A novel method for sensorless speed detection of brushed DC motors

Ernesto Vazquez-Sanchez, Joseph Sottile, Jaime Gomez-Gil

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


Many motor applications require accurate speed measurement. For brushed dc motors, speed can be measured with conventional observers or sensorless observers. Sensorless observers have the advantage of not requiring any external devices to be attached to the motor. Instead, voltage and/or current are measured and used to estimate the speed. The sensorless observers are usually divided into two groups: those based on the dynamic model, and those based on the ripple component. This paper proposes a method that measures the current of brushed dc motors and analyses the position of its spectral components. From these spectral components, the method estimates the motor speed. Three tests, performed each with the speeds ranging from 2000 to 3000 rpm either at constant-speed, at slowly changing speeds, or at rapidly changing speeds, showed that the average error was below 1 rpm and that the deviation error was below 1.5 rpm. The proposed method: (i) is a novel method that is not based on either the dynamic model or on the ripple component; (ii) requires only the measurement of the current for the speed estimation; (iii) can be used for brushed dc (direct current) motors with a large number of coils; and (iv) achieves a low error in the speed estimation.

Original languageEnglish
Article number14
JournalApplied Sciences (Switzerland)
Issue number1
StatePublished - 2017

Bibliographical note

Publisher Copyright:
© 2016 by the authors.


  • Brushed dc motor
  • Current
  • Sensorless
  • Spectral analysis
  • Speed observer

ASJC Scopus subject areas

  • General Materials Science
  • Instrumentation
  • General Engineering
  • Process Chemistry and Technology
  • Computer Science Applications
  • Fluid Flow and Transfer Processes


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