Current regulation blanking time apparatus and methods
AssigneeTexas Instruments Incorporated
InventorsWenchao Qu, Anuj Jain, Ryan Paul Kehr
Life of this patent
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Abstract
Stepper motor winding current regulation methods and apparatus adapt a maximum blanking period to generate an adapted blanking period that is proportional to a currently-selected current regulation set-point. Sensed winding current feedback is ignored at a current regulation controller during the adapted blanking period or during a minimum blanking period, whichever longer, to avoid attempting to track noise imposed upon a sensed winding current feedback signal at an initiation of rapid current changes di/dt. Doing so may decrease ripple in the motor winding current waveform and reduce zero-crossing distortion by decreasing overshoot of the current regulation set-point by the sensed winding current.
Claims20
A method of adapted blanking associated with stepper motor winding current regulation, comprising:
- receiving a value MIN_BLANK corresponding to a minimum blanking period;
- receiving a value MAX_BLANK corresponding to a maximum blanking period;
- receiving a value of a reciprocal current factor ALPHA_I of units 1/I, ALPHA_I to be used to scale a magnitude of a current regulation set-point ITRIP to establish an adapted blanking period A_BLANK;
- determining the adapted blanking time A_BLANK as a product of MAX_BLANK, ALPHA_I, and ITRIP (MAX_BLANK*ALPHA_I*ITRIP);
- and
- ignoring at least one sensed winding current feedback signal at the PWM controller during a blanking period of A_BLANK or MIN_BLANK, whichever longer, to avoid attempting to track noise imposed upon the sensed winding current feedback signal at an initiation of rapid current changes di/dt_large.
A method of adapted blanking associated with stepper motor winding current regulation, comprising:
- receiving a value MIN_BLANK corresponding to a minimum blanking period;
- receiving a value MAX_BLANK corresponding to a maximum blanking period;
- dividing a peak value of a scaled winding current regulation set-point ITRIP_MAX into a set of n ranges of winding current regulation set-points ITRIP(range1)<I_TRIP(range 2)<ITRIP(range3) . . . <ITRIP(rangen);
- selecting a magnitude of a motor winding current regulation set-point ITRIP_REPRESENTATIVE representing all values of ITRIP within a range including a currently-selected ITRIP value from a group consisting of a highest magnitude value of ITRIP within the range, a lowest magnitude value of ITRIP within the range, and an average of a selected set of ITRIP values within the range;
- receiving a value of a reciprocal current scaling factor ALPHA_I of units 1/I;
- determining an adapted blanking time A_BLANK as a product of MAX_BLANK, ALPHA_I, and ITRIP_REPRESENTATIVE;
- and
- ignoring at least one sensed winding current feedback signal at the PWM controller during a blanking period of A_BLANK or MIN_BLANK, whichever longer, to avoid attempting to track noise imposed upon the sensed winding current feedback signal at an initiation of rapid current changes di/dt_large.
A stepper motor winding current regulation apparatus, comprising:
- a current sensing circuit to sense a magnitude of current flowing in a winding (“winding current”) of a stepper motor and to generate at least one sensed winding current feedback signal including a feedback signal IS_MAG representing the magnitude of the winding current;
- a pulse-width modulation (“PWM”) cycle controller coupled to the current sensing circuit to regulate the winding current as a function of the sensed winding current feedback signal;
- a blanking time adaptation controller portion of the PWM cycle controller to establish an adapted blanking period A_BLANK during which the sensed winding current feedback signal is ignored at the PWM controller to avoid attempting to track noise imposed upon the sensed winding current feedback signal at an initiation of rapid current changes di/dt_large.
Dependencies are inferred from the claim text.