Patent ID: 7564206

Claim:
A positioning unit for a brushless DC motor comprising: a rotational position detector that detects a rotational position of the brushless DC motor; a control phase angle generator that generates a control phase angle corresponding to the rotational position detected by the rotational position detector; a rotational speed detector that detects a rotational speed based on the rotational position or the control phase angle; a position controller that calculates a target rotational speed based on a difference between a target stop position and the rotational position detected by the rotational position detector and that specifies a command d-axis voltage at zero when the difference is greater than a predetermined reference value, and at a predetermined exciting voltage when the difference is equal to or less than the predetermined reference value; a speed controller that generates a command q-axis voltage based on a difference between the target rotational speed and the rotational speed detected by the rotational speed detector; a coordinate transformer that performs rotational coordinate transformation of the command d-axis voltage and the command q-axis voltage by using the control phase angle to form a three-phase command voltage; and a conductive signal generator that generates three-phase conductive signal for the brushless DC motor based on the three-phase command voltage.