H∞ based robust observer for high-performance sensor-less direct vector control of AC driving systems

Due to the natural structure of the asynchronous motor, the estimation of the rotor or stator flux is essential for the synthesis of the control law for high-performance drive applications. Based on linear matrix inequality (LMI) framework, we propose, in this paper, an approach to provide a robust rotor flux observer of the three-phase induction motor. Furthermore, based upon the notion of quadratic H_∞ performance, a robust self-gain scheduling observers design method results from the constraint satisfaction stability and takes into account certain performance specifications for all admissible trajectories of the rotor speed in the operating range. Finally, Digital simulations implemented in a Simulink environment demonstrate the validity and effectiveness of the designed state observer algorithm.