Calibration technique for electric motor
AssigneeLexmark International, Inc.
InventorsMichael Anthony Marra, III, Randall David Mayo
Life of this patent
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Abstract
A method for calibrating electric motors using current-sensing only is disclosed. The method involves applying a voltage in pulse-width modulated fashion for a short time to insure motion of the motor. Following startup, varying voltages are pulsed to the motor, switching polarity at regular intervals. The current generated in the motor by each level of voltage is measured. The data generated provide a reasonably accurate view of the properties of the motor, allowing for more precise velocity control.
Claims15
A method of calibrating a DC motor, comprising the steps of:
- a) choosing at least one PWM duty cycle value of interest;
- b) applying a startup PWM duty cycle of sufficient magnitude to insure motion of said motor;
- c) performing a first test wherein the first chosen duty cycle is applied in at least two periods, each of said periods being of opposite polarity from the period preceding it, and the current in the motor is measured dig each of said periods;
- d) performing a test for each additional chosen PWM duty cycle value of interest, wherein each of said PWM duty cycles is applied in at least two periods, each of said periods being of opposite polarity from the period preceding it, and the current in the motor is measured during each of said periods;
- and
- e) calculating the apparent resistance of the motor.
A method of calibrating a DC motor, comprising the steps of:
- a) choosing at least one direct current voltage of interest;
- b) applying a startup direct current voltage of sufficient magnitude to insure motion of said motor;
- c) performing a first test wherein the first chosen voltage is applied in at least two periods, each of said periods being of opposite polarity from the period preceding it, and the current in the motor is measured during each of said periods;
- d) performing an additional test for each chosen voltage of interest, wherein each of said voltages is applied in at least two periods, each of said periods being of opposite polarity from the period preceding it, and the current in the motor is measured during each of said periods;
- and
- e) calculating the apparent resistance of the motor.
Dependencies are inferred from the claim text.