Method for establishing the rotational speed of mechanically commutated d.c. motors

Abstract

The method for determining the rotational speed and/or the angle of rotation of mechanically commutated d.c. motors from the variation with respect to time of the ripple of the motor current occurring during commutation is supplemented and checked by a motor state model that functions in parallel to it and is based on the electromechanical motor equations. A probable value of the actual speed is extrapolated from the motor current and the motor voltage and a permissible reference time range is determined for the next commutation. If no commutation time can be established in the reference time range, the extrapolated value is used. Otherwise, the current speed is determined precisely from the commutation time measured in the reference time range. The load-dependent motor constant for the motor state model can be preset as a fixed value or it can be adjusted to the actual speed after commutation processes have been detected. Faults in the measurement and evaluation of the motor current ripple that occurs during commutation can be avoided and the interference-free forwarding of the actual values needed for determining and controlling positions of electrically operated parts can be safeguarded.

Dependencies are inferred from the claim text.