A model based stator resistance estimation technique in the low speed region for sensor less field oriented control of induction motor

Rotor speed estimation technique for the purpose of induction motor speed control without speed sensors has been the research topic for quite a few years. Various schemes are available for this purpose. However, the parameter variation problem, particularly near zero speed imposes a challenge in the speed estimation. In this paper, a model-based technique is introduced to estimate the stator resistance while measuring the instantaneous angular displacement of stator current vector from the stator voltage vector. The proposed technique uses inverse-Gamma model equivalent circuit of the machine. This technique dynamically computes the stator resistance in the low frequency region in order to make the control less sensitive to parameter variation problem. Simulation results based on this technique are given which are also verified by experimental results.