The invention relates to a method for sensor-free position determination of the rotor position of an electronically commutated multiple-phase EC motor comprising a rotor, and a stator and comprising a commutation device for generating string currents in the coil system of the stator by applying a test signal in the coil system, measuring the current value i in the strand during the measurement phase (PHMess) as a current response to the test signal, calculating i for determining the envelope determining of the current response and determining the rotor position therefrom.