| 摘要 |
A magnetic bearing structure is provided for supporting a rotatable member in a suspended position relative to a stationary member utilizing a constant flux axially polarized magnetic field and a variable flux radially polarized electromagnetic field. In one preferred form of the invention the bearing structure includes axially spaced apart rings associated with the stationary member, which hold a plurality of electromagnetic coils circumferentially about and radially spaced from a rotatable shaft. Electrical current is supplied to the coils generate a radially polarized electromagnetic field surrounding the shaft. At least one cylindrically shaped permanent magnet surrounds a portion of the shaft and is positioned generally between the pair of arcuate rings. The permanent magnet is axially polarized and is linked magnetically to the arcuate rings. Substantially all of the magnetic flux generated by the electromagnetic coils and the permanent magnet is direct radially through only a pair of air gaps between the shaft and the rings. Position sensors, along with a servo control circuit, detect and compensate for any radial displacement of the shaft to maintain it in a metastable position relative to the stationary member. In alternative embodiments the rotatable member may encircle the stationary member, and the permanent magnet may be replaced by a constant flux electromagnet.
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