Patent ID: 8698445
Filing Date: 2014-04-15
Classification: H02P

Abstract:
1. A method for activating an asynchronous motor comprising a first winding and one or more second windings, wherein for the purpose of rotational speed change a first switch is provided that decouples the first winding from the one or more second windings when closed, and one or more second switches are provided that couple at least one of the one or more second windings in series with the first winding when closed and the first switch is open, the first switch and the one or more second switches being arranged in parallel relative to each other, wherein for switching from an initial effective voltage prevailing at the first winding resulting from a closed state of an initial switch selected from the first switch and the one or more second switches to a final effective voltage prevailing at the first winding resulting from a closed state of a final switch selected from the first switch and the one or more second switches, the initial and final switches are activated into opening for one or more time intervals during a switching period such that an effective voltage prevailing at the first winding during the switching period is between the initial and final effective voltages and is changed in a stepped manner from the initial to the final effective voltage.