An electric machine, including a housing, a rotor which includes a rotor shaft and a rotor laminated core, and a stator which includes a stator laminated core. The stator laminated core includes grooves in which stator windings are received. A respective tooth of the stator laminated core is arranged between two respective grooves that are arranged adjacent to one another in a circumferential direction of the stator laminated core. An annular gap is configured between the rotor laminated core and the stator laminated core, and a tooth head ring is arranged in the annular gap, a respective recess of the tooth head ring arranged between two tooth arranged adjacent to one another in a circumferential direction of the tooth head ring. A relative position of the stator laminated core and the tooth head ring is adjustable to a first and second relative position.

The invention relates to the field of electrical engineering, and more particularly to electric motors, and can be used in adaptive electric drive designs, for example, for electric vehicles. Claimed is an operating method of an electric motor in which a rotating magnetic field is excited in a rotor or in a stator, according to which the radial position of a magnetic field source (3) in relation to the axis of rotation (6) of a disc rotor (2) is adjusted according to the speed of rotation of a shaft (4) of the rotor and/or the torque on the rotor shaft (4) while the electric motor is in operation.