High dynamic sensorless BLDCM drive with very wide speed range

This paper develops an tin-attenuated BEMF detection method for sensorless BLDCM drive. The un-attenuated BEMF can be directly obtained from the terminal voltage of the floating phase without voltage dividing and filtering. As a result, this approach makes it possible to detect the rotor position over a wide speed range, especially at a lower speed. A simply correction is proposed to asymmetry back EMF ZCP detection due to parasitic capacitance and discontinuous current at light load. Also a fast startup procedure is presented for the induced BEMF signals are zero when motor is at rest. Experimental results show that the schemes implemented are feasible and very wide speed range and high dynamic performance are achieved.