Method for determining the angular position of the rotor in a rotating electric machine

Abstract

A method is suggested for determining the angular position of the rotor in a rotating electric machine, which machine has a stator winding set with at least three stator windings, and the stator winding set is powered by a converter device. Firstly, a first voltage (U) is applied to the stator winding set via the converter device within a first definable time period (t), and a first current gradient is calculated therefor, and a second voltage (U) is applied to the stator winding set via the converter device within the first definable time period (t), and a second current gradient is calculated therefor. A third voltage (U) is then applied to the stator winding set via the converter device within a second definable time period (t), and a third current gradient is calculated therefor, and a fourth voltage (U) is applied to the stator winding set via the converter device within the second definable time period (t), and a fourth current gradient is calculated therefor. A partial rotor position (γ) is calculated from the first, second, third and fourth current gradients The stator voltage (U) at the stator winding set and the stator current (I) at the stator winding set are also determined continuously and a first stator flux signal (ψ) is calculated from the stator voltage (U) and the stator current (I), and a second stator flux signal (ψ) is calculated from the stator current (I) and a magnetisation flux (ψ) of the stator winding set. Moreover, the cosine angle function of the first stator flux signal (ψ) and of the second stator flux signal (ψ) is derived, wherein the difference is derived from the cosine angle function of the first stator flux signal (ψ) and the cosine angle function of the second stator flux signal (ψ). If the difference lies outside an adjustable tolerance range, a correction phase angle (ψ) is added to the partial rotor position angle (γ).