Patent ID: 8836262

Claim:
Method for detecting the dynamic state of an electric motor ( 1 ) which has a stator and a rotor ( 2 ), in particular of a brushless, electronically commutated direct current small servomotor, comprising unambiguous determinations of rotational positions of the rotor ( 2 ) within one revolution of the rotor ( 2 ), specifically of a current rotational position (φ total ) relative to a current initial rotational position (A) as well as of this current initial rotational position (A) relative to a reference initial rotational position (O), wherein an incremental position encoder ( 7 ) is used which respectively outputs an output signal (S) for a number of increments within one revolution of the rotor ( 2 ), which output signal (S) is produced by superposition of a basic signal (SG) with chronologically randomly and systematically fluctuating signal interference (Z), wherein the basic signal (SG) is composed of at least two component signals (S 1 , S 2 ) which change periodically in each case in accordance with the rotational position of the rotor ( 2 ) and are in a fixed angular relationship with one another, wherein the current initial rotational position (A) is determined exclusively from the output signal (S) of the position encoder ( 7 ) and is determined by comparing the time profile of the portion of the systematically fluctuating signal interference (Z) of measured values of a current signal sequence (x(i)) with a time profile of the portion of the systematically fluctuating signal interference (Z) of measured values of a signal sequence (y(i)), acquired from the reference initial rotational position (O), of the output signal (S) of the position encoder ( 7 ).