Optimum arrangement of PMs in surface-mounted PM machines: cogging torque and flux density harmonics

2020 ◽  
Vol 102 (3) ◽  
pp. 1117-1127 ◽  
Author(s):  
Vahid Zamani Faradonbeh ◽  
Samad Taghipour Boroujeni ◽  
Noureddine Takorabet
Keyword(s):  
Flux Density ◽  
Cogging Torque ◽  
Optimum Arrangement

Performance Comparison between Surface-Mounted and Interior Brushless DC Motor

2013 ◽  
Vol 416-417 ◽  
pp. 133-138
Author(s):  
Nan Nan Zhao ◽  
Qian Yang ◽  
Ming Hui Zhang ◽  
Wei Guo Liu
Keyword(s):  
Permanent Magnet ◽  
Flux Density ◽  
Eddy Current ◽  
Skin Effect ◽  
Performance Comparison ◽  
Brushless Dc Motor ◽  
Eddy Current Losses ◽  
Cogging Torque ◽  
Brushless Dc ◽  
Copper Loss

In this paper, the cogging torque, airgap flux density, back-emf, and losses of a surface-mounted and a hybrid magnetization interior brushless machines with the same stator, airgap width, armature core length, material, permanent magnet consumption, speed and copper loss are compared. The analysis reveals that the loss in rotor back iron of interior motor is higher than that in surface-mounted motor due to the skin effect while the eddy current losses in sleeve and magnets of surface-mounted motor are significant, causing the total losses of surface-mounted motor are higher than that of interior motor.

scholarly journals Optimization Analysis of Automotive Asymmetric Magnetic Pole Permanent Magnet Motor by Taguchi Method

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Wenchao Zhang ◽  
Liwei Shi ◽  
Kaiwen Liu ◽  
Lintao Li ◽  
Jianning Jing
Keyword(s):  
Taguchi Method ◽  
Permanent Magnet ◽  
Flux Density ◽  
Magnetic Circuit ◽  
Harmonic Distortion ◽  
Air Gap ◽  
Total Harmonic Distortion ◽  
Initial Structure ◽  
Cogging Torque ◽  
Output Torque

In order to improve the air-gap flux density of the permanent magnet synchronous motor and reduce the cogging torque, a novel structure with asymmetric magnetic poles for automobile was proposed. Based on the characteristics of the parallel magnetic circuit, the magnetic flux path diagram is established. And the equivalent magnetic circuit model is established by the equivalent magnetic circuit method. The Taguchi method is used to be a multiobjective optimization algorithm. The total harmonic distortion of the air-gap flux density is the first optimization goal. The second and third optimization goals are the cogging torque and the average of output torque, respectively. And the torque ripple is a constraint condition. The optimized parameter combination is obtained by the Taguchi method. Finite element simulation analysis and prototype test are carried out for the optimized motor structure. The results show that the total harmonic distortion of air-gap flux density is reduced by 36.7% comparing with the initial structure. The cogging torque is reduced by 26.0%. And the average output torque is increased by 4.8%.

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.

scholarly journals Influence of Material and Geometrical Properties of Permanent Magnets on Cogging Torque of BLDC

2018 ◽  
Vol 8 (2) ◽  
pp. 2656-2662
Author(s):  
M. Yildirim ◽  
H. Kurum ◽  
D. Miljavec ◽  
S. Corovic
Keyword(s):  
Magnetic Flux ◽  
Flux Density ◽  
Permanent Magnets ◽  
Air Gap ◽  
Magnetic Flux Density ◽  
Cogging Torque ◽  
Geometrical Properties ◽  
Brushless Dc ◽  
Stator Current ◽  
2D Numerical Model

Aim of this study is to investigate the influence of both material and geometrical properties of surface mounted permanent magnets (PM) on cogging torque of a brushless DC motor (BLDC) by means of numerical modeling based on finite element method (FEM). To this end, a 2D numerical model of the BLDC motor is built by using the software package Ansys Maxwell. In this study, we analyze the machine properties in no excitation mode (i.e. no stator current is applied) and calculate the distribution of magnetic flux density within the entire motor, the magnetic flux density in the air gap, the cogging torque and the back electromotor force (EMF). Firstly, analysis is performed for four different magnets. It is seen that while cogging torque, back EMF, and magnetic flux density in the air gap for the strongest magnet material have the highest values, the lowest values of these are obtained for the weakest magnet. In the second part of the study, the effect of variation of magnet geometry on the cogging torque, magnetic field density and back EMF of BLDC is examined. Three magnet embrace values are handled in this study. When the magnet embrace increases, the value of the cogging torque reduces. Besides, the maximum values of the back EMF are approximately the same for different magnet embraces, while shapes of the back EMF only change based on the magnet embrace. According to the results, the cogging torque strongly depends on the material and geometrical properties of the magnets.

Field Distribution of Strongly Excited Magnetic Lenses

1975 ◽  
Vol 33 ◽  
pp. 140-141
Author(s):  
M. Strojnik
Keyword(s):  
Flux Density ◽  
Field Distribution ◽  
Optical Axis ◽  
Operating Point ◽  
Pole Piece ◽  
Partial Saturation ◽  
Axial Flux ◽  
The Stability

Magnetic lenses operating in partial saturation offer two advantages in HVEM: they exhibit small cs and cc and their power depends little on the excitation IN. Curve H, Fig. 1, shows that the maximal axial flux density Bz max of one of the lenses investigated changes between points (3) and (4) by 5% as the excitation varies by 40%. Consequently, the designer can relax the requirements concerning the stability of the lens current supplies. Saturated lenses, however, can only be used if (i) unwanted fields along the optical axis can be controlled, (ii) 'wobbling' of the optical axis due to inhomogeneous saturation around the pole piece faces is prevented, (iii) ample ampere-turns can be squeezed into the space available, and (iv) the lens operating point covers a sufficient range of accelerating voltages.

The Added Value of Graphical Input and Display for Electron Lens Design

1990 ◽  
Vol 48 (1) ◽  
pp. 190-191
Author(s):  
B. Lencova ◽  
G. Wisselink
Keyword(s):  
Flux Density ◽  
Numerical Data ◽  
Added Value ◽  
Lens Design ◽  
Step Size ◽  
Magnetic Lens ◽  
Flux Lines ◽  
Fine Mesh ◽  
Electron Lens ◽  
User Friendly

Recent progress in computer technology enables the calculation of lens fields and focal properties on commonly available computers such as IBM ATs. If we add to this the use of graphics, we greatly increase the applicability of design programs for electron lenses. Most programs for field computation are based on the finite element method (FEM). They are written in Fortran 77, so that they are easily transferred from PCs to larger machines.The design process has recently been made significantly more user friendly by adding input programs written in Turbo Pascal, which allows a flexible implementation of computer graphics. The input programs have not only menu driven input and modification of numerical data, but also graphics editing of the data. The input programs create files which are subsequently read by the Fortran programs. From the main menu of our magnetic lens design program, further options are chosen by using function keys or numbers. Some options (lens initialization and setting, fine mesh, current densities, etc.) open other menus where computation parameters can be set or numerical data can be entered with the help of a simple line editor. The "draw lens" option enables graphical editing of the mesh - see fig. I. The geometry of the electron lens is specified in terms of coordinates and indices of a coarse quadrilateral mesh. In this mesh, the fine mesh with smoothly changing step size is calculated by an automeshing procedure. The options shown in fig. 1 allow modification of the number of coarse mesh lines, change of coordinates of mesh points or lines, and specification of lens parts. Interactive and graphical modification of the fine mesh can be called from the fine mesh menu. Finally, the lens computation can be called. Our FEM program allows up to 8000 mesh points on an AT computer. Another menu allows the display of computed results stored in output files and graphical display of axial flux density, flux density in magnetic parts, and the flux lines in magnetic lenses - see fig. 2. A series of several lens excitations with user specified or default magnetization curves can be calculated and displayed in one session.

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