Closed loop resonance compensation circuit for stepper motors
AssigneeBodine Electric Company
InventorMichael Marhoefer
Life of this patent
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Abstract
A closed loop resonance compensation method and circuit for a stepper motor stabilizes the stepper motor control system while operating in the mid-frequency range. The stepper motor stabilization method and means corrects for mid-frequency resonance errors by deriving a velocity error signal from the total current in the motor windings and uses this signal, through feedback to the source of clock pulses, to correct the short term rotor velocity with respect to the stator field.
Claims12
A closed loop resonance compensation circuit for a stepper motor comprising
- (a) a source of command pulses,
- (b) a pulse width modulator and pulse width bias optimization means connected to said source for receiving command pulses therefrom,
- (c) driving means for the stepper motor windings connected to the output of said pulse width modulator,
- (d) comparator means connected to said stepper motor windings for comparing the averaged sum of the winding currents with the sum of the instantaneous winding currents and for generating a signal having a pulse width corresponding to the difference between the compared currents,
- (e) integrating and differentiating means connected to said comparator means for providing a velocity error signal representing rotor velocity variations about a nominal rotor speed,
- (f) feedback means between the integrating and differentiating means, and the pulse width modulator for applying the velocity error signal to the pulse width modulator to modulate the width of the pulse width modulator output pulse to the motor driving means to correct the average rotor velocity with respect to the stator field.
A closed loop resonance compensation circuit for a stepper motor comprising
- (a) a source of command pulses,
- (b) pulse width modulator means connected to said source for receiving command pulses therefrom,
- (c) driving means for the stepper motor windings connected to the output of said pulse width modulator means,
- (d) comparator means connected to said stepper motor windings for comparing the averaged sum of the winding currents with the sum of the instantaneous winding currents and for generating a velocity error signal having a pulse width corresponding to the difference between the compared currents,
- (e) feedback means between the comparator means and the pulse width modulator means for applying the velocity error signal to the pulse width modulator to modulate the width of the pulse width modulator output pulse.
An improved method of stabilizing a stepper motor control system while operating in the mid-frequency resonance region comprising the steps of
- (a) applying command pulses to a pulse width modulator means,
- (b) applying the output of the pulse width modulator means to driving means for the stepper motor windings,
- (c) comparing the averaged sum of the winding currents with the sum of the instantaneous winding currents and generating a velocity error signal having a pulse width corresponding to the difference between the compared currents,
- (d) feeding back the velocity error signal to the pulse width modulator means to modulate the width of the pulse width modulator output pulse to the motor driving means to correct the average rotor velocity with respect to the stator field.
An improved method of stabilizing a stepper motor control system while operating in the mid-frequency resonance region comprising the steps of
- (a) comparing the averaged sum of the motor winding currents with the sum of the instantaneous winding currents,
- (b) generating a velocity error signal representative of rotor velocity variations about a nominal rotor speed, and
- (c) feeding back the velocity error signal to modulate the width of the motor step command pulse to correct the average rotor velocity with respect to the stator field.
An improved method of stabilizing a stepper motor control system while operating in the mid-frequency resonance region comprising the steps of
- (a) comparing the averaged sum of the motor winding currents with the sum of the instantaneous winding currents,
- (b) generating a velocity error signal representative of rotor velocity variations about a nominal rotor speed, and
- (c) feeding back the velocity error signal to cause the active edge of the step command pulse to be shifted in or out by a time delay proportional to the velocity error signal.
A closed loop resonance compensation circuit for a stepper motor comprising
- (a) a source of command pulses,
- (b) pulse width modulator means connected to said source for receiving command pulses therefrom,
- (c) driving means for the stepper motor windings connected to the output of said pulse width modulator,
- (d) current sensing means connected to stepper motor windings for deriving a velocity error signal from the total current in the motor windings, and
- (e) feedback means between the current sensing means and the pulse width modulator means for applying the velocity error signal to the pulse width modulator means to correct the average rotor velocity with respect to the stator field.
Dependencies are inferred from the claim text.