CORRECTION OF COUNTING ERRORS UPON EVALUATION OF CURRENT RIPPLES IN A DC MOTOR

摘要

A method for detecting a regulating variable of a mechanically commutated DC motor in a positioning device for a motor vehicle is provided. The DC motor has a standard ripple pattern, which contains per engine cycle or semi-cycle at least one index ripple, which is classified with regard to amplitude, duration and/or time position. The counter-electromotoric power is calculated from a measured motor current and the measured motor voltage by a motor model. An alternating element corresponding to the current ripples is extracted from the counter-electromotoric power, which in turn is used to determine the current ripples. Further, in at least one engine cycle or engine semi-cycle the index ripple is identified and the total identified current ripples are counted. The result of the count is hereby corrected when the index ripple is not counted at the expected position.