Vibrationless alignment algorithm for incremental encoder based BLDC drives

Incremental encoder based BLDC drives are widely employed in industry whenever smooth and efficient operation is needed in the whole speed range. Their weak spot lies in the need for a phase of initial alignment, traditionally performed by forcing the motor through a series of fixed phase supply configurations in an open loop stepping mode. This strategy of alignment causes ample mechanical vibrations which can be intolerable for certain applications.This paper presents a novel algorithm for determining the initial rotor sector and aligning the encoder with the motor while minimizing vibrations and oscillations.

► BLDC alignment is usually performed through a fixed motor phase supply sequence, resulting in vibrations and oscillations.
► A new iterative alignment algorithm is presented which minimizes vibrations during startup.
► After at most three iterations the starting sector is univocally determined.
► Both simulations and experimental tests show a definite improvement in the smoothness of the starting procedure.
► Many industrial applications requiring smooth operation during the whole work cycle can benefit from the proposed technique.