Sensed motor winding current adapting blanking period between max/min values

摘要

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.

主权项

1. A process of establishing an adapted blanking period in a pulse width modulated cycle providing current through a motor winding to a set point level of motor winding current ITRIP, comprising:
(a) storing a minimum blanking period value in a minimum register and a maximum blanking period value in a maximum register; (b) passing a motor winding current through the motor winding and parasitic tank circuitry coupled to the motor winding, the parasitic tank circuitry including a sensing resistor; (c) sensing a motor winding current through the resistor; (d) determining in controller circuitry the adapted blanking period based on the sensed motor winding current; (e) limiting the adapted blanking period to be between the minimum blanking period value and the maximum blanking period value; and (f) blanking the sensing of the motor winding current during the adapted blanking period.