Velocity measurement method for PMSMs through external stray magnetic field sensing

Xuyang Liu, Philip W.T. Pong, Chunhua Liu

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Scopus citations


This paper presents a method to measure the velocity of permanent magnet synchronous motors (PMSMs) by sensing the external stray magnetic field (SMF) outside the stator surface. First, a magnetic circuit model of PMSM was developed to analyze the distribution of SMF. The key is to sense the SMF by a magnetic sensor and extract the frequency through a zero-crossing comparison to obtain the velocity. Then, the proposed method was validated by the finite-element-method (FEM). Moreover, a 5.5 kW three-phase PMSM testbed was built up for experimental verification. A triaxial tunneling magnetoresistive (TMR) sensor was utilized to sense the SMF in the testbed. The experimental results demonstrate that the measurement accuracy is less than ±0.15% in the range from 100 rpm to 1000 rpm. Thus, it verifies the proposed methodology can provide a cost-effective and high-accuracy alternative to the velocity measurement for PMSMs.

Original languageEnglish (US)
Title of host publicationIEEE SENSORS 2017 - Conference Proceedings
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages3
ISBN (Electronic)9781509010127
StatePublished - Dec 21 2017
Externally publishedYes
Event16th IEEE SENSORS Conference, ICSENS 2017 - Glasgow, United Kingdom
Duration: Oct 30 2017Nov 1 2017

Publication series

NameProceedings of IEEE Sensors
ISSN (Print)1930-0395
ISSN (Electronic)2168-9229


Conference16th IEEE SENSORS Conference, ICSENS 2017
Country/TerritoryUnited Kingdom

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering


  • Magnetoresistive sensor
  • PMSMs
  • Stray magnetic field
  • Velocity measurement


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