Control for stabilizing the alignment position of the rotor of a synchronous motor

Claim 1

A method of stabilizing the rotational alignment of the rotating rotor of a synchronous motor driven with a period of rotation determined by a drive signal that is generally synchronized to a clock signal generated by a master clock, wherein the master clock includes means for permitting abrupt changes in the frequency of the drive signal, comprising the steps of: magnetically sensing the rotor and generating a pulse in response to said rotor reaching a predetermined angular position; generating an error signal by generating high frequency clock pulses, accumularing a count of said clock pulses on a plurality of successive periods of rotation of the rotor, the count to an analog count value, differentiating the analog count value, generating a change pulse of preselected duration in response to the abrupt change in frequency, said change pulse having a polarity determined by the direction of the abrupt change in frequency, and adding the change pulse to the result of differentiating the analog count value to produce the error signal; phase shifting the drive signal in response to the error signal to compensate for a change in period.

Claim 2

A method of stabilizing the rotational alignment of the rotating rotor of a synchronous motor driven with a period of rotation determined by a drive signal that is generally synchronized to a clock signal generated by a master clock, wherein the master clock includes means for permitting abrupt changes in the frequency of the drive signal, comprising the steps of: magnetically sensing the rotor and generating a pulse in response to said rotor reaching a predetermined angular position; generating an error signal by generating high frequency clock pulses, accumularing a count of said clock pulses on a plurality of successive periods of rotation of the rotor, the count to an analog count value, differentiating the analog count value, generating a change pulse of preselected duration in response to the abrupt change in frequency, said change pulse having a polarity determined by the direction of the abrupt change in frequency, and adding the change pulse to the result of differentiating the analog count value to produce the error signal; phase shifting the drive signal in response to the error signal to compensate for a change in period.

Claim 6

An apparatus for stabilizing the rotational alignment of the rotating rotor of a synchronous motor driven with a period of rotation determined by a drive signal that is generally synchronous to a clock signal generated by a master clock, wherein the master clock includes means for permitting abrupt changes in the frequency of the drive signal to produce a changed rate of rotation of the rotor, the apparatus comprising: means for magnetically sensing the rotor and generating a pulse in response to said rotor reaching a predetermined angular position; means for generating an error signal by generating high frequency clock pulses, accumulating a count of said clock pulses on a plurality of successive periods of rotation of the rotor, converting the count to an analog count value, and differentiating the analog count value; means for generating a change pulse of preselected duration in response to the abrupt change in frequency, said change pulse having a polarity determined by the direction of the abrupt change in frequency; means for adding the change pulse to the result of differentiating the analog count value to produce the error signal; and means for phase shifting the drive signal in response to the error signal to compensate for a change in period.

Claim 7

An apparatus for stabilizing the rotational alignment of the rotating rotor of a synchronous motor driven with a period of rotation determined by a drive signal that is generally synchronous to a clock signal generated by a master clock, wherein the master clock includes means for permitting abrupt changes in the frequency of the drive signal to produce a changed rate of rotation of the rotor, the apparatus comprising: means for magnetically sensing the rotor and generating a pulse in response to said rotor reaching a predetermined angular position; means for generating an error signal by generating high frequency clock pulses, accumulating a count of said clock pulses on a plurality of successive periods of rotation of the rotor, converting the count to an analog count value, and differentiating the analog count value; means for generating a change pulse of preselected duration in response to the abrupt change in frequency, said change pulse having a polarity determined by the direction of the abrupt change in frequency; means for adding the change pulse to the result of differentiating the analog count value to produce the error signal; and means for phase shifting the drive signal in response to the error signal to compensate for a change in period.