Patent ID: 7388367

Claim:
A method for determining a rotor position of a stationary or slowly rotating synchronous machine, the method comprising: evaluating electrical test pulses that are obtained by applying voltage pulses to the individual phase windings of the stator, wherein changes in the inductance of the phase windings which are caused by saturation of a stator iron depending on the rotor position, are determined in opposite directions of current by calculating differences in an amount of current of two test pulses, and angle values being predetermined by a number of the phase windings are associated with the differences in the amount of current, wherein prior to the first test pulse I meas1 , a bias pulse I bias whose polarity is inverted in relation to the first pulse I meas1 is generated, with the switch-on times t 1 of the associated voltage pulses U bias and −U meas1 being equal, and in that the respectively first test pulse I meas1 generated in the corresponding phase winding (U, V, W) acts as a bias pulse in the same phase winding (U, V, W).