Patent ID: 7038417

Claim:
A method for ascertaining through integration a bias calibration level for a current control loop of a driver motor, the driver motor includes a current controller having as inputs a demand signal, a bias signal, and a feedback signal, the current controller includes an integrator having an output that is coupled to the output of the current controller, the method comprises: setting the demand signal to a zero current level; setting the bias signal to a level that substantially prevents the integrator from driving the output toward the positive voltage direction; stepping down the bias signal by an amount quantified by a step size to form a stepped down bias signal; measuring a sense parameter at the output of the current controller; determining whether the sense parameter is high for the stepped down bias signal; and when the determination is made that the sense parameter is high, setting the bias calibration level to a level sufficiently above the stepped down bias signal such that the integrator is not driving the output toward the positive voltage direction when the demand signal is set to the zero current level.