Fuzzy Observation for Stator Resistance of An Induction Motor in A Direct Torque Control System

The variation pattern in the stator resistance of an induction motor with the coil temperature is investigated. One kind of fuzzy observers, based on fuzzy logic and for measuring instantaneous resistance is introduced.The two variables, T and △T/△t, measured at the coil ends and directly related to the stator resistance are selected as the input of fuzzy observer to simplify the fuzzy relations. Thus the real-time property of the system will be improved. The fuzzy control rules and membership functions are obtained by analyzing the experimental results. The observing accuracy can meet the requirement for the direct torque control system. It is proved to be an effective way to improve the low-speed performance of the system. The results, observed and gained through experiments are compared in the later part.