Speed-Sensorless Control of Induction Motors With an Open-Loop Synchronization Method

Huimin Wang, Yongheng Yang, Dunzhi Chen, Xinglai Ge*, Songtao Li, Yun Zuo

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

8 Citations (Scopus)
14 Downloads (Pure)


Speed estimation schemes based on the closed-loop synchronization (CLS) methods for speed-sensorless control of motor drives attract much popularity due to several advantages, e.g., easy implementation, high flexibility, and acceptable performance. However, most of the existing CLS-based estimation schemes may suffer from performance degradation during frequency ramps. Considering this, an attempt of the type-3 phase-locked loop (PLL)-based scheme is made. This solution, however, may adversely affect the system dynamics and stability margin. To address these issues, an open-loop synchronization (OLS) method is proposed for speed-sensorless control of induction motor drives in this paper. In the proposed scheme, the estimated speed is obtained according to the sinusoidal signals and their time-delay signals, rather than increasing the system order. With this, system dynamics and stability margin are maintained. In practice, the disturbance of DC offsets is of concern in induction motor drives. Thus, a closed-loop flux observer is adopted to guarantee the estimation performance under DC offsets. The performance of the proposed OLS scheme is investigated and compared with that of the CLS schemes and the type-3 PLL scheme through experimental tests.
Original languageEnglish
JournalIEEE Journal of Emerging and Selected Topics in Power Electronics
Issue number2
Pages (from-to)1963-1977
Number of pages15
Publication statusPublished - 1 Apr 2022


  • Estimation error
  • Frequency estimation
  • Frequency locked loops
  • Open-loop synchronization (OLS)
  • Phase locked loops
  • Power electronics
  • Rotors
  • Synchronization
  • closed-loop flux observer
  • induction motor drives
  • speed estimation scheme


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