1. PRECISE ACCELERATED TORQUE CONTROL FOR SMALL
INDUCTANCE BRUSHLESS DC MOTOR
ABSRACT:
In this paper, precise accelerated torque control for a small inductance brushless dc motor (BLDCM)
is achieved by electromagnetic torque control and disturbance torque suppression. First, the electromagnetic
torque ripple is reduced in commutation and conduction regions. In the former region, the ripple is
suppressed by overlapping commutation control and optimizing the duty ratio of the active controller. In the
latter region, the unbalance ripple caused by the unbalanced three phase windings is reduced by the
proposed asymmetry compensation function, and the disturbance ripple created by the back electromotive
force (EMF) is compensated by feed forward control. Second, the disturbance torque has been observed and
compensated through the improved disturbance torque controller whose compensation coefficient is
obtained by line-to-line back EMF coefficient estimation. And, both the disturbance observation and speed
measurement are all synchronized with the encoder pulse alteration. Experimental results are presented to
demonstrate the validity and effectiveness of the proposed accelerated torque control scheme.