The Origin of Permanent Magnet Induced Vibration in Electric Machines

1991 ◽  
Vol 113 (4) ◽  
pp. 476-481 ◽  
Author(s):  
B. S. Rahman ◽  
D. K. Lieu
Keyword(s):  
Permanent Magnet ◽  
Motor Performance ◽  
Permanent Magnets ◽  
Electric Machines ◽  
Permanent Magnet Motors ◽  
Forcing Function ◽  
Surrounding Structure ◽  
Resonant Modes ◽  
Principal Source ◽  
The Magnetic Field

A principal source of vibration in permanent magnet motors and generators is the induced travelling forces from the rotating permanent magnets acting on the stator. The form of the magnetic field and resulting forcing function in the airgap of such machines is critical. The stator is modelled as a solid ring, with no teeth. Various motor parameters were investigated, including the effects of radial versus parallel magnetization, magnetization tolerances, and radial offset. The results were determined with analytical and FEM models. It was concluded that radial magnetization of the permanent magnets was preferable for both vibration and motor performance. Magnetization tolerances and radial offsets yielded a relatively more populated frequency spectrum for the forcing function and thus could lead to a greater probability of resonant modes being excited in the surrounding structure.

Optimization of Magnetic Pole Geometry for Field Harmonic Control in Electric Motors

1994 ◽  
Vol 116 (2) ◽  
pp. 173-178 ◽  
Author(s):  
B. S. Rahman ◽  
D. K. Lieu
Keyword(s):  
Optimization Algorithm ◽  
Permanent Magnets ◽  
Optimization Problems ◽  
Permanent Magnet Motors ◽  
Combinatorial Optimization Problems ◽  
Harmonic Control ◽  
Forcing Function ◽  
Resonant Modes ◽  
Modes Of Vibration ◽  
The Cost

A principal source of vibration in permanent magnet motors and generators is the induced stress from the rotating permanent magnets. The harmonic content of this forcing function may excite resonant modes of vibration in the motor or surrounding structure. Thus attenuation of specific harmonics is of considerable interest. This paper describes a method for optimal shaping of the permanent magnets to eliminate one or more of these harmonics. The analytical model for an optimized 4-pole motor consisted of segmented PMs and a solid ring stator. The permanent magnets were modeled as a number of thin radially cut annular layers with specific sector angles. Changing the shape of the PMs resulted in a different flux density field and thus a different frequency spectrum of the forcing function. Attenuation of specified higher harmonics could be achieved at the expense of increasing other harmonics. For a 4-pole motor, the optimization algorithm was fairly successful at eliminating any one of the 8th, 12th or 16th harmonics. The algorithm used was developed to solve combinatorial optimization problems, and drew heavily upon principles from statistical mechanics. The final pole geometry is dependent upon the choice of the cost function used in the optimization algorithm.

scholarly journals Design of a New 1D Halbach Magnet Array with Good Sinusoidal Magnetic Field by Analyzing the Curved Surface

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2522
Author(s):  
Guangdou Liu ◽  
Shiqin Hou ◽  
Xingping Xu ◽  
Wensheng Xiao
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Permanent Magnet ◽  
Flux Density ◽  
Permanent Magnets ◽  
Air Gap ◽  
Curved Surface ◽  
Magnetic Flux Density ◽  
Sinusoidal Magnetic Field ◽  
The Magnetic Field

In the linear and planar motors, the 1D Halbach magnet array is extensively used. The sinusoidal property of the magnetic field deteriorates by analyzing the magnetic field at a small air gap. Therefore, a new 1D Halbach magnet array is proposed, in which the permanent magnet with a curved surface is applied. Based on the superposition of principle and Fourier series, the magnetic flux density distribution is derived. The optimized curved surface is obtained and fitted by a polynomial. The sinusoidal magnetic field is verified by comparing it with the magnetic flux density of the finite element model. Through the analysis of different dimensions of the permanent magnet array, the optimization result has good applicability. The force ripple can be significantly reduced by the new magnet array. The effect on the mass and air gap is investigated compared with a conventional magnet array with rectangular permanent magnets. In conclusion, the new magnet array design has the scalability to be extended to various sizes of motor and is especially suitable for small air gap applications.

Analysis of a Tubular Linear Permanent Magnet Motor for Reciprocating Compressor Applications

2013 ◽  
Vol 448-453 ◽  
pp. 2114-2119 ◽  
Author(s):  
Izzeldin Idris Abdalla ◽  
Taib Ibrahim ◽  
Nursyarizal Mohd Nor
Keyword(s):  
Permanent Magnet ◽  
Permanent Magnets ◽  
Outer Radius ◽  
Design Parameters ◽  
Reciprocating Compressor ◽  
Permanent Magnet Motors ◽  
Permanent Magnet Motor ◽  
Element Analysis ◽  
Split Ratio ◽  
Single Coil

This paper describes a design optimization to achieve optimal performance of a two novel single-phase short-stroke tubular linear permanent magnet motors (TLPMMs) with rectangular and trapezoidal permanent magnets (PMs) structures. The motors equipped with a quasi-Halbach magnetized moving-magnet armature and slotted stator with a single-slot carrying a single coil. The motors have been developed for reciprocating compressor applications such as household refrigerators. It is observed that the TLPMM efficiency can be optimized with respect to the leading design parameters (dimensional ratios). Furthermore, the influence of mover back iron is investigated and the loss of the motor is computed. Finite element analysis (FEA) is employed for the optimization, and the optimal values of the ratio of the axial length of the radially magnetized magnets to the pole pitch as well as the ratio of the PMs outer radius-to-stator outer radius (split ratio), are identified.

Generic Models of Electric Machine Applications in Hybrid Electric Vehicles Power Train Simulations

2013 ◽  
pp. 95-150
Keyword(s):  
Magnetic Field ◽  
Permanent Magnet ◽  
Rotational Speed ◽  
Electric Machines ◽  
Simulation Studies ◽  
Permanent Magnet Motors ◽  
Power Train ◽  
Field Weakening ◽  
Generic Models ◽  
Hybrid Power

Chapter 4 presents an approach to obtain the power simulation model of electric machines that would be practically useful in hybrid power train simulation studies. The induction motor (AC) and the permanent magnet motor’s (PM) mathematical dynamic models are based on the necessary and fundamental knowledge conveyed in the previous chapter. These generic models are here adapted to the hybrid power train requirements, while the mechanical characteristics of the vehicle’s driving system are relegated to the background. The vector field oriented control of induction and permanent magnet motors is applied in the conducted mathematical modeling. The influence of the controlled voltage frequency is discussed as well. In the case of permanent magnet motors, the adjusted method of magnetic field weakening is very important during pulse modulation (PWM) control. The chapter presents the model of synchronous permanent motor magnetic field weakening. The basic simulation studies’ results dedicated especially to the above-mentioned electric motors are included. One of the targets of these simulations is the determination of these electric machines’ static characteristics (motor’s map) as the function: output mechanical torque versus the motors’ shaft rotational speed. This feature is indicated as the map of electric machines connected with its efficiency in a four quarterly operation (4Q), which means the operation of the motor/generator mode in two directions of the shaft rotational speed, which appears very useful in practice.

scholarly journals Alternative Approach for the Calculation of Magnetic Field due to Magnet for Magnetic Field Visualization and Evaluation

2020 ◽  
Vol 15 (1) ◽  
pp. 150-160
Author(s):  
Kishor Kaphle ◽  
Gyanendra Karki ◽  
Amrit Panthi
Keyword(s):  
Magnetic Field ◽  
Permanent Magnet ◽  
Field Distribution ◽  
Permanent Magnets ◽  
Magnetic Field Distribution ◽  
Geometrical Shape ◽  
Shape Transformation ◽  
Basic Principles ◽  
Alternative Approach ◽  
The Magnetic Field

 The magnetic field of different geometry of the permanent magnet is analytically calculated by using basic principles of the magnetism in very easier approach. Concept of origin shifting and geometrical shape transformation are used to formulate the formula for cuboidal, cubical and cylindrical permanent magnets. This concept can be used for the analysis of magnetic field distribution in space around for permanent magnet as well as electromagnet in a very easier approach. Handy and simplified software is made to calculate the magnetic field due to permanent magnet and electromagnet at any desired position on space. Magnetic field visualization is also done in both magnitude and direction by using MATLAB.  

Magnetic Field Analysis of Surface-Mounted Permanent-Magnet Motors

2011 ◽  
Vol 52-54 ◽  
pp. 285-290
Author(s):  
Yi Chang Wu ◽  
Feng Ming Ou ◽  
Bo Wei Lin
Keyword(s):  
Magnetic Field ◽  
Permanent Magnet ◽  
Magnetic Circuit ◽  
Circuit Model ◽  
Field Analysis ◽  
Permanent Magnet Motors ◽  
Element Analysis ◽  
Magnetic Field Analysis ◽  
Field Estimation ◽  
The Magnetic Field

The prediction of the magnetic field is a prerequisite to investigate the motor performance. This paper focuses on the magnetic field estimation of surface-mounted permanent-magnet (SMPM) motors based on two approximations, i.e., the magnetic circuit analysis and the finite-element analysis (FEA). An equivalent magnetic circuit model is applied to analytically evaluate the magnetic field of a SMPM motor with exterior-rotor configuration. The two-dimensional FEA is then applied to numerically calculate the magnetic field and to verify the validity of the magnetic circuit model. The results show that the errors between the analytical predictions and FEA results are less than 6%. It is of benefit to further design purposes and optimization of SMPM motors.

Research on the Magnetic Force of a Blood Pump Driven by Large Gap External Magnetic Field

2012 ◽  
Vol 271-272 ◽  
pp. 1636-1640
Author(s):  
Xiao Yan Tang ◽  
Zhong Yun ◽  
Chuang Xiang
Keyword(s):  
Magnetic Field ◽  
Permanent Magnet ◽  
Magnetic Force ◽  
Permanent Magnets ◽  
Magnetic Field Intensity ◽  
Current Theory ◽  
Calculation Model ◽  
Blood Pump ◽  
Single Turn ◽  
The Magnetic Field

The calculation model of the single turn rectangle current carrying coil was established. The theoretic formula for calculating the magnetic field intensity of any point in space was derived. For a pair of radial magnetizing permanent magnets, the formula for calculating the magnetic force of permanent magnet in the magnetic field was deduced based on the equivalent current theory of permanent magnet. According to the formula, the influencing factors and the changing rules for the magnetic force of permanent magnet can be seen directly: the current, the coil turns are proportional to its magnetic force, while the coupling distance is inversely proportional to its magnetic force.

Temperature suppression of metal panel in electromagnetic field

Circuit World ◽  
2020 ◽  
Vol 46 (4) ◽  
pp. 317-324
Author(s):  
Guochao Zheng ◽  
Fuli Wang ◽  
Baiping Yan ◽  
Runting Cheng
Keyword(s):  
Permanent Magnet ◽  
Magnetic Induction ◽  
Permanent Magnets ◽  
Magnetic Field Intensity ◽  
Metal Plate ◽  
Content Type ◽  
Magnetic Induction Intensity ◽  
Metal Panels ◽  
The Magnetic Field ◽  
Field Intensity Distribution

Purpose The purpose of this study is to suppress the temperature rise of high voltage wall bushing metal plate. Design/methodology/approach First, the authors built a model of a traditional metal plate and got the magnetic field intensity distribution by FEA tools. Optimized according to the magnetic field intensity distribution, the authors slot the traditional metal plate and embed permanent magnets in the slot. Finally, the authors got the temperature distribution diagrams of the above three cases at different current levels by FEA tools. Findings Slotted metal plate is beneficial to suppress magnetic induction intensity, but the improvement of the magnetic induction intensity uniformity is not obvious. The method of embedding a permanent magnet in a slotted metal plate can optimize the magnitude and uniformity of the magnetic induction intensity in the metal plate. The larger the current passing through the metal plate, the better the temperature suppression effect of the slotted metal plate and the slotted metal plate embedded in the permanent magnet. Originality/value The effect of structural factors, slotting plate and setting permanent magnets on slots on the temperature of supporting plate is studied. The paper proposes two methods, slotting metal panels and embedding permanent magnet metal panels, to solve the problems of eddy current loss and high calorific value of the panel, which is of great significance to the safety of the grid equipment.

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