A new robust flux, speed and rotor time constant estimation for wide range sensorless control of an induction machine

Abstract

In this study, a new sliding mode current observer is proposed for the flux and speed estimation of an induction machine. The flux estimation accuracy is guaranteed through the current observer, i.e. the error between the actual current and observed current converges to zero which guarantees the accuracy of the flux estimation. The rotor speed is then estimated by using the estimated flux and sliding functions. During this process Euler approximation is used for derivation. The resulting algorithm guarantees that the correct speed and rotor time constant estimation is possible even before the system trajectories reach the sliding manifold, which enables the correct estimation before the observed currents converges the measured values. The new approach is verified by simulation and experimental results, which show the robustness and performance of the proposed observer structure.