Title: Encoder-less field-oriented control of permanent magnet synchronous motor by using a full order adaptive state observer

Authors: Sudhanwa Kelkar; B.B. Sharma

Addresses: Electrical Engineering Department, National Institute of Technology, Hamirpur, HP, India ' Electrical Engineering Department, National Institute of Technology, Hamirpur, HP, India

Abstract: This paper proposes a full order adaptive state observer, for the field-oriented control of a permanent magnet synchronous motor (PMSM), without using a speed sensor. The observer is designed in the estimated field-synchronous coordinate system. The rotor speed is treated as an unknown parameter. The adaptive law for speed is derived by using Lyapunov's stability theorem. Since control algorithms and models are processed in micro computers, the proposed observer has been discretised by Euler's method. To make the observer dynamically faster than the motor dynamics, observer poles are fixed proportionally to those of the motor by using pole placement technique. The simplifying assumptions used to discretise the observer, along with the stator current harmonics, introduce ripples in the estimated rotor speed. To mitigate this effect, various counter-measures are explored. The validity of proposed scheme is verified through MATLAB Simulink.

Keywords: encoder-less; estimated field synchronous coordinate system; rotor speed; unknown parameter; MATLAB simulink; permanent magnet synchronous motor; PMSM; adaptive state observer; pole placement; Lyapunov's stability theorem; Euler's discretisation.

DOI: 10.1504/IJAAC.2019.102664

International Journal of Automation and Control, 2019 Vol.13 No.6, pp.755 - 771

Received: 07 Apr 2017
Accepted: 31 Mar 2018
Published online: 01 Oct 2019 *

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