Position control and monitoring circuit and method for an electric motor
OwnerRoger Charles Hey Sideyinventor
Life of this patent
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Abstract
A position control and monitoring circuitry is provided for an electric motor having a plurality of coils and a movable element. A drive circuit generates a square wave drive signal of variable mark/space ratio to drive the coils to position the movable element. A monitoring circuit modulates square wave transitions at a sub-harmnonic of the drive signal frequency and generates a monitoring signal for injection into the coils. A sensor senses the monitoring signal from the coils to determine the position of the movable element. A difference circuit drives the drive circuit with a difference between an input signal and an output signal of the sensor.
Claims8
A position control and monitoring circuitry for an electric motor having a plurality of coils and a movable element, comprising:
- drive means generating a square wave drive signal of variable mark/space ratio to drive the coils to position the movable element, the square wave drive signal having a drive signal frequency;
- monitoring means for modulating square wave transitions at a sub-harmonic of the drive signal frequency to generate a monitoring signal for supply to the coils;
- sensing means for sensing the monitoring signal from the coils to thereby determine the position of the movable element;
- and
- difference means for driving the drive means with a difference between an input signal and an output signal of the sensing means.
A position control and monitoring method for control and monitoring an electric motor having a plurality of coils and a movable element, comprising the steps of:
- with a drive circuit, generating a square wave drive signal of variable mark/space ratio to drive the coils to position the movable element, the square wave drive signal having a drive signal frequency;
- modulating square wave transitions at a sub-harmonic of the drive signal frequency to generate a monitoring signal for supply to the coils;
- sensing the monitoring signal from the coils to thereby determine the position of the movable element;
- and
- driving the drive circuit with a difference between an input signal and an output signal of the sensing step.
Dependencies are inferred from the claim text.