Novel Controller for Induction Motor without Mechanical Sensor and Experimental Validation

In this paper, a new sensorless output feedback controller for induction motor is designed. The design includes an observer to estimate the mechanical and magnetic variables from only stator currents and voltages measurements. The speed and flux estimation are used by a controller system achieving the speed/flux tracking for induction motor without mechanical and magnetic sensors. Stability analysis based on Lyapunov theory is proved and sufficient conditions are given in order to guarantee the stability of whole closed-loop system "controller+observer". Furthermore, a benchmark is defined for sensorless induction motor controllers validation under three operating conditions: 1) Low speed with nominal load. 2) High speed with nominal load. 3) The motor state is unobservable (at low frequencies). The proposed controller using an observer has been tested and validated on the reference trajectories of this benchmark. This benchmark is applied on an experimental set-up located at IRCCyN Laboratory (Nantes, France). Robustness tests with respect to parameters variations show the applicability of the designed controller