Permanent magnet synchronous motor observability analaysis for sensorless control design

Abstract EN

Since many observers for Permanent Magnet Synchronous Motor (PMSM) sensor-less control are available, the main research stream has been focused on searching for reliable speed and position estimation methods with the aim to replace the mechanical sensors with the observer in the control system.

However, the current problems to successfully apply these sensorless control techniques for PMSM are the existence of operating conditions for which the observer performance is remarkably deteriorated.

This is due to difficulties in estimating correctly the rotor position at low speed.

The failure of sensor-less schemes in some particular operating conditions has been always recognized in experimental settings.

Nevertheless, there are no sufficient theoretical observability analyses for the PMSM.

In the literature, only the sufficient observability condition has been presented.

Therefore, the current work is aimed specially to the necessary observability condition analysis.

In this paper, observability of both the Interior PMSM and the Surface PMSM is studied and discussed at different operating conditions then the necessary and sufficient observability condition is presented.

A Sliding Mode Observer is designed to estimate the rotor speed and position and to illustrate the theoretical results.