| 摘要 |
PROBLEM TO BE SOLVED: To provide a brushless motor drive circuit which can drive a brushless motor by the same control method, without requiring changeover between start control and normal control. SOLUTION: At starting of a brushless motor 1, the output of a comparator circuit 10 becomes nearly equal to that of a V/f conversion circuit 11, because both the impressed voltage and induced voltage are low and the outputs of sample hold circuits 6 and 7 are nearly equal to each other. Consequently, the same starting method as the conventional starting method is used. However, when the rotating speed of the motor 1 increases and the induced voltage begins to be observed, the drive voltage automatically turns into a stateir which the voltage is automatically controlled to an appropriated value, with respect to the rotating speed and load of the motor each time. Therefore, no change-over operation occurs between the start control and normal control. |
