| 摘要 |
A motor system includes an air core motor having a rotor with opposed permanent magnet poles defining therebetween a magnetic airgap and driving magnetic flux across the magnetic airgap. A stationary armature with air core windings is located within the magnetic airgap. The permanent magnet poles produce a magnetic flux density through the air core windings to produce a back emf in the windings comparable to the voltage of the line power when the rotation of the permanent magnet poles is synchronous with the line power. A electronic variable speed drive coupled by a switch to the air core windings ramps up the frequency of power to the air core windings for accelerating the rotor to near line synchronous speed. When the frequency of the back emf approaches the frequency of the line power, the switch decouples the electronic variable speed drive and couples the air core windings to the line power for synchronous operation.
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