Stray flux-based rotation angle measurement for bearing fault diagnosis in variable-speed BLDC motors

Xiaoxian Wang, Siliang Lu, Wenping Cao, Min Xia, Kang Chen, Jianming Ding, Shiwu Zhang

Research output: Contribution to journalArticlepeer-review


Angle of rotation is a key parameter in motor fault diagnosis under varying speed conditions, and is usually measured by an optical encoder. However, the use of encoders is intrusive and in many scenarios its signal is difficult to access due to technical or commercial reasons. In this study, a novel rotation angle measurement method based on stray flux analysis is proposed and applied to bearing fault diagnosis of brushless direct-current (BLDC) motors. The measurement accuracy of the proposed method is comparable to that from an encoder. The developed method is flexible, noninvasive, and nondestructive. It is easy to implement and eliminates the need for long cables and access of the motor control system. The proposed method can be extended to the diagnosis of motor electrical and drive faults. If implemented with an Internet of Things (IoT) or a hand-held device, it can further improve the reliability of sensorless motor drive systems in industrial automation so as to meet Industry 4.0 requirements.
Original languageEnglish
Pages (from-to)3156-3166
Number of pages11
JournalIEEE Transactions on Energy Conversion
Issue number4
Early online date12 May 2021
Publication statusPublished - 1 Dec 2021

Bibliographical note

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Funding: Open Project Program of the Traction Power State Key Laboratory of Southwest Jiaotong University; 10.13039/501100001809-National Natural Science Foundation of China.


  • BLDC motors
  • Bearing fault
  • fault diagnosis
  • rotation angle measurement
  • stray flux
  • vibration signal analysis


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