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Dynamic pulse-width modulation motor control and medical device incorporating same

  • US 8,603,026 B2
  • Filed: 03/20/2012
  • Issued: 12/10/2013
  • Est. Priority Date: 03/20/2012
  • Status: Active Grant
First Claim
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1. An infusion device, comprising:

  • a stepper motor having a rotor, the stepper motor having a first number of motor steps per revolution of the rotor;

    a shaft mechanically coupled to the rotor, the shaft being displaced to deliver fluid in response to rotation of the rotor;

    an incremental position sensor to obtain a measured number of incremental rotations of the rotor, the incremental position sensor detecting a second number of incremental rotations of the rotor per revolution of the rotor; and

    a control module coupled to the stepper motor and the incremental position sensor to;

    operate the motor to provide a number of commanded motor steps of rotation of the rotor while a modulated voltage is applied to the motor;

    determine an expected number of incremental rotations expected to be detected by the incremental position sensor in response to the number of commanded motor steps based on the number of commanded motor steps and a relationship between the first number and the second number; and

    adjust a duty cycle for the modulated voltage in response to a difference between the expected number of incremental rotations and the measured number of incremental rotations obtained after operating the motor to provide the number of commanded motor steps.

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