Improved Closed-Loop Flux Observer Based Sensorless Control Against System Oscillation for Synchronous Reluctance Machine Drives

Research output: Contribution to journalJournal articleResearchpeer-review

72 Downloads (Pure)


Flux-linkage based sensorless control method is well-known and has been widely used in the control of electrical machines. The closed-loop flux observer (CLFO), which is the adaptive combination of the machine voltage and current models, is commonly adopted. It can cover a wide speed operation range and was considered to be able to solve the dc drift and initial value problem associated to the pure integrator used in the observer. However, it is reported in this paper that this popular CLFO cannot always work as expected. In some situations, dc-offsets cannot be removed by this flux observer, causing large system oscillation at fundamental frequency and is very harmful to the drive system. This important issue has not been reported and discussed in the existing literatures of the CLFO. In this paper, this phenomenon is experimentally illustrated and solution to damp this harmful oscillation is proposed and verified experimentally on a synchronous reluctance machine drive system.

Original languageEnglish
Article number8434357
JournalIEEE Transactions on Power Electronics
Issue number5
Pages (from-to)4593 - 4602
Number of pages10
Publication statusPublished - May 2019



  • DC-offset
  • flux observer
  • nonideal proportional-resonant controller
  • sensorless
  • stability
  • synchronous reluctance machine (SynRM)

Cite this