Discrete-time observer design for sensorless synchronous motor drives

Hafiz Asad Ali Awan, Toni Tuovinen, Seppo E. Saarakkala, Marko Hinkkanen

Research output: Contribution to journalArticleScientificpeer-review

35 Citations (Scopus)
217 Downloads (Pure)


This paper deals with the speed and position estimation of interior permanent-magnet synchronous motor (IPM) and synchronous reluctance motor (SyRM) drives. A speed-adaptive full-order observer is designed and analyzed in the discrete-time domain. The observer design is based on the exact discrete-time motor model, which inherently takes the delays in the control system into account. The proposed observer is experimentally evaluated using a 6.7-kW SyRM drive. The analysis and experimental results indicate that major performance improvements can be obtained with the direct discrete-time design, especially if the sampling frequency is relatively low compared to the fundamental frequency. The ratio below 10 between the sampling and fundamental frequencies is achieved in experiments with the proposed discrete-time design.
Original languageEnglish
Pages (from-to)3968-3979
JournalIEEE Transactions on Industry Applications
Issue number5
Publication statusPublished - 24 May 2016
MoE publication typeA1 Journal article-refereed


  • modeling errors
  • observer
  • speed sensorless
  • stability conditions


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