Patent ID: 6144179
Filing Date: 2000-11-07
Classification: G01P,H02P

Abstract:
Method for establishing the rotational speed (n) and/or the angle of rotation (.phi.) of mechanically commutated d.c. motors from the variation with respect to time of the ripple of the motor current (I.sub.a (t)) that occurs during commutation, in thata) the variation with respect to time of the ripple of the motor current (I.sub.a (t)) is measured, the time points of the commutation (T.sub.k) are determined and the speed (n) and/or the angle of rotation (.phi.) are derived from this in an evaluation unit 3,whereinb) in parallel to measuring the ripple of the motor current (I.sub.a (t)) from a motor state model based on the electromechanical motor equations, a permissible reference time range (T(m+1).+-..DELTA.T) is determined from the motor current (I.sub.a (t)) and the motor voltage (U.sub.M (t)),c) the time points of commutation (T.sub.k (m)) are allowed for by the evaluation unit (3) only if these are within the permissible reference time range (T(m+1).+-..DELTA.T),d) if within the permissible reference time range (T(m+1).+-..DELTA.T) no ripple of a commutation can be assigned, the evaluation unit (3) extrapolates a probable commutation time T(m) for this reference time range (T(m+1).+-..DELTA.T) from the motor state model.