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Design of Powder Core Motors

Reinap, Avo LU (2005)
Abstract
The goal of the study presented in this thesis is to evaluate the advantages and drawbacks of using powder technology in the design of the iron core of small claw-pole electric motors. The use of soft magnetic composites (SMC) and compaction technology allows the creation of complex 3D iron cores. The additional dimension opens for new solutions of the electromechanical energy conversion. A claw-pole motor among the transversal flux machines that has particularly high specific torque is in the focus of research interest. Generally, as the iron core can be more complicated, the winding is chosen to be simpler in the powder core motors. The thesis focuses on the machine design of a single-phase and a two-phase low-power claw-pole motor. The... (More)
The goal of the study presented in this thesis is to evaluate the advantages and drawbacks of using powder technology in the design of the iron core of small claw-pole electric motors. The use of soft magnetic composites (SMC) and compaction technology allows the creation of complex 3D iron cores. The additional dimension opens for new solutions of the electromechanical energy conversion. A claw-pole motor among the transversal flux machines that has particularly high specific torque is in the focus of research interest. Generally, as the iron core can be more complicated, the winding is chosen to be simpler in the powder core motors. The thesis focuses on the machine design of a single-phase and a two-phase low-power claw-pole motor. The predicted results compare well with measurements of the prototype motors.



The motor design process in this thesis uses a magnetic equivalent circuit (MEC) model of the outer-rotor claw-pole motors that is accurate enough to describe the physics of the electromagnetic conversion. Additional equivalent circuits are made to evaluate the mechanic and thermal loading of the machines. The outcome of the equivalent circuit models is enough to estimate roughly the optimal size of the motor and the motor output according to the materials selected.



After the rough design process, which is based on equivalent circuits, is finished, a series of FE magnetostatic analyses are made in order to evaluate the static characteristics of the motors, to specify the magnetization losses and to carry out a sensitivity study for the proposed size of the motors. Finally, the magnetic, mechanic and thermal design is analyzed dynamically and statically by the use of coupled multiphysics. The task of the coupled multiphysics is to find out the cooling capability and the thermal limit of the motor as well as the mechanic stress in the motor parts due to magneto-mechanic loading. It is discussed how the discrepancy between the calculated and measured cogging torque depends on the fineness of the 3D FE air gap mesh.



Iron loss estimation based on the results of the FE-analysis is made taking the local rotation, and not only pulsation, of the magnetic flux into consideration. It is shown that the loss coefficients in the material model must be adapted to account for flux rotation.



A part from the output of the machine as an electromechanical energy converter is their controllability in the electric drive system. Based on the static characteristics, which are calculated in the FE-analysis and verified in prototype measurements, a tailor made control method is developed for the machines designed. Results are presented of extensive simulations and experimental verifications of the proposed control strategy and power electronic circuitry. The high-speed four-pole single-phase motor shows satisfactory results. The other motor, which has 20 poles and two phases, has a main weakness in its complex assembling and a large cogging torque. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Jack, Alan G., University of Newcastle upon Tyne, UK
organization
publishing date
type
Thesis
publication status
published
subject
keywords
claw-pole motor, Soft magnetic composite, Electrical engineering, 3D finite element analysis, Elektroteknik
pages
220 pages
publisher
Department of Industrial Electrical Engineering and Automation, Lund Institute of Technology
defense location
Lecture hall M:B, at M-Building, Ole Römers väg 1, Lund
defense date
2005-01-13 10:15
ISBN
91-88934-36-5
language
English
LU publication?
yes
id
201f2882-ed2a-42b5-8dc1-d3eddce31a41 (old id 24312)
date added to LUP
2007-05-31 15:45:04
date last changed
2016-09-19 08:45:05
@phdthesis{201f2882-ed2a-42b5-8dc1-d3eddce31a41,
  abstract     = {The goal of the study presented in this thesis is to evaluate the advantages and drawbacks of using powder technology in the design of the iron core of small claw-pole electric motors. The use of soft magnetic composites (SMC) and compaction technology allows the creation of complex 3D iron cores. The additional dimension opens for new solutions of the electromechanical energy conversion. A claw-pole motor among the transversal flux machines that has particularly high specific torque is in the focus of research interest. Generally, as the iron core can be more complicated, the winding is chosen to be simpler in the powder core motors. The thesis focuses on the machine design of a single-phase and a two-phase low-power claw-pole motor. The predicted results compare well with measurements of the prototype motors.<br/><br>
<br/><br>
The motor design process in this thesis uses a magnetic equivalent circuit (MEC) model of the outer-rotor claw-pole motors that is accurate enough to describe the physics of the electromagnetic conversion. Additional equivalent circuits are made to evaluate the mechanic and thermal loading of the machines. The outcome of the equivalent circuit models is enough to estimate roughly the optimal size of the motor and the motor output according to the materials selected.<br/><br>
<br/><br>
After the rough design process, which is based on equivalent circuits, is finished, a series of FE magnetostatic analyses are made in order to evaluate the static characteristics of the motors, to specify the magnetization losses and to carry out a sensitivity study for the proposed size of the motors. Finally, the magnetic, mechanic and thermal design is analyzed dynamically and statically by the use of coupled multiphysics. The task of the coupled multiphysics is to find out the cooling capability and the thermal limit of the motor as well as the mechanic stress in the motor parts due to magneto-mechanic loading. It is discussed how the discrepancy between the calculated and measured cogging torque depends on the fineness of the 3D FE air gap mesh.<br/><br>
<br/><br>
Iron loss estimation based on the results of the FE-analysis is made taking the local rotation, and not only pulsation, of the magnetic flux into consideration. It is shown that the loss coefficients in the material model must be adapted to account for flux rotation.<br/><br>
<br/><br>
A part from the output of the machine as an electromechanical energy converter is their controllability in the electric drive system. Based on the static characteristics, which are calculated in the FE-analysis and verified in prototype measurements, a tailor made control method is developed for the machines designed. Results are presented of extensive simulations and experimental verifications of the proposed control strategy and power electronic circuitry. The high-speed four-pole single-phase motor shows satisfactory results. The other motor, which has 20 poles and two phases, has a main weakness in its complex assembling and a large cogging torque.},
  author       = {Reinap, Avo},
  isbn         = {91-88934-36-5},
  keyword      = {claw-pole motor,Soft magnetic composite,Electrical engineering,3D finite element analysis,Elektroteknik},
  language     = {eng},
  pages        = {220},
  publisher    = {Department of Industrial Electrical Engineering and Automation, Lund Institute of Technology},
  school       = {Lund University},
  title        = {Design of Powder Core Motors},
  year         = {2005},
}