Circuit for shaping and making use of armature current ripple as generated by a D.C. motor, in particular for position control
First Claim
1. A circuit for shaping ripple in D.C. motor armature current, wherein the circuit includes;
- a phase-locked loop comprising;
a phase comparator having two inputs and an output;
a first voltage controlled oscillator having a main input, a control input and an output, said output of the first voltage controlled oscillator being connected to a first input of the phase comparator; and
a first lowpass filter connected between the output of said phase comparator and the main input of said voltage controlled oscillator;
means for sensing armature current of a D.C. motor having a mean back-electro-motive force;
a second lowpass filter having an input connected to the sensing means and generating an output signal to be applied to the second input of the phase comparator; and
means connected to the sensing means for generating a signal proportional to the mean back-electro-motive force of the motor, said signal proportional to the mean back-electro-motive force being applied to the control input of the voltage controlled oscillator for controlling the frequency of the phase-locked loop,wherein the output of the shaping circuit is the output of the first voltage controlled oscillator.
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Accused Products
Abstract
The present invention provides a circuit for shaping ripple in the armature current of a D.C. motor. The circuit includes a phase-locked loop (100). In addition, the circuit preferably includes a back-e.m.f. circuit (300) suitable for generating a signal proportional to the back-e.m.f. of the motor and for controlling the frequency of the phase-locked loop (100) on the basis of the signal obtained in this way and/or the back-e.m.f. circuit (300) suitable for generating a signal proportional to the back-e.m.f. of the motor, a voltage controlled oscillator (500) controlled by the signal proportional to the back-e.m.f., and a switched capacitor filter (400) controlled by the output of the oscillator (500), the filter being connected upstream from the phase-locked loop (100).
69 Citations
20 Claims
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1. A circuit for shaping ripple in D.C. motor armature current, wherein the circuit includes;
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a phase-locked loop comprising; a phase comparator having two inputs and an output; a first voltage controlled oscillator having a main input, a control input and an output, said output of the first voltage controlled oscillator being connected to a first input of the phase comparator; and a first lowpass filter connected between the output of said phase comparator and the main input of said voltage controlled oscillator; means for sensing armature current of a D.C. motor having a mean back-electro-motive force; a second lowpass filter having an input connected to the sensing means and generating an output signal to be applied to the second input of the phase comparator; and means connected to the sensing means for generating a signal proportional to the mean back-electro-motive force of the motor, said signal proportional to the mean back-electro-motive force being applied to the control input of the voltage controlled oscillator for controlling the frequency of the phase-locked loop, wherein the output of the shaping circuit is the output of the first voltage controlled oscillator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A circuit for shaping ripple in D.C. motor armature current comprising:
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a phase locked loop including; a phase comparator having two inputs and an output; a first voltage controlled oscillator having a main input, a control input and an output, said output of the first voltage controlled oscillator being connected to a first input of the phase comparator; and a first low pass filter connected between the output of said phase comparator and the main input of said voltage controlled oscillator; said circuit further comprising; means for sensing armature current of a D.C. motor having a mean back electromotive force; a second lowpass filter having an input connected to the sensing means and generating an output signal to be applied to the second input of the phase comparator; and a second voltage controlled oscillator having a control input and an output; means connected to the sensing means for generating a signal proportional to the mean back-electro-motive force being applied to the control input of the second voltage controlled oscillator; and a switched capacitor filter controlled by the output from the second voltage controlled oscillator and connected between the output of the second lowpass filter and the second input of the phase comparator, wherein the output of the shaping circuit is the output of the first voltage controlled oscillator. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification