A New Load Adaptive Identification Method Based on an Improved Sliding Mode Observer for PMSM Position Servo System

Wenqi Lu*, Bo Tang, Kehui Ji, Kaiyuan Lu, Dong Wang, Zhijun Yu

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

25 Citations (Scopus)


The effective identification of the load torque is one of the key methods to improve the positioning accuracy of the position servo system, and the sliding mode observer (SMO) is a common identification method in the speed control system because of its advantages of insensitive parameters and easy physical realisation. However, the existing SMO cannot achieve high precision and high response identification of load torque in the full speed range when the motor is running at variable-speed or variable-load, which limits its application in the position servo system. Based on the analysis of the stability and the adaptive law of feedback gain coefficient, an improved SMO for adaptive identification based on adaptive control and improvement of cut-off frequency is proposed. To verify the proposed method, the dedicated simulation model and test platform are built. The results show that the proposed observer can realize the adaptive identification of the load torque under the condition of variable-speed or variable-load, and the estimation accuracy is high. The position servo system designed by the proposed observer can improve the response against load change, which is an effective method for high-precision positioning control of the position servo system with a variable-speed or variable-load.
Original languageEnglish
Article number9167462
JournalIEEE Transactions on Power Electronics
Issue number3
Pages (from-to)3211-3223
Number of pages13
Publication statusPublished - Mar 2021

Bibliographical note

Funding Information:
Manuscript received March 18, 2020; revised July 5, 2020; accepted August 5, 2020. Date of publication August 14, 2020; date of current version October 30, 2020. This work was supported in part by the Zhejiang Provincial Natural Science Foundation of China under Grants LY18E070006 and LY19E070006, in part by the National Natural Science Foundation of China under Grant 51677172, and in part by the Fundamental Research Funds of Zhejiang Sci-Tech University under Grant 2019Q031. Recommended for publication by Associate Editor T. Shi. (Corresponding authors: Wenqi Lu; Kaiyuan Lu.) Wenqi Lu, Bo Tang, and Kehui Ji are with the Faculty of Mechanical Engineering and Automation, Zhejiang Sci-Tech University, Hangzhou 310018, China (e-mail: luwenqi@zstu.edu.cn; tangbok@163.com; jkh@zstu.edu.cn).

Publisher Copyright:
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Copyright 2020 Elsevier B.V., All rights reserved.


  • Adaptive identification
  • high-precision positioning
  • improved sliding mode observer (SMO)
  • position servo system


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