Patent ID: 7548039

Claim:
A motor control unit, comprising: a rotational position detector that detects a rotational position of a brushless DC motor; a current detector that detects a current of the brushless DC motor; a coordinate transformer that executes rotational coordinate transformation of the current detected by the current detector by using a control phase angle and that obtains a d-axis current constituting a magnetic flux component and a q-axis current constituting a torque component perpendicular thereto; a current controller that generates a command d-axis voltage based on a difference between a command d-axis current and a d-axis current detected by the current detector, and that generates a command q-axis voltage based on a difference between a command q-axis current and a q-axis current detected by the current detector; a coordinate transformer that generates a three-phase command voltage by executing rotational coordinate transformation of the command d-axis voltage and the command q-axis voltage by using the control phase angle; a conductive signal generator that generates a three-phase conductive signal based on the three-phase command voltage; and a position controller that, when executing a positioning operation, maintains the command d-axis current at a constant value and the command q-axis current at zero, and that controls the control phase angle based on a difference between a target stop rotational position and a rotational position detected by the rotational position detector.