Simplified Wide Speed-Range Sensorless Control Scheme for a Permanent Magnet Synchronous Machine

The present paper deals with a wide speed-range sensorless control for a permanent magnet synchronous machine (PMSM), where an enhanced voltage model and a signal injection technique are used to drive the machine at low- and high-speed regions, respectively. A combined angle observer is developed to obtain a smooth speed transition between the two-speed ranges. The main difference to the well-known methods is that the injection method uses a very simple algorithm based on a Fast-Fourier Transform for the extraction of the high-frequency (HF) component of the current. A phase-locked loop fed by this HF signal delivers the estimate of the rotor position.