Patent ID: 8222847
Filing Date: 2012-07-17
Classification: H02P

Abstract:
1. A device for determining the rotational position of the rotor of an electric machine with a pole winding circuit with phase strands ( 1 - 3 ) that are star-connected, with a first unit ( 5 , 7 ) for applying voltage pulses ( 14 - 16 ; 11 a - 13 a ) to at least one of the phase strands ( 1 - 3 ), and with a second unit ( 6 , 8 ) which evaluates the star point potentials (U 1 , U 2 , U 3 ) generated by the voltage pulses in order to determine the rotational position of the rotor, wherein the first unit ( 5 , 7 ) is provided for applying the voltage pulses ( 14 - 16 ; 11 a - 13 a ) during motor operation of the electric machine by pulse-wide modulation within at least one modulation period in succession to different pole winding phase strands ( 1 - 3 ), wherein the voltage pulses ( 14 - 16 ; 11 a - 13 a ) deal with particular pulses ( 14 - 16 ) in addition to the operation voltage pulses ( 11 - 13 ) or the operation voltage pulses ( 11 a - 13 a ) themselves, and the second unit ( 6 , 8 ) is provided for determining the rotational position based on at least one difference (M 1 , M 2 , M 3 ) between the star point potentials (U 1 , U 2 , U 3 ) simultaneously generated with the voltage pulses ( 14 - 16 ; 11 a - 13 a ).