Low-speed salient-pole BLDC-machine control by using a single sensor

This paper discusses an enhancement for salient-pole brushless dc-drives using a single current sensor in the dc-bus. The improvement is made by replacing the hall sensors with a rotor-position estimator, increasing the reliability of the drive and reducing its cost. As a result, the BLDC-drive is controlled by using a single sensor only, requiring a minimum amount of electronics to process the measurements. The additional advantage of a position estimator in BLDC-drives is the high resolution in the rotor position information. This allows to use advanced model-based controllers (e.g. programmed current control) and to extend the range of operation (e.g. higher speed by field weakening).