Dynamics Evaluation of a PMSM Drive used for Residential Applications Employing Different Sensorless Techniques

The study concerns with evaluating the dynamic behaviour of a PMSM drive utilizing two distinct sensorless approaches. The evaluation process also considers the use of a load profile that emulates the torque of a compressor in a home refrigerator, i.e., simulating the coolant's compression and suction processes. The first sensorless method stands on comparing two stator voltage values in two different coordinates (real and hypothesis) to estimate the speed and position. Meanwhile the second method compares two current vectors expressed in the two coordinates to evaluate the speed signal. The two-coordinates are expressed in the direct-quadrature frame. To control the drive dynamics, a simple vector control scheme is adopted. The performance analysis is made easier by the presentation of the thorough mathematical derivations for each system component. Additionally, each sensorless scheme's theoretical base is thoroughly explained. The comparative analysis's aim is to highlight the differences between the two sensorless techniques over the considered operating conditions. The system's robustness and speed estimation error are used to provide the judgment. Additionally, a low-speed operating range is selected while applying the domestic load profile to illustrate the limitation of both senseless. The obtained results reveal and confirm the superiority of the current vector-based sensorless scheme via achieving lower estimation error and better system robustness against model uncertainties. Statistically, the sensitivity of the current-variant based recorded a reduction of 37.5%, 55.175 and 99.8% of the sensitivity of the voltage variant based, when considering respectively a change of 30% of stator resistance, stator inductance and permanent flux.