Patent ID: 9347489
Filing Date: 2016-05-24
CPC Classification: F04D,F16C

Claim Text:
1. A magnetic bearing device for supporting a body to be supported using an electromagnet in a non-contact manner, comprising: a sine wave discrete value generating section for generating a sine wave discrete value by a digital arithmetic process; a carrier wave generating section for generating a carrier wave signal based on the sine wave discrete value; a displacement detecting section for modulating the carrier wave signal depending on a supporting position of the body to be supported so as to output a modulation wave signal; an AD converting section for AD-converting the modulation wave signal into a digital signal at a sampling frequency fs that satisfies fc=(n+½)·fs (n is an integer of not less than 0) and at a predetermined timing that synchronizes with the sine wave discrete value when a frequency of the carrier wave signal is denoted by fc; a demodulation arithmetic section for performing demodulation arithmetic based on the AD-converted digital signal; and a controller for controlling a current of the electromagnet based on a demodulation calculated result of the demodulation arithmetic section so as to control the supporting position of the body to be supported, wherein the predetermined timing is a timing at which the sampling timing is in a vicinity of a maximum peak position of the carrier wave signal and a timing at which the sampling timing is in a vicinity of a minimum peak position, and the demodulation arithmetic section outputs, as the demodulation calculated result, a value d3 calculated with d3=(d1−d2)/2 when a data value of the digital signal sampled in the vicinity of the maximum peak position is denoted by d1 and a data value of the digital signal sampled in the vicinity of the minimum peak position is denoted by d2.