Patent ID: 6825627
Filing Date: 2004-11-30
Classification: H02P

Abstract:
A method of controlling commutation of an electronically commutated motor having: a rotor (108);a stator having a stator winding arrangement (102); a microcomputer (40) and a program associated therewith; a counter which, during operation, counts continuously; means (110) for retrieving a count state from said counter (TIMER1) at a point in time at which, in operation, the rotor (108) passes through a specified first rotational position (âˆ‚0), said method comprising the steps of: a) predictively calculating a first time span (t_BLOCK_START, t_BLOCK_END) that the rotor (108) will need, at the current rotation speed, for rotation through a specified rotation angle that lies between a first rotational position (âˆ‚0) and a second rotational position (âˆ‚1) subsequent thereto, at which latter position a switching operation is to be effected, in order to influence a current (i1, i2) in the stator winding arrangement; b) upon actual passage through said first rotational position (âˆ‚0), retrieving, from said counter, a reference time (RefTime_HSR/LSL; RefTime_HSR/LSR) and storing said time (FIG. 16,: S 458, S470); c) after actual passage through said first rotational position (âˆ‚0), repeatedly calculating a time difference (t_CALC) between a time retrieved from the counter and the stored reference time (FIG. 24: S754, S756); d) comparing (FIG. 25: S800, S820) a result of said calculation to the predicted first time span (t_BLOCK_START, t_BLOCK_END); and e) if said time difference (t_CALC) stands in a predetermined relationship to said predicted first time span, triggering said switching operation (FIG. 25: S808, S810, S834).