Sensorless control of PM synchronous motors with non-sinusoidal back EMF for home appliance

This paper presents the study and realisation of a sensorless drive for small permanent magnet synchronous motors, whose use is domestic appliances is a growth industry in the coming decade. As a trade-off with a simple and Inexpensive manufacture, their back electromotive force (back EMF) is often distorted. The corrupted back EMF waveforms unfavourably affect the conventional estimation algorithm, acting as a disturbance in the current loops. The paper discloses several design hints to get both reduced current and torque ripple and reliable sensorless operation in a wide speed range. Experimental results, carried out on a laboratory prototype, support the mathematical theory outlined is the paper.