Implementation of a lowcost sinusoidal supply for BLDC motor

In many applications, industry has tried to develop sinusoidal supply for brushless DC (BLDC) motors. This paper describes a method that still keeps a simple 2 phases-on sensorless method and achieves sinusoidal supply, which is needed to avoid speed oscillations due to the very low mechanical constant of small motors. The method is based on back-EMF sensing. Principles, measures and extensions are proposed. The results of industrial applications are exposed and discussed