PMSM control based on edge field measurements by Hall sensors

Great merits of utilizing Hall sensors as a position detector lie in the cost effectiveness and relatively easiness in installation. In this work, the axial component of the rotor PM edge field is detected by linear Hall sensors. The measured values by the two Hall sensors look like sin ¿ and cos ¿, but contain a significant amount of third harmonics which causes angle estimation error. In this work, a phase locked loop (PLL) is utilized with the adaptive notch filter (ANF) for the purpose of filtering out the third order harmonics from the PLL input signals. The PLL yields both speed and angle estimates, and is used for speed feedback and coordinate change into the synchronous reference frame, respectively. Experiments showed satisfactory results in current and speed regulations. This kind of edge field detection method is advantageous, since the edge field is not strong enough to saturate the commercial Hall sensors and the edge field measuring is not affected by the stator current.