Magnet bearing device and rotor rotary-drive apparatus

Patent metadata

Field	Value
Publication number	US-10408262-B2
Application number	US-201615234538-A
Country	US
Kind code	B2
Filing date	Aug 11, 2016
Priority date	Oct 16, 2015
Publication date	Sep 10, 2019
Grant date	Sep 10, 2019

Abstract

A magnetic bearing device comprises: a magnetic bearing configured to magnetically levitate and support a rotor rotatably driven by a sensor-less motor; a detector configured to detect displacement from a levitation target position of the rotor to output a displacement signal; a signal processor configured to compensate, based on motor rotation information from a motor controller of the sensor-less motor, for the displacement signal to reduce a vibration component of electromagnetic force of the magnetic bearing; and a current controller configured to generate control current of the magnetic bearing based on the displacement signal having been processed in the signal processor.

First claim

What is claimed is:

1. A magnetic bearing device comprising:
a magnetic bearing magnetically levitating and supporting a rotor rotatably driven by a sensor-less motor;
a detector detecting displacement from a levitation target position of the rotor to output a displacement signal;
a signal processor compensating, based on motor rotation information from a motor controller of the sensor-less motor, for the displacement signal to reduce a vibration component of electromagnetic force of the magnetic bearing; and
a current controller generating control current of the magnetic bearing based on the displacement signal having been processed in the signal processor, wherein
the signal processor includes:
a first signal processor generating a signal component cancelling a rotational component of the displacement signal, based on the motor rotation information; and
a second signal processor generating a signal component generating electromagnetic force canceling electromagnetic force caused due to the rotational component of the displacement, based on the motor rotation information, wherein
the vibration component of electromagnetic force is expressed by Expression
Δ F =(4 kI/D 2 )(−Gcont)Δ ds +(4 kI 2 /D 3 )Δ dr,

the control current is controlled such that the first and second terms of the Expression are cancelled by each other,
in the Expression, “D” denotes a gap dimension when a rotor shaft is magnetically levitated to a levitation target position, “I” denotes a bias current flowing through an magnetic bearing electromagnet, “Gcont” denotes a transfer function in magnetic levitation control, “Δds” denotes displacement signal, “Δdr” denotes actual displacement and “k” denotes a coefficient of the magnetic bearing electromagnet.

2. The magnetic bearing device according to claim 1 , wherein
the second signal processor generates the signal component by
correcting, based on the motor rotation information, phase shift caused in the rotational component of the displacement signal after passage through the detector until control current generation by the current controller, and
correcting a gain in the current controller.

3. The magnetic bearing device according to claim 1 , wherein
the current controller includes
a magnetic levitation controller configured to generate a current control signal, and
an excitation amplifier configured to generate the control current,

the magnetic levitation controller generates the current control signal based on a signal obtained by addition of the signal component generated in the first signal processor to the displacement signal, and
the excitation amplifier generates the control current based on a signal obtained by addition of the signal component generated in the second signal processor to the current control signal generated in the magnetic levitation controller.

4. A rotor rotary-drive apparatus comprising:
the magnetic bearing device according to claim 3 ;
a sensor-less motor configured to rotatably drive a rotor magnetically levitated and supported by the magnetic bearing device;
a motor controller configured to control the sensor-less motor; and
a field programmable gate array circuit, referred to as an FPGA circuit, on which at least the motor controller and the signal processor of the magnetic bearing device are mounted.

5. The magnetic bearing device according to claim 1 , wherein
the current controller generates the control current based on a signal obtained by addition of the signal components generated in the first and second processors to the displacement signal.

6. The magnetic bearing device according to claim 1 , wherein
the first signal processor includes;
a first conversion processor, converting a signal from a fixed coordinate system into a rotating coordinate system rotating at an electrical angle θ from the motor controller,
a low-pass filter, low-pass filtering for the signal output from the first conversion processor, and
a second conversion processor, converting the signal output from the low-pass filter from the rotating coordinate system into the fixed coordinate system, using an electrical angle θ from the motor controller, so that the signal only with the rotational component of the signal is generated.

7. A magnetic bearing device comprising:
a magnetic bearing magnetically levitating and supporting a rotor rotatably driven by a sensor-less motor;
a detector detecting displacement from a levitation target position of the rotor to output a displacement signal;
a signal processor compensating, based on motor rotation information from a motor controller of the sensor-less motor, for the displacement signal to reduce a vibration component of electromagnetic force of the magnetic bearing; and
a current controller generating control current of the magnetic bearing based on the displacement signal having been processed in the signal processor, wherein
the signal processor includes:
a first signal processor generating a signal component cancelling a rotational component of the displacement signal, based on the motor rotation information; and
a second signal processor generating a signal component generating electromagnetic force canceling electromagnetic force caused due to the rotational component of the displacement, based on the motor rotation information,

the first signal processor includes:
a first conversion processor, converting a signal from a fixed coordinate system into a rotating coordinate system rotating at an electrical angle θ from the motor controller,
a low-pass filter, low-pass filtering for the signal output from the first conversion processor, and
a second conversion processor, converting the signal output from the low-pass filter from the rotating coordinate system into the fixed coordinate system, using an electrical angle θ from the motor controller, so that the signal only with the rotational component of the signal is generated, and

wherein
the second signal processor includes;
the first conversion processor,
the low-pass filter,
a third conversion processor, converting the signal output from the low-pass filter from the rotating coordinate system into the fixed coordinate system, using the electrical angle from the motor controller, electrical angle whose phase shift is corrected and,
a compensator correcting an amplitude of signal output from the third conversion processor using a correction factor.

Assignees

• Shimadzu Corp

Inventors

• Kozaki Junichiro

Classifications

• F16C32/0402

  combined with other supporting means, e.g. hybrid bearings with both magnetic and fluid supporting means · CPC title

• F16C2360/45

  Turbo-molecular pumps · CPC title

• F16C32/0451

  Details of controllers, i.e. the units determining the power to be supplied, e.g. comparing elements, feedback arrangements with P.I.D. control · CPC title

• F16C32/0493

  integrated in an electrodynamic machine, e.g. self-bearing motor · CPC title

• F16C41/00

  Other accessories, {e.g. devices integrated in the bearing not relating to the bearing function as such} · CPC title