Fractional Order Transfer Function Identification of Six-Phase Induction Motor Using Dual-Chirp Signal

The control performance of induction motor (IM) drive is related to its accurate identified transfer function model. Fractional order transfer function (FOTF) identification of the realistic world dynamics is necessary to get the desired performance. In this article, six-phase IM FOTF is accurately identified using dual-chirp signal excitation in current control loop of field oriented control (FOC) IM structure. The model identification based on the parameters such as speed and current measured with chirp signal excitation provides FOTF. The frequency-domain identification approach uses an estimated state space model having fractional order (FO) coefficients with square error minimization. The identification results are in a close realization with the actual speed response obtained; moreover, a comparison has been performed to infer the actual hardware magnitude response using integer order and fractional order models. This FO identification model of six-phase IM is found to be more accurate in speed open-loop and current closed loop in consideration of frequency-domain error index and best fit.