Non-invasive load monitoring of induction motor drives using magnetic flux sensors

Zheng Liu, Guiyun Tian, Wenping Cao*, Xuewu Dai, Brian Shaw, Robert Lambert

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Existing load monitoring methods for induction machines are generally effective, but suffer from sensitivity problems at low speeds and non-linearity problems at high supply frequencies. This study proposes a new noninvasive load monitoring method based on giant magnetoresistance flux sensors to trace stray flux leaking from induction motors. Finite element analysis is applied to analyse stray flux features of test machines. Contrary to the conventional methods of measuring stator and/or rotator rotor voltage and current, the proposed method measures the dynamic magnetic field at specific locations and provides time-spectrum features (e.g. spectrograms), response time load and stator/rotor characteristics. Three induction motors with different starting loading profiles are tested at two separate test benches and their results are analysed in the time-frequency domain. Their steady features and dynamic load response time through spectrograms under variable loads are extracted to correlate with load variations based on spectrogram information. In addition, the transient stray flux spectrogram and time information are more effective for load monitoring than steady state information from numerical and experimental studies. The proposed method is proven to be a low-cost and non-invasive method for induction machine load monitoring.

Original languageEnglish
Pages (from-to)189-195
Number of pages7
JournalIET Power Electronics
Issue number2
Publication statusPublished - 10 Feb 2017

Bibliographical note

This paper is a postprint of a paper submitted to and accepted for publication in IET Power Electronics and is subject to Institution of Engineering and technology Copyright. The copy of the records is available at the IET Digital Library.

Funding: FP7 HEMOW Project (FP7-PEOPLE-2010-IRSES, 269202) and EPSRC Project (EP/K008552/3).


Dive into the research topics of 'Non-invasive load monitoring of induction motor drives using magnetic flux sensors'. Together they form a unique fingerprint.

Cite this