Adaptive-Based Accurate Rotor Initial Position Estimation in Synchronous Reluctance Motors

Accurate estimation of initial rotor position is of importance in synchronous reluctance motor (SynRM) drives to gain maximum starting torque and to prevent the overcurrent fault and reverse rotation. This article presents an accurate algorithm, subsumed under the category of voltage pulse injection methods, to define the rotor initial position. In this method, first, the rotor initial sector (with a resolution of 30 electrical degrees) is estimated according to the peak currents acquired by the injection of the symmetrical pulses. Then, the data of an optimum switching vector are introduced to an adaptive-based algorithm to result in the lowest possible error. The efficacy of the proposed method is checked experimentally on a 0.5-hp SynRM drive system and the accuracy of the method is proven high against two other practical pulse-injection-based methods, i.e., conventional and iterative pulse injection-based methods. In addition, experimental results of the high-frequency square-wave method prove the higher accuracy and faster estimation time of the proposed method. The implementation of the proposed method is simple and straightforward. Furthermore, it is robust to the variations and uncertainties of the stator resistance.