Axial Flux Permanent Magnet Generators for Direct-Drive Wind Turbines - Review and Optimal Design Studies

Matin Vatani; Ali Mohammadi; Donovin D. Lewis; John Frederic Eastham; Dan M. Ionel

doi:10.1109/TIA.2025.3577150

Axial Flux Permanent Magnet Generators for Direct-Drive Wind Turbines - Review and Optimal Design Studies

Matin Vatani
, Ali Mohammadi
, Donovin D. Lewis
, John Frederic Eastham
, Dan M. Ionel

Research output: Contribution to journal › Article › peer-review

3 Scopus citations

Abstract

This paper presents a comprehensive analysis of the feasibility, cost, and electromagnetic performance of five distinct types of axial flux permanent magnet (AFPM) generators designed for direct-drive wind turbines. The generator configurations investigated include a single-sided AFPM generator with a surface-mounted PM rotor (AFPMG), a double-sided AFPM generator featuring PMs on the stator and a reluctance rotor (AFPMG-RR), a coreless stator AFPM generator with surface PMs (CAFPMG-SPM), and a coreless stator AFPM generator with a Halbach PM array rotor (CAFPMG-Hal). Each generator’s operating principles and configurations are thoroughly explained and compared. Large-scale multi-objective design optimizations were conducted on each type, taking advantage of symmetric computational models and using a differential evolution algorithm based on 3D finite element analysis (FEA) to minimize cost and mass while maximizing efficiency for all designs. A comprehensive discussion of the optimization results highlights the merits of each configuration. The findings indicate and confirm that AFPM generators can potentially achieve superior performance compared to their radial counterparts, as reported in the literature, while also benefiting from more robust and compatible mechanical integration with wind turbines.

Original language	English
Pages (from-to)	9615-9627
Number of pages	13
Journal	IEEE Transactions on Industry Applications
Volume	61
Issue number	6
DOIs	https://doi.org/10.1109/TIA.2025.3577150
State	Published - 2025

Bibliographical note

Publisher Copyright:
© 1972-2012 IEEE.

Funding

Boulder Wind Power, supported by funding from the US Department of Energy (DOE), developed a single-stage coreless stator AFPM generator with a rated power of 6 MW and an outer diameter of 20 meters [14]. The stator design utilizes printed circuit board (PCB) materials based on the concept first introduced in [23]. This PCB-based approach accelerates production, minimizes human error through automation, and significantly reduces costs compared to Litze wire, particularly in mass production scenarios. This work was supported in part by the National Science Foundation (NSF) under Award 1809876. The work of Donovin Lewis was supported in part by an NSF Fellowship under Grant 2239063, in part by ANSYS Inc., and in part by the University of Kentucky’s L. Stanley Pigman Chair in Power Endowment. Any findings and conclusions expressed herein are those of the authors and do not necessarily reflect the views of the NSF.

Funders	Funder number
US Department of Energy
ANSYS
University of Kentucky
TUNL DOE
National Science Foundation Arctic Social Science Program	2239063, 1809876

Keywords

3D FEA
Axial flux PM machines
Halbach array
axial flux switching
coreless AFPM
differential evolution
direct-drive wind turbine

ASJC Scopus subject areas

Control and Systems Engineering
Industrial and Manufacturing Engineering
Electrical and Electronic Engineering

Access to Document

10.1109/TIA.2025.3577150

Cite this

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title = "Axial Flux Permanent Magnet Generators for Direct-Drive Wind Turbines - Review and Optimal Design Studies",

abstract = "This paper presents a comprehensive analysis of the feasibility, cost, and electromagnetic performance of five distinct types of axial flux permanent magnet (AFPM) generators designed for direct-drive wind turbines. The generator configurations investigated include a single-sided AFPM generator with a surface-mounted PM rotor (AFPMG), a double-sided AFPM generator featuring PMs on the stator and a reluctance rotor (AFPMG-RR), a coreless stator AFPM generator with surface PMs (CAFPMG-SPM), and a coreless stator AFPM generator with a Halbach PM array rotor (CAFPMG-Hal). Each generator{\textquoteright}s operating principles and configurations are thoroughly explained and compared. Large-scale multi-objective design optimizations were conducted on each type, taking advantage of symmetric computational models and using a differential evolution algorithm based on 3D finite element analysis (FEA) to minimize cost and mass while maximizing efficiency for all designs. A comprehensive discussion of the optimization results highlights the merits of each configuration. The findings indicate and confirm that AFPM generators can potentially achieve superior performance compared to their radial counterparts, as reported in the literature, while also benefiting from more robust and compatible mechanical integration with wind turbines.",

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author = "Matin Vatani and Ali Mohammadi and Lewis, \{Donovin D.\} and Eastham, \{John Frederic\} and Ionel, \{Dan M.\}",

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AU - Ionel, Dan M.

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N2 - This paper presents a comprehensive analysis of the feasibility, cost, and electromagnetic performance of five distinct types of axial flux permanent magnet (AFPM) generators designed for direct-drive wind turbines. The generator configurations investigated include a single-sided AFPM generator with a surface-mounted PM rotor (AFPMG), a double-sided AFPM generator featuring PMs on the stator and a reluctance rotor (AFPMG-RR), a coreless stator AFPM generator with surface PMs (CAFPMG-SPM), and a coreless stator AFPM generator with a Halbach PM array rotor (CAFPMG-Hal). Each generator’s operating principles and configurations are thoroughly explained and compared. Large-scale multi-objective design optimizations were conducted on each type, taking advantage of symmetric computational models and using a differential evolution algorithm based on 3D finite element analysis (FEA) to minimize cost and mass while maximizing efficiency for all designs. A comprehensive discussion of the optimization results highlights the merits of each configuration. The findings indicate and confirm that AFPM generators can potentially achieve superior performance compared to their radial counterparts, as reported in the literature, while also benefiting from more robust and compatible mechanical integration with wind turbines.

AB - This paper presents a comprehensive analysis of the feasibility, cost, and electromagnetic performance of five distinct types of axial flux permanent magnet (AFPM) generators designed for direct-drive wind turbines. The generator configurations investigated include a single-sided AFPM generator with a surface-mounted PM rotor (AFPMG), a double-sided AFPM generator featuring PMs on the stator and a reluctance rotor (AFPMG-RR), a coreless stator AFPM generator with surface PMs (CAFPMG-SPM), and a coreless stator AFPM generator with a Halbach PM array rotor (CAFPMG-Hal). Each generator’s operating principles and configurations are thoroughly explained and compared. Large-scale multi-objective design optimizations were conducted on each type, taking advantage of symmetric computational models and using a differential evolution algorithm based on 3D finite element analysis (FEA) to minimize cost and mass while maximizing efficiency for all designs. A comprehensive discussion of the optimization results highlights the merits of each configuration. The findings indicate and confirm that AFPM generators can potentially achieve superior performance compared to their radial counterparts, as reported in the literature, while also benefiting from more robust and compatible mechanical integration with wind turbines.

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KW - Halbach array

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KW - differential evolution

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Axial Flux Permanent Magnet Generators for Direct-Drive Wind Turbines - Review and Optimal Design Studies

Abstract

Bibliographical note

Funding

Keywords

ASJC Scopus subject areas

Access to Document

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