Patent ID: 7808200
Filing Date: 2010-10-05
Classification: H02P

Abstract:
1. A method of compensating for misalignment of Hall-effect sensors that generate sensor signals providing motor position information to control commutation of motor drive current through windings of a motor, comprising: in a normal operating mode, (1) providing motor drive current to the windings based on the sensor signals such that pairs of the windings are driven in a normal commutation sequence corresponding to a sequence of states of the sensor signals, and (2) monitoring for occurrence of a motor stall condition, the monitoring of the motor stall condition including: upon detecting the motor stall condition with the sensor signals in a given state that in the normal operating mode results in driving the windings according to a corresponding given commutation state, (1) in a first driving step, momentarily driving the windings according to one of an advanced commutation state and a delayed commutation state each adjacent to the given commutation state in the normal commutation sequence, (2) determining whether the motor stall condition persists after the first driving step, and (3) if the stall condition persists after the first driving step then in a second driving step momentarily driving the windings according to the other of the advanced commutation state and the delayed commutation state.