Drive arrangement with collectorless D.C. motor

Claim 1

Drive arrangement having a collectorless d.c. motor comprising a permanent-magnet rotor and a stator winding arrangement; an angular-position transducer arrangement which during operation furnishes angular-position signals that are a function of the angular position of the rotor; an electrical commutation arrangement which receives the angular-position signals and selectively connects the stator winding arrangement to a current source; an rpm-measuring arrangement for generating an actual-rpm signal corresponding to the rotor's actual rpm; a desired-value signal generator for furnishing a signal corresponding to the desired rotor rpm; an rpm-regulating arrangement having respective inputs for the actual-rpm signal and desired-rpm signal and an output, for generating a regulator signal that appears at the output of the rpm-regulating arrangement and is a function of the deviation of the actual rpm from the desired rpm of the rotor, and which controls the supply of current to the stator winding arrangement; and an arrangement for modulating the regulator signal in synchronism with the rotor's rotation, in such a fashion that the current flowing in the stator winding arrangement between each two successive commutation operations initially builds up beginning at a point in time at least approximately coinciding with the point in time at which the commutation occurs, and then drops off again until a point in time at least approximately coinciding with the point in time at which the next-following commutation occurs.