Periodic voltage frequency determination circuit for motor e.g. for vehicle electric window, uses comparison of phase-shifted versions of AC input voltage after removal of DC component with frequency evaluation of comparator output

摘要

The frequency determination circuit has an AC voltage coupling across the input signal terminals (A1,A2) for removing the superimposed DC component, followed by a comparator (K), receiving 2 versions of the AC input voltage which are phase offset relative to one another, with evaluation of the comparator output voltage. Also included are Independent claims for the following: (a) a commutator motor; (b) a method for determining the frequency of a periodic voltage with superimposed noise