Active EMF Concept: A Unified Observer for AC Machines

This work proposes a unified back Active Electromotive Force (AEMF) observer for AC machines based on the SuperTwisting Algorithm (STA). This study aims to create a universal observer structure that could drive Synchronous Machines (SMs) and Induction Machines (IMs) without modifying the observer structure. It is shown that the proposed unified observer can be applied to SMs and IMs with minimum machine parameters, negating the need for machine-type knowledge, or at the very least, the rotor flux model. The active EMF, a generalized version of the original back EMF, is used to achieve this. The Lyapunov theory guarantees the convergence of the proposed observer. Finally, to confirm our theoretical results, the proposed observer was validated on a Permanent Magnet SM (PMSM) and IM using MATLAB/Simulink simulations and experimental tests conducted on a real test bench.