Patent ID: 7830056
Filing Date: 2010-11-09
Classification: F16C

Abstract:
1. A magnetic bearing device for rotatably supporting a magnetic piece in a levitating state at a predetermined position comprising: an electromagnet for supporting the magnetic piece in a levitating state by magnetic force; displacement detection means for detecting a displacement of the magnetic piece based on impedance change in the electromagnet; and a driver for applying an excitation current to the electromagnet so as to support the magnetic piece in a levitating state at a predetermined position based on a detection signal from the displacement detection means; wherein the magnetic piece is interposed between a plurality of electromagnets installed opposite each other, the driver is a pulse width modulation driver to control an excitation current of the electromagnet by modulating a pulse width of a pulse voltage driven at a predetermined carrier frequency, and includes an alternating current transfer means for setting a direct current component of the excitation current to zero, and when excitation current flows to one of the electromagnets installed facing each other, then the alternating current transfer means sets a direct current component of the excitation current of the other electromagnet to zero.