Shimadzu Corporation

Masaki Ofuji

Junichiro Kozaki

Yoshihiro Nagano

A magnetic levitation type vacuum pump includes an electromagnet magnetically levitating a rotor by a magnetic force, an electromagnet driving circuit supplying an electromagnet current including a magnetic levitation control current component and a carrier wave current component having a frequency band higher than the magnetic levitation control current component to the electromagnet coil, a levitated position detecting circuit detecting the carrier wave current component and generating a levitated position signal of the rotor, a magnetic levitation control circuit inputting a current command of the magnetic levitation control current component to the electromagnet driving circuit based on the levitated position signal. The electromagnet coil has a primary coil and a secondary coil connected in parallel with the primary coil. An interrupting circuit connected in series with the secondary coil for the carrier wave current component passing therethrough and interrupting the magnetic levitation control current component is further included.

Magnetic levitation type vacuum pump and magnetic levitation device

A magnetic bearing control device includes a rotation speed sensor for detecting a rotational speed of a rotating member supported on an axial magnetic bearing and a radial magnetic bearing without contact, and a displacement sensor for detecting an axial displacement of the rotating member. A control unit outputs a control signal of the axial magnetic bearing based on a signal from the displacement sensor. A filter unit reduces a signal with a specific frequency from the control signal output from the control unit, and passes a remaining signal, and a driving unit drives the axial magnetic bearing based on the signal output from the filter unit. The filter unit includes several notch filters with different ranges of the specific frequencies, and a selection device for selecting at least one of the notch filters according to the rotational speed.

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Kyoto, Japan

Masaki Ofuji