Convergence analysis of back-EMF MRAS observers used in sensorless control of induction motor drives

• The design of two Model Reference Adaptive System speed estimators is presented.
• Dynamic tracking performances of the MRAS based on rotor flux estimation are studied.
• Stability analysis of Back-EMF MRAS estimator is explored to find unstable regions.
• We propose a new adaptation law which allows reducing of unstable zones.
• Simulation results show effectiveness of the estimator with the new adaptation law.

This paper seeks to analyse stability and dynamics of back EMF MRAS based approach used in sensorless control of induction motors. Stability analysis is investigated to show unstable zones and it is explored using a state representation. A new rotor speed estimator is designed to achieve the stability in the various operating modes except for the inobservability line.