Method for determining state of electric motor, and corresponding electric motor and fan

The invention relates to a method for determining the state of an electric motor which has a stator (2) and a rotor (3) rotatably mounted relative to the stator (2). On the basis of a rotational movement of the rotor (3), a pressure difference (p) relative to the surroundings (15) of the electric motor (1, 1', 1", 1"') is produced in an air space (16) within the electric motor (1, 1', 1", 1"'). In a normal state of the electric motor (1, 1', 1", 1"'), the pressure difference is based on the actual rotational speed (n) of the rotor (3). The method has the steps of: ascertaining the actual pressure difference (p) between the air space (16) and the surroundings (15) of the electric motor (1, 1', 1", 1"'),; ascertaining the actual rotational speed (n) of the rotor (3); calculating a parameter (k) on the basis of the actual pressure difference (p) and the actual rotational speed (n), thereby producing a parameter (k) which represents the state of the electric motor; comparing the parameter (k) with a threshold; an