Conformable fractional-order extended EMF observer design and implementation for PMSM sensorless control system

Abstract

This study presents a fractional-order observer method based on extended electromotive force (EEMF) for sensorless permanent magnet synchronous motor (PMSM) speed control. The novelty of this paper is the theoretical design of a fractional-order EEMF observer and its first implementation in an experimental setup. The conformable method is chosen in fractional calculus part for its flexible structure as a fractional derivative operator. The stability of the proposed fractional-order EEMF (FO-EEMF) observer is demonstrated using the Lyapunov stability theorem. This approach enhances flexibility and adaptability in modeling the dynamic behavior of PMSMs while enabling more accurate speed estimation in sensorless PMSM control. Optimal observer coefficients are determined through particle swarm optimization. Both the proposed fractional-order and integer-order EEMF observers are evaluated under various conditions, including start-up, variable step, and variable ramp tests, using a dedicated experimental setup. The significantly lower oscillation amplitudes observed in the proposed fractional-order observer compared to the integer-order version highlight its effectiveness. Experimental results clearly demonstrate the feasibility and efficiency of the proposed method.