Adapted Back-EMF Sensorless Control for Permanent Magnet Synchronous Motors

In this paper, a sensorless control for permanent magnet synchronous motors is presented. It is based on the reconstruction of the rotor speed and position using the traditional back-electromotive force (emf) method with the addition of an innovative speed observation. The observer parameters are computed according to the speed through an appropriate adaptation law that allows real time gain calculations Furthermore, the speed is calculated from the back-emf observer which induces a velocity offset due to the observation errors inherent to the emfs sinusoidal forms. To overcome this drawback, the use of the position derivative is proposed taking discontinuities into account. Simulation and experimental results validate the proposed method.