Method and device for determining a rotor position of an electronically commutated electric machine

A method is disclosed for determining a rotor position of an electrically excited electrical machine by injecting voltage test signals at a plurality of space vector angles with a fundamental frequency which lies in a frequency range in which there is a difference in admittance in space vector angles; calculating resulting values of an excitation current indicator variable as Fourier coefficients of the excitation current resulting from the voltage test signal with reference to the fundamental frequency of the voltage test signal at the corresponding space vector angles; and determining the rotor position on the basis of the profile of the excitation current indicator variable.