Method of controlling a brushless permanent-magnet motor

Abstract

A method of controlling a brushless permanent-magnet motor having a phase winding and a rotor, includes applying voltages of first and second opposing polarities to the phase winding when the rotor is oscillating about a parking position, measuring a plurality of first times, each first time including a time taken for current flowing through the phase winding in response to an applied voltage of the first polarity to exceed a threshold and measuring a plurality of second times, each second time including a time taken for current flowing through the phase winding in response to an applied voltage of the second polarity to exceed the threshold. The method includes determining which of an average magnitude of the plurality of first times and an average magnitude of the plurality of second times has the smaller average magnitude, and determining an amplitude peak of the plurality of times having the smaller average magnitude. The method includes using the amplitude peak to calculate a time window, setting a timer corresponding to the time window at a subsequent determined amplitude peak, and applying a drive voltage to the phase winding during the time window.

Dependencies are inferred from the claim text.