Patent ID: 6351091
Filing Date: 2002-02-26
Classification: H02P

Abstract:
An electrically commutable motor comprising:excitation windings; a stator; a permanent magnet rotor; semiconductor output stages; and an electronic control unit for providing pulse-width modulated control signals to the output stages to supply current to the excitation windings, a magnetic field being generated in the stator, the magnetic field setting the rotor in rotational motion, wherein, during a preselected start-up phase of the motor, the control unit drives the output stages in overlapping control phases using the pulse-width modulated control signals, a pulse-width ratio of the control signals rising from a minimum to a maximum and then falling again to the minimum, wherein overlapping areas of the control phases generate in affected areas of the excitation windings currents which yield a substantially continuous torque curve, and wherein, in the start-up phase, by shortening a commutation time between successive ones of the control phases, a commutation frequency and, thus, a rotational speed of the motor are increased.