Patent ID: 8975854
Filing Date: 2015-03-10
Classification: H02P

Abstract:
1. A stepper motor assembly comprising: a stepper motor having a first coil, a second coil, a stator and a motor shaft, the motor shaft coupled to a first part of a device and the stator coupled to a second part of the device that moves relative to the first part, the stepper motor to rotate the first part to a control position or maintain the first part in the control position with respect to the second part; an encoder to detect rotation of the motor shaft and output position feedback in response to the detected rotation, the position feedback corresponding to an actual position of the motor shaft relative to the stator; a driver to receive a vector control signal and to generate a vector control current to be output to the stepper motor to cause the stepper motor, when unhindered, to rotate to the control position or maintain the control position, the vector control current having a first current applied to the first coil and a second current applied to the second coil; and a controller to receive the position feedback, to generate the vector control signal for the driver to cause the stepper motor to rotate to the control position or to maintain the control position, and to adjust a torque applied by the stepper motor by: