Electromagnetic unit, magnetic bearing device, and vacuum pump

A magnetic bearing device comprising:

• an electromagnet unit comprising:
• a plurality of radial direction magnetic force generating means for supporting a rotating body in a radial direction by magnetic force without contact;
• a plurality of radial direction displacement detecting means for detecting displacement of the rotating body in the radial direction;
• and
• a core around which coils of the plurality of radial direction magnetic force generating means and coils of the plurality of radial direction displacement detecting means are wound, wherein
• two of the plurality of radial direction magnetic force generating means that are adjacent to each other in a circumferential direction of the core are disposed such that adjacent magnetic poles belonging respectively to the two of the plurality of radial direction magnetic force generating means are homopolar,
• a low magnetic flux interference region is formed between the two of the plurality of radial direction magnetic force generating means,
• each of the plurality of radial direction displacement detecting means is disposed in the low magnetic flux interference region,
• the plurality of radial direction displacement detecting means comprise two mutually different magnetic poles arranged in an axial direction of the rotating body, and
• magnetic poles to which the coils of the plurality of radial direction magnetic force generating means are wound do not overlap, in the radial direction, magnetic poles to which the coils of the plurality of radial direction displacement detecting means are wound;
• and
• a control means for controlling the electromagnet unit.

A vacuum pump comprising:

• a magnetic bearing device comprising:
• an electromagnet unit comprising:
• a plurality of radial direction magnetic force generating means for supporting a rotating body in a radial direction by magnetic force without contact;
• a plurality of radial direction displacement detecting means for detecting displacement of the rotating body in the radial direction;
• and
• a core around which coils of the plurality of radial direction magnetic force generating means and coils of the plurality of radial direction displacement detecting means are wound, wherein
• two of the plurality of radial direction magnetic force generating means that are adjacent to each other in a circumferential direction of the core are disposed such that adjacent magnetic poles belonging respectively to the two of the plurality of radial direction magnetic force generating means are homopolar,
• a low magnetic flux interference region is formed between the two of the plurality of radial direction magnetic force generating means,
• each of the plurality of radial direction displacement detecting means is disposed in the low magnetic flux interference region,
• the plurality of radial direction displacement detecting means comprise two mutually different magnetic poles arranged in an axial direction of the rotating body, and
• magnetic poles to which the coils of the plurality of radial direction magnetic force generating means are wound do not overlap, in the radial direction, magnetic poles to which the coils of the plurality of radial direction displacement detecting means are wound;
• and
• a control means for controlling the electromagnet unit.