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Title:
MAGNETIC BEARING CONTROL DEVICE AND VACUUM PUMP
Document Type and Number:
WIPO Patent Application WO/2019/102835
Kind Code:
A1
Abstract:
[Problem] To provide a magnetic bearing control device and a vacuum pump with which a displacement sensor is not required, with which high precision control is possible, and which are compact and low in cost. [Solution] A rate of change (di/dt), which is a time differential of a current value Im flowing through an electromagnet 5, changes in accordance with the magnitude of a displacement of a gap 3 between a target member 1 and the electromagnet 5. Here, the rate of change (di/dt) can be obtained by detecting a voltage value Vs generated between two ends of an inductive element 9. Therefore, by detecting the voltage value Vs, the magnitude of the displacement of the gap 3 can be estimated by calculation. The inductive element 9 is connected in series with the electromagnet 5, and the voltage Vs across the inductive element 9 is detected using a differential input amplifier 21. The period of one cycle of switching of a PWM switching amplifier 11 comprises a current control period of the electromagnet 5 and a displacement detection period for detecting the rate of change (di/dt). The displacement detection period further comprises a current increasing period and a current decreasing period having fixed time periods. The current increasing period and the current decreasing period are equal.

Inventors:
YAMAMOTO Masayuki (1078-1 Yoshihash, Yachiyo-shi Chiba 23, 〒2768523, JP)
Application Number:
JP2018/041069
Publication Date:
May 31, 2019
Filing Date:
November 05, 2018
Export Citation:
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Assignee:
EDWARDS JAPAN LIMITED (1078-1, Yoshihashi Yachiyo-shi Chiba, 23, 〒2768523, JP)
International Classes:
F16C32/04; F04D19/04
Domestic Patent References:
WO1998031946A11998-07-23
Foreign References:
JP2014532868A2014-12-08
JP2004132537A2004-04-30
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