Patent ID: 6327177
Filing Date: 2001-12-04
Classification: G04C,H02P

Abstract:
A method for controlling a stepping motor including a rotor provided with permanent magnet and a coil magnetically coupled to said magnet, said method including the application of a driving pulse to said coil each time that said rotor has to rotate by one step, said driving pulse including connection periods during which said coil is connected to an electric power source and disconnection periods during which said coil is disconnected from said source, the ratio between the total duration of said connection periods and the total duration of said driving pulse being equal to a desired chopping rate, said method including the steps of:subdividing said driving pulse into a first number of consecutive elementary periods, of at least substantially equal duration and each beginning at a determined instant;determining at least indirectly, at each determined instant, an effective chopping rate which is equal to the ratio between on the one hand, a second number which is the number of said elementary periods which have elapsed since the beginning of said driving pulse and which form part of said connection periods, and, on the other hand, a third number which is the total number of said elementary periods which have elapsed since the beginning of said driving pulse;comparing at least indirectly, at said each determined instant said effective chopping rate and said desired chopping rate;connecting said coil to said source at said determined instant if said comparison shows that said effective chopping rate is less than or equal to said desired chopping rate; anddisconnecting said coil from said source at said each determined instant if said comparison shows that said effective chopping rate is greater than said desired chopping rate.