Performance evaluation, analysis, and comparison of the back-EMF-based sensorless FOC and stable V/f control for PMSM

The paper presents an analysis of two different sensorless control strategies for PMSM. The first technique is sensorless FOC with Luenberger type back-EMF observer based on a mathematical model of PMSM suitable for the mid and high-speed region. However, such an observer provides just an estimation position error. Therefore, a phase-locked loop is employed to obtain an estimated position and speed from such a signal. Consequently, it leads to a complex sensorless technique challenging to microcontroller unit performance. The second sensorless strategy is the stable V/f control in voltage vector reference frame $d_{\mathrm{v}}q_{\mathrm{v}}$ with a unity power factor loop independent of the machine model. Compared to the previous approach, it offers a low-cost sensorless solution. These techniques are mathematically described and analyzed in the article. Simulation analyses were performed to determine and compare the control performance of both sensorless algorithms.