Patent ID: 6885163
Filing Date: 2005-04-26
Classification: H02P

Abstract:
1. Process to start a brushless direct current motor with a rotor ( 13 ) that is excited by a permanent magnet or direct current and a stator ( 11 ) bearing a multiphase stator winding ( 12 ) as well as with a switching device ( 14 ) controlled by a control device ( 15 ) for the logical connection of the winding phases ( 121 , 122 , 123 ) of the stator winding ( 12 ) to a mains direct current, in which, during rotor standstill, a plurality of current impulses is intruded on the stator winding ( 12 ) by corresponding control of the switching device ( 14 ), the current rise time until a current threshold is reached is measured in the stator winding ( 12 ) with every current impulse and the rotor position is derived from the measured current rise times, characterized in that a plurality of test current impulses is successively intruded on the stator winding ( 12 ) in such a way that the test current impulses generate stator flow vectors ( 25 ) offset by the same angular increments over 360° electrically, and that the current rise time for each stator flow vector ( 25 ) is measured in the total current of the stator winding ( 12 ) and the phase position (α) of the stator flow vector with the smallest current rise time is determined as the rotor position.