| 摘要 |
PROBLEM TO BE SOLVED: To restrain a large current over a long time in a start period.SOLUTION: A synchronous motor 2 is started from an idle state. In a start period, positioning control for positioning a rotor 2a at a start position is executed first. After the positioning control, external control for gradually increasing the number of revolutions of the synchronous motor is executed. In the positioning control, a motor current Ist is gradually increased so that a magnetic field of stator revolutions equal to a prescribed angle (0°) is formed. In the positioning control, the motor current Ist increases up to an upper-limit value Imx. The upper-limit value Imx is smaller than a peak value IFF in the external control. The external control is begun from an angle equivalent to the upper-limit value Imx. Therefore, in even early stages where the number of revolutions is low and a current change is few, the motor current Ist is smaller than the peak value IFF. As a result, a large current is restrained over a long time in the start period. |
