On-Line Parameter Identification of an Induction Motor With Closed-Loop Speed Control Using the Least Square Method

The control system of induction motors is designed to achieve dynamic stability, allowing accurate tracking of flux and speed. However, changes in electrical parameters, due to temperature rise or saturation level, can lead to undesirable errors of speed and position, eventually resulting in instability. This paper presents two modes for parametric identification of the induction motor based on the least squares method: batch estimator and recursive estimator. The objective is to update the electrical parameters during operation when the motor is driven by a vector control system. A drawback related to the batch estimator is the need for high quantity of available memory to make the process of identification robust enough. The proposed algorithm allows the batch estimator to be viewed as a single matrix problem reducing the need for processing memory. The identification procedure is based on the stator currents measurement and stator fluxes estimation. Basically, both modes of identification will be analyzed. Experimental results are presented to demonstrate the theoretical approach.