• Title, Summary, Keyword: permanent magnet machines

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Improved Method for Calculating Magnetic Field of Surface-Mounted Permanent Magnet Machines Accounting for Slots and Eccentric Magnet Pole

  • Zhou, Yu;Li, Huaishu;Wang, Wei;Cao, Qing;Zhou, Shi
    • Journal of Electrical Engineering and Technology
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    • v.10 no.3
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    • pp.1025-1034
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    • 2015
  • This paper presented an improved analytical method for calculating the open-circuit magnetic field in the surface-mounted permanent magnet machines accounting for slots and eccentric magnet pole. Magnetic field produced by radial and parallel permanent magnet is equivalent to that produced by surface current according to equivalent surface-current method of permanent magnet. The model is divided into two types of subdomains. The field solution of each subdomain is obtained by applying the interface and boundary conditions. The magnet field produced by equivalent surface current is superposed according to superposition principle of vector potential. The investigation shows harmonic contents of radial flux density can be reduced a lot by changing eccentric distance of eccentric magnet poles compared with conventional surface-mounted permanent-magnet machines with concentric magnet poles. The FE(finite element) results confirm the validity of the analytical results with the proposed model.

Characteristic Analysis of Rotor Losses in High-Speed Permanent Magnet Synchronous Motor (초고속 영구자석형 동기 전동기의 회전자 손실 특성해석)

  • 장석명;조한욱;이성호;양현섭
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.53 no.3
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    • pp.143-151
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    • 2004
  • High-speed permanent magnet machines are likely to be a key technology for electric drives and motion control systems for many applications, since they are conductive to high efficiency, high power density, small size and low weight. In high-speed machines, the permanent magnets are often contained within a retaining sleeve. However, the sleeve and the magnets are exposed to high order flux harmonics, which cause parasitic eddy current losses. Rotor losses of high-speed machines are of great importance especially in high-speed applications, because losses heat the rotor, which is often very compact construction and thereby difficult to cool. This causes a danger of demagnetization of the NdFeB permanent magnets. Therefore, special attention should be paid to the prediction of the rotor losses. This paper is concerned with the rotor losses in permanent magnet high-speed machines that are caused by permeance variation due to stator slotting. First, the flux harmonics are determined by double Fourier analysis of the normal flux density data over the rotor surface. And then, the rectilinear model was used to calculate rotor losses in permanent magnet machines. Finally, Poynting vector have been used to investigate the rotor eddy current losses of high-speed Permanent magnet machine.

Electromagnetic Analysis of Slotless Brushless Permanent Magnet Machines According to Magnetization Patterns (슬롯리스 브러시리스 영구자석기기의 자화 패턴에 따른 전자기적 특성해석)

  • Jang Seok-Myeong;Choi Jang-Young;Cho Han-Wook;Park Ji-Hoon
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.54 no.12
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    • pp.576-585
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    • 2005
  • This paper deals with the electromagnetic field analysis of slotless brushless permanent magnet machines with three different magnetization patterns such as Halbach, parallel and radial magnetization. The magnetization modeling of Halbach, parallel and radial magnetization is performed analytically. And then, analytical solutions for open-circuit field distributions, armature reaction field distributions, flux linkages due to PMs and stator windings, torque, back-emf and inductance are derived in terms of magnetic vector potential and two-dimensional (2-d) polar coordinate systems. The analytical results are validated extensively by finite element (FE) analyses. The magnet volume required in order to produce identical flux density is compared with each magnetization. Finally, analytical solutions and derivation procedures of those presented in this paper can be applied to slotless and slotted brushless permanent magnet AC and DC machines.

Sinusoidal Back-EMF of Vernier Permanent Magnet Machines

  • Li, Dawei;Qu, Ronghai
    • Journal of international Conference on Electrical Machines and Systems
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    • v.3 no.1
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    • pp.40-47
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    • 2014
  • Sinusoidal back-EMF waveform of vernier Permanent Magnet (PM) machines is analyzed in this paper. An analytical expression of Electromotive Force (EMF) of electric machines including vernier machines is developed to analyze EMF harmonics, and the effect of vernier PM machine pole ratio, the ratio of number of rotor poles to stator poles, on the EMF waveform. Moreover, this paper represents several Finite Element Analysis (FEA) models to verify the analysis based on the proposed expression, and the effect of tooth width ratio, which is the ratio of tooth width to tooth pitch, on back-EMF of vernier PM machines, and optimal tooth width ratio is obtained and verified by FEA. Finally, this paper makes comparisons between EMF waveform of vernier PM machines and that of traditional PM machines from the point of view of analytical EMF expression.

Electromagnetic Analysis of Reluctance Type Machines with Permanent Magnet/Electromagnet (영구자석/전자석을 갖는 릴럭턴스 타입 기기의 전자기적 특성 해석)

  • Jang, Seok-Myeong;Park, Ji-Hoon;Choi, Jang-Young
    • Proceedings of the KIEE Conference
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    • pp.80-82
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    • 2006
  • This paper deals with electormagnetic analysis of reluctance type machines with permanent magnet/electromagn et. First, we calculated flux density of relucta nce type machines with permanent magnet/electromagnet according to position. Second, analyzed normal force and horizontal force from flux density of machine according to position. Also, analysis result compares with data that is derived through a finite element analysis (FEA), and proved validity.

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Design and Comparison of Multistage Axial Flux Permanent Magnet Machines for Potable Generating Application

  • Lee, Jiyoung;Park, Byounggun;Woo, Byungchul
    • Journal of Magnetics
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    • v.20 no.4
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    • pp.413-420
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    • 2015
  • In this study, we present a comparison of multistage axial flux permanent-magnet machines (AFPMs) with different topologies for use as 100 W-class portable generating systems. Three topologies were selected, and the maximum power density and high level of efficiency were achieved by following the response surface methodology (RSM) in the design. Three-dimensional finite element analysis (FEA) was used to conduct numerical experiments to obtain the optimum design using the RSM and suggest a proper configuration of the portable generating system.

Analysis on Static Characteristics of Slotless Type Permanent Magnet Electrical Machines Using the Electromagnetic Transfer Relations (전자기 전달관계를 이용한 슬롯리스형 영구자석 전기기기의 정특성 해석)

  • Jang, Seok-Myeong;Choi, Jang-Young;Lee, Sung-Ho;Cho, Han-Wook
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.55 no.3
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    • pp.138-145
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    • 2006
  • It is well known that the accurate calculation of the field distribution is essential for the design of electrical machines. The analytical techniques for electromagnetic field can quickly and exactly determine airgap magnetic field distribution in electrical machines. Many analytical techniques have been investigated to predict the magnetic field distribution in PM machines equipped with permanent magnets. Using the analytical technique by transfer relations, D. L. Trumper and K. R. Davey already presented the design and analysis of linear permanent-magnet machines and induction machines, respectively. Using the transfer relations (Melcher's general methodology) to describe electromagnetic phenomena, this paper deals with the analysis on the magnetic field distribution due to PM and winding current, the induced voltage and the static torque characteristics in surface-mounted slotless type permanent magnet machine. The validity of the analysis results is confirmed by finite element (FE) analysis.

State of the Art on Permanent Magnet Brushless DC Motor Drives

  • Singh, Bhim;Singh, Sanjeev
    • Journal of Power Electronics
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    • v.9 no.1
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    • pp.1-17
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    • 2009
  • Permanent magnet brushless DC (PMBLDC) motors are the latest choice of researchers due to their high efficiency, silent operation, compact size, high reliability and low maintenance requirements. These motors are preferred for numerous applications; however, most of them require sensorless control of these motors. The operation of PMBLDC motors requires rotor-position sensing for controlling the winding currents. The sensorless control would need estimation of rotor position from the voltage and current signals, which are easily sensed. This paper presents state of the art PMBLDC motor drives with an emphasis on sensorless control of these motors.

Voltage Vector Selection Area of the Direct Torque Control for Permanent Magnet Synchronous Motor

  • Li, Yaohua;Ma, Jian;Yu, Qiang;Liu, Jingyu
    • Journal of international Conference on Electrical Machines and Systems
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    • v.1 no.2
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    • pp.23-29
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    • 2012
  • The control of stator flux, torque angle, excitation torque, reluctance torque and total torque of the direct torque control (DTC) for a permanent magnet synchronous motor (PMSM) are studied in this paper. Simplified expressions to represent the changes of these variables due to the application of a voltage vector are given. Finally, a voltage vector selection area and the implementation of a voltage vector selection strategy are proposed.

Permanent Magnet Eddy Current Analysis of SPM Synchronous Motors according to Magnet Shapes

  • Lee, Sun-Kwon;Kang, Gyu-Hong;Kim, Byoung-Woo;Hur, Jin
    • Journal of international Conference on Electrical Machines and Systems
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    • v.3 no.4
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    • pp.398-402
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    • 2014
  • This paper presents the comparison study of permanent magnet (PM) eddy current of concentrated winding type surface permanent magnet synchronous motor (SPMSM) with different rare-earth magnet shapes. The fractional slot winding having 10 poles and 12 slots is studied. The PM eddy current is analyzed to compare for each shape by 2 dimensional (2D) finite element analysis (FEA). The eddy current and their loss of particular position of PM as well as their distributions are displayed for each model. The effect of partly enlarged air-gap made by PM shape to PM eddy current is compared.