Magnetic bearing control device

A magnetic bearing control device for a rotating member supported on an axial magnetic bearing and a radial magnetic bearing without contact, comprising:

• a rotation speed sensor for detecting a rotational speed of the rotating member,
• a displacement sensor for detecting an axial displacement of the rotating member,
• a filter unit for reducing a signal with a specific frequency band from a signal transferred from the displacement sensor and passing a remaining signal, said filter unit having a plurality of notch filters with different specific frequency bands, and a selection device for selecting at least one of the notch filters according to the rotational speed detected by the rotation speed sensor and inputting the signal transferred from the displacement sensor to the at least one of the notch filters selected by the selection device,
• a control unit for outputting a control signal of the axial magnetic bearing, said control unit being disposed before or after the filter unit, and
• a driving unit for driving the axial magnetic bearing based on the filtered output from the filter unit,
• wherein said selecting device selects more than two notch filters from the plurality of notch filters according to the rotational speed detected by the rotation speed sensor, and connects the more than two notch filters in series to thereby operate as a forming device for forming a group of notch filters, said control signal being input to the more than two notch filters formed by forming device or prepared by signals passing through the notch filters.