| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a brushless motor whose drive system can smoothly be changed from a forced drive to a sensorless drive. <P>SOLUTION: In the forced drive (during a period of time t5 in Fig.), because a rotary magnetic field is not caused by the rotational position of a magnetic rotor 54 but forced to occur to a three-phase armature winding 52, conduction changing timing delays in comparison with the sensorless drive, in which the rotary magnetic filed is caused to occur while detecting the rotational position of the magnetic rotor 54. Thus, a sensorless drive transient period (during the period of time t6 in Fig.) is provided when the forced drive is shifted to the sensorless drive (during the period of time t7 in Fig.). During this sensorless drive transient period, the delay in the conduction changing timing by the forced drive can be eliminated by keeping the rotational speed of the magnetic rotor 54 at a changed rotational speed, and by fixing an electrical angle that delays a rotational position signal. As a result, a step-out is removed when the force drive is shifted to the sensorless drive so that the drive system can smoothly be changed. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
