Patent ID: 9506475
Filing Date: 2016-11-29
CPC Classification: F04D,F16C,H02K

Claim Text:
1. A sensorless magnetic levitation vacuum pump comprising: a rotor provided with an exhaust function unit; a motor for rotating the rotor; an electromagnet for magnetically levitating the rotor using magnetic force; an electromagnet drive circuit for supplying, to the electromagnet, an electromagnet current including a magnetic levitation control current component for magnetically levitating the rotor and a carrier current component for detecting a levitation position of the rotor, the carrier current component having a higher frequency band than the magnetic levitation control current component; a levitation position detecting circuit for detecting the carrier current component to generate a levitation position signal of the rotor; and a magnetic levitation control circuit for inputting a current command of the magnetic levitation control current component to the electromagnet drive circuit based on the levitation position signal, wherein the electromagnet comprises a core having a pair of magnetic poles; a primary coil wound around the core; and a series circuit of a first secondary coil wound around the first one of the magnetic poles of the core, a second secondary coil wound around the second one of the magnetic poles of the core, and a capacitor, the primary coil and the series circuit being connected in parallel, and each of the first and second magnetic poles is divided into a plurality of divided magnetic poles, the first secondary coil comprising a plurality of split secondary coils wound around the plurality of divided magnetic poles, respectively, of the first magnetic pole so that the mutual inductance with the primary coil becomes zero, and the second secondary coil comprising a plurality of split secondary coils wound around the plurality of divided magnetic poles, respectively, of the second magnetic pole so that the mutual inductance with the primary coil becomes zero.