Vacuum pump and magnetic bearing control device

Abstract

To propose a vacuum pump and a magnetic bearing control device for which, if information stored in a writable non-volatile memory is damaged, recovery is possible without a specialized engineer or the like.SOLUTION: A vacuum pump 100 comprises, in a control unit 100B, determination / overwriting means that: determines whether first storage means 204 is normal, and if the first storage means 204 is abnormal, recognizes individual identification information stored in third storage means 203 as accurate and overwrites individual identification information stored in the first storage means 204; or determines whether second storage means 202 is normal, and if the second storage means 202 is abnormal, recognizes the individual identification information stored in the third storage means 203 as accurate and overwrites individual identification information stored in the second storage means 202.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a vacuum pump and a magnetic bearing control device. [Background technology]

[0002] In vacuum pumps such as turbomolecular pumps, a magnetic bearing device is used that magnetically levitates and holds the rotating shaft without contact. The magnetic bearing device is equipped with a sensor that detects the displacement of the rotating shaft and an electromagnet that adjusts the position of the rotating shaft, and the sensor and electromagnet are electrically connected to a magnetic bearing control device. The magnetic bearing control device controls the excitation of the electromagnet based on the displacement detected by the sensor, thereby magnetically levitating the rotating shaft (see, for example, Patent Document 1). In addition, when a vacuum pump is used to exhaust process gas from a chamber of a semiconductor manufacturing device, etc., a heater and a cooling device are provided to maintain the inside of the magnetic bearing device within a predetermined temperature range in order to prevent the process gas from solidifying and by-products from accumulating in the magnetic bearing device. The magnetic bearing control device also controls these heaters and cooling devices.

[0003] In such magnetic bearing devices, the characteristics of the control for magnetically levitating the rotating shaft, such as the current value and reference value, differ depending on the model. Also, the error between the mechanical center position and the electrical center position of the rotating body including the rotating shaft differs for each individual device, and the temperature parameters in the case where a heater or the like is provided are set for each individual device, so the characteristics related to these in the control of the magnetic bearing device differ for each individual device.

[0004] In conventional vacuum pumps such as that of Patent Document 1, the magnetic bearing device is provided with resistors whose resistance values ​​differ for each model and a writable non-volatile memory (EEP-ROM), and the writable non-volatile memory stores individual identification information for identifying each individual magnetic bearing device (e.g., the serial number of the magnetic bearing device, etc.), and control information related to the characteristics of each model and each individual magnetic bearing device. The magnetic bearing control device also has a writable non-volatile memory, and this writable non-volatile memory stores model information for identifying the model of the magnetic bearing device, individual identification information for identifying each individual magnetic bearing device, and control information related to the characteristics of each model and each individual magnetic bearing device. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 3130890 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, the magnetic bearing device and the magnetic bearing control device transmit and receive signals, for example, via serial communication, but there is a risk that the information stored in the writable non-volatile memory may be corrupted due to electromagnetic noise during communication or the control process being unintentionally terminated during communication.As shown in Patent Document 1, a conventional vacuum pump stores the same information in the non-volatile memory of the magnetic bearing device and the magnetic bearing control device, and has a function of overwriting the control information, etc. stored in one non-volatile memory with the control information, etc. stored in the other non-volatile memory.

[0007] The operating condition of the magnetic bearing device is set so that it operates when the individual identification information stored in the non-volatile memory of the magnetic bearing device matches the individual identification information stored in the non-volatile memory of the magnetic bearing control device. This is because, particularly in vacuum pumps in which the magnetic bearing device and the magnetic bearing control device can be separated, the combination of the magnetic bearing device and the magnetic bearing control device may be changed, and it is necessary to confirm that the currently connected magnetic bearing device and the magnetic bearing control device are the ones that were last combined. Here, if the individual identification information in the writable non-volatile memory is damaged, the individual identification information of one side and the individual identification information of the other side will not match, so it is not possible to overwrite the control information, etc., and only a specialized engineer can restore the vacuum pump.

[0008] In view of these circumstances, the present invention aims to provide a vacuum pump and a magnetic bearing control device that enable even non-specialized engineers to recover information stored in a writable non-volatile memory if the information is corrupted. [Means for solving the problem]

[0009] The present invention relates to a vacuum pump having a magnetic bearing device that magnetically levitates a rotating shaft and holds it in a non-contact manner, It is information to identify an individual.The magnetic bearing device is characterized in that it comprises a control unit that controls the magnetic bearing device based on individual identification information and control information related to various characteristics of the magnetic bearing device, a writable first storage means within the control unit in which the individual identification information is stored, a writable second storage means within the magnetic bearing device in which the individual identification information is stored, and a non-writable third storage means within the magnetic bearing device in which the individual identification information is stored, and a determination and overwrite means within the control unit that determines whether the first storage means is normal and, if the first storage means is abnormal, takes the individual identification information stored in the third storage means to be true and overwrites the individual identification information stored in the first storage means, or that determines whether the second storage means is normal and, if the second storage means is abnormal, takes the individual identification information stored in the third storage means to be true and overwrites the individual identification information stored in the second storage means.

[0010] In such a vacuum pump, it is preferable that the first storage means stores the control information, the second storage means stores the control information, and the third storage means stores the control information, and the determination and overwrite means determines whether the first storage means is normal, and if the first storage means is abnormal, the control information stored in the third storage means is taken as correct and overwrites the control information stored in the first storage means, or determines whether the second storage means is normal, and if the second storage means is abnormal, the control information stored in the third storage means is taken as correct and overwrites the control information stored in the second storage means.

[0011] The present invention also provides a magnetic bearing control device for controlling a magnetic bearing device that magnetically levitates a rotating shaft and holds it in a non-contact manner, the magnetic bearing control device comprising: It is information to identify an individual.and a control unit that controls the magnetic bearing device based on individual identification information and control information related to various characteristics of the magnetic bearing device, the control unit comprising: a first writable storage means in which the individual identification information is stored; an access means in the control unit for accessing a second writable storage means provided in the magnetic bearing device and in which the individual identification information is stored, and a third unwritable storage means provided in the magnetic bearing device and in which the individual identification information is stored; and a determination and overwrite means in the control unit for determining whether the first storage means is normal and, if the first storage means is abnormal, for overwriting the individual identification information stored in the first storage means with the individual identification information stored in the third storage means as true, or for determining whether the second storage means is normal and, if the second storage means is abnormal, for overwriting the individual identification information stored in the second storage means with the individual identification information stored in the third storage means as true. Effect of the Invention

[0012] In the vacuum pump of the present invention, a writable first storage means in which individual identification information is stored is provided in the control unit, and a writable second storage means in which individual identification information is stored and an unwritable third storage means in which individual identification information is stored are provided in the magnetic bearing device. That is, since the third storage means is unwritable, the individual identification information stored in the third storage means is not damaged even if noise is mixed in during communication or the control process is unintentionally terminated during communication. Here, the determination overwriting means provided in the control unit is configured to determine whether the first storage means is normal, and if the first storage means is abnormal, to overwrite the individual identification information stored in the first storage means with the individual identification information stored in the third storage means as true, or to determine whether the second storage means is normal, and if the second storage means is abnormal, to overwrite the individual identification information stored in the second storage means with the individual identification information stored in the third storage means as true. That is, although the individual identification information stored in the first storage means or the second storage means determined to be abnormal may be corrupted, this can be overwritten with normal individual identification information stored in the third storage means, so that the individual identification information stored in the first storage means and the second storage means will match. Therefore, since it is possible to overwrite the other with either the control information related to the characteristics of the magnetic bearing device stored in a writable storage means (e.g., the first storage means) in the control unit or the control information related to the characteristics of the magnetic bearing device stored in a writable storage means (e.g., the second storage means) in the magnetic bearing device, even if the person is not a specialized engineer, the vacuum pump can be restored. [Brief description of the drawings]

[0013] [Figure 1] 1 is a vertical cross-sectional view that shows a schematic diagram of an embodiment of a vacuum pump according to the present invention. [Diagram 2] FIG. 2 is a circuit diagram of an amplifier circuit of the vacuum pump shown in FIG. [Diagram 3] 6 is a time chart showing control when a current command value is larger than a detection value. [Figure 4]6 is a time chart showing control when a current command value is smaller than a detection value. [Diagram 5] 2 is a diagram illustrating an outline of the electrical configuration of a magnetic bearing device and a magnetic bearing control device. FIG. [Figure 6] 4 is a flowchart showing a flow when the magnetic bearing device is controlled by the magnetic bearing control device. [Figure 7] 7 is a flowchart relating to A and B shown in FIG. 6. [Figure 8] 7 is a flowchart showing a modification of FIG. 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A turbomolecular pump, which is one embodiment of a vacuum pump according to the present invention, will be described below with reference to the drawings.

[0015] A longitudinal sectional view of this turbomolecular pump 100 is shown in FIG. 1. The turbomolecular pump 100 is composed of a magnetic bearing device 100A and a magnetic bearing control device 100B. The magnetic bearing control device 100B in this embodiment is shown as being separate from the magnetic bearing device 100A and electrically connected to the magnetic bearing device 100A via a cable, but it may be incorporated into the magnetic bearing device 100A. The magnetic bearing control device 100B corresponds to the "control unit" in the present specification and the like. In FIG. 1, the magnetic bearing device 100A is provided with an intake port 101 at the upper end of a cylindrical outer tube 127. A rotor 103 that rotates around a central axis CA is provided inside the outer tube 127. The rotor 103 is provided with multiple rotors 102 (102a, 102b, 102c, . . . ) which are turbine blades for sucking and exhausting gas, arranged radially and in multiple stages on the periphery. A rotor shaft 113 (rotating shaft) is attached to the center of the rotating body 103, and this rotor shaft 113 is supported in the air and its position is controlled by, for example, a five-axis controlled magnetic bearing. The rotating body 103 is generally made of a metal such as aluminum or an aluminum alloy.

[0016] The upper radial electromagnets 104 are 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 each of the upper radial electromagnets 104. The upper radial sensors 107 are, for example, inductance sensors or eddy current sensors having conductive windings, and detect the position of the rotor shaft 113 based on the change in inductance of the conductive windings that changes according to the position of the rotor shaft 113. The upper radial sensors 107 are configured to detect the radial displacement of the rotor shaft 113, i.e., the rotating body 103 fixed thereto, and send the detected displacement to the magnetic bearing control device 100B.

[0017] In this magnetic bearing control device 100B, for example, a compensation circuit having a PID adjustment function generates an excitation control command signal for the upper radial electromagnet 104 based on a position signal detected by the upper radial sensor 107, and an amplifier circuit 150 (described later) shown in Figure 2 controls the excitation of the upper radial electromagnet 104 based on this excitation control command signal, thereby adjusting the upper radial position of the rotor shaft 113.

[0018] The rotor shaft 113 is made of a material with high magnetic permeability (iron, stainless steel, etc.) and is attracted by the magnetic force of the upper radial electromagnet 104. Such adjustment is performed 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, and adjust the lower radial position of the rotor shaft 113 in the same manner as the upper radial position.

[0019] Furthermore, axial electromagnets 106A and 106B are arranged above and below a circular metal disk 111 provided at the bottom of rotor shaft 113. 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 rotor shaft 113, and an axial position signal is sent to magnetic bearing control device 100B.

[0020] In the magnetic bearing control device 100B, a compensation circuit having, for example, a PID adjustment function generates excitation control command signals for each of the axial electromagnets 106A and 106B based on the axial position signal detected by the axial sensor 109, and the amplifier circuit 150 controls the excitation of the axial electromagnets 106A and 106B based on these excitation control command signals, so that the axial electromagnet 106A attracts the metal disk 111 upward by magnetic force and the axial electromagnet 106B attracts the metal disk 111 downward, thereby adjusting the axial position of the rotor shaft 113.

[0021] In this way, the magnetic bearing control device 100B appropriately adjusts the magnetic force that the axial electromagnets 106A, 106B exert on the metal disk 111, magnetically levitating the rotor shaft 113 in the axial direction and holding it in space without contact. The amplifier circuit 150 that controls the excitation of the upper radial electromagnets 104, the lower radial electromagnets 105, and the axial electromagnets 106A, 106B will be described later.

[0022] On the other hand, motor 121 has a plurality of magnetic poles arranged circumferentially so as to surround rotor shaft 113. Each magnetic pole is controlled by magnetic bearing control device 100B so as to rotate rotor shaft 113 via electromagnetic force acting between the magnetic pole and rotor shaft 113. Also, motor 121 incorporates a rotational speed sensor such as a Hall element, resolver, or encoder (not shown), and the rotational speed of rotor shaft 113 is detected by a detection signal from this rotational speed sensor.

[0023] Furthermore, for example, a phase sensor (not shown) is attached near the lower radial sensor 108 to detect the phase of rotation of the rotor shaft 113. In the magnetic bearing control device 100B, the detection signals of this phase sensor and the rotational speed sensor are used together to detect the position of the magnetic pole.

[0024] A plurality of fixed blades 123 (123a, 123b, 123c...) are arranged on the inner periphery side of the outer cylinder 127 and on the outer periphery side of the rotor 103, separated by a small gap from the rotor blades 102 (102a, 102b, 102c...). The rotor blades 102 (102a, 102b, 102c...) are formed at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113 in order to transport exhaust gas molecules downward by collision. The fixed blades 123 (123a, 123b, 123c...) are made of metal such as aluminum, iron, stainless steel, copper, or an alloy containing these metals as components.

[0025] Similarly, the fixed blades 123 are formed at an inclination at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113, and are arranged alternately with the stages of the rotor blades 102 toward the inside of the outer cylinder 127. The outer peripheral ends of the fixed blades 123 are supported in a state where they are inserted between a plurality of stacked stages of fixed blade spacers 125 (125a, 125b, 125c, etc.).

[0026] The fixed vane spacer 125 is a ring-shaped member and is made of metal such as aluminum, iron, stainless steel, copper, or an alloy containing these metals as components. An outer cylinder 127 is fixed to the outer periphery of the fixed vane spacer 125 with a small gap therebetween. A base portion 129 is disposed at the bottom of the outer cylinder 127. An exhaust port 133 is formed in the base portion 129 and communicates with the outside. The exhaust gas that enters the intake port 101 from the chamber (vacuum chamber) side and is transported inside the magnetic bearing device 100A is sent to the exhaust port 133 on the downstream side.

[0027] Furthermore, depending on the application of the magnetic bearing device 100A, a threaded spacer 131 is disposed between the lower part of the fixed blade spacer 125 and the base part 129. The threaded spacer 131 is a cylindrical member made of metal such as aluminum, copper, stainless steel, iron, or an alloy containing these metals, and has a plurality of helical thread grooves 131a engraved on its inner peripheral surface. The helical direction of the thread groove 131a is the direction in which, when exhaust gas molecules move in the rotation direction of the rotor 103, the molecules are transported toward the exhaust port 133. A cylindrical part 102d hangs down from the lowest part (the part facing the threaded spacer 131) following the rotors 102 (102a, 102b, 102c, etc.) of the rotor 103. 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 specified gap therebetween. The exhaust gas transferred to the thread groove 131a by the rotor 102 and the fixed blade 123 is sent to the base portion 129 while being guided by the thread groove 131a.

[0028] The base portion 129 is a disk-shaped member that constitutes the base of the turbomolecular pump 100, and is generally made of metal such as iron, aluminum, stainless steel, etc. The base portion 129 physically holds the turbomolecular pump 100 and also functions as a heat conduction path, so it is desirable to use a metal that has rigidity and high thermal conductivity, such as iron, aluminum, or copper.

[0029] In this configuration, when the rotor 102 is rotated together with the rotor shaft 113 by the motor 121, the exhaust gas is sucked from the chamber through the intake port 101 by the action of the rotor 102 and the fixed blade 123. The rotation speed of the rotor 102 is usually 20,000 rpm to 90,000 rpm, and the peripheral speed at the tip of the rotor 102 reaches 200 m / s to 400 m / s. The exhaust gas sucked through the intake port 101 passes between the rotor 102 and the fixed blade 123 and is transferred to the base part 129. At this time, the temperature of the rotor 102 rises due to frictional heat generated when the exhaust gas comes into contact with the rotor 102 and conduction of heat generated by the motor 121, and the like, but this heat is transferred to the fixed blade 123 side by radiation or conduction by gas molecules of the exhaust gas, and the like.

[0030] The fixed blade spacers 125 are joined to each other at their outer peripheries, and transmit to the outer casing 127 heat received by the fixed blades 123 from the rotor blades 102 and frictional heat generated when exhaust gas comes into contact with the fixed blades 123 .

[0031] In the above description, the threaded spacer 131 is disposed on the outer periphery of the cylindrical portion 102d of the rotor 103, and the thread groove 131a is formed on the inner periphery of the threaded spacer 131. However, there are also cases where the thread groove is formed on the outer periphery of the cylindrical portion 102d, and a spacer having a cylindrical inner periphery is disposed around the outer periphery of the cylindrical portion 102d.

[0032] Depending on the application of the magnetic bearing device 100A, in order to prevent the gas sucked in from the intake port 101 from entering the electrical equipment section consisting of the upper radial electromagnet 104, the upper radial sensor 107, the motor 121, the lower radial electromagnet 105, the lower radial sensor 108, the axial electromagnets 106A and 106B, the axial sensor 109, etc., the electrical equipment section may be surrounded by a stator column 122, and the inside of this stator column 122 may be kept at a predetermined pressure by purge gas.

[0033] In this case, piping (not shown) is provided in the base portion 129, and purge gas is introduced through this piping. The introduced purge gas is sent to the exhaust port 133 through gaps between the protective bearing 120 and the rotor shaft 113, between the rotor and stator of the motor 121, and between the stator column 122 and the inner cylindrical portion of the rotor blades 102.

[0034] Here, the magnetic bearing device 100A requires control based on control parameters (control information related to the characteristics of each model and each individual device) for each model and each individual device. In order to store this control information, the magnetic bearing device 100A has an electronic circuit section 141 in its main body. The electronic circuit section 141 in this embodiment is composed of a writable nonvolatile memory such as an EEPROM (a second storage means 202 described later), a non-writable nonvolatile memory (a third storage means 203 described later), electronic components such as semiconductor elements for accessing the memory, and a substrate 143 for mounting the components. The electronic circuit section 141 is housed below a rotational speed sensor (not shown) near the center of a base section 129 constituting the lower part of the turbo molecular pump 100, for example, and is closed by an airtight bottom cover 145.

[0035] In the semiconductor manufacturing process, some process gases introduced into the chamber have the property of becoming solid when their pressure exceeds a predetermined value or their temperature falls below a predetermined value. Inside the magnetic bearing device 100A, the pressure of the exhaust gas is lowest at the intake port 101 and highest at the exhaust port 133. If the pressure of the process gas becomes higher than a predetermined value or the temperature falls below a predetermined value while the process gas is being transferred from the intake port 101 to the exhaust port 133, the process gas becomes solid and adheres to and accumulates inside the magnetic bearing device 100A.

[0036] For example, when SiCl4 is used as the process gas in an Al etching device, at low vacuum (760 [torr] to 10-2 [torr]) and low temperature (approximately 20 [°C]), solid products (e.g. AlCl3) precipitate and deposit inside the magnetic bearing device 100A, as can be seen from the vapor pressure curve. If deposits of the process gas accumulate inside the magnetic bearing device 100A, these deposits narrow the pump flow path, causing a decrease in the performance of the magnetic bearing device 100A. The aforementioned products are prone to solidification and adhesion in areas of high pressure near the exhaust port 133 and near the threaded spacer 131.

[0037] Therefore, in order to solve this problem, in the past, a heater (not shown) or a circular water-cooled tube (cooling device) was wrapped around the outer periphery of the base portion 129, and a temperature sensor (e.g., a thermistor) (not shown) was embedded in the base portion 129, and the heating of the heater and the cooling by the water-cooled tube were controlled based on the signal from this temperature sensor to keep the temperature of the base portion 129 at a constant high temperature (set temperature) (hereinafter referred to as TMS; Temperature Management System).

[0038] Next, regarding the magnetic bearing device 100A configured as above, an amplifier circuit 150 that controls excitation of the upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A and 106B will be described. A circuit diagram of this amplifier circuit 150 is shown in FIG.

[0039] 2, one end of an electromagnet winding 151 constituting the upper radial electromagnet 104 etc. is connected to a positive electrode 171a of a power source 171 via a transistor 161, and the other end is connected to a negative electrode 171b of the power source 171 via a current detection circuit 181 and a transistor 162. The transistors 161 and 162 are so-called power MOSFETs, and have a structure in which a diode is connected between the source and drain.

[0040] At this time, the transistor 161 has a cathode terminal 161a of the diode connected to the positive electrode 171a, and an anode terminal 161b connected to one end of the electromagnet winding 151. The transistor 162 has a cathode terminal 162a of the diode connected to the current detection circuit 181, and an anode terminal 162b connected to the negative electrode 171b.

[0041] On the other hand, the current regeneration diode 165 has its cathode terminal 165a connected to one end of the electromagnet winding 151 and its anode terminal 165b connected to the negative electrode 171b. Similarly, the current regeneration diode 166 has its cathode terminal 166a connected to the positive electrode 171a and its anode terminal 166b connected to the other end of the electromagnet winding 151 via a current detection circuit 181. The current detection circuit 181 is composed of, for example, a Hall sensor type current sensor or an electric resistance element.

[0042] The amplifier circuit 150 configured as above corresponds to one electromagnet. Therefore, when the magnetic bearing is controlled by five axes and there are a total of ten electromagnets 104, 105, 106A, and 106B, a similar amplifier circuit 150 is configured for each electromagnet, and the ten amplifier circuits 150 are connected in parallel to the power supply 171.

[0043] Furthermore, the amplifier control circuit 191 is configured, for example, by a digital signal processor section (hereinafter referred to as a DSP section) (not shown) of the magnetic bearing control device 100B, and this amplifier control circuit 191 switches the transistors 161 and 162 on and off.

[0044] The amplifier control circuit 191 is adapted to compare the current value detected by the current detection circuit 181 (a signal reflecting this current value is called a current detection signal 191c) with a predetermined current command value. Then, based on the result of this comparison, the magnitude of the pulse width (pulse width times Tp1, Tp2) to be generated within a control cycle Ts, which is one period of PWM control, is determined. As a result, gate drive signals 191a, 191b having this pulse width are output from the amplifier control circuit 191 to the gate terminals of the transistors 161, 162.

[0045] In addition, when the rotor 103 passes through a resonance point during an accelerating operation of the rotation speed, or when a disturbance occurs during a constant speed operation, it is necessary to control the position of the rotor 103 at high speed and with a strong force. For this reason, a high voltage of, for example, about 50 V is used as the power supply 171 so that the current flowing through the electromagnet winding 151 can be rapidly increased (or decreased). In addition, a capacitor (not shown) is usually connected between the positive pole 171a and the negative pole 171b of the power supply 171 to stabilize the power supply 171.

[0046] In this configuration, when both transistors 161, 162 are turned on, the current flowing through the electromagnet winding 151 (hereinafter referred to as electromagnet current iL) increases, and when both are turned off, the electromagnet current iL decreases.

[0047] Moreover, when one of the transistors 161, 162 is turned on and the other is turned off, a so-called flywheel current is maintained. By passing a flywheel current through the amplifier circuit 150 in this manner, the hysteresis loss in the amplifier circuit 150 can be reduced, and the power consumption of the entire circuit can be kept low. Furthermore, by controlling the transistors 161, 162 in this manner, high-frequency noise such as harmonics generated in the magnetic bearing device 100A can be reduced. Furthermore, by measuring this flywheel current with the current detection circuit 181, the electromagnet current iL flowing through the electromagnet winding 151 can be detected.

[0048] That is, when the detected current value is smaller than the current command value, both of the transistors 161 and 162 are turned on for a time period corresponding to the pulse width time Tp1 only once in a control cycle Ts (e.g., 100 μs) as shown in Fig. 3. Therefore, the electromagnet current iL during this period increases toward a current value iLmax (not shown) that can flow from the positive electrode 171a to the negative electrode 171b via the transistors 161 and 162.

[0049] On the other hand, when the detected current value is larger than the current command value, both of the transistors 161 and 162 are turned off for a time period corresponding to the pulse width time Tp2 only once during the control cycle Ts, as shown in Fig. 4. Therefore, the electromagnet current iL during this period decreases toward a current value iLmin (not shown) that can be regenerated from the negative pole 171b to the positive pole 171a via the diodes 165 and 166.

[0050] In either case, after the pulse width times Tp1 and Tp2 have elapsed, one of the transistors 161 and 162 is turned on. Therefore, a flywheel current is maintained in the amplifier circuit 150 during this period.

[0051] Next, the electrical configuration of the electronic circuit unit 141 provided in the magnetic bearing device 100A and the magnetic bearing control device 100B will be described with reference to Fig. 5. The electronic circuit unit 141 includes a resistor 201, a second storage means 202, for example a writable nonvolatile memory, and a third storage means 203, for example a nonwritable nonvolatile memory. The magnetic bearing control device 100B includes a first storage means 204, for example a writable nonvolatile memory, and a ROM table 205.

[0052] The resistor 201 has a resistance value determined according to the model of the magnetic bearing device 100A, and the model of the magnetic bearing device 100A can be identified by measuring the resistance value of the resistor 201. Here, information relating to the model of the magnetic bearing device 100A is referred to as model information.

[0053] In this embodiment, the second storage means 202 stores individual identification information, control information, and history information in addition to the above-mentioned model information. Here, the individual identification information is information for identifying an individual magnetic bearing device 100A, and for example, the manufacturing number attached to each magnetic bearing device 100A corresponds to this information. The control information is information on various characteristics of the magnetic bearing device 100A, and in this embodiment, it is information consisting of model control information and individual control information. Here, the model control information is control information specified for each model of the magnetic bearing device 100A, and for example, control parameters set corresponding to the model of the magnetic bearing device 100A (as a specific example, a current value when magnetically levitating the rotor shaft 113 by the upper radial electromagnet 104, etc.). Also, the individual control information is control information specified for each individual magnetic bearing device 100A, and for example, control parameters set corresponding to the individual magnetic bearing device 100A, and for example, data for correcting an error between the mechanical center position and the electrical center position of the rotating body 103 in the magnetic bearing device 100A. This individual control information also includes temperature-related parameters and the like when a heater or the like is provided in the turbo molecular pump 100 in which the magnetic bearing device 100A is incorporated. And the history information is information related to the operation history of the magnetic bearing device 100A (as a specific example, the date and time when the operation of the magnetic bearing device 100A started and the date and time when the operation was stopped, etc.).

[0054] In this embodiment, the third storage means 203 stores the above-mentioned model information, individual identification information, and control information (model control information and initial individual control information).

[0055] In this embodiment, the first storage means 204 stores the above-mentioned model information, individual identification information, control information (model control information and individual control information), and history information.

[0056] In this embodiment, the ROM table 205 stores control information (model control information and initial individual control information) for each model of the multiple types of magnetic bearing devices 100A.

[0057] The magnetic bearing control device 100B also includes a semiconductor element (e.g., a microprocessor) (not shown) for implementing the functions of transmitting and receiving signals to and from the magnetic bearing device 100A via a cable electrically connected thereto, and of controlling the operation of the magnetic bearing device 100A. In response to commands from this semiconductor element, the magnetic bearing control device 100B functions as an access means and a judgment overwrite means as described herein. In this embodiment, the magnetic bearing device 100A and the magnetic bearing control device 100B transmit and receive signals via serial communication. Furthermore, the magnetic bearing device 100A and the magnetic bearing control device 100B each include a power switch for turning on and off their respective power supplies, as well as a RESET switch (described later).

[0058] Next, a flow of operations performed when the magnetic bearing control device 100B controls the magnetic bearing device 100A will be described with reference to FIGS.

[0059] When the power supply of the magnetic bearing control device 100B is turned on (S1 in FIG. 6), the magnetic bearing control device 100B operates the access means to access the resistor 201 and acquire the model information of the magnetic bearing device 100A. This makes it possible to identify the model of the magnetic bearing device 100A (S2 in FIG. 6). In identifying the model of the magnetic bearing device 100A, the magnetic bearing control device 100B may access the third storage means 203 and acquire the model information stored in the third storage means 203. The magnetic bearing control device 100B may also access both the resistor 201 and the third storage means 203 to check whether the model information is the same, and if it is the same, execute the following operation, whereas if it is not the same, execute a warning operation.

[0060] Next, the magnetic bearing control device 100B judges whether or not the second storage means 202 is present in the electronic circuit section 141 of the magnetic bearing device 100A (S3 in FIG. 6). If it is judged that the second storage means 202 is not present, the magnetic bearing control device 100B executes control according to the flowchart shown in FIG. 7, which will be described later.

[0061] If it is determined that the second storage means 202 exists (YES in S3 in FIG. 6), the magnetic bearing control device 100B determines whether the second storage means 202 is normal or not (S4 in FIG. 6). Factors that may cause the second storage means 202 to become abnormal include, for example, the inclusion of noise during communication, unintentional termination of control processing during communication, and the temperature inside the magnetic bearing device 100A rising beyond the allowable value of the second storage means 202. Whether the second storage means 202 is normal or not may be determined by fault diagnosis using, for example, a checksum or a cyclic redundancy check (CRC), or by whether the information stored in the second storage means 202 matches the information stored in the first storage means 204.

[0062] When the second storage means 202 is judged to be abnormal (NO in S4 of FIG. 6), various information stored in the writable second storage means 202 may be corrupted. In this case, the magnetic bearing control device 100B regards the individual identification information stored in the third storage means 203 as correct and overwrites the individual identification information stored in the second storage means 202 (S5 of FIG. 6). Since the third storage means 203 is, for example, a non-writable non-volatile memory, the information stored in the third storage means 203 will not be corrupted even if noise is mixed in when the magnetic bearing device 100A and the magnetic bearing control device 100B communicate with each other. That is, since the individual identification information written in the magnetic bearing device 100A remains in the third storage means 203 as it is, the individual identification information stored in the second storage means 202 can be overwritten with the individual identification information stored in the third storage means 203 to rewrite the individual identification information stored in the second storage means 202 to its original correct state.

[0063] When the second storage means 202 is judged to be normal in S4 of FIG. 6 (YES in S4 of FIG. 6) or when the process of S5 of FIG. 6 is performed, the magnetic bearing control device 100B judges whether the model information stored in the second storage means 202 matches the model information acquired in S2 of FIG. 6 (S6 of FIG. 6). When it is judged that the model information does not match (NO in S6 of FIG. 6), the magnetic bearing control device 100B executes a warning operation (S7 of FIG. 6). The warning operation is, for example, an operation of outputting an alarm sound from the magnetic bearing device 100A or the magnetic bearing control device 100B, blinking a warning lamp, displaying the warning content on a monitor provided in the magnetic bearing device 100A or the magnetic bearing control device 100B, etc. After executing the warning operation, the magnetic bearing control device 100B prohibits (locks) the operation of the magnetic bearing device 100A (S8 of FIG. 6).

[0064] On the other hand, if it is determined that the model information matches (YES in S6 in FIG. 6), the magnetic bearing control device 100B determines whether the first storage means 204 is normal or not (S9 in FIG. 6). The determination of whether the first storage means 204 is normal or not may be based on a fault diagnosis using, for example, a checksum or a cyclic redundancy check (CRC), as in the case of the second storage means 202, or may be based on whether the information stored in the first storage means 204 matches the information stored in the second storage means 202. Here, if it is determined that the first storage means 204 is abnormal (NO in S9 in FIG. 6), various information stored in the writable first storage means 204 may be corrupted, so the magnetic bearing control device 100B executes the processes of S14 to S16 shown in FIG. 6 to overwrite various information stored in the first storage means 204. The processes of S14 to S16 will be described later.

[0065] If it is determined in S9 of Fig. 6 that the first storage means 204 is normal (YES in S9 of Fig. 6), the magnetic bearing control device 100B determines whether or not the model information acquired in S2 of Fig. 6 matches the model information stored in the first storage means 204 (S10 of Fig. 6). If it is determined that the model information does not match (NO in S10 of Fig. 6), the magnetic bearing control device 100B executes a warning operation (S11 of Fig. 6) and further prohibits (locks) the operation of the magnetic bearing device 100A (S12 of Fig. 6).

[0066] If it is determined in S10 of Fig. 6 that the model information matches (YES in S10 of Fig. 6), the magnetic bearing control device 100B determines whether the individual identification information, control information (model control information and individual control information) and history information stored in the second storage means 202 match the individual identification information, control information (model control information and individual control information) and history information stored in the first storage means 204 (S13 of Fig. 6). If it is determined that all the information matches (YES in S13 of Fig. 6), the magnetic bearing control device 100B controls the magnetic bearing device 100A normally to operate the magnetic bearing device 100A (S17 of Fig. 6), and then stops the magnetic bearing device 100A (S18 of Fig. 6).

[0067] On the other hand, when S13 in Fig. 6 is executed, if the individual identification information, control information (model control information and individual control information) and history information stored in the second storage means 202 do not match even partially with the individual identification information, control information (model control information and individual control information) and history information stored in the first storage means 204, the magnetic bearing control device 100B executes a warning operation (S14 in Fig. 6). The warning operation here may be an alarm sound output or a warning lamp flashing, or it may be preferable to display on a monitor provided in the magnetic bearing device 100A or the magnetic bearing control device 100B which information does not match the individual identification information, control information (model control information and individual control information) and history information. For example, if the individual identification information and history information do not match, it is considered that the magnetic bearing control device 100B used when the magnetic bearing device 100A was last operated has been removed and another magnetic bearing control device 100B has been connected to the magnetic bearing device 100A. By checking the contents displayed on the monitor, the operator can connect the magnetic bearing device 100A and the magnetic bearing control device 100B in the correct combination and determine whether or not to overwrite the information as described below.

[0068] Here, when the operator operates the RESET switch provided on the magnetic bearing device 100A or the magnetic bearing control device 100B for a predetermined time or more (S15 in FIG. 6), the magnetic bearing control device 100B overwrites the individual identification information, control information (model control information and individual control information) and history information stored in the first storage means 204 with the individual identification information, control information (model control information and individual control information) and history information stored in the second storage means 202 (S16 in FIG. 6). Note that the information to be overwritten may be all of the individual identification information, control information (model control information and individual control information) and history information, or only the mismatched information. By executing the process of S16 in FIG. 6 in this way, the individual identification information, control information (model control information and individual control information) and history information stored in the second storage means 202 can be matched with the individual identification information, control information (model control information and individual control information) and history information stored in the first storage means 204. Thereafter, the magnetic bearing control device 100B controls the magnetic bearing device 100A in the normal manner to operate the magnetic bearing device 100A (S17 in FIG. 6), and then stops the magnetic bearing device 100A (S18 in FIG. 6).

[0069] Here, the flow shown in S3 of Fig. 6 when the magnetic bearing control device 100B judges whether or not the second storage means 202 exists in the electronic circuit section 141 of the magnetic bearing device 100A, and judges that the second storage means 202 does not exist (NO in S3 of Fig. 6) will be described with reference to Fig. 7. In this case, the magnetic bearing control device 100B judges whether or not the first storage means 204 is normal (S21 of Fig. 7). The judgment of whether or not the first storage means 204 is normal may be based on a fault diagnosis using, for example, a checksum or a cyclic redundancy check (CRC), as in the case of the second storage means 202, or may be based on whether or not the information stored in the second storage means 202 matches the information stored in the second storage means 202.

[0070] If it is determined that the first storage means 204 is normal (YES in S21 of FIG. 7), the magnetic bearing control device 100B determines whether the model information acquired in S2 of FIG. 6 matches the model information stored in the first storage means 204 (S22 of FIG. 6). If it is determined that the model information matches (YES in S22 of FIG. 6), it is determined that there is no abnormality in the various information stored in the first storage means 204 and that the model information corresponding to the magnetic bearing device 100A is stored, and the magnetic bearing control device 100B is able to operate the magnetic bearing device 100A. On the other hand, if it is determined that the model information does not match (NO in S22 of FIG. 6), the magnetic bearing control device 100B executes a warning operation (S23 of FIG. 6) and further prohibits (locks) the operation of the magnetic bearing device 100A (S24 of FIG. 6).

[0071] On the other hand, if it is determined that the first storage means 204 is abnormal (NO in S21 in FIG. 7), various information stored in the writable first storage means 204 may be corrupted. At this point, the magnetic bearing control device 100B executes a warning operation (S25 in FIG. 6). The warning operation here may include outputting an alarm sound, flashing a warning lamp, or displaying on a monitor a message indicating that various information stored in the first storage means 204 needs to be initialized. This allows the operator to determine whether or not to perform the initialization described below by checking the content displayed on the monitor.

[0072] When the operator operates the RESET switch provided on the magnetic bearing device 100A or the magnetic bearing control device 100B for a predetermined time or longer (S26 in Fig. 6), the magnetic bearing control device 100B selects one piece of control information from the control information for each model stored in the ROM table 205, based on the model information acquired in S2 in Fig. 6, and overwrites the model control information in the first storage means 204 with that control information (S27 in Fig. 6). This makes it possible to initialize the various pieces of information stored in the first storage means 204.

[0073] Although one embodiment of the present invention has been described above, the present invention is not limited to the specific embodiment, and various modifications, changes, and combinations are possible within the scope of the spirit of the present invention described in the claims unless otherwise specifically limited in the above description. Furthermore, the effects of the above embodiment are merely examples of the effects resulting from the present invention, and do not mean that the effects of the present invention are limited to the above effects.

[0074] For example, the flow of control of the magnetic bearing device 100A by the magnetic bearing control device 100B described with reference to Fig. 6 may be as shown in Fig. 8. In the control shown in Fig. 8, in S9 it is determined whether the first storage means 204 is normal or not, and if it is determined to be abnormal (NO in S9 in Fig. 8), the magnetic bearing control device 100B takes the individual identification information stored in the third storage means 203 to be correct and overwrites the individual identification information stored in the first storage means 204 (S19 in Fig. 8). As described above, since the individual identification information originally written remains in the third storage means 203, it is possible to rewrite the individual identification information stored in the first storage means 204 to its original correct state.

[0075] In addition, in the process of S5 shown in FIG. 6 and FIG. 8, the magnetic bearing control device 100B may overwrite the individual identification information and the control information stored in the second storage means 202 by considering not only the individual identification information stored in the third storage means 203 but also the control information (model control information and initial individual control information) as correct. Here, only the model control information may be used when overwriting the control information. In addition, in the process of S19 shown in FIG. 8, the magnetic bearing control device 100B may overwrite the individual identification information and the control information stored in the first storage means 204 by considering not only the individual identification information stored in the third storage means 203 but also the control information (model control information and initial individual control information) as correct. Here, only the model control information may be used when overwriting the control information. The control information stored in the third storage means 203 is maintained in the initial state even if noise is mixed in during communication or the control process is unintentionally terminated during communication, so that it can be overwritten with information with higher reliability than when overwriting with the control information stored in the first storage means 204 or the second storage means 202.

[0076] In addition, in the process of S27 shown in Fig. 7, when the control information corresponding to the model information acquired in S2 of Fig. 6 is stored in the third storage means 203, the magnetic bearing control device 100B may compare the date and time when the control information was stored in the ROM table 205 with the date and time when the control information was stored in the first storage means 204 to determine which is newer, and overwrite the control information stored in the first storage means 204 with the new control information. The manufacturing date of the magnetic bearing device 100A and the manufacturing date of the magnetic bearing control device 100B are not necessarily the same, and therefore the versions of the control information stored in each may differ. However, by using the above function, it is possible to overwrite the control information stored in the first storage means 204 with the new version of the control information. Note that the control information to be overwritten may be only the model control information. [Explanation of symbols]

[0077] 100: Turbo molecular pump (vacuum pump) 100A: Magnetic bearing device 100B: Magnetic bearing control device (control unit, judgment overwrite means, access means) 202:Second storage means 203:Third storage means 204: 1st storage means

Claims

1. A vacuum pump equipped with a magnetic bearing device that magnetically levitates a rotating shaft and holds it in a non-contact manner, a control unit that controls the magnetic bearing device based on individual identification information, which is information for identifying an individual of the magnetic bearing device, and control information related to various characteristics of the magnetic bearing device; a writable first storage means in which the individual identification information is stored within the control unit; a writable second storage means in the magnetic bearing device in which the individual identification information is stored; a third non-writable storage means in the magnetic bearing device, in which the individual identification information is stored; a determination and overwrite means, within the control unit, for determining whether the first storage means is normal, and if the first storage means is abnormal, for overwriting the individual identification information stored in the first storage means with the individual identification information stored in the third storage means as true, or for determining whether the second storage means is normal, and if the second storage means is abnormal, for overwriting the individual identification information stored in the second storage means with the individual identification information stored in the third storage means as true.

2. the first storage means stores the control information; the second storage means stores the control information; the third storage means stores the control information; 2. The vacuum pump according to claim 1, wherein the determination and overwriting means determines whether the first storage means is normal, and if the first storage means is abnormal, treats the control information stored in the third storage means as correct and overwrites the control information stored in the first storage means, or determines whether the second storage means is normal, and if the second storage means is abnormal, treats the control information stored in the third storage means as correct and overwrites the control information stored in the second storage means.

3. A magnetic bearing control device that controls a magnetic bearing device that magnetically levitates a rotating shaft and holds it in a non-contact manner, a control unit that controls the magnetic bearing device based on individual identification information, which is information for identifying an individual of the magnetic bearing device, and control information related to various characteristics of the magnetic bearing device; a writable first storage means in which the individual identification information is stored within the control unit; access means for accessing a second writable storage means provided in the magnetic bearing device and storing the individual identification information, and a third non-writable storage means provided in the magnetic bearing device and storing the individual identification information, in the control unit; a determination and overwrite means, within the control unit, for determining whether the first storage means is normal, and, if the first storage means is abnormal, for overwriting the individual identification information stored in the first storage means with the individual identification information stored in the third storage means as true, or for determining whether the second storage means is normal, and, if the second storage means is abnormal, for overwriting the individual identification information stored in the second storage means with the individual identification information stored in the third storage means as true.

Images