Development of an Optimisation Tool for the Mechanical Design of Permanent Magnet Rotors in High-Speed Electric Machines

2021 ◽  
Author(s):  
Levi Mallin ◽  
Simon Barrans
Keyword(s):  
Permanent Magnet ◽  
High Speed ◽  
Mechanical Design ◽  
Electric Machines

Particular Coupled Electromagnetic, Thermal, Mechanical Design of High-Speed Permanent-Magnet Motor

2020 ◽  
Vol 56 (3) ◽  
pp. 1-5 ◽  
Author(s):  
A. Koronides ◽  
C. Krasopoulos ◽  
D. Tsiakos ◽  
M. S. Pechlivanidou ◽  
A. Kladas
Keyword(s):  
Permanent Magnet ◽  
High Speed ◽  
Mechanical Design ◽  
Permanent Magnet Motor

Microturbine Rotational Speed Selection

2013 ◽  
Author(s):  
C. Rodgers
Keyword(s):  
Permanent Magnet ◽  
Output Power ◽  
Thermal Efficiency ◽  
Rotational Speed ◽  
High Speed ◽  
Mechanical Design ◽  
Pressure Ratio ◽  
Direct Drive ◽  
Power Turbine ◽  
Speed Selection

This paper delves upon the Aero-Thermodynamic performance and Mechanical design aspects of microturbines comprising a single shaft radial compressor driven by a single stage radial inflow turbine with a combustor and recuperator sized to directly drive a permanent magnet type high speed generator with an output power in the 5–10KW bracket and commensurate rotational speeds in the 100–200 krpm range. It is initially shown that stipulation of a cycle design point output power, turbine inlet or exit temperatures, and compressor pressure ratio delivering optimum thermal efficiency inherently confines rotational speed selection, and that independent rotational speed choice away from those identified optimum speed regimes may result in cycle thermal efficiency compromises. Confining the cycle analysis within temperature limits of cost competitive superalloys and foil materials reveals that the achievement of optimum thermal efficiency is more dependent on temperature at the turbine exit rather than at inlet. Albeit the choice of rotational speed is of particular importance in the compressor and turbine design it moreover is dominant in the mechanical design of the rotating assembly in terms of high speed bearing life and shaft dynamic stability. As a consequence rotating assembly and bearing design options suitable for direct drive permanent magnet generators are reviewed and recommendations offered as to the prime candidate assemblies for future microturbines in the 5.0 to 10.0 kW power output range.

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 Performance Analysis of High-Speed Electric Machines Supplied by PWM Inverters Based on the Harmonic Modeling Method

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2606
Author(s):  
Marko Merdžan
Keyword(s):  
Finite Element ◽  
Performance Analysis ◽  
Permanent Magnet ◽  
Eddy Current ◽  
Pulse Width ◽  
High Speed ◽  
Electric Machines ◽  
Switching Frequency ◽  
Eddy Current Losses ◽  
Pulse Width Modulated

This paper presents a method for the performance analysis of high-speed electric machines supplied with pulse-width modulated voltage source inverters by utilizing a fast analytical model. By applying a strict mathematical procedure, effective expressions for the calculation of rotor eddy current losses and electromagnetic torque are derived. Results obtained by the approach suggested in this study are verified by the finite element model, and it is shown that the proposed method is superior in comparison to the finite element method in terms of computation time. The proposed method enables fast parameter variation analysis, which is demonstrated by changing the inverter switching frequency and electric conductivity of the rotor and analyzing the effects of these changes on rotor eddy current losses. The presented work separately models effects of the permanent magnet and pulse-width modulated stator currents, making it suitable for the analysis of both high-speed permanent magnet machines and high-speed induction machines.

scholarly journals Significance of Anisotropic Thermal Expansion in High Speed Electric Machines Employing NdFeB Permanent Magnets

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7558
Author(s):  
Ram Kumar ◽  
Antonino La Rocca ◽  
Gaurang Vakil ◽  
David Gerada ◽  
Chris Gerada ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Rare Earth ◽  
High Speed ◽  
Permanent Magnets ◽  
Mechanical Design ◽  
Electric Machines ◽  
Mechanical Environment ◽  
Anisotropic Thermal Expansion ◽  
Working Temperature ◽  
Rotor Design

Many high speed applications employ a surface permanent magnet (PM) machine topology with a retaining sleeve due to its robustness and ability to achieve high overall peripheral speeds as well as efficiencies. One often overlooked feature in the mechanical design of such machines, which has not achieved sufficient attention to date is the anisotropic thermal expansion of rare earth magnets, the degree of which varies for different magnet technologies. This paper investigates the effects of the aforementioned on the mechanical design of a high speed PM spindle machine with NdFeB magnets. The maximum allowable interference is found to be limited by the working temperature of the magnets while the minimum required interference is increased due to their anisotropic thermal expansion. Based on this, appropriate conditions are formulated to integrate a Neodymium Iron Boron (NdFeB) PM in high speed rotors. These modifications considering the shaft together with the magnet anisotropic thermal expansion are included in a proposed rotor design and validated using simulations in ANSYS mechanical environment.

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.

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