Brushless motor controller and brushless motor

1. A brushless motor controller that performs rotation control for a brushless motor by detecting a rotational position and a rotation speed of a rotor based on a detection signal from a rotation sensor and determining an energizing timing of a three-phase stator coil based on the detected rotational position and rotation speed of the rotor, the brushless motor controller comprising:

a normal timing generation unit which generates a normal energizing timing determined by the rotational position of the rotor;

an advancing angle timing generation unit which generates an advancing angle energizing timing determined by the rotational position of the rotor and advanced by a predetermined amount from the normal energizing timing, generates a delay amount that changes in correspondence with the rotation speed of the rotor, and generates a final advancing angle energizing timing delayed by the delay amount from the advancing angle energizing timing; and

a control switching unit which switches rotation control of the motor between a first rotation control executed when the rotation speed of the rotor is less than a predetermined value and a second rotation control executed when the rotation speed of the rotor is greater than or equal to the predetermined value, wherein the motor is controlled in accordance with the normal energizing timing in the first rotation control, and the motor is controlled in accordance with the final advancing angle energizing timing in the second rotation control.

2. The brushless motor controller according to claim 1 , wherein the control switching unit temporarily deactivates the motor when switching from the first rotation control to the second rotation control.

3. The brushless motor controller according to claim 1 , wherein the normal timing generation unit and the advancing angle timing generation unit include:

a basic timing generation unit which generates a basic timing determined by the rotational position of the rotor; and

an output switching unit controlled by the control switching unit to selectively generate the normal energizing timing and the advancing angle energizing timing from the basic timing.

4. The brushless motor controller according to claim 1 , wherein the advancing angle timing generation unit is configured to generate among the advancing angle energizing timings in intervals of 60°, an advancing angle energizing timing that is greater than a necessary advancing angle amount of the motor and is a minimum angle.

5. The brushless motor controller of claim 1 , wherein the controller is formed integrally with the motor.

6. A method for controlling a brushless motor that performs rotation control for the brushless motor by detecting a rotational position and a rotation speed of a rotor based on a detection signal from a rotation sensor and determining an energizing timing of a three-phase stator coil based on the detected rotational position and rotation speed of the rotor, the method comprising:

generating a normal energizing timing determined by a rotational position of the rotor;

generating an advancing angle energizing timing determined by the rotational position of the rotor and advanced by a predetermined amount from the normal energizing timing;

generating a delay amount related to the advancing angle energizing timing that changes in correspondence with the rotation speed of the rotor;

generating a final advancing angle energizing timing delayed by the delay amount from the advancing angle energizing timing;

controlling the motor in accordance with the normal energizing timing when the rotation speed of the rotor is less than a predetermined value; and

controlling the motor in accordance with the final advancing angle energizing timing when the rotation speed of the rotor is greater than or equal to the predetermined value.