Stepper motor controllers
AssigneeMotorola, Inc.
InventorMichel Burri
Life of this patent
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Abstract
A driver for a stepper motor including means (Q45, 45, 47, 402) for sampling the current in a motor winding (43) at an instant determined by means (401, 400)for generating a predetermined delay following winding commutation. The sample is compared with winding current by a comparator (403) the output of which is stored at a subsequent instant in a flip-flop (416) to provide an output (42). Current generated within the windings due to rotor motion provide a difference in output when the motor is running or blocked. The invention provides a solution to the problem of motion detection of a stepper motor without recourse to a positional sensor.
Claims11
A stepper motor controller for providing a drive signal to a stepper motor and for detecting when the driven stepper motor is in a blocked or running state, wherein the blocked state current flowing in a winding of the stepper motor is dependent on the electrical parameters of the winding, said current being the blocked current and in the running state the current flowing int h winding is dependent on a motion current superimposed on the blocked current, wherein the stepper motor controller comprises:
- detection means for sampling the current flowing in the winding a predetermined interval after coil commutation and for providing a first output signal in response to detecting the superimposed motion current and a second output signal when no superimposed motion current is detected, wherein the first output signal indicates the stepper motor is in the running state, and the second output signal indicates the stepper motor is in the blocked state.
Dependencies are inferred from the claim text.