Patent ID: 7103498

Claim:
A method for determining the angular position (φ) of a rotor ( 15 ) of an electronically commutated motor ( 10 ) having a plurality of winding coils (A, B, C, D) wherein said winding coils (A, B, C, D) are respectively energized in a cyclic sequence during a predeterminable current flow angle (α), to provide a closed loop motor control signal said method comprising the following steps: a) selecting an angular detection position (φ 1 ) out of angular rotor positions (φ), wherein said angular detection position (φ 1 ) is defined by an electromotive force (U EMK , A ) induced in one of said winding coils (A) during an entire dynamic range of said current flow angle (α), said electromotive force (U EMK , A ) being present as a coil voltage (U SA ), b) performing a calibration phase while said electronically commutated motor ( 10 ) is running, by adjusting an instantaneous running motor r.p.m. (n ist ) to a calibration r.p.m. (n K ) and by adjusting a reference voltage (U R ) to a calibration voltage (U kal ) that is equal to said electromotive force (U EMK , A ) induced in said one winding coil (A) when said running rotor passes through said angular detection position (φ 1 ), and c) performing a measuring phase by ascertaining said instantaneous, running motor r.p.m. (n ist ), by updating said reference voltage (U R ) to an updated reference voltage value (U Rakt ) equal to the product of said calibration voltage (U kal ) times a ratio between said instantaneous running motor r.p.m. (n ist ) and said calibration r.p.m. (n k ) thus: U Rakt =U kal ·( n ist /n K ), and identifying said angular detection position (φ 1 ) as a position of said rotor ( 15 ) at which said electromotive force (U EMK , A ) induced in said one winding coil (A) is equal to said updated reference voltage value (U Rakt ).