A New Load Torque Identification Sliding Mode Observer for Permanent Magnet Synchronous Machine Drive System

Wenqi Lu, Zhenyi Zhang, Dong Wang, Kaiyuan Lu, Di Wu, Kehui Ji, Liang Guo

Research output: Contribution to journalJournal articleResearchpeer-review

28 Citations (Scopus)
632 Downloads (Pure)


Effective identification of the load torque is one of the key aspects in improving the performance of servo drive systems against load disturbances. Sliding mode variable structure control has become a popular method in the development of a load torque identification (LTID) algorithm due to its parameter insensitivity and easy realization features. However, existing LTID sliding mode observers (SMO) with conventional structure have the disadvantages of high-frequency chattering and poor estimation accuracy, which limit its application in high-performance servo systems. In this paper, the mathematical model of the conventional LTID-SMO is deduced and analyzed. A new LTID-SMO is proposed by replacing the sign function with a saturation function and an additional feedback loop in the load torque observer. The effectiveness of the proposed observer is verified by various experiments. The results show that compared to conventional load torque observer, the proposed observer can identify the load torque with higher accuracy and faster response in different operational conditions.

Original languageEnglish
Article number8534417
JournalIEEE Transactions on Power Electronics
Issue number8
Pages (from-to)7852-7862
Number of pages11
Publication statusPublished - 2019


  • Chattering
  • Delays
  • Load torque identification
  • Mathematical model
  • Observers
  • Robustness
  • Sliding mode observer
  • Sliding mode variable structure control
  • Switches
  • Torque
  • sliding mode variable structure control
  • robustness
  • load torque identification (LTID)
  • sliding mode observer (SMO)


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