Method for operating an electric machine which has a rotating part, in particular a rotor, that is movable relative to a stator, wherein the mechanical speed of the rotating part relative to the stator, in particular the rotational speed of the rotor, is detected or estimated, in particular by control electronics (53, 64), wherein a winding, that is to say a rotor winding, is arranged on the rotating part, said rotor winding being designed as a rotating field winding, wherein a stator winding is arranged on the stator, said stator winding likewise being designed as a rotating field winding, wherein the rotor has an active region, in particular for generating torque when the active region interacts with the magnetic field generated by the stator, wherein the active region has conductor tracks of a multilayer printed circuit board, that is to say of a printed circuit board composed of multiple layers, through which conductor tracks an electric current can flow, wherein the rotor winding has a lower inductance than the stator winding, in particular wherein the stator winding has a ferrous coil core and/or a laminated core, wherein each rotating field winding is fed by a respective inverter, that is to say in particular the rotating-part-side and/or rotor-side rotating field winding is fed by a rotating-part-side and/or rotor-side inverter and the stator-side rotating field winding is fed by a stator-side inverter, wherein an electrical frequency ω S,Soll of the voltage fed from the stator-side inverter to the stator winding, in particular the electrical frequency of the rotating field generated on the stator side, that is to say in particular the stator supply frequency, is determined from the mechanical rotational speed Ω according to a characteristic curve, in particular wherein the characteristic curve represents a hysteresis-affected dependence of the electrical frequency ω S,Soll on the mechanical speed, wherein the characteristic curve is designed such that, in a rotational speed range at least from Ω min to Ω 0, the magnitude of the stator supply frequency ω S is lowered to less than the magnitude of a minimum frequency ω S,min and/or is lowered to the magnitude of a minimum frequency of zero hertz, in particular wherein the minimum frequency has a constant magnitude in the rotational speed range from Ω min to Ω 0, and wherein the characteristic curve is designed such that the magnitude of the supply frequency ω S of the stator winding is selected to be greater than the magnitude of the minimum frequency if the mechanical rotational speed Ω exceeds the second rotational speed Ω 0, wherein Ω min is a first rotational speed, and wherein Ω 0 is a second rotational speed, the magnitude of the second rotational speed Ω 0 being greater than the magnitude of the first rotational speed, in particular wherein the rotational speed range covered by the hysteresis is limited in terms of magnitude by the magnitude of the first rotational speed Ω min, wherein the magnitude of the electrical rotor-side supply frequency ω r does not fall below the magnitude of a non-vanishing minimum value ω r,min, in particular in order to ensure an EMF-based rotor position detection, characterized in that electrical power can be supplied via an inductive coupling to the active region, the rotor winding and/or the electronic circuit comprising electronic components mounted on the printed circuit board, wherein the rotor is connected to a secondary winding which is inductively coupled to a primary winding that is connected to the stator in a rotationally fixed manner, wherein a medium-frequency current, preferably having a frequency between 100 and 200 kHz, is impressed in the primary winding by an electrical feed-in which has a gyrator acting as a current source.