High-Frequency Signal Injection Method Based on Duty Cycle Shifting Without Maximum Fundamental Voltage Magnitude Loss

Dong Wang*, Kaiyuan Lu, Peter Omand Rasmussen

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

4 Citations (Scopus)


High-frequency signal injection (HFSI) method is widely used in machine sensorless control in low speed operation range. The conventional HFSI methods are to superimpose high-frequency voltage signals onto the commanded stator voltage vector. Thus, the magnitude of the voltage used for machine torque production is sacrificed and these methods are not applicable for high-speed operation range. In this paper, a new HFSI method, in which high-frequency signal is generated by shifting the duty cycles between two neighboring switching periods, is proposed. This method allows injecting a high-frequency signal at half of the switching frequency without the necessity to sacrifice the machine fundamental voltage amplitude. This may be utilized to develop a new position estimation algorithm without involving the machine inductance in the medium- to high-speed range. As an application example, a new position estimation algorithm using the proposed HFSI method is developed and applied to a synchronous reluctance machine drive system. The proposed algorithm focuses on the medium- to high-speed range with the advantage of no filter needed for position information extraction and a machine-inductance-independent sensorless control implementation scheme is achieved. Experimental results are given to support the proposed new approaches.
Original languageEnglish
Article number7891043
JournalIEEE Journal of Emerging and Selected Topics in Power Electronics
Issue number3
Pages (from-to)1225-1236
Number of pages12
Publication statusPublished - Sep 2017


  • Duty cycle shifting
  • High-frequency signal injection (HFSI)
  • Parameter independent
  • Sensorless control
  • Voltage magnitude loss


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