WO2023032767A1 - 磁気軸受装置及び真空ポンプ - Google Patents
磁気軸受装置及び真空ポンプ Download PDFInfo
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- WO2023032767A1 WO2023032767A1 PCT/JP2022/031777 JP2022031777W WO2023032767A1 WO 2023032767 A1 WO2023032767 A1 WO 2023032767A1 JP 2022031777 W JP2022031777 W JP 2022031777W WO 2023032767 A1 WO2023032767 A1 WO 2023032767A1
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- magnetic bearing
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C32/00—Bearings not otherwise provided for
- F16C32/04—Bearings not otherwise provided for using magnetic or electric supporting means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D19/00—Axial-flow pumps
- F04D19/02—Multi-stage pumps
- F04D19/04—Multi-stage pumps specially adapted to the production of a high vacuum, e.g. molecular pumps
Definitions
- the present invention relates to a magnetic bearing device and a vacuum pump, and in particular, to a floating system using a magnetic bearing, it is possible to recover from an abnormal state such as oscillation with high operating efficiency and safety, and it is possible to reduce false detection of abnormalities and achieve reliability. It relates to high magnetic bearing devices and vacuum pumps.
- turbomolecular pumps are also used in equipment such as electron microscopes to create a highly vacuum state in the chambers of electron microscopes and the like in order to prevent electron beam refraction due to the presence of dust and the like.
- This turbo-molecular pump has a magnetic bearing device for magnetic levitation control of the rotating body. In this magnetic bearing device, it is necessary to control the position of the rotating body at high speed and with a strong force when the rotating body passes through the resonance point during accelerated operation or when noise occurs during constant speed operation. be.
- the position control of this rotating body is performed by feedback control.
- feedback control when vibration occurs in the rotating body, the vibration is suppressed by magnetic force synchronized with the vibration. For this reason, an oscillation phenomenon may occur when the design of feedback control is inappropriate.
- various abnormalities such as noise, vibration, power failure, etc. may occur in the turbomolecular pump depending on the environment.
- Patent Document 1 when automatic reset is enabled, the magnetic bearing device is reset by restarting and operation is continued to return to normal, while automatic reset is not possible. An example is disclosed in which the operation of the magnetic bearing device is stopped when the setting is made.
- Patent Documents 2 and 3 disclose a filter setting method that enables stable control even if the change occurs. Furthermore, the bending natural frequency of the rotor varies with the rotor speed. Patent Document 4 discloses a method of setting a filter that can be stably controlled even when such a change occurs.
- Patent Document 1 there is a risk that normal recovery may not be possible if, for example, the state of the system such as the number of revolutions, temperature, or time changes. In order to recover from these abnormalities, it is necessary to readjust the control parameters.
- Patent Documents 2 and 3 do not assume changes in the natural vibration during operation of the pump, so it is assumed that this adjustment is performed immediately after tool replacement, that is, while the operation of the pump is stopped.
- Patent Document 4 mentions a method of setting a filter that takes into consideration changes in the natural vibration due to the number of revolutions for a pre-designated natural vibration mode.
- an abnormality such as oscillation due to an unexpected natural vibration mode occurs during operation of the pump, if the attenuation or line width of the notch filter set in advance is inappropriate, or if temperature changes or changes over time It may not be possible to respond to changes in the natural frequency. Also, momentary noise can appear unexpectedly while the pump is running.
- Patent Document 5 An example is disclosed (Patent Document 5).
- the present invention has been made in view of such conventional problems.
- a floating system using magnetic bearings it is possible to recover from an abnormal state such as oscillation with high operating efficiency and safety, and to prevent erroneous detection of abnormalities.
- the present invention (claim 1) is a magnetic bearing device comprising a rotating body, a magnetic bearing that levitates and supports the rotating body in the air by magnetic force, and a magnetic bearing controller that controls the magnetic bearing.
- a first abnormality detection means for detecting an abnormality in the control by the magnetic bearing controller based on a predetermined first abnormality condition; and when the first abnormality detection means detects an abnormality in the control, the magnetic control parameter correction means for correcting the control parameter of the magnetic bearing controller while continuing the operation of the bearing device; and a stop means for stopping the operation of the magnetic bearing device when the control abnormality is detected by the second abnormality detection means.
- the present invention is an invention of a magnetic bearing device, wherein the control parameter modifying means includes a changing step of changing the control parameter from the control parameter one step before; A control step of performing control by the magnetic bearing controller using a control parameter, and a state of an abnormality in the control as a result of the control performed in the control step compared with the result of the control performed one step before the control step.
- the value after the change is held as the control parameter, and on the other hand, if there is no improvement in the abnormal state of the control and a state improvement determination step of returning the control parameters to the control parameters one step before when it is determined that the
- the present invention is the invention of a magnetic bearing device, wherein the control parameter correcting means is provided in the post-stage when it is judged that the abnormal state of the control has been improved in the state improvement judging step. Then, it is determined whether or not the abnormal state of control has been resolved based on the first abnormal condition, and it is determined that the abnormal state of control determined by the first abnormal condition has not been resolved. When it is determined that the abnormal state of the control determined by the first abnormal condition has been resolved, the control parameter at that time is retained. prepared and configured.
- the present invention is a magnetic bearing device, wherein the control parameter correction means includes the control parameters determined under the first abnormal condition in the first abnormality elimination determination step. After determining that the state of abnormality has been resolved, the operation of the magnetic bearing device using the control parameters saved in the first abnormality resolution determination step is performed by the magnetic bearing controller.
- the magnetic bearing control further comprises a stability evaluation step for evaluating whether or not it has a predetermined stability that does not cause an abnormality, and when the stability is evaluated to be insufficient in the stability evaluation step. It is characterized by redoing the correction of the control parameters of the device.
- the present invention (claim 5) is a magnetic bearing device, wherein the stability evaluation step includes applying a vibration signal, increasing the control gain of the magnetic bearing controller, and increasing the control gain of the magnetic bearing controller. is evaluated using at least one of a decrease in the control gain of
- the present invention is a magnetic bearing device, wherein in the process of correcting the control parameters by the control parameter correcting means, the abnormality of the control determined based on the second abnormal condition is When detected, the control parameter correcting means applies the control parameter set in the past and then stops the operation of the magnetic bearing device.
- the present invention is an invention of a magnetic bearing device, wherein the control parameter correction means, when the first abnormality detection means detects an abnormality in the control, decelerates the rotor. and modifying the control parameters of the magnetic bearing controller.
- the control parameters of the magnetic bearing controller are readjusted during the deceleration operation of the rotating body, the rated rotation speed can be reached more quickly than when readjustment is performed after the operation is stopped at zero rotation speed. . Therefore, the operating efficiency is improved. Further, since the readjustment is performed during the deceleration operation of the rotating body, the number of revolutions during the readjustment is smaller than that when the abnormality is detected. The damage at touchdown is smaller as the number of rotations is lower, and can be ignored especially if the number of rotations is below a predetermined number. Therefore, it is possible to reduce the damage in the event that anomalies increase during readjustment and touchdown occurs. Therefore, safety is improved.
- the present invention is a magnetic bearing device, wherein the control parameter correction means adjusts the number of rotations of the rotor when the first abnormality detection means detects an abnormality in the control.
- the control is stopped and the control parameters of the magnetic bearing controller are corrected while the rotating body is in a free-run state.
- the absolute value of the torque applied to the rotating body is reduced by stopping the rotation speed control and free running the rotating body. This reduces the vibration of the rotor. Therefore, the S/N ratio of the input signal to the magnetic bearing controller is improved, and the accuracy of readjustment is improved. Therefore, readjustment can be performed at high speed. In addition, compared to the case where the rotating body is decelerated or readjusted after the operation is stopped, the rated rotation speed can be reached more quickly, so the operating efficiency is improved.
- the present invention is a magnetic bearing device, wherein the control parameter correction means adjusts the number of rotations of the rotor when the first abnormality detection means detects an abnormality in the control.
- the control is characterized in that the control parameters of the magnetic bearing controller are corrected while performing constant speed control at the rotation speed when the abnormality is detected.
- the present invention is a magnetic bearing device, wherein the control parameter correction means, when the first abnormality detection means detects an abnormality in the control, accelerates the rotating body. and modifying the control parameters of the magnetic bearing controller.
- the readjustment is performed while the rotating body is accelerating, and the acceleration continues immediately after the first abnormality is resolved, so the rated rotation speed can be reached as soon as possible. Therefore, the operating efficiency is improved.
- the present invention is an invention of a magnetic bearing device, wherein after correcting the control parameters of the magnetic bearing controller, when the abnormal state under the first abnormal condition is eliminated, the rotating body is accelerated.
- the engine continues to accelerate immediately after the first abnormality is resolved, so it can quickly reach the rated rotation speed. Therefore, the operating efficiency is improved.
- the present invention is an invention of a vacuum pump, characterized in that the magnetic bearing device according to any one of claims 1 to 11 is mounted.
- a vacuum pump has a large number of natural vibration modes, such as a rotating body, and there is a risk of oscillation due to these natural vibrations. Shortening the recovery time improves the operating efficiency of the vacuum pump.
- the present invention is a magnetic bearing device comprising a rotating body, a magnetic bearing that levitates and supports the rotating body in the air by magnetic force, and a magnetic bearing controller that controls the magnetic bearing, an abnormality detection means for detecting an abnormality in control by the magnetic bearing controller based on a predetermined abnormality condition; a control parameter correction means for correcting control parameters of the magnetic bearing controller; a region of a predetermined range set including any point on the time axis, the rotation speed axis, or the frequency axis, and a mitigation means for mitigating the predetermined abnormal condition in the region of the predetermined range configured with
- Anomalies in control by the magnetic bearing controller are detected based on predetermined abnormal conditions. Noise is likely to occur in the control system when the control parameters are corrected. However, since this noise is not caused by an abnormality, erroneous detection should be avoided. For this reason, the predetermined abnormal condition is relaxed in the area of the predetermined range. On the other hand, when the control parameters are not corrected, the abnormal conditions are judged to be unrelaxed, so the abnormality can be quickly detected.
- the present invention is an invention of a magnetic bearing device, wherein the predetermined abnormal conditions are composed of a plurality of types, and the abnormal conditions alleviated by the mitigating means include an abnormal condition based on a displacement signal. characterized by being included.
- Types of abnormal conditions include displacement or current abnormalities, contact with touchdown bearings, abnormal passage of time, abnormal changes in DC link voltage, and the like.
- only displacement is set as the abnormal condition to be alleviated when correcting the control parameters, and other abnormal conditions are not alleviated.
- the control parameters are modified, large noise tends to appear in the displacement signal, while noise in other signals is small. Therefore, it is possible to prevent false detection of noise when modifying the control parameters, and to quickly detect an abnormal state such as a power failure that happens to occur at the same time as the modification of the control parameters, thereby improving reliability. .
- the present invention is a magnetic bearing device, wherein the region of the predetermined range is composed of a front region forward of the point and a rear region rearward of the point. A region is characterized in that it is larger than the front region.
- the region behind any point on the time axis, the rotation speed axis, or the frequency axis where the control parameter is corrected is larger than the front region in terms of time, rotation speed, or frequency. set.
- the present invention is an invention of a magnetic bearing device, and is characterized in that the area of the predetermined range is constituted only by a rear area behind the point.
- the present invention is an invention of a vacuum pump, characterized in that the magnetic bearing device according to Claim 13 or Claim 14 is mounted.
- control parameter correction means for correction and stop means for stopping the operation of the magnetic bearing device when a control abnormality is detected by the second abnormality detection means Abnormalities caused by Therefore, the robustness of the magnetic bearing control is increased and the operating efficiency is improved. Also, the control parameters can be readjusted without stopping the operation. As a result, the operating efficiency is improved by shortening the time until recovery. Furthermore, safety can be ensured by setting a plurality of abnormality criteria and stopping the operation when necessary.
- FIG. 1 is a configuration diagram of a turbomolecular pump used in an embodiment of the present invention
- FIG. Conceptual flow chart of how to retune control parameters A flow chart specifically showing how to readjust the control parameters Diagrammatic representation of the adjustment procedure for each adjustment step based on a hypothetical example Processing method when the second abnormality is detected Another processing method when the second abnormality is detected
- Explanatory diagram of readjustment processing method considering stability Concrete operation example of the relationship between readjustment and pump operation when the first abnormality is detected (Part 1) Concrete operation example (Part 2) Specific operation example (Part 3) Concrete operation example (Part 4) Concrete operation example (Part 5) Concrete operation example (Part 6) Specific operation example (Part 7) Concrete operation example (Part 8) Specific operation example (Part 9) Specific operation example (10) Specific operation example (11)
- Control parameter modification flow chart Control parameter correction timing chart Example of operation when modifying control parameters (Part 1) Example of operation when modifying control parameters (Part 2) Example of operation when modifying control parameters (Part 3)
- FIG. 1 shows a configuration diagram of a turbomolecular pump used in an embodiment of the present invention.
- a turbo-molecular pump 100 has an intake port 101 formed at the upper end of a cylindrical outer cylinder 127 .
- a rotating body 103 having a plurality of rotating blades 102 (102a, 102b, 102c, . is provided inside the outer cylinder 127.
- a rotor shaft 113 is attached to the center of the rotor 103, and the rotor shaft 113 is levitated in the air and position-controlled by, for example, a 5-axis control magnetic bearing.
- the rotor 103 is generally made of metal such as aluminum or aluminum alloy.
- the upper radial electromagnet 104 has four electromagnets arranged in pairs on the X-axis and the Y-axis.
- Four upper radial sensors 107 are provided adjacent to the upper radial electromagnets 104 and corresponding to the upper radial electromagnets 104, respectively.
- the upper radial sensor 107 is, for example, an inductance sensor or an eddy current sensor having a conductive winding, and detects the position of the rotor shaft 113 based on the change in the inductance of this conductive winding, which changes according to the position of the rotor shaft 113 . to detect
- the upper radial sensor 107 detects the radial displacement of the rotor shaft 113, that is, the rotating body 103 fixed thereto, and sends it to a central processing unit (CPU) of a control device (not shown).
- CPU central processing unit
- This central processing unit is equipped with the function of a magnetic bearing controller.
- a compensation circuit having a PID control function controls the upper radial electromagnet 104 based on the position signal detected by the upper radial sensor 107.
- a magnetic bearing inverter (not shown) excites and controls the upper radial electromagnets 104 based on the excitation control command signal, thereby adjusting the upper radial position of the rotor shaft 113. be.
- the rotor shaft 113 is made of a high magnetic permeability material (iron, stainless steel, etc.) or the like, and is attracted by the magnetic force of the upper radial electromagnet 104 . Such adjustments are made independently in the X-axis direction and the Y-axis direction.
- the lower radial electromagnet 105 and the lower radial sensor 108 are arranged in the same manner as the upper radial electromagnet 104 and the upper radial sensor 107 so that the lower radial position of the rotor shaft 113 is set to the upper radial position. adjusted in the same way.
- the axial electromagnets 106A and 106B are arranged so as to vertically sandwich a disc-shaped metal disk 111 provided below the rotor shaft 113 .
- the metal disk 111 is made of a high magnetic permeability material such as iron.
- An axial sensor 109 is provided to detect the axial displacement of the rotor shaft 113, and its axial position signal is sent to a central processing unit (CPU) of the controller (not shown).
- CPU central processing unit
- a compensating circuit having, for example, a PID control function detects axial electromagnet 106A and axial electromagnet 106A based on the axial position signal detected by axial sensor 109.
- 106B and a magnetic bearing inverter (not shown) controls the excitation of the axial electromagnets 106A and 106B based on these excitation control command signals.
- 106A attracts the metal disk 111 upward by magnetic force
- the axial electromagnet 106B attracts the metal disk 111 downward, and the axial position of the rotor shaft 113 is adjusted.
- control device appropriately adjusts the magnetic force exerted on the metal disk 111 by the axial electromagnets 106A and 106B, magnetically levitates the rotor shaft 113 in the axial direction, and holds the rotor shaft 113 in the space without contact.
- the motor 121 has a plurality of magnetic poles circumferentially arranged to surround the rotor shaft 113 .
- Each magnetic pole is controlled by a control device so as to rotationally drive the rotor shaft 113 through electromagnetic force acting between the magnetic poles and the rotor shaft 113 .
- the motor 121 incorporates a rotation speed sensor (not shown) such as a Hall element, resolver, encoder, etc., and the rotation speed of the rotor shaft 113 is detected by the detection signal of this rotation speed sensor.
- a phase sensor (not shown) is attached, for example, near the lower radial direction sensor 108 to detect the phase of rotation of the rotor shaft 113 .
- the control device detects the position of the magnetic pole using both the detection signals from the phase sensor and the rotational speed sensor.
- a plurality of fixed wings 123 (123a, 123b, 123c, .
- the rotor blades 102 (102a, 102b, 102c, . . . ) are inclined at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113 in order to move molecules of the exhaust gas downward by collision.
- the fixed wings 123 (123a, 123b, 123c, . . . ) are made of metal such as aluminum, iron, stainless steel, or copper, or metal such as an alloy containing these metals as components.
- the fixed blades 123 are also inclined at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113, and are arranged inwardly of the outer cylinder 127 in a staggered manner with the stages of the rotary blades 102. ing.
- the outer peripheral end of the fixed wing 123 is supported by being inserted between a plurality of stacked fixed wing spacers 125 (125a, 125b, 125c, . . . ).
- the stationary wing spacer 125 is a ring-shaped member, and is made of, for example, metal such as aluminum, iron, stainless steel, or copper, or metal such as an alloy containing these metals as components.
- An outer cylinder 127 is fixed to the outer circumference of the stationary blade spacer 125 with a small gap therebetween.
- a base portion 129 is provided at the bottom of the outer cylinder 127 .
- An exhaust port 133 is formed in the base portion 129 and communicates with the outside. Exhaust gas that has entered the intake port 101 from the chamber (vacuum chamber) side and has been transferred to the base portion 129 is sent to the exhaust port 133 .
- a threaded spacer 131 is arranged between the lower portion of the stationary blade spacer 125 and the base portion 129 depending on the application of the turbomolecular pump 100 .
- the threaded spacer 131 is a cylindrical member made of a metal such as aluminum, copper, stainless steel, iron, or an alloy containing these metals, and has a plurality of helical thread grooves 131a on its inner peripheral surface. It is stipulated.
- the spiral direction of the thread groove 131 a is the direction in which the molecules of the exhaust gas move toward the exhaust port 133 when they move in the rotation direction of the rotor 103 .
- a cylindrical portion 102d is suspended from the lowermost portion of the rotor 103 following the rotor blades 102 (102a, 102b, 102c, . . . ).
- the outer peripheral surface of the cylindrical portion 102d is cylindrical and protrudes toward the inner peripheral surface of the threaded spacer 131, and is adjacent to the inner peripheral surface of the threaded spacer 131 with a predetermined gap therebetween.
- the exhaust gas transferred to the screw groove 131a by the rotary blade 102 and the fixed blade 123 is sent to the base portion 129 while being guided by the screw groove 131a.
- the base portion 129 is a disk-shaped member forming the base portion of the turbomolecular pump 100, and is generally made of metal such as iron, aluminum, or stainless steel.
- the base portion 129 physically holds the turbo-molecular pump 100 and also functions as a heat conduction path. Therefore, a metal having high rigidity and high thermal conductivity such as iron, aluminum, or copper is used. is desirable.
- a touchdown bearing 141 is arranged at the upper end of the stator column 122 between the upper radial direction sensor 107 and the rotor 103 . On the other hand, below the lower radial direction sensor 108, a touchdown bearing 143 is arranged.
- Both the touchdown bearing 141 and the touchdown bearing 143 are composed of ball bearings.
- the touchdown bearing 141 and the touchdown bearing 143 are designed to safely shift the rotating body 103 to a non-floating state when the rotating body 103 becomes unable to magnetically levitate for some reason, such as when the rotating body 103 rotates abnormally or when there is a power failure. It is set up so that
- FIG. 2 shows a conceptual flow chart of a method of readjusting control parameters by correction by the control parameter correction means.
- step 1 abbreviated as S1 in the figure, the same applies hereinafter
- the central processing unit (CPU) of the control device detects a first abnormality based on a predetermined criterion.
- This first abnormality determination criterion is the case where it is desirable to continue the operation of the pump by readjusting the magnetic bearing control parameters even when an abnormality occurs.
- the predetermined criterion for determining the first abnormality is, for example, when the amplitude of the displacement spectrum reaches, for example, 0.5 ⁇ m when oscillation is assumed, or when the amplitude of the current spectrum reaches, for example, 0.2 A.
- the time when the peak-to-peak value of the displacement time waveform reaches, for example, 20 ⁇ m may be set. Since this value is a time waveform, Fourier transform is not necessary, and the amount of calculation of the central processing unit (CPU) can be reduced.
- the time when the peak-to-peak value of the current-time waveform reaches 1A may be set as the criterion for determining the first abnormality.
- a different value may be set for each frequency component of the spectrum as the criterion for determining the first abnormality.
- the rotation frequency component of the magnetic bearing and its harmonic component have large spectral amplitudes, so the reference is increased.
- the criterion for determining the first abnormality may be changed according to the operating state. For example, when the motor 121 is not energized, the displacement spectrum amplitude of 0.5 ⁇ m is used as the determination reference value as described above, but when the motor 121 is energized, the displacement spectrum amplitude of 1 ⁇ m is used as the determination reference value. This is because the S/N ratio of the displacement signal is better when the current is not supplied.
- the central processing unit (CPU) modifies the magnetic bearing control parameters.
- the correction at this time is performed, for example, by setting a new filter such as a notch filter, phase lead filter, low-pass filter, or band-pass filter, or by deleting an existing filter.
- this correction may be made by changing parameters such as the center frequency, line width, size, etc. of the existing filter.
- this correction may be performed by taking correlation with information such as the number of revolutions of the rotating body 103, temperature, etc., and changing the control parameters of the filter accordingly.
- this correction may be performed by the central processing unit (CPU) changing the proportional gain, integral gain, and derivative gain of the control parameters.
- the correction during this period may be performed when the rotating body 103 floats and rotates, or may be performed when the rotating body 103 floats and when the rotating body 103 is stationary.
- the central processing unit detects the second abnormality based on predetermined judgment criteria.
- This second abnormality is an abnormality that cannot be dealt with by readjusting the magnetic bearing control parameters, or an abnormality that requires immediate stoppage of operation under certain circumstances. That is, when the oscillation is larger in amplitude than the oscillation of the first abnormality, the rotating body 103 contacts the touchdown bearing 141 and the touchdown bearing 143, or the time set in this contact state is timed out. , the DC link voltage abnormally increases or decreases, or other abnormalities occur.
- the predetermined criterion for determining the second abnormality is a larger value than the predetermined criterion for determining the first abnormality.
- the condition for the first abnormality is set when the amplitude of the displacement spectrum reaches 0.5 ⁇ m or when the amplitude of the current spectrum reaches 0.2 A
- the condition for the second abnormality is when the displacement It is set when the spectrum amplitude reaches 5 ⁇ m or when the current spectrum amplitude reaches 0.5A.
- the first abnormality condition is when the peak to peak value of the displacement time waveform reaches 20 ⁇ m or when the peak to peak value of the current time waveform reaches 1 A
- the second Abnormal judgment criteria are set when the peak-to-peak value of the displacement time waveform reaches 50 ⁇ m or when the peak-to-peak value of the current time waveform reaches 2A. Since this value is a time waveform, Fourier transform is not necessary, and the amount of calculation of the central processing unit (CPU) can be reduced.
- a different value may be set for each frequency component of the spectrum as the second abnormality criterion.
- the rotation frequency component of the magnetic bearing and its harmonic component have large spectral amplitudes, so the reference is increased.
- the criteria for judging this second abnormality may be changed according to the operating state. For example, when the motor 121 is not energized, the displacement spectrum amplitude of 5 ⁇ m is used as the determination reference value as described above, but when the motor 121 is energized, the displacement spectrum amplitude of 10 ⁇ m is used as the determination reference value. This is because the S/N ratio of the displacement signal is better when the current is not supplied.
- the displacement detected by the upper radial direction sensor 107, the lower radial direction sensor 108, and the axial direction sensor 109 exceeds a predetermined value, and the rotor 103 touches.
- Set when contact with the down bearing 141 and touchdown bearing 143 is estimated, or when it is confirmed by a contact detection sensor (not shown) that the rotating body 103 is in contact with the touchdown bearing 141 and touchdown bearing 143. may The contact may be set once or a specified number of times.
- the criterion for determining the second abnormality may be set when the first abnormality is not resolved even after the control parameter is readjusted a predetermined number of times. Alternatively, it may be set when the first abnormality has not been resolved even after a predetermined period of time has elapsed.
- the second abnormality determination criterion may be set when an abnormality that cannot be dealt with by the control parameters, such as power failure, disconnection, or other failure detection, is detected. It should be noted that the criterion for determining the second abnormality may be changed according to the operating state. For example, when the number of revolutions of the rotating body 103 is zero, the operation of the pump is continued by excluding contact with the touchdown bearings 141 and 143 from the second abnormality determination criteria. This is because it is safe even if the rotating body 103 contacts the touchdown bearings 141 and 143 when the rotation speed of the rotating body 103 is zero. On the other hand, when the rotating body 103 is rotating and it is determined that the contact with the touchdown bearings 141 and 143 is detected, the operation of the pump is stopped.
- the second abnormality determination criterion may be changed. For example, a displacement spectrum amplitude of 30 ⁇ m is used as the second abnormality determination criterion, and a displacement spectrum amplitude of 15 ⁇ m is used in the case of normal operation. This is because it is known in advance that the increase in gain is temporary and that the dangerous state will be immediately resolved.
- the central processing unit (CPU) detects the second abnormality in step 9
- the central processing unit (CPU) stops the operation of the pump in step 11. At this time, the operation is stopped by setting the rotational speed command value to zero and decelerating. At this time, the levitation of the rotating body 103 is continued.
- the energization may be stopped by stopping the energization of any one of the upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A and 106B.
- This operation can be stopped by either setting the rotational speed command value to zero and decelerating while the rotating body 103 is rotating, or by stopping the energization of the magnetic bearings.
- the control parameter readjustment method shown in FIG. 2 can be performed by the operation of the central processing unit (CPU) as described above. However, it may be performed by an externally set device.
- whether readjustment of control parameters can be performed may be set as permitted or not permitted.
- the transition to permission occurs at initial setting immediately after shipment, immediately after power-on, after a certain period of time, when the pump is attached/removed, when the cable is replaced, when a change in state is detected such as when there is a temperature change, or Can be done when specified by the user.
- the transition to non-permission can be made when the rated rotation speed is reached in the permission state, when the operation is stopped after reaching the rated rotation speed in the permission state, or when specified by the user.
- the rotation driving device for the rotating body 103 is not limited to the motor 121, and can be applied to a generator, a gas turbine, a steam turbine, an impulse water turbine, a reaction water turbine, and the like.
- the control parameters can be readjusted without stopping the operation. As a result, the operating efficiency is improved by shortening the time until recovery. Furthermore, safety can be ensured by setting a plurality of abnormality criteria and stopping the operation when necessary.
- FIG. 4 is a diagrammatic representation of the adjustment procedure for each adjustment step based on a virtual example.
- the central processing unit (CPU) detects the first abnormality based on the above-described predetermined criteria.
- the central processing unit (CPU) detects the second abnormality based on the above-described predetermined judgment criteria.
- the central processing unit (CPU) detects the first abnormality and does not detect the second abnormality.
- Time series number 0 in FIG. 4 is the initial state, that is, the state immediately before the first abnormality detection.
- Time sequence number 1 represents the adjustment step immediately after the first anomaly was detected. Since the first abnormality has been detected, the process proceeds to step 23, and the control parameter with time series number 0, which is the initial state, is stored in the central processing unit (CPU). Then, in step 25, the central processing unit (CPU) changes the control parameters (change process), and performs magnetic bearing control using the control parameters (control process). That is, as indicated by time series number 1 in FIG. 4, the central processing unit (CPU) performs the magnetic bearing control with the filter a added to the central processing unit (CPU).
- the control parameter correction is explained as addition of a filter, but other methods may be used.
- step 27 the central processing unit (CPU) determines whether or not the state of the first abnormality has improved (state improvement determination step). Specifically, at time series number 1 in FIG. 4, the central processing unit (CPU) determines whether or not the first abnormal state has improved compared to one step before. The improvement here is the result of comparison with the state one step before, and does not necessarily mean that the first abnormality has been resolved. If it has been improved, the control parameters at that point in time are retained, and the process proceeds to step 29 to determine whether or not the first abnormality has been eliminated (first abnormality elimination determining step). In time series number 1 in FIG. 4, although the first abnormal state has been improved, the first abnormality has not been eliminated, so the process returns to step 23 . Therefore, the filter set at the end of time series number 1 in FIG. 4 is filter a.
- step 23 the filter a, which is the control parameter set with the time series number 1, is stored in the central processing unit (CPU).
- the central processing unit (CPU) adds the filter b in addition to the filter a (change step), and performs magnetic bearing control using the control parameters (control step).
- step 27 the central processing unit (CPU) determines whether or not the state of the first abnormality has improved (state improvement determination step). That is, at time series number 2, it is determined whether or not the first abnormal condition has improved compared to one step before.
- step 29 the filters set at the time when the time series number 2 in FIG. 4 ends are the filters a and b.
- step 23 The processing in the next step 23 is the third round of processing, so it is indicated by chronological number 3 in FIG.
- filter a and filter b which are control parameters set in time series number 2 are stored in the central processing unit (CPU).
- step 25 the central processing unit (CPU) adds filter c to filter a and filter b (change step), and performs magnetic bearing control using the control parameters (control step).
- step 27 the central processing unit (CPU) determines whether or not the state of the first abnormality has improved (state improvement determination step). That is, at time series number 3, it is determined whether or not the first abnormal state has improved compared to one step before. At time series number 3 in FIG. 4, the central processing unit (CPU) determined that the first abnormal condition was not improved. At this time, the process proceeds to step 31, and the central processing unit (CPU) restores the filter settings to filter a and filter b, which are the values of time series number 2 one step before. After that, the process returns to step 23 again. Therefore, the filters set at the end of time series number 3 in FIG. 4 remain the filters a and b.
- step 23 The processing in the next step 23 is the fourth round of processing, so it is indicated by chronological number 4 in FIG.
- filter a and filter b which are the control parameters set in chronological number 3, are stored in the central processing unit (CPU).
- the central processing unit (CPU) adds the filter d in addition to the filter a and the filter b (change process), and performs magnetic bearing control using the control parameters (control process).
- step 27 the central processing unit (CPU) determines whether or not the state of the first abnormality has improved (state improvement determination step). That is, at time series number 4, it is determined whether or not the first abnormal condition has improved compared to one step before.
- the control parameters at that time are held, and the process proceeds to step 29 to determine whether or not the first abnormality has been resolved (first 1 abnormality elimination judgment step). Since the first abnormality has not been resolved, the process returns to step 23 again. Therefore, the filters set at the end of time series number 4 in FIG. 4 are filter a, filter b, and filter d.
- step 23 Since the processing in the next step 23 is the fifth round of processing, it is indicated by time series number 5 in FIG.
- filter a, filter b, and filter d which are the control parameters set in time series number 4, are stored in the central processing unit (CPU).
- the central processing unit (CPU) adds filter e in addition to filter a, filter b, and filter d (change step), and performs magnetic bearing control using the control parameters (control step).
- step 27 the central processing unit (CPU) determines whether or not the state of the first abnormality has improved (state improvement determination step). That is, at time series number 5, it is determined whether or not the first abnormal condition has improved compared to one step before.
- state improvement determination step 5 that is, at time series number 5, it is determined whether or not the first abnormal condition has improved compared to one step before.
- step 27 since it is determined in step 27 that the first abnormal state has improved, the control parameters at that time are retained, and the process proceeds to step 29 to determine whether the first abnormality has been resolved. is determined (first abnormality elimination determination step). Since it is determined in step 29 that the first abnormality has been resolved, the control parameters at that time are held and the process proceeds to step 35 .
- step 35 the filter a, filter b, filter d, and filter e set at this time are saved, and the readjustment is completed. Therefore, the filters set at the end of time series number 5 in FIG. 4 are filter a, filter b, filter d, and filter e. Subsequent operations are performed according to the control parameters saved in step 35 . For the time series numbers 0 to 5 in FIG. 4, it is assumed that the second abnormality was not detected in step 41 for the sake of simplicity.
- time series number 0 to time series number 3 are the same as in FIG. 4, so the description is omitted.
- filter a and filter b which are control parameters set in time series number 3, are stored in the central processing unit (CPU).
- the central processing unit (CPU) adds the filter d in addition to the filter a and the filter b (change process), and performs magnetic bearing control using the control parameters (control process).
- step 27 the central processing unit (CPU) determines whether or not the state of the first abnormality has improved (state improvement determination step). That is, at time series number 4, it is determined whether or not the first abnormal condition has improved compared to one step before. At time series number 4 in FIG. 5, the central processing unit (CPU) determined that the first abnormal condition was not improved. At this time, the process proceeds to step 31, and the central processing unit (CPU) restores the control parameters to the values of filter a and filter b one step before. After that, the process returns to step 23 again. Therefore, the filters set at the end of time series number 4 in FIG. 5 remain the filters a and b.
- step 23 The processing in the next step 23 is the fifth round of processing, so it is indicated by time series number 5 in FIG.
- filter a and filter b which are the control parameters set in time series number 4 are stored in the central processing unit (CPU).
- the central processing unit (CPU) adds the filter e in addition to the filters a and b (change step), and performs magnetic bearing control using the control parameters (control step).
- step 41 the second abnormality is detected by the central processing unit (CPU) in step 41, which is being processed in parallel. Therefore, the process is forcibly advanced to step 43, and the control parameters are returned to the past values by the central processing unit (CPU). That is, in the case of FIG. 5, the filter a and the filter b are set as the best parameters at that time, and the process proceeds to step 45, where the operation is stopped.
- the operation is stopped.
- the second abnormality should be detected immediately when it occurs and the operation should be stopped. Therefore, it is desirable to perform step 41 as frequently as possible independently of the readjustment step after the first abnormality detection.
- time series number 0 to time series number 4 are the same as in FIG. 5, so description thereof is omitted.
- the second abnormality was detected by the central processing unit (CPU) in step 41, as in FIG. Therefore, the process is forcibly advanced to step 43 and the control parameters are returned to the past values. That is, in the case of FIG. 6, the control parameters are returned to their initial values by the central processing unit (CPU).
- the filter proceeds to step 45 with the initial value, and the pump is stopped.
- the central processing unit (CPU) detects the first abnormality based on the above-described predetermined judgment criteria. Also, at step 71 in FIG. 7, the central processing unit (CPU) detects the second abnormality based on the above-described predetermined judgment criteria.
- step 52 the control parameters are set to the central processing unit (CPU ).
- step 53 the central processing unit (CPU) changes the control parameters (change process), and performs magnetic bearing control using the control parameters (control process).
- step 54 the central processing unit (CPU) determines whether or not the state of the first abnormality has improved (state improvement determination step). If not improved, the control parameters are restored in step 56 and the process returns to step 52 .
- step 55 the central processing unit (CPU) determines whether or not the first abnormality has been resolved (state improvement determination step). . If the first abnormality has not been resolved, the process returns to step 52 . On the other hand, if it is determined in step 55 that the first abnormality has been resolved, the process proceeds to step 57, where the central processing unit (CPU) performs stability evaluation (stability evaluation step). This not only confirms that the first anomaly has been resolved, but also determines whether the resolution is stable and not temporary.
- This stability evaluation is performed by, for example, a central processing unit (CPU) generating an excitation signal and applying it to the magnetic bearing device, and measuring its transfer function by the central processing unit (CPU).
- a central processing unit (CPU) generates an excitation signal and applies it to the magnetic bearing device, and the central processing unit (CPU) measures step responses or impulse responses.
- the excitation signal is, for example, a step signal, impulse signal, white noise, single-frequency sine wave, frequency-swept sine wave, swept sine, or the like.
- the stability may be determined by whether or not the first abnormality or the second abnormality occurs by the central processing unit (CPU) increasing or decreasing the magnetic bearing control gain.
- transfer function measurements, step response measurements, and impulse response measurements may be combined with increases and decreases in magnetic bearing control gains.
- the excitation signal may be generated by a central processing unit (CPU), or may be input from an external device. This enables readjustment in consideration of stability.
- the first abnormality has been resolved, it is possible to prevent a situation in which another abnormality occurs. As a result, operating efficiency is improved and safety is improved. It should be noted that if the central processing unit (CPU) detects the second abnormality in step 71, the operation of the pump is stopped in step 73.
- the central processing unit (CPU) detects the first abnormality at the point indicated by "X1" in the figure when starting the pump, the central processing unit (CPU) decelerates or free-runs the rotor 103 .
- free-running means stopping energization in the case of a motor or generator. During coasting, the energization is stopped, which reduces the disturbance force acting on the rotating body and the noise in the sensor signal. /N ratio is improved.
- the central processing unit (CPU) performs constant speed control.
- the point indicated by "X5" is a point where it is assumed that the damage at the time of touchdown is small. In this case, the readjustment may be started while the central processing unit (CPU) is decelerating, or may be performed after the speed becomes constant.
- the central processing unit (CPU) confirms that the first abnormality has been resolved at the point indicated by "X6"
- the central processing unit (CPU) accelerates the rotating body 103.
- the central processing unit (CPU) performs the readjustment during the deceleration operation of the rotating body 103 or during the constant speed operation, compared to the case where the operation is stopped after the rotation speed is set to zero, the readjustment is performed. can reach the rated speed faster. Therefore, the operating efficiency is improved.
- FIG. 12 the operation example of FIG. 12 is almost the same as the operation example of FIG.
- the point is that the central processing unit (CPU) performs readjustment while the rotating body 103 is free-running.
- the central processing unit CPU
- the motor 121 By stopping the energization of the motor 121 and making it free-run, the electric current does not flow. This reduces the vibration of the motor 121 and reduces the noise. Therefore, the S/N ratio of the displacement signal of the rotating body and the current signal of the magnetic bearing, which are the input signals to the magnetic bearing controller, is improved, and the accuracy of readjustment is improved. Therefore, readjustment can be performed at high speed.
- the central processing unit (CPU) free-runs the rotor 103 and performs readjustment. Then, when the central processing unit (CPU) detects the second abnormality at the point indicated by “X12”, the central processing unit (CPU) stops the rotating body 103 . This ensures the safety of the pump.
- FIG. 16 shows characteristics of changes in the natural frequency of the rotating body 103 due to the gyroscopic effect in the operation example of FIG. Due to the gyroscopic effect, the natural frequency of the rotor 103 changes according to the number of revolutions.
- the natural frequency of the rotating body 103 has the relationship between the time and the natural frequency shown in FIG.
- the turbo-molecular pump 100 has a rotor blade 102, and an abnormality such as oscillation due to its natural vibration is likely to occur.
- the central processing unit CPU performs readjustment while performing constant speed control from the point indicated by "X16" in the figure to the point indicated by "X17". That is, since the natural frequency is constant during readjustment, the accuracy of readjustment is improved. Therefore, the operating efficiency of the pump can be improved.
- the central processing unit (CPU) detects the first abnormality at the point indicated by "X1" in the figure, the central processing unit (CPU) performs acceleration control while Readjust. After that, when the central processing unit (CPU) confirms that the first abnormality has been resolved at the point indicated by “X18”, the central processing unit (CPU) continues to accelerate the rotating body 103 . Readjustment is performed during acceleration, and acceleration is continued immediately after the abnormality is resolved, so that the rated rotation speed can be reached as quickly as possible.
- the central processing unit (CPU) when the central processing unit (CPU) detects the first abnormality at the point indicated by "X1" in the drawing, the central processing unit (CPU) performs acceleration control while restarting. make adjustments. However, after that, when the central processing unit (CPU) detects the second abnormality at the point indicated by "X20" in the drawing, the central processing unit (CPU) stops the rotor 103. FIG. This ensures the safety of the pump.
- the central processing unit (CPU) selects readjustment during acceleration because it is desirable to accelerate in order to reach the rated speed sooner. Also, if the driving state just before is deceleration, there is no point in accelerating, so the central processing unit (CPU) selects readjustment while decelerating. Furthermore, if the operating state just before is such that the temperature changes during rated rotation and oscillates, the central processing unit (CPU) stops energizing the motor 121 in order to reduce noise. Choose to free run. As a result, even if an abnormality such as oscillation occurs due to inappropriate control parameters, the operation of the pump can be recovered without stopping.
- the operation is performed under the normal abnormality detection condition.
- operation is performed under this normal state abnormality detection condition from time 0 to time t1.
- the abnormality detection condition for the normal state is a condition set so that the first abnormal state and the second abnormal state can be detected.
- the central processing unit determines that the conditions for changing the predetermined control parameters have been met.
- the determination at this time is that the central processing unit (CPU) is ready to change the control parameters, such as adding filter a to the central processing unit (CPU) as indicated by time series number 1 in FIG. It means that the arithmetic processing unit (CPU) has decided.
- the abnormality detection condition is switched to the relaxed state.
- the reason why the abnormality detection condition is switched to the relaxed state in this way is that the abnormality detection condition is relaxed so that the abnormality is not detected by the central processing unit (CPU) due to the noise generated by the process of changing the control parameters. It is for
- the abnormality detection by the abnormality detection means of the central processing unit (CPU) is stopped.
- the reference value of the abnormality detection condition may be increased in the central processing unit (CPU).
- the first abnormality criterion is a displacement spectrum amplitude of 1 ⁇ m during relaxation, and a displacement spectrum amplitude of 0.5 ⁇ m during normal operation.
- step 87 control parameters are changed at time t0 in FIG.
- the filter a is added to the central processing unit (CPU) at time series number 1 .
- step 89 a standby is performed for a predetermined time from time t0 to time t2 in FIG.
- step 91 the abnormality detection condition is switched to the normal state at time t2 in FIG. 20, and in step 93, the operation is continued.
- the operation during this period will be described in detail based on FIG. Relax at least one of the conditions. That is, the abnormality detection condition is relaxed in the shaded portion in FIG. 20 .
- control parameters include, for example, (1) changing the filter according to a predetermined number of revolutions, or (2) detecting the first abnormality and controlling the central processing unit (CPU). (3) When a control parameter correction command is input to the magnetic bearing controller through external communication.
- the central processing unit (CPU) systematically sets the relaxation time only at the limited timing of correcting the control parameters.
- a certain relaxation time is always set after an abnormality is detected.
- the abnormality detection speed can be increased, and the reliability of the magnetic bearing device is improved. That is, during the relaxation time set by the central processing unit (CPU), for example, 2 seconds, noise due to control parameter correction is not erroneously detected, and during other time periods, the occurrence of an abnormality is instantaneously detected. detectable.
- the rotation speed is 18,000 rpm or more and less than 24,000 rpm
- This filter is turned ON at , and turned OFF at other rotation speeds.
- this filter is switched from OFF to ON, and when it reaches 18,240 rpm, the abnormality detection condition is relaxed. Return to normal state.
- the control parameter correction means of the central processing unit (CPU) newly sets a notch filter with a center frequency of 800 Hz.
- the abnormality detection condition is first relaxed, and 0.005 seconds later, at time t0, the control parameters are changed. back to Alternatively, the abnormality detection condition may be relaxed and the control parameter changed at the same time, and the abnormality detection condition may be returned to the normal state after two seconds have elapsed.
- a command to correct control parameters is input to the magnetic bearing controller through external communication by a user's operation.
- User operations are performed, for example, when a notch filter with a center frequency of 800 Hz is newly set while rotating at the rated speed of 27,000 rpm, or when the center frequency of the notch filter is changed from 800 Hz to 900 Hz.
- the proportional gain is changed to 0.9 times the previous one.
- the central processing unit (CPU) of the controller sends a command.
- the central processing unit (CPU) first relaxes the abnormality detection conditions, and changes the control parameters at time t0 after 0.005 seconds. Then, at time t2 after two seconds have elapsed, the abnormality detection condition is returned to the normal state.
- the abnormality detection conditions are relaxed and the control parameters are changed at the same time, and at time t2 after two seconds have passed, the abnormality detection conditions may be returned to the normal state.
- the abnormality detection conditions implemented in the central processing unit (CPU) include excessive displacement and current due to oscillation, fluctuations in the displacement spectrum and current spectrum, contact of the touchdown bearings 141 and 143, DC link voltage
- the temporarily relaxed anomaly detection conditions may be part or all of these implemented anomaly detection conditions.
- only the abnormality detection condition based on the displacement signal is relaxed, and other abnormality detection conditions are not relaxed.
- the control parameters are modified, large noise tends to appear in the displacement signal, while noise in other signals is small.
- Time t0, time t10, and rotation speed ⁇ 0 correspond to points on the time axis, rotation speed axis, and frequency axis at which the control parameters are corrected. corresponds to the area of the predetermined range.
- the range from time t1 to t0 and the range from ⁇ 1 to ⁇ 0 correspond to the front region, and the range from time t0 to t2 and the range from ⁇ 0 to ⁇ 2 correspond to the rear region.
- turbomolecular pump 102 rotor blade 103 rotor 104 upper radial electromagnet 105 lower radial electromagnet 106A, 106B axial electromagnet 107 upper radial sensor 108 lower radial sensor 109 axial sensor 111 metal disk 113 rotor shaft 121 motor 141, 143 touchdown bearing
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Abstract
Description
これらの半導体は、極めて純度の高い半導体基板に不純物をドープして電気的性質を与えたり、エッチングにより半導体基板上に微細な回路を形成したりなどして製造される。
そして、これらの作業は空気中の塵等による影響を避けるため高真空状態のチャンバ内で行われる必要がある。このチャンバの排気には、一般に真空ポンプが用いられているが、特に残留ガスが少なく、保守が容易等の点から真空ポンプの中の一つであるターボ分子ポンプが多用されている。
更に、ターボ分子ポンプは、電子顕微鏡等の設備において、粉塵等の存在による電子ビームの屈折等を防止するため、電子顕微鏡等のチャンバ内の環境を高度の真空状態にするのにも用いられている。
このターボ分子ポンプは回転体を磁気浮上制御するため磁気軸受装置を備えている。そして、この磁気軸受装置では、回転体の加速運転中に共振点を通過する際や定速運転中にノイズが発生した際等に、高速かつ強い力での回転体の位置制御をする必要がある。
この異常の発生に対し特許文献1では、自動リセット可の設定がされている場合に、磁気軸受装置に対し再起動によるリセットを行って運転を継続することで正常復帰させ、一方、自動リセット不可の設定がされている場合には磁気軸受装置を運転停止させる例が開示されている。
更に、ロータの曲げ固有振動数はロータの回転数に応じて変化する。その変化が発生しても安定に制御可能なフィルタの設定方法が特許文献4では開示されている。
しかしながら、上記した特許文献1のようにリセットのみでは、例えば、回転数、温度、時間など系の状態が変化したような場合には正常に復帰が出来ないおそれがある。これらによる異常から復帰するためには、制御パラメータを再調整する必要がある。
更に、特許文献4では、事前に指定された固有振動モードに対して、回転数による固有振動の変化を考慮したフィルタの設定方法が言及されている。
しかし、ポンプの運転中に、想定外の固有振動モードに起因する発振等の異常が発生した場合や、事前に設定したノッチフィルタの減衰や線幅が不適切な場合、温度変化や経時変化による固有振動数の変化などには、対応できないおそれがある。
また、ポンプの運転中には、瞬間的なノイズが予期せずに出現することがある。このようなノイズの場合に、必ずしも警報等を行う必要はなく、運転を継続しても問題の無いことも多くある。このため、ノイズが検出された場合であっても、誤動作とならないようにするために、2秒程度異常信号が続くか否かを判断し、続いた場合に警報を鳴動若しくは表示させるようにした例が開示されている(特許文献5)。
仮にポンプの運転中に制御パラメータの再調整を行った場合には、誤った再調整などにより異常が悪化してタッチダウンし、機器の破損などが発生する可能性がある。このため、不安全かつ修理の時間・コストが必要となる。
また、磁気軸受装置の制御パラメータの設定不良などにより、安定限界に極めて近い状態で運転されている場合には、わずかな環境変化に対して発振等の異常が発生しやすい。このような状態では、製造ばらつきや設置環境の影響を受けやすい。
更に、磁気軸受装置の制御パラメータを修正する際には、修正に伴うノイズが発生することがある。そして、このノイズは磁気軸受装置によって異常状態と判断される可能性がある。しかし、これは一時的なものであり、対応の必要なく自然に解消する。従って、異常と判断されるべきではない。
特許文献5に記載の方法では、制御パラメータ修正に伴うノイズによる異常誤検知を減らすことができる一方で、制御パラメータ修正時以外には異常検知が遅れてしまう。特に回転体の発振時には、直ちに異常検知して対応しなければ、回転体がタッチダウンベアリングに接触し、タッチダウンベアリングの寿命を縮める恐れがある。
解消したと判断したときその時点の前記制御パラメータを保持する、第1の異常解消判断工程を備えて構成した。
れ、運転効率が向上する。
また、回転体の減速運転中に再調整を行うようにしたので、再調整時の回転数は異常検知時よりも小さい。タッチダウン時のダメージは回転数が小さいほど小さく、特に所定の回転数以下でならば、無視することができる。従って、再調整中に異常が増大し、タッチダウンが発生した場合のダメージを小さくすることが出来る。このため、安全性が向上する。
また、回転体を減速又は運転停止後に再調整する場合と比べて、より早く定格回転数に到達できるため、運転効率が向上する。
回転体を減速又は運転停止後に再調整する場合と比べて、より早く定格回転数に到達できるため、運転効率が向上する。
制御パラメータ修正時には、変位信号に大きなノイズが現れやすい一方で、その他の信号のノイズは小さい。そのため、制御パラメータの修正を行なう際のノイズを誤検知せず、かつ、制御パラメータの修正と同時にたまたま発生した、例えば停電等の異常状態を高速に検知することが可能となり、信頼性が向上する。
回転翼102(102a、102b、102c・・・)とわずかの空隙を隔てて複数枚の固定翼123(123a、123b、123c・・・)が配設されている。回転翼102(102a、102b、102c・・・)は、それぞれ排気ガスの分子を衝突により下方向に移送するため、ロータ軸113の軸線に垂直な平面から所定の角度だけ傾斜して形成されている。固定翼123(123a、123b、123c・・・)は、例えばアルミニウム、鉄、ステンレス、銅などの金属、又はこれらの金属を成分として含む合金などの金属によって構成されている。
固定翼スペーサ125はリング状の部材であり、例えばアルミニウム、鉄、ステンレス、銅などの金属、又はこれらの金属を成分として含む合金などの金属によって構成されている。固定翼スペーサ125の外周には、わずかの空隙を隔てて外筒127が固定されて
いる。外筒127の底部にはベース部129が配設されている。ベース部129には排気口133が形成され、外部に連通されている。チャンバ(真空チャンバ)側から吸気口101に入ってベース部129に移送されてきた排気ガスは、排気口133へと送られる。
また、上側径方向センサ107と回転体103の間のステータコラム122の上端部には、タッチダウンベアリング141が配設されている。一方、下側径方向センサ108の下方には、タッチダウンベアリング143が配設されている。
図2に制御パラメータ修正手段による修正により、制御パラメータを再調整する方法の概念フローチャートを示す。ステップ1(図中S1と略す。以下同旨)で、制御装置の中央演算処理装置(CPU)が第1の異常を所定の判断基準に基づき検知する。
また、この第1の異常の判断基準としては、変位時間波形のpeak to peak値が例えば20μmに至ったときを設定してもよい。この値は時間波形なのでフーリエ変換は不要であり、中央演算処理装置(CPU)の演算量を軽減できる。
更に、この第1の異常の判断基準としては、電流時間波形のpeak to peak値が例えば1Aに至ったときを設定してもよい。
また、この第1の異常の判断基準は、運転状態によって変更してもよい。例えば、モータ121の非通電時には上記の通り変位スペクトル振幅0.5μmを判断基準値とするが、モータ121の通電時には変位スペクトル振幅1μmを判断基準値とする。これは非通電時の方が変位信号のS/N比がよいためである。
更に、この修正は、中央演算処理装置(CPU)が、制御パラメータの比例ゲインや積分ゲインや微分ゲインを変更することで行っても良い。
第2の異常の所定の判断基準は、具体的には、第1の異常の所定の判断基準よりも大きい値である。例えば、第1の異常の条件を、変位スペクトルの振幅が0.5μmに至ったとき、あるいは、電流スペクトル振幅が0.2Aに至ったときと設定した場合、第2の異常の条件を、変位スペクトルの振幅が5μmに至ったとき、あるいは、電流スペクトル振幅が0.5Aに至ったときと設定する。
また、例えば、第1の異常の条件を、変位時間波形のpeak to peak値が20μmに至ったとき、あるいは、電流時間波形のpeak to peak値が1Aに至ったときとした場合、第2の異常の判断基準を、変位時間波形のpeak to peak値が50μmに至ったとき、あるいは、電流時間波形のpeak to peak値が2Aに至ったときと設定する。この値は時間波形なのでフーリエ変換は不要であり、中央演算処理装置(CPU)の演算量を軽減できる。
また、この第2の異常の判断基準は、運転状態によって変更してもよい。例えば、モータ121の非通電時には上記の通り変位スペクトル振幅5μmを判断基準値とするが、モータ121の通電時には変位スペクトル振幅10μmを判断基準値とする。これは非通電時の方が変位信号のS/N比がよいためである。
また、この第2の異常の判断基準は、制御パラメータの再調整を所定の回数行っても第1の異常が解消しなかったときに設定されてもよい。あるいは、所定の時間を経過しても第1の異常が解消しなかったときに設定されてもよい。
なお、この第2の異常の判断基準は運転状態によって変更してもよい。例えば、回転体103の回転数がゼロのときには、上記したタッチダウンベアリング141及びタッチダウンベアリング143への接触を第2の異常の判断基準から除外してポンプの運転を継続する。これは、回転体103の回転数がゼロのときには、回転体103がタッチダウンベアリング141及びタッチダウンベアリング143に接触しても安全なためである。一方、回転体103が回転中のときにはタッチダウンベアリング141及びタッチダウンベアリング143への接触が判断されたときにはポンプの運転を停止する。
そして、ステップ9で中央演算処理装置(CPU)が第2の異常を検知したときには、ステップ11で中央演算処理装置(CPU)はポンプの運転を停止する。このときの運転の停止方法は、回転数指令値をゼロに設定し減速することで行う。そして、このときには、回転体103の浮上を継続する。
この運転停止は、回転体103の回転中には、回転数指令値をゼロに設定し減速することで行う方法と、磁気軸受の通電を停止する方法のいずれかを選択可能である。一方、静止浮上時においては、磁気軸受の通電を停止する方法のみが可能である。
図2で示す制御パラメータの再調整方法は、上述の通り中央演算処理装置(CPU)の演算で行うことが可能である。しかしながら、外部設定された装置で行うようにしてもよい。
以上のように、制御パラメータの再調整により系の状態変化による異常に対応できる。従って、磁気軸受制御のロバスト性が増加し、運転効率が向上する。また、運転を止めることなく制御パラメータを再調整できる。このため、復帰までの時間短縮により運転効率が向上する。更に、複数の異常基準を設け、必要な場合には運転を停止させるので安全性を確保できる。
このとき、中央演算処理装置(CPU)により、第1の異常が検知され、かつ、第2の異常が検知されていない状況を仮想する。図4の時系列番号0は初期状態、つまり、第1の異常検知直前の状態である。時系列番号1は、第1の異常が検知された直後の調整ステップを表す。第1の異常が検知されたので、ステップ23に進み、初期状態である時系列番号0の制御パラメータを中央演算処理装置(CPU)に記憶する。そして、ステップ25で、中央演算処理装置(CPU)は制御パラメータを変更し(変更工程)、その制御パラメータをもって磁気軸受制御を行う(制御工程)。即ち、図4の時系列番号1で示すように、このときフィルタaを中央演算処理装置(CPU)に追加した形で中央演算処理装置(CPU)は磁気軸受制御を行う。なお、以下では簡単のため制御パラメータ修正をフィルタの追加として説明するが、その他の手法でも良い。
なお、図4の時系列番号0-5では、簡単のためにステップ41での第2の異常は検知されなかったと仮想した。
図5において、時系列番号0から時系列番号3までは図4と同じなので説明は省略する。図5の時系列番号4では、まず、ステップ23で、時系列番号3で設定した制御パラメータであるフィルタaとフィルタbを中央演算処理装置(CPU)に記憶する。ステップ25で、中央演算処理装置(CPU)はフィルタaとフィルタbに加えて、フィルタdを追加し(変更工程)、その制御パラメータをもって磁気軸受制御を行う(制御工程)。
以上のように、再調整によって状態が却って悪化し直ちに運転停止が必要な場合にも、制御パラメータを過去の値に戻すことで、比較的安全な状態にて運転停止できる。
また、安全を確保するためには、第2の異常は発生時に直ちに検知され、運転が停止されることが重要である。従って、第1の異常検知後の再調整のステップとは独立に、なるべく高頻度にステップ41を実行することが望ましい。
図6の時系列番号5では、図5と同様にステップ41で、中央演算処理装置(CPU)により第2の異常が検知された。このため、強制的にステップ43に進み制御パラメータが過去の値に戻される。即ち、図6の場合には、制御パラメータが中央演算処理装置(CPU)により初期値に戻される。フィルタは初期値のままでステップ45に進み、ポンプの運転停止状態に移行する。
図7において、ステップ51で中央演算処理装置(CPU)が第1の異常を前述した所定の判断基準に基づき検知する。また、図7のステップ71で、中央演算処理装置(CPU)が第2の異常を前述した所定の判断基準に基づき検知する。
そして、ステップ54で第1の異常の状態が改善したか否かを中央演算処理装置(CPU)は判断する(状態改善判断工程)。改善されていない場合には、ステップ56で制御パラメータを元に戻した後、ステップ52に戻る。一方改善された場合には、その時点の制御パラメータを保持し、ステップ55に進み、中央演算処理装置(CPU)により第1の異常が解消されたか否かが判断される(状態改善判断工程)。第1の異常が解消されていない場合にはステップ52に戻る。一方、ステップ55で第1の異常が解消されたと判断された場合には、ステップ57に進み、中央演算処理装置(CPU)により安定性評価が行われる(安定性評価工程)。これは第1の異常が解消されたことの確認だけではなく、その解消が一時的なものではなく安定的なのかどうかを判断するものである。この安定性評価は、例えば中央演算処理装置(CPU)が加振信号を発生させて磁気軸受装置に与え、中央演算処理装置(CPU)がその伝達関数を測定することで行う。あるいは、中央演算処理装置(CPU)が加振信号を発生させて磁気軸受装置に与え、中央演算処理装置(CPU)がステップ応答を測定したり、インパルス応答を測定する。
これにより、安定性を考慮した再調整が可能となる。第1の異常を解消したが、また異常が発生するような状態を防ぐことが出来る。このため、運転効率が向上し、安全性が向上する。
なお、ステップ71で中央演算処理装置(CPU)が第2の異常を検知した場合には、ステップ73でポンプの運転を停止する。
まず、図8の運用例では、ポンプの起動の際に、図中「X1」で示す地点で中央演算処理装置(CPU)が第1の異常を検知したとき、中央演算処理装置(CPU)は回転体103の減速制御をしつつ再調整を行う。ここに減速制御とは、モータを回生運転する、発電機を出力させる、等のように回転数を低下させるトルクを与える制御を意味する。そして、「X2」で示す地点で、中央演算処理装置(CPU)が第1の異常の解消を確認後には、中央演算処理装置(CPU)は回転体103を加速させる。
また、回転体103の減速動作中に中央演算処理装置(CPU)が再調整を行うようにしたので、再調整時の回転数は異常検知時よりも小さい。タッチダウン時のダメージは回転数が小さいほど小さく、特に所定の回転数以下でならば、無視することができる。従って、再調整中に異常が増大し、タッチダウンが発生した場合のダメージを小さくすることが出来る。このため、安全性が向上する。
このとき、「X9」で示す地点で中央演算処理装置(CPU)が第1の異常が解消したことを確認したときには、中央演算処理装置(CPU)が回転体103を加速させる。これにより、第1の異常が生じた場合でも、「X10」で示す地点で定格回転数に至るまでの時間を節約できるため、定格回転数への復帰が早くなる。
その後、「X13」で示す地点で、中央演算処理装置(CPU)が第1の異常が解消したことを確認したときには、中央演算処理装置(CPU)は回転体103を加速させる。
このことにより、「X14」で示す地点で定格回転数に至るまでの時間を節約できるため、定格回転数への復帰が早くなる。
このことにより、制御パラメータが不適切であったために、発振等の異常を生じた場合であっても、ポンプの運転を停止することなく復帰できる。
例えば、比例ゲイン、微分ゲイン、位相進みフィルタ、ノッチフィルタ、ABS(Auto Balance System)などの制御パラメータを修正する場合には、制御パラメータの変更が行われる。この制御パラメータの変更時には、制御系にノイズが生じ易い。しかし、このノイズは異常によるものではないので、中央演算処理装置(CPU)が誤検知しないようにする。その一方で、制御パラメータの変更以外により生じたノイズは、中央演算処理装置(CPU)が異常として素早く検知できるようにする。
グチャートに基づき動作を説明する。
図19のステップ81では、通常状態の異常検知条件にて運転がされている。図20のタイミングチャートでは、時刻0から時刻t1までの間で、この通常状態の異常検知条件での運転がされている。通常状態の異常検知条件とは、例えば先述した実施例の場合には、第1の異常状態、第2の異常状態を検知できるように設定された条件である。ステップ83では、中央演算処理装置(CPU)が、所定の制御パラメータの変更を行なうための条件が満たされたと判断する。このときの判断は、例えば、図4の時系列番号1で示すようにフィルタaを中央演算処理装置(CPU)に追加するというような制御パラメータの変更を行なうための準備が整ったことを中央演算処理装置(CPU)が判断したという意味である。そして、ステップ85では、図20の時刻t1において異常検知条件を緩和状態に切り替える。このように異常検知条件を緩和状態に切り替えるのは、制御パラメータを変更する処理を行ったことに伴い生じたノイズにより、中央演算処理装置(CPU)で異常が検知されないように異常検知条件を緩和するためである。
また、中央演算処理装置(CPU)において、異常検知条件の基準値を大きくしてもよい。例えば、第1の異常の判断基準として、緩和時には変位スペクトル振幅1μmとし、通常運転の場合には、変位スペクトル振幅0.5μmとする。
更に、特定の周波数成分を無視するようにしてもよい。例えば、緩和時には100Hz以下の振動成分を無視し、通常運転の場合には、100Hz以下を含めた全周波数成分で異常を検知する。制御パラメータの変更に伴うノイズによる変位信号の応答は、回転翼の固有振動と比べて遅いため、制御パラメータの変更に伴うノイズの影響を低減しながら、回転翼の固有振動による異常を直ちに検知することができる。
この間の運転を図20を基に詳述すると、制御パラメータ変更の時刻をt0として、変更前の時刻t1から変更後の時刻t2までの時間のみ、第1の異常検知条件と第2の異常検知条件の内のいずれか少なくとも一つを緩和する。即ち、図20の塗りつぶし部で、異常検知条件を緩和する。
制御パラメータを修正する場合の例としては、例えば、(1)所定の回転数に応じてフィルタを変更する場合であったり、(2)第1の異常が検知され、中央演算処理装置(CPU)の制御パラメータ修正手段が制御パラメータを修正する場合であったり、(3)外部通信による制御パラメータ修正指令が磁気軸受制御器に入力される場合である。
制御パラメータ修正時には修正に伴うノイズを異常であると誤検知せず、制御パラメータ修正時以外には、従来のように緩和時間を設定しないために、常に異常検出後の一定の緩和時間を設定している場合に比べて、異常検出の速度を速くでき、磁気軸受装置の信頼性が向上する。
即ち、中央演算処理装置(CPU)が緩和時間を設定している例えば2秒の間には制御パラメータ修正によるノイズを誤検知しないと共に、それ以外の時間帯では、瞬時に異常の生じたことを検出できる。
まず、上記(1)の所定の回転数に応じてフィルタを変更する場合についての動作例を説明する。
所定の回転数以上で、変位信号から回転数同期成分を取り除くフィルタABS(Auto Balance System)に対し、例えば、定格回転数27,000rpmの真空ポンプにおいて、回転数12,000rpm以上でABSをONとし、回転数12,000rpm未満でABSをOFFとする。この場合には、加速中、回転数11,940rpmに到達したら異常検知条件を緩和し、回転数12,000rpmに到達したらABSをOFFからONに切り替え、12,240rpmに到達したら異常検知条件を通常状態に戻す。
この場合、例えば、定格回転数27,000rpmで回転中、中央演算処理装置(CPU)の制御パラメータ修正手段が中心周波数の800Hzのノッチフィルタを新たに設定する。図21に示すように、時刻t1で、まず異常検知条件を緩和し、その0.005秒後の時刻t0で制御パラメータを変更し、さらに2秒経過後の時刻t2において異常検知条件を通常状態に戻す。あるいは、まず異常検知条件の緩和と制御パラメータの変更を同時に行い、2秒経過後に異常検知条件を通常状態に戻すようにしてもよい。
ポンプの運転中、図23に示すように、時刻t3において、ユーザー操作によって外部通信による制御パラメータの修正指令が磁気軸受制御器に入力された場合である。ユーザー操作が行なわれるのは、例えば、定格回転数27,000rpmで回転中、中心周波数の800Hzノッチフィルタが新たに設定される場合や、ノッチフィルタの中心周波数が800Hzから900Hzに変更される場合、比例ゲインが直前と比較して0.9倍に変更される場合などである。この場合、時刻t1で、制御装置の中央演算処理装置(CPU)が指令を送信する。中央演算処理装置(CPU)は、まず異常検知条件を緩和し、その0.005秒後の時刻t0に制御パラメータを変更する。そして、更に2秒経過後の時刻t2に異常検知条件を通常状態に戻す。
なお、中央演算処理装置(CPU)に実装される異常検知条件は先述した通り、発振による過大な変位や電流、変位スペクトルや電流スペクトルの変動等、タッチダウンベアリング141、143の接触、DCリンク電圧であるが、一時的に緩和する異常検知条件は、これらの実装された異常検知条件の一部でもよいし、全部でもよい。好適には、変位信号に基づく異常検知条件のみを緩和し、そのほかの異常検知条件を緩和しない。制御パラメータ修正時には、変位信号に大きなノイズが現れやすい一方で、その他の信号のノイズは小さい。これにより、制御パラメータ修正によるノイズを誤検知せず、かつ、制御パラメータ修正によるノイズと同時にたまたま発生した、例えば停電などのノイズ以外の異常状態を高速に検知することが可能となり、信頼性が向上する。
本発明は、本発明の精神を逸脱しない限り種々の改変をなすことが出来、そして、本発明が当該改変されたものにも及ぶことは当然である。また、上述した各実施形態は種々組み合わせても良い。
102 回転翼
103 回転体
104 上側径方向電磁石
105 下側径方向電磁石
106A、106B 軸方向電磁石
107 上側径方向センサ
108 下側径方向センサ
109 軸方向センサ
111 金属ディスク
113 ロータ軸
121 モータ
141、143 タッチダウンベアリング
Claims (17)
- 回転体と、
該回転体を磁力で空中に浮上支持する磁気軸受と、
該磁気軸受を制御する磁気軸受制御器とを備えた磁気軸受装置であって、
前記磁気軸受制御器による制御の異常を所定の第1の異常条件に基づき検知する第1の異常検知手段と、
該第1の異常検知手段で前記制御の異常が検知されたとき、前記磁気軸受装置の運転を継続しつつ前記磁気軸受制御器の制御パラメータを修正する制御パラメータ修正手段と、
前記磁気軸受制御器による前記制御の異常を前記第1の異常条件よりも異常の度合いの大きい所定の第2の異常条件に基づき検知する第2の異常検知手段と、
該第2の異常検知手段で前記制御の異常が検知されたとき前記磁気軸受装置の運転を停止する停止手段とを備えたことを特徴とする磁気軸受装置。 - 前記制御パラメータ修正手段が、
前記制御パラメータを1ステップ前の制御パラメータから変更する変更工程と、
該変更工程で変更された制御パラメータをもって前記磁気軸受制御器による制御を行う制御工程と、
該制御工程で制御を行った結果、該制御工程の前記1ステップ前に行われた制御の結果と比べて前記制御の異常の状態に改善があったか否かを判断し、前記制御の異常の状態に改善があったと判断したときに、前記制御パラメータとして変更後の値を保持し、一方、前記制御の異常の状態に改善が無かったと判断したときに、前記制御パラメータを前記1ステップ前の制御パラメータに戻す状態改善判断工程とを備えたことを特徴とする請求項1記載の磁気軸受装置。 - 前記制御パラメータ修正手段には、前記状態改善判断工程にて前記制御の異常の状態に改善があったと判断した場合の後段に、前記第1の異常条件に基づき前記制御の異常の状態が解消したか否かを判断し、前記第1の異常条件で判断される前記制御の異常の状態が解消していないと判断したとき前記変更工程に戻り、一方、前記第1の異常条件で判断される前記制御の異常の状態が解消したと判断したときその時点の前記制御パラメータを保持する、第1の異常解消判断工程を備えたことを特徴とする請求項2記載の磁気軸受装置。
- 前記制御パラメータ修正手段には、前記第1の異常解消判断工程にて前記第1の異常条件で判断される前記制御の異常の状態が解消したと判断した場合の後段に、前記第1の異常解消判断工程にて保存された前記制御パラメータを適用した前記磁気軸受装置の運転が、前記磁気軸受制御器による前記制御の異常が生じない所定の安定性を有するものになっているか否かを評価する安定性評価工程を更に備え、
該安定性評価工程で前記安定性が十分でないと評価されるとき、前記磁気軸受制御器の前記制御パラメータの修正をやり直すことを特徴とする請求項3に記載の磁気軸受装置。 - 前記安定性評価工程が、加振信号の印加、前記磁気軸受制御器の制御ゲインの増加、及び、前記磁気軸受制御器の制御ゲインの減少の少なくともいずれか一つを用いて評価されることを特徴とする請求項4に記載の磁気軸受装置。
- 前記制御パラメータ修正手段による前記制御パラメータの修正の過程において、前記第2の異常条件に基づき判断される前記制御の異常が検知されたとき、前記制御パラメータ修正手段が過去に設定された前記制御パラメータを適用した上で前記磁気軸受装置の運転を停止することを特徴とする請求項1~5のいずれか一項に記載の磁気軸受装置。
- 前記制御パラメータ修正手段では、前記第1の異常検知手段で前記制御の異常が検知されたとき、前記回転体の減速運転をしつつ前記磁気軸受制御器の前記制御パラメータを修正することを特徴とする請求項1~5のいずれか一項に記載の磁気軸受装置。
- 前記制御パラメータ修正手段では、前記第1の異常検知手段で前記制御の異常が検知されたとき、前記回転体の回転数制御を停止し、該回転体がフリーランの状態で前記磁気軸受制御器の前記制御パラメータを修正することを特徴とする請求項1~5のいずれか一項に記載の磁気軸受装置。
- 前記制御パラメータ修正手段では、前記第1の異常検知手段で前記制御の異常が検知されたとき、前記回転体の回転数制御を該異常が検知されたときの回転数にて定速制御を行いつつ前記磁気軸受制御器の前記制御パラメータを修正することを特徴とする請求項1~5のいずれか一項に記載の磁気軸受装置。
- 前記制御パラメータ修正手段では、前記第1の異常検知手段で前記制御の異常が検知されたとき、前記回転体の加速運転をしつつ前記磁気軸受制御器の前記制御パラメータを修正することを特徴とする請求項1~5のいずれか一項に記載の磁気軸受装置。
- 前記磁気軸受制御器の前記制御パラメータを修正後に、前記第1の異常条件での異常状態が解消されたとき前記回転体の加速が行われる請求項7に記載の磁気軸受装置。
- 請求項1~5のいずれか一項に記載の磁気軸受装置を搭載した真空ポンプ。
- 回転体と、
該回転体を磁力で空中に浮上支持する磁気軸受と、
該磁気軸受を制御する磁気軸受制御器とを備えた磁気軸受装置であって、
前記磁気軸受制御器による制御の異常を所定の異常条件に基づき検知する異常検知手段と、
前記磁気軸受制御器の制御パラメータを修正する制御パラメータ修正手段と、
該制御パラメータ修正手段が前記制御パラメータの修正を行なう、時間軸上、回転数軸上、周波数軸上のいずれかの地点を含み設定された所定範囲の領域と、
該所定範囲の領域において前記所定の異常条件を緩和する緩和手段とを備えたことを特徴とする磁気軸受装置。 - 前記所定の異常条件は複数種類で構成され、
前記緩和手段で緩和される異常条件には、変位信号に基づく異常条件が含まれることを特徴とする請求項13に記載の磁気軸受装置。 - 前記所定範囲の領域が前記地点よりも前方の前方領域と、前記地点よりも後方の後方領域とで構成され、該後方領域が前記前方領域よりも大きいことを特徴とする請求項13又は請求項14に記載の磁気軸受装置。
- 前記所定範囲の領域が前記地点よりも後方の後方領域のみで構成されたことを特徴とする請求項13又は請求項14に記載の磁気軸受装置。
- 請求項13又は請求項14に記載の磁気軸受装置を搭載した真空ポンプ。
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JP2001293637A (ja) | 2000-04-12 | 2001-10-23 | Matsushita Electric Ind Co Ltd | 磁気軸受装置 |
JP2002188630A (ja) | 2000-12-21 | 2002-07-05 | Matsushita Electric Ind Co Ltd | 磁気軸受の制御装置およびこれを用いた磁気軸受スピンドル装置 |
JP2006145006A (ja) | 2004-11-24 | 2006-06-08 | Jtekt Corp | 磁気軸受装置 |
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JP2014137116A (ja) * | 2013-01-17 | 2014-07-28 | Shimadzu Corp | 磁気軸受装置および真空ポンプ |
JP2019138415A (ja) * | 2018-02-14 | 2019-08-22 | 株式会社島津製作所 | 磁気浮上制御装置および真空ポンプ |
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JPH09236122A (ja) | 1996-02-29 | 1997-09-09 | Matsushita Electric Ind Co Ltd | 磁気軸受制御装置 |
JP2000110777A (ja) | 1998-10-01 | 2000-04-18 | Mitsubishi Heavy Ind Ltd | ターボ分子ポンプとその保護動作方法 |
JP2001293637A (ja) | 2000-04-12 | 2001-10-23 | Matsushita Electric Ind Co Ltd | 磁気軸受装置 |
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