Observability Study and Observer-Based Interconnected Form for Sensorless Induction Motor

In this paper, the observability analysis of induction motor is studied. The aim is to clarify observability problems found in particular when the motor operates at low frequencies. From this study, a sensorless observer benchmark is defined for sensorless induction motor observers validation. An observer based on interconnected form to estimate the mechanical and magnetic states of sensorless induction motor is designed. Taking into account the parameter uncertainties of induction motor and based on Lyapunov theory, the proof of the observer convergence is given. The proposed observer is tested and validated on reference trajectories of our bench-mark.This benchmark is applied on an experimental set-up located at IRCCyN (Nantes, France). Robustness tests with respect to parameters variations show the applicability of the designed observer