Enhanced Dynamic Operation of Heavily Saturated IPMSM in Signal-Injection Sensorless Control With Ancillary Reference Frame

This article proposes a signal-injection sensorless control (SISC) algorithm with an enhanced dynamic performance for heavily saturated interior permanent-magnet synchronous motors (IPMSMs). Considering the magnetic saturations and spatial harmonics of IPMSM, the convergence characteristics of SISC algorithms are analyzed. To improve dynamic performance of SISC, ancillary angles including voltage injection angle and current observation angle are employed. Additionally, position observer's pole placements of the proposed method are also analyzed with root-loci to set the proper input gain of the observer. For the optimization of the proposed method, a performance index defined in this article which represents the convergence performance of the proposed method should be maximized. This index implies both characteristics of the effective signal magnitude and the convergence range. To implement the proposed method, high-frequency inductances, ancillary angles, and compensation current should be extracted, and all of the extraction methods are specified with a flowchart. The superiority of the proposed method is verified with simulations and experiments under various speeds with stepwise high torque.