| 摘要 |
PROBLEM TO BE SOLVED: To suppress the fluctuation of the rotational speed of an electric motor even when the voltage of a power source has been lowered. SOLUTION: A rotation sensor 11 and a pressure sensor 12 are connected to the control circuit 14 of an air compressor 2. The control circuit 14 is composed of a rotational speed commanding portion 15 for outputting a target value N0 of the rotational speed based on the pressure P detected by the pressure sensor 12, and a rotational speed controlling portion 16 for feedback-controlling the electric motor 3 based on the target value N0 and the rotational speed N detected by the rotation sensor 11. The rotational speed commanding portion 15 calculates the target value N0 of the rotational speed based on the pressure P such that the driving current I of the electric motor 3 is smaller than the maximum current Imax. By this configuration, some margin can be secured in the driving current I of the electric motor 3. Therefore, when the voltage V of the power source has lowered, the fluctuation of the rotational speed of the electric motor 3 can be suppressed by increasing the driving current I. COPYRIGHT: (C)2007,JPO&INPIT
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