Adaptive speed observer with disturbance torque compensation for sensorless induction motor drives using RT-Lab

Authors: MOHAN KRISHNA , FEBIN DAYA

Abstract: This paper presents an improved version of the extended Luenberger observer with joint estimation of rotor speed and disturbance torque. The mechanical model of the induction motor is also utilized for the estimation of disturbance torque to add to the robustness of the observer. The estimated disturbance torque is treated as a model disturbance and physically incorporated into the observer state dynamic equation. The dynamic performance and efficacy of the modified observer is tested for variations in external load and inertia coefficient in the mechanical model. The above observer model is first built offline, using MATLAB/Simulink block sets, and simulated. Further, the offline simulated results are validated in real time by incorporating RT-Lab block sets into the Simulink model and implementing it in the OP4500 real-time simulator developed by Opal-RT. The implementation of the above concept in a relatively new real-time environment adds more strength to the offline findings and provides an exact replica of how the actual physical system would behave.

Keywords: Disturbance torque, extended Luenberger observer, induction motor, model reference adaptive systems, Opal-RT, speed estimation

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