author(s):  
Yixiang Xu ◽  
Chong Di ◽  
Xiaohua Bao ◽  
Dongying Xu
Keyword(s):  
Magnetic Field ◽  
Permanent Magnet ◽  
Torque Ripple ◽  
Air Gap ◽  
Analysis Model ◽  
Machine Model ◽  
Asymmetric Rotor ◽  
Rotor Flux ◽  
Air Gap Magnetic Field ◽  
Intermediate Variables

The torque ripple is affected by both the stator and the rotor magnetic field harmonics. In synchronous reluctance motors (SynRM), there are only rotor permeance harmonics existing on the rotor side for the absence of the rotor windings. Since the asymmetric rotor flux barriers are widely applied in the SynRM rotor, it is difficult to calculate the rotor permeance accurately by the analytical method. In this article, the effects of the rotor permeance harmonics on the air-gap magnetic field are studied by a virtual permanent magnet harmonic machine (VPMHM), which is a finite-element (FE) based magnetostatic analysis model. The air-gap flux density harmonics produced by the SynRM rotor are extracted from the VPMHM model and used as the intermediate variables for the torque ripple optimization. The proposed method does not need to solve the transient process of motor motion. Hence, the time of the optimization process can be significantly shortened. Finally, a full electric cycle is simulated by dynamic FE simulation, and the torque ripple is proved to be effectively reduced.

Electromagnetic Field Analysis of Hybrid Excitation Vehicle Generator with Low Voltage and High Current

2012 ◽  
Vol 229-231 ◽  
pp. 945-948
Author(s):  
Yue Jun An ◽  
Li Min Zhou ◽  
Li Ping Xue ◽  
Yong Li
Keyword(s):  
Magnetic Field ◽  
Permanent Magnet ◽  
Permanent Magnets ◽  
Low Voltage ◽  
Air Gap ◽  
Installation Space ◽  
Velocity Variation ◽  
High Current ◽  
Hybrid Excitation ◽  
Air Gap Magnetic Field

In order to further improve the power supply system reliability of low voltage high current vehicle generator, hybrid excitation is used and the permanent magnets are added between the main magnetic poles body and pole shoes. Aiming at reply the problem of limited installation space, the asymmetric pole structure, non-uniform commutating pole, single wave windings playing a role of the pressure line and oblique brush etc are investigated for improving commutation. This paper researched on the distribution of the flux line, the waveform of the air gap magnetic field, and analysis inner magnetic field at the loading by hybrid excitation and no loading by permanent magnet excitation alone respectively with the method of finite element. The results reveal that the magnetic field established by several excitation systems is still symmetric and uniform although the asymmetric structure, so it ensures the provision of suitable medium space for mechanical and electrical energy conversion. By comparing the permanent magnets excitation alone and hybrid excitation in a generator magnetic field distribution and air gap magnetic field waveform, the permanent magnet excitation and electricity excitation realized the superposition of magnetic field, and common establish main generator magnetic field. Hybrid excitation also reduces the current density of excitation coils and improves the heat dissipating performance compared with electrically excited alone. Through the performance analysis of the hybrid excitation, the output voltage waveform is very stable. The curve of auxiliary excitation current along with velocity variation provide important basis for excitation control devices and the development of control algorithm. It will help to improve the stability, reliability and security of the generator, the results can provide key technical support to the development of low-voltage high-current hybrid excitation vehicle generator.

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.

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