Operation control device and method of vacuum pumps

An operation control devices and operation methods thereof so as to eliminate the difficulties in such a case of introduction of vacuum sensors and/or inverter control is disclosed. The disclosure relates to a control of plural sets of vacuum pumps. In order to comply with the subjects to overcome the difficulties, the disclosure proposes to utilize current detection approach instead of direct pressure detection approach, while showing how to estimate a vacuum degree achieved under the operation of the pumps as well as presenting a method on the control of the number of pumps. It is also described how organically a current detecting device, a vacuum degree estimating device, a working pump control device and related methods to satisfy the subjects are linked.