Flux Deviation Sensorless Control of IPM Synchronous Motors

The paper presents a position sensorless vector control able to drive Interior Permanent Magnet Synchronous Motors in any operating conditions, including low and zero speed. According to the proposed approach a constant frequency sinusoidal signal (voltage or current) is injected in the machine along a given direction so that, thanks to the rotor saliency, a periodic stator signal component is generated along a direction orthogonal to that of the injected signal. The amplitude of such an orthogonal signal depends on the phase displacement between the rotor d axis and the direction along which the additional signal is injected. A robust rotor position tracking is obtained by adjusting the direction of the additional signal in order to minimize the amplitude of the generated orthogonal response. Experimental results confirm the validity and good performance of the proposed sensorless technique.