Determining commutated DC motor drive shaft position, involves computing rotation angle since ripple detection, and anticipated time of next ripple detection from motor current

摘要

The method involves evaluating current ripple in the armature current and correcting a counting result for missing or double ripples. After detecting current ripple at intervals less than the ripple period, the rotation angle since ripple detection and the anticipated time of next detection are computed from the actual motor current and characteristic data. The result is corrected if there is inadequate agreement between computed and actual times.