Design and Electromagnetic Performance Optimization of a MEMS Miniature Outer-Rotor Permanent Magnet Motor

In this study, we present the design and electromagnetic performance optimization of a micro-electromechanical system (MEMS) miniature outer-rotor permanent magnet motor. With increased attention towards higher torque density and lower torque pulsations in MEMS micromotor designs, an adaptation of a...

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Main Authors: Kaibo Lei, Haiwang Li, Shijia Li, Tiantong Xu
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Micromachines
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Online Access:https://www.mdpi.com/2072-666X/16/7/815
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author Kaibo Lei
Haiwang Li
Shijia Li
Tiantong Xu
author_facet Kaibo Lei
Haiwang Li
Shijia Li
Tiantong Xu
author_sort Kaibo Lei
collection DOAJ
description In this study, we present the design and electromagnetic performance optimization of a micro-electromechanical system (MEMS) miniature outer-rotor permanent magnet motor. With increased attention towards higher torque density and lower torque pulsations in MEMS micromotor designs, an adaptation of an external rotor can be highly attractive. However, with the design complexity involved in such high-performance MEMS outer-rotor motor designs, the ultra-miniature 3D coil structures and the thin-film topology surrounding the air gap have been one of the main challenges. In this study, an ultra-thin outer-rotor motor with 3D MEMS silicon-based coils and a MEMS-compatible manufacturing method for the 3D coils is presented. Additionally, finite element simulations are conducted for the thin-film topology around the air gap to optimize performance characteristics such as torque developed, torque pulsations, and back electromotive force amplitude. Ultimately, the average magnetic flux density increased by 37.1%, from 0.361 T to 0.495 T. The root mean square (RMS) value of the back EMF per phase rises by 14.4%. Notably, the average torque is improved by 11.3%, while the torque ripple is significantly reduced from 1.281 mNm to 0.74 mNm, corresponding to a reduction of 49.9% in torque ripple percentage.
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spelling doaj-art-8fe41ddb7a2a4fe693dc2e4fb86504232025-08-20T03:58:27ZengMDPI AGMicromachines2072-666X2025-07-0116781510.3390/mi16070815Design and Electromagnetic Performance Optimization of a MEMS Miniature Outer-Rotor Permanent Magnet MotorKaibo Lei0Haiwang Li1Shijia Li2Tiantong Xu3National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics, Beihang University, Beijing 100191, ChinaNational Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics, Beihang University, Beijing 100191, ChinaNational Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics, Beihang University, Beijing 100191, ChinaNational Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics, Beihang University, Beijing 100191, ChinaIn this study, we present the design and electromagnetic performance optimization of a micro-electromechanical system (MEMS) miniature outer-rotor permanent magnet motor. With increased attention towards higher torque density and lower torque pulsations in MEMS micromotor designs, an adaptation of an external rotor can be highly attractive. However, with the design complexity involved in such high-performance MEMS outer-rotor motor designs, the ultra-miniature 3D coil structures and the thin-film topology surrounding the air gap have been one of the main challenges. In this study, an ultra-thin outer-rotor motor with 3D MEMS silicon-based coils and a MEMS-compatible manufacturing method for the 3D coils is presented. Additionally, finite element simulations are conducted for the thin-film topology around the air gap to optimize performance characteristics such as torque developed, torque pulsations, and back electromotive force amplitude. Ultimately, the average magnetic flux density increased by 37.1%, from 0.361 T to 0.495 T. The root mean square (RMS) value of the back EMF per phase rises by 14.4%. Notably, the average torque is improved by 11.3%, while the torque ripple is significantly reduced from 1.281 mNm to 0.74 mNm, corresponding to a reduction of 49.9% in torque ripple percentage.https://www.mdpi.com/2072-666X/16/7/815MEMS motorouter-rotor permanent magnet motorelectromagnetic performance optimizationback EMFtorquecogging torque
spellingShingle Kaibo Lei
Haiwang Li
Shijia Li
Tiantong Xu
Design and Electromagnetic Performance Optimization of a MEMS Miniature Outer-Rotor Permanent Magnet Motor
Micromachines
MEMS motor
outer-rotor permanent magnet motor
electromagnetic performance optimization
back EMF
torque
cogging torque
title Design and Electromagnetic Performance Optimization of a MEMS Miniature Outer-Rotor Permanent Magnet Motor
title_full Design and Electromagnetic Performance Optimization of a MEMS Miniature Outer-Rotor Permanent Magnet Motor
title_fullStr Design and Electromagnetic Performance Optimization of a MEMS Miniature Outer-Rotor Permanent Magnet Motor
title_full_unstemmed Design and Electromagnetic Performance Optimization of a MEMS Miniature Outer-Rotor Permanent Magnet Motor
title_short Design and Electromagnetic Performance Optimization of a MEMS Miniature Outer-Rotor Permanent Magnet Motor
title_sort design and electromagnetic performance optimization of a mems miniature outer rotor permanent magnet motor
topic MEMS motor
outer-rotor permanent magnet motor
electromagnetic performance optimization
back EMF
torque
cogging torque
url https://www.mdpi.com/2072-666X/16/7/815
work_keys_str_mv AT kaibolei designandelectromagneticperformanceoptimizationofamemsminiatureouterrotorpermanentmagnetmotor
AT haiwangli designandelectromagneticperformanceoptimizationofamemsminiatureouterrotorpermanentmagnetmotor
AT shijiali designandelectromagneticperformanceoptimizationofamemsminiatureouterrotorpermanentmagnetmotor
AT tiantongxu designandelectromagneticperformanceoptimizationofamemsminiatureouterrotorpermanentmagnetmotor