Patent ID: 7449880

Claim:
Method for determining the angular position of a rotor in a rotating electric machine, which machine has a stator winding set with at least three stator windings, in which the stator winding set is powered by a converter device, wherein a first voltage (U 1 ) is applied to the stator winding set via the converter device within a first definable time period (t x1 ), and a first current gradient ( ⅆ i ⅆ t ⁢ | U ⁢ ⁢ 1 ) is calculated therefor, and a second voltage (U 2 ) is applied to the stator winding set via the converter device within the first definable time period (t x1 ), and a second current gradient ( ⅆ i ⅆ t ⁢ | U ⁢ ⁢ 2 ) is calculated therefor, a third voltage (U 3 ) is applied to the stator winding set via the converter device within a second definable time period (t x2 ), and a third current gradient ( ⅆ i ⅆ t ⁢ | U ⁢ ⁢ 3 ) is calculated therefor, and a fourth voltage (U 4 ) is applied to the stator winding set via the converter device within the second definable time period (t x2 ), and a fourth current gradient ( ⅆ i ⅆ t ⁢ | U ⁢ ⁢ 4 ) is calculated therefor, a partial rotor position (γ) is calculated from the first, second, third and fourth current gradients ( ⅆ i ⅆ t ⁢ | U ⁢ ⁢ 1 , ⅆ i ⅆ t ⁢ | U ⁢ ⁢ 2 , ⅆ i ⅆ t ⁢ | 3 , ⅆ i ⅆ t ⁢ | U ⁢ ⁢ 4 ) , the stator voltage (U S ) at the stator winding set and the stator current (I S ) at the stator winding set are determined continuously, and a first stator flux signal (ψ 1 ) is calculated from the stator voltage (U S ) and the stator current (I S ), and a second stator flux signal (ψ 2 ) is calculated from the stator current (I S ) and a magnetisation flux (ψ M ) of the stator winding set, the cosine angle function of the first stator flux signal (ψ 1 ) and of the second stator flux signal (ψ 2 ) is derived, the difference is derived from the cosine angle function of the first stator flux signal (ψ 1 ) and the cosine angle function of the second stator flux signal (ψ 2 ), and a correction phase angle (ψ K ) is added to the partial rotor position angle (γ) if the difference lies outside an adjustable tolerance range.