Sensorless control of surface permanent magnet synchronous motor at low speed

Based on saliency tracking idea, a scheme based on high-frequency voltage signal injection is described to solve traditional problems at low speeds. For surface permanent magnet synchronous motor (SPMSM) which does not have structural saliency, a fluctuating high-frequency voltage signal injection scheme is presented. This scheme is realized by developing saturated saliency which has information about rotor position, so rotor speed and position can be estimated by tracking the magnetic saliency. In this work, a simplified high-frequency model of an SPMPM in estimated rotor reference frame is developed and a sensorless rotor position and speed estimation algorithm is described. The proposed sensorless control scheme makes it possible to drive SPMSMs in a low speed region under various conditions. The simulation results verify that the performance of the proposed sensorless algorithm has good feasibility and effectiveness.