Method and apparatus for determining motor rotation in a power window system or the like

摘要

A method and apparatus for determining the position of a rotor of a motor in a power window system is disclosed. The current applied to the motor is measured with respect to time so that the counter electromotive force resulting from rotor inertia may be calculated by the control system of the power window system using a motor equation solved for the counter electromotive force. The time at which the sign of the counter electromotive force changes corresponds to the time at which the rotor has change direction so that the position of the rotor may be determined with a higher precision.