| 摘要 |
PROBLEM TO BE SOLVED: To detect loaded situation of an electric motor with high accuracy.SOLUTION: In a control device 23 which controls the rotation number of an electric motor 14, a triac 57 controls AC voltage applied to the electric motor by a conduction angle based on a control signal. A rotation number detection circuit 53 detects the rotation number of the electric motor. A control part 54 creates the control signal on the basis of the rotation number of the electric motor 14 detected by the rotation number detection circuit 53, and outputs it to the triac 57. And, the control part 54 determines that the electric motor 14 is under a loaded situation and controls the electric motor 14 to become a first rotation number set by a setting signal when the conduction angle of the triac 57 is larger than a load determination reference value, and determines that the electric motor 14 is under no loaded situation and controls the electric motor 14 to become a second rotation number less than the first rotation number set by the setting signal when the conduction angle of the triac 57 becomes less than a no-load determination reference value. |
