scholarly journals Comparison of theoretical approaches to determine the stresses in surface mounted permanent magnet rotors for high speed electric machines

2021 ◽  
pp. 030932472110076
Author(s):  
Levi Mallin ◽  
Simon Barrans
Keyword(s):  
Permanent Magnet ◽  
Plane Strain ◽  
Plane Stress ◽  
High Speed ◽  
Electric Machines ◽  
Mechanical Transmission ◽  
Element Analysis ◽  
Theoretical Approaches ◽  
Rotor Design ◽  
Stress Plane

High-speed electrical machines (HSEMs) are becoming more popular in applications such as air handling devices. Using surface-mounted permanent magnet (PM) rotors manufactured from rare earth metals, they provide benefits over their mechanical transmission counterparts. However, these PMs have low tensile strength and are prone to failure under large centrifugal loads when rotating. Therefore, retaining sleeves are used to hold the PMs in compression to eliminate tensile stress and reduce failure risk. The magnets are also often held on a back iron or carrier, forming an assembly of three cylinders. The ability to predict these stresses is extremely important to rotor design. Current published work shows a lack of exploration of analytical methods of calculating these stresses for three-cylinder assemblies. This paper shows the development of plane stress, plane strain and generalised plane strain (GPS) theories for three cylinders. For a range of rotor designs, these theories are compared with finite element analysis (FEA). GPS is shown to be more accurate than plane stress or plane strain for the central region of long cylinders. For short cylinders and for the ends of cylinders, all three theories give poor results.

scholarly journals A Review of the High-speed Permanent Magnet Rotor Stress Analysis used for Automotive Air-handling Machines

2020 ◽  
Vol 5 (4) ◽  
pp. 448-456
Author(s):  
Levi Ryan Mallin ◽  
Simon Mark Barrans
Keyword(s):  
Permanent Magnet ◽  
Plane Strain ◽  
High Speed ◽  
Element Analysis ◽  
Interference Fit ◽  
Centrifugal Load ◽  
High Speed Rotation ◽  
Speed Rotation ◽  
Rotor Assembly ◽  
Analytical Approaches

Machines incorporating high-speed electrical machines (HSEM) are becoming increasingly common place in applications including air handling, energy storage and medical devices. They are of increasing interest within the automotive field for air handling applications. HSEM’s use surface-mounted permanent magnet (PM) rotors, manufactured from rare earth metals. However, these PM’s have low tensile strength and are susceptible to failure under the centrifugal load produced at high speed rotation. Retaining sleeves which are an interference fit around the magnets, provide compression and hence resistance to tensile stress. The ability to predict the stresses within the rotor assembly is essential for robust design. This review paper examines existing analytical calculations and finite element analysis (FEA) models. The analytical approaches include both plane stress and plane strain models and the limitations of these are discussed. For relatively long rotors, a generalised plane strain approach is suitable, however it is seldom used. In addition, this latter approach has not been extended to assemblies where the magnets are assembled onto a carrier or shaft. Optimisation of rotors has been addressed in a relatively small number of papers. However, further work is required in this area to ensure that the optimised rotors can be manufactured.

Performance analysis of magnetic gear with Halbach array for high power and high speed

2020 ◽  
Vol 64 (1-4) ◽  
pp. 959-967
Author(s):  
Se-Yeong Kim ◽  
Tae-Woo Lee ◽  
Yon-Do Chun ◽  
Do-Kwan Hong
Keyword(s):  
Permanent Magnet ◽  
Eddy Current ◽  
High Power ◽  
High Speed ◽  
Torque Ripple ◽  
Eddy Current Loss ◽  
Element Analysis ◽  
Current Loss ◽  
Halbach Array ◽  
Magnetic Gear

In this study, we propose a non-contact 80 kW, 60,000 rpm coaxial magnetic gear (CMG) model for high speed and high power applications. Two models with the same power but different radial and axial sizes were optimized using response surface methodology. Both models employed a Halbach array to increase torque. Also, an edge fillet was applied to the radial magnetized permanent magnet to reduce torque ripple, and an axial gap was applied to the permanent magnet with a radial gap to reduce eddy current loss. The models were analyzed using 2-D and 3-D finite element analysis. The torque, torque ripple and eddy current loss were compared in both models according to the materials used, including Sm2Co17, NdFeBs (N42SH, N48SH). Also, the structural stability of the pole piece structure was investigated by forced vibration analysis. Critical speed results from rotordynamics analysis are also presented.

scholarly journals Elastic soil

1971 ◽  
Vol 4 (2) ◽  
pp. 258-269
Author(s):  
A. J. Carr ◽  
P. J. Moss
Keyword(s):  
Plane Strain ◽  
Plane Stress ◽  
Soil Structure ◽  
Soil Structure Interaction ◽  
Mode Shapes ◽  
Element Analysis ◽  
Structure Interaction ◽  
Stiffness Properties ◽  
Acceleration History ◽  
Elastic Soil

This paper presents a refined finite element analysis for the analysis of two-dimensional plane stress and plane strain structures with particular emphasis being placed on the ability to solve problems of soil-structure interaction under earthquake loadings. The structure and
the soil are idealized as an assemblage of quadrilateral plane stress and plane strain elements having a cubic variation in displacement enabling a more accurate representation of the stiffness properties of the system than that previously available. The response of the system to the earthquake acceleration history is achieved by a superposition of normal mode responses and the methods of obtaining the mode shapes and frequencies are outlined. Examples are presented to illustrate the capability of this approach.

Torque imporvement of IPM motors with skewing magnetic designs

2021 ◽  
pp. 3-10
Author(s):  
Dinh Hai Linh
Keyword(s):  
Permanent Magnet ◽  
High Speed ◽  
Torque Ripple ◽  
Maintenance Cost ◽  
Permanent Magnet Motor ◽  
Element Analysis ◽  
Speed Range ◽  
Interior Permanent Magnet ◽  
Interior Permanent Magnet Motor ◽  
Wide Speed Range

In this paper, a type interior permanent magnet synchronous motor designs is proposed for sport scooter application to improve constant torque wide speed performance. Interior Permanent Magnet machines are widely used in automotive applications for their wide-speed range operation and low maintenance cost. An existing permanent magnet motor (commercial QS Motor) is 3 kW-3000 rpm. In order to improve torque and power in wide speed range, a IPM electric motor 5.5 kW -5000 rpm can run up to 100 km/h: An Step-Skewing Interior Permanent Magnet motor alternatives is designed and optimized in detail with optimal magnetic segment V shape. The electromagnetic charateristics of Interior Permanent Magnet motors with V shape are compared with the reference Surface Permanent Magnet motor for the same geometry parameter requirements. Detailed loss and efficiency result is also analyzed at rate and maximum speeds. A prototype motor is manufactured, and initial experimental tests are performed. Detailed comparison between Finite Element Analysis and test data are also presented. It is shown that it is possible to have an optimized Interior Permanent Magnet motor for such high-speed traction application. This paper will figure out optimal angle of magnetic V shape for maximum torque and minimum torque ripple.

Design and analysis of a high speed double-sided axial flux permanent magnet motor suspended vertically by magnetic bearings

2020 ◽  
pp. 1-15
Author(s):  
Ömer Faruk Güney ◽  
Ahmet Çelik ◽  
Ahmet Fevzi Bozkurt ◽  
Kadir Erkan
Keyword(s):  
Permanent Magnet ◽  
High Speed ◽  
Permanent Magnets ◽  
Mechanical Analysis ◽  
Magnetic Bearings ◽  
Permanent Magnet Motor ◽  
Axial Flux ◽  
Element Analysis ◽  
Shaft System ◽  
Rotor Disk

This paper presents the electromagnetic and mechanical analysis of an axial flux permanent magnet (AFPM) motor for high speed (12000 rpm) rotor which is vertically suspended by magnetic bearings. In the analysis, a prototype AFPM motor with a double-sided rotor and a coreless stator between the rotors are considered. Firstly, electromagnetic analysis of the motor is carried out by using magnetic equivalent circuit method. Then, the rotor disk thickness is determined based on a rotor axial displacement due to the attractive force between the permanent magnets placed on opposite rotor disks. Hereafter, an analytical solution is carried out to determine the natural frequencies of the rotor-shaft system. Finally, 3D finite element analysis (FEA) is carried out to verify the analytical results and some experimental results are given to verify the analytical and numerical results and prove the stable high-speed operation.

scholarly journals Design of High-Speed Permanent Magnet Motor Considering Rotor Radial Force and Motor Losses

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5872 ◽  
Author(s):  
Nai-Wen Liu ◽  
Kuo-Yuan Hung ◽  
Shih-Chin Yang ◽  
Feng-Chi Lee ◽  
Chia-Jung Liu
Keyword(s):  
Permanent Magnet ◽  
High Speed ◽  
Radial Force ◽  
Nonlinear Finite Element ◽  
Motor Speed ◽  
Power Losses ◽  
Permanent Magnet Motor ◽  
Element Analysis ◽  
Radial Forces ◽  
Selection Of

Different from the design of conventional permanent magnet (PM) motors, high-speed motors are primarily limited by rotor unbalanced radial forces, rotor power losses, and rotor mechanical strength. This paper aimed to propose a suitable PM motor with consideration of these design issues. First, the rotor radial force is minimized based on the selection of stator tooth numbers and windings. By designing a stator with even slots, the rotor radial force can be canceled, leading to better rotor strength at high speed. Second, rotor power losses proportional to rotor frequency are increased as motor speed increases. A two-dimensional sensitivity analysis is used to improve these losses. In addition, the rotor sleeve loss can be minimized to less than 8.3% of the total losses using slotless windings. Third, the trapezoidal drive can cause more than a 33% magnet loss due to additional armature flux harmonics. This drive reflected loss is also mitigated with slotless windings. In this paper, six PM motors with different tooth numbers, stator cores, and winding layouts are compared. All the design methods are verified based on nonlinear finite element analysis (FEA).

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