Method for operation control of vacuum pump and control system for vacuum pump

摘要

A vacuum pump has an alternating current motor, a rotary shaft and a gas transferring body. The alternating current motor runs at a certain speed based on frequency of alternating current and is sufficiently supplied with the alternating current. Gas is transferred from a certain space by the gas transferring body driven by the alternating current motor through the rotary shaft. A method for controlling a vacuum pump includes keeping a rotational speed of the alternating current motor at a second predetermined rotational speed, detecting a value of the alternating current to the alternating current motor, keeping the rotational speed at a first predetermined rotational speed that is higher than the second predetermined rotational speed when the detected alternating current value exceeds a first predetermined value, and keeping the rotational speed at the second predetermined rotational speed when the detected alternating current value becomes equal to a second predetermined value.