JP7614247B2 - Vacuum pump, magnetic bearing control device, and compression/decompression method - Google Patents

Description

The present invention relates to a vacuum pump, a magnetic bearing control device, and a compression/decompression method.

One magnetic bearing control device identifies the model of the magnetic bearing device, reads the characteristics of the identified model from a memory unit, and uses them to control the magnetic bearing (see, for example, Patent Document 1).

JP 2000-240649 A

However, when a large amount of control setting data is used for magnetic bearing control, the amount of control setting data becomes large.

The present invention has been made in consideration of the above problems, and aims to provide a vacuum pump, a magnetic bearing control device, and a compression/decompression method that can control a magnetic bearing with a small amount of control setting data.

The vacuum pump according to the present invention comprises a magnetic bearing device that supports a rotor shaft in at least two directions, and a magnetic bearing control device that controls the magnetic bearing device. The magnetic bearing control device comprises a control circuit that controls the magnetic bearing device, a memory unit that stores control setting data for multiple models of magnetic bearing devices, and a data setting unit that selects the control setting data for the magnetic bearing device to be controlled by the magnetic bearing control device from the control setting data for the multiple models of magnetic bearing devices and sets it in the control circuit. Here, the control setting data includes control setting values for multiple items, and in the control setting data for a certain model among the multiple models, for items among the multiple items for which the control setting values for the above-mentioned two directions are the same, the control setting value for one of the two directions is included, but the control setting value for the other of the two directions is not included. Then, the data setting unit (a) for items among the multiple items for which the control setting values for the above-mentioned two directions are the same, identifies the control setting value for the other of the two directions from the control setting value for one of the two directions, and (b) sets the two control setting values for the two directions in the control circuit.

The magnetic bearing control device according to the present invention is a magnetic bearing control device that controls a magnetic bearing device that supports a rotor shaft in a vacuum pump in at least two directions, and includes the above-mentioned memory unit and the above-mentioned data setting unit.

The compression/decompression method according to the present invention is a method for compressing and decompressing control setting data for controlling a magnetic bearing device that supports a rotor shaft in a vacuum pump in at least two directions. In this compression/decompression method, a memory unit stores control setting data for multiple models of magnetic bearing devices, and the control setting data includes control setting values for multiple items. In the control setting data for a certain model among the multiple models, for items among the multiple items for which the control setting values for the two directions are the same, the control setting value for one of the two directions is included, but the control setting value for the other of the two directions is not included, thereby compressing the control setting data. Then, for items among the multiple items for which the control setting values for the two directions are the same, the control setting value for the other of the two directions is identified from the control setting value for one of the two directions, thereby decompressing the compressed control setting data.

The present invention provides a vacuum pump, a magnetic bearing control device, and a compression/decompression method that can control a magnetic bearing with a small amount of control setting data.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

FIG. 1 is a vertical cross-sectional view showing a turbomolecular pump. FIG. 2 is a circuit diagram showing an amplifier circuit that controls excitation of the electromagnets of the turbo molecular pump shown in FIG. FIG. 3 is a time chart showing the control when the current command value is larger than the detection value. FIG. 4 is a time chart showing the control when the current command value is smaller than the detection value. FIG. 5 is a block diagram showing the configuration of the control device 200 appearing in FIG. FIG. 6 is a diagram showing an example of a memory map of the memory unit 212a in FIG. FIG. 7 is a flowchart illustrating the operation of the control device 200 shown in FIGS.

The following describes an embodiment of the present invention with reference to the drawings.

A longitudinal cross-sectional view of this turbomolecular pump 100 is shown in FIG. 1. In FIG. 1, the turbomolecular pump 100 has an intake port 101 formed at the upper end of a cylindrical outer tube 127. Inside the outer tube 127, a rotor 103 is provided, which has multiple rotors 102 (102a, 102b, 102c, ...) that are turbine blades for sucking in and exhausting gas, formed radially on the periphery in multiple stages. A rotor shaft 113 is attached to the center of this rotor 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 rotor 103 is generally made of a metal such as aluminum or an aluminum alloy.

The upper radial electromagnets 104 are arranged in pairs on the X-axis and Y-axis. Four upper radial sensors 107 are provided in close proximity 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, which 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 it to the control device 200.

In this control device 200, for example, a compensation circuit having a PID adjustment function generates an excitation control command signal for the upper radial electromagnet 104 based on the position signal detected by the upper radial sensor 107, and the amplifier circuit 150 (described later) shown in FIG. 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.

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.

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 the axial position signal is sent to control device 200.

In the control device 200, a compensation circuit having, for example, a PID adjustment function generates excitation control command signals for the axial electromagnet 106A and the axial electromagnet 106B based on the axial position signal detected by the axial sensor 109, and the amplifier circuit 150 controls the excitation of the axial electromagnet 106A and the axial electromagnet 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.

In this way, the control device 200 appropriately adjusts the magnetic force that the axial electromagnets 106A and 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 electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A and 106B will be described later.

On the other hand, the motor 121 has multiple magnetic poles arranged circumferentially to surround the rotor shaft 113. Each magnetic pole is controlled by the control device 200 so as to rotate the rotor shaft 113 via electromagnetic forces acting between the magnetic poles and the rotor shaft 113. In addition, the motor 121 incorporates a rotational speed sensor, such as a Hall element, resolver, or encoder (not shown), and the rotational speed of the rotor shaft 113 is detected by the detection signal of this rotational speed sensor.

In addition, a phase sensor (not shown) is attached, for example, near the lower radial sensor 108, to detect the phase of rotation of the rotor shaft 113. The control device 200 uses the detection signals of both this phase sensor and the rotation speed sensor to detect the position of the magnetic poles.

Multiple fixed blades 123 (123a, 123b, 123c...) are arranged with a small gap between 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 metals such as aluminum, iron, stainless steel, copper, etc., or alloys containing these metals as components.

The fixed blades 123 are also formed at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113, and are arranged in a staggered manner with the rotor blades 102 toward the inside of the outer cylinder 127. The outer peripheral end of the fixed blades 123 is supported by being inserted between a plurality of stacked fixed blade spacers 125 (125a, 125b, 125c, ...).

The fixed wing spacer 125 is a ring-shaped member, and is made of metals such as aluminum, iron, stainless steel, copper, or alloys containing these metals. An outer cylinder 127 is fixed to the outer periphery of the fixed wing spacer 125 with a small gap between them. 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 is connected to the outside. Exhaust gas that enters the intake port 101 from the chamber (vacuum chamber) side and is transferred to the base portion 129 is sent to the exhaust port 133.

Depending on the application of the turbomolecular pump 100, a threaded spacer 131 is disposed between the lower part of the fixed vane 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 the molecules of the exhaust gas are transported toward the exhaust port 133 when they move in the rotation direction of the rotor 103. A cylindrical part 102d hangs down from the lowest part of the rotor 103, which is connected to the rotor vanes 102 (102a, 102b, 102c, ...). The outer peripheral surface of the cylindrical part 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 thread groove 131a by the rotor 102 and the fixed blade 123 is guided by the thread groove 131a and sent to the base portion 129.

The base portion 129 is a disk-shaped member that forms the base of the turbomolecular pump 100, and is generally made of a metal such as iron, aluminum, or stainless steel. The base portion 129 not only physically holds the turbomolecular pump 100, but also functions as a heat conduction path, so it is desirable to use a metal that is rigid and has high thermal conductivity, such as iron, aluminum, or copper.

In this configuration, when the rotor 102 is rotated together with the rotor shaft 113 by the motor 121, the rotor 102 and the fixed blades 123 act to draw exhaust gas from the chamber through the intake port 101. 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 drawn in from the intake port 101 passes between the rotor 102 and the fixed blades 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, but this heat is transferred to the fixed blades 123 side by radiation or conduction by gas molecules of the exhaust gas.

The fixed blade spacers 125 are joined together at their outer periphery and transmit to the outside 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.

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 engraved on the inner periphery of the threaded spacer 131. However, there are also cases where the opposite is true, that is, a thread groove is engraved on the outer periphery of the cylindrical portion 102d, and a spacer having a cylindrical inner periphery is disposed around it.

Depending on the application of the turbomolecular pump 100, the electrical equipment section may be covered by a stator column 122 to prevent the gas sucked in from the intake port 101 from entering the electrical equipment section, which is composed 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., and the inside of the stator column 122 may be kept at a predetermined pressure by purging gas.

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 the 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.

The turbomolecular pump 100 requires control based on the model identification and individually adjusted unique parameters (e.g., various characteristics corresponding to the model). To store these control parameters, the turbomolecular pump 100 has an electronic circuit section 141 in its main body. The electronic circuit section 141 is composed of a semiconductor memory such as an EEP-ROM, electronic components such as semiconductor elements for accessing the memory, and a substrate 143 for mounting these components. The electronic circuit section 141 is housed below a rotational speed sensor (not shown), for example near the center of the base section 129 that constitutes the lower part of the turbomolecular pump 100, and is closed by an airtight bottom cover 145.

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 turbomolecular pump 100, 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 its 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 turbomolecular pump 100.

For example, when SiCl ₄ is used as a process gas in an Al etching apparatus, at low vacuum (760 [torr] to 10 ⁻² [torr]) and low temperature (about 20° C.), a solid product (e.g., AlCl ₃ ) precipitates and adheres to and accumulates inside the turbomolecular pump 100, as can be seen from the vapor pressure curve. As a result, when precipitates of the process gas accumulate inside the turbomolecular pump 100, the deposits narrow the pump flow path, causing a decrease in the performance of the turbomolecular pump 100. The above-mentioned product is prone to solidification and adhesion in high pressure areas near the exhaust port 133 and near the threaded spacer 131.

Therefore, in order to solve this problem, conventionally, a heater (not shown) or a circular water-cooled tube 149 is wrapped around the outer periphery of the base portion 129, etc., and a temperature sensor (e.g., a thermistor) (not shown) is embedded in the base portion 129, and the heating of the heater and the cooling by the water-cooled tube 149 are 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; TMS; Temperature Management System).

Next, regarding the turbomolecular pump 100 configured in this manner, we will explain the amplifier circuit 150 that controls the excitation of the upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A and 106B. A circuit diagram of this amplifier circuit 150 is shown in Figure 2.

In FIG. 2, one end of the electromagnet winding 151 constituting the upper radial electromagnet 104 etc. is connected to the positive pole 171a of the power supply 171 via the transistor 161, and the other end is connected to the negative pole 171b of the power supply 171 via the current detection circuit 181 and the 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.

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

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 pole 171b. Similarly, the current regeneration diode 166 has its cathode terminal 166a connected to the positive pole 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 electrical resistance element.

The amplifier circuit 150 configured as above corresponds to one electromagnet. Therefore, if the magnetic bearing is controlled on 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.

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 control device 200, and this amplifier control circuit 191 is configured to switch the transistors 161 and 162 on and off.

The amplifier control circuit 191 compares 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, it determines the size of the pulse width (pulse width times Tp1, Tp2) to be generated within a control cycle Ts, which is one period of PWM control. 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 transistors 161, 162.

When the rotor 103 passes through a resonance point during accelerated operation or when a disturbance occurs during constant speed operation, it is necessary to control the position of the rotor 103 at high speed and with 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.

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

Furthermore, 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 turbo molecular pump 100 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.

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

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

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

As described above, the vacuum pump according to the embodiment of the present invention includes an upper radial electromagnet 104 and an upper radial sensor 107 as well as a lower radial electromagnet 105 and a lower radial sensor 108 as (active) magnetic bearing devices that support the rotor shaft in at least two directions (here, the X-axis direction and the Y-axis direction that are perpendicular to the rotor shaft and perpendicular to each other), and a control device 200 as a magnetic bearing control device that controls the magnetic bearing devices.

Figure 5 is a block diagram showing the configuration of the control device 200 in Figure 1. For example, as shown in Figure 5, the control device 200 includes a control circuit 211 and an arithmetic processing device 212.

The control circuit 211 controls the above-mentioned magnetic bearing device. Specifically, the control circuit 211 controls the above-mentioned magnetic bearing device by supplying a drive current corresponding to the sensor signal (position signal) from the sensors 107, 108 to the electromagnets 104, 105 in accordance with the control setting data corresponding to the model of the magnetic bearing device. For example, the control circuit 211 is a digital signal processor or the like, and includes the above-mentioned amplifier circuit 150.

The arithmetic processing device 212 has a built-in non-volatile memory unit 212a such as a flash memory, and operates as a specified processing unit by executing a specified program on a computer. For example, the arithmetic processing device 212 is a CPU (Central Processing Unit), an MPU (Micro Processing Unit), etc. Here, the arithmetic processing device 212 operates as a data setting unit 212b.

The memory unit 212a stores control setting data for multiple models of magnetic bearing devices.

The data setting unit 212b (a) selects the control setting data of the magnetic bearing device to be controlled by the control device 200 (i.e., the magnetic bearing device to which the control device 200 is actually connected) from the control setting data of the multiple models of magnetic bearing devices, and (b) sets the selected control setting data in the control circuit 211. The control circuit 211 controls the magnetic bearing device according to the set control setting data.

Here, the control setting data set in the control circuit 211 includes control setting values for multiple items. Furthermore, for a specific item among the multiple items, there is a control setting value for each of the two directions mentioned above (here, the X-axis direction and the Y-axis direction).

The control setting values include the control parameters of the PID control in the feedback control system from the sensors 107, 108 to the electromagnets 104, 105, the mechanical constants of the magnetic bearing device, and the like. For example, the control setting data contains about 50 to 100 control setting values (integer data, real number data, etc.) per axial direction. Also, the number of items (i.e., control setting values) contained in the control setting data may differ depending on the model.

On the other hand, in the control setting data stored in memory unit 212a for a specific model among the multiple models described above, for items among the multiple items described above for which the control setting values for the two directions described above are the same, the control setting value for one of the two directions described above (e.g., the X-axis direction) is included in the control setting data, and the control setting value for the other of the two directions described above (e.g., the Y-axis direction) is not included in the control setting data. In this way, in the control setting data for a certain model, one of the control setting values in the X-axis direction and the Y-axis direction is omitted for a certain item, which reduces the size of the control setting data for that model.

The data setting unit 212b (a) determines, for any of the above-mentioned multiple items having the same control setting value for the above-mentioned two directions, the control setting value for the other of the above-mentioned two directions from the control setting value for one of the above-mentioned two directions (i.e., the control setting value stored in the memory unit 212a), and (b) sets the two control setting values for the above-mentioned two directions in the control circuit 211.

Specifically, the data setting unit 212b reads out the control setting data for the magnetic bearing device to be controlled from the memory unit 211, and for items in the read control setting data where the control setting values for the two directions mentioned above are the same, it identifies the control setting value for one of the two directions mentioned above, and uses the same value as the identified control setting value as the control setting value for the other of the two directions mentioned above.

Figure 6 is a diagram showing an example of a memory map of memory unit 212a in Figure 5. In this embodiment, as shown in Figure 6, for example, memory unit 212a has multiple memory areas 221-1 to 221-N of the same fixed length (e.g., 2048 bytes) in which the control setting data of the magnetic bearings of the multiple models described above is stored. In other words, one memory area 221-i stores the control setting data of one model.

For the control setting data of a certain model among the multiple models described above, if the control setting values of both of the two directions described above are included but do not exceed the size of one memory area 221-i (the fixed length described above), the control setting data of that model (hereinafter also referred to as normal size data) is stored in the memory area 221-i corresponding to that model, including the control setting values of both of the two directions described above.

On the other hand, when the control setting data of a certain model among the multiple models described above includes control setting values in both of the two directions described above, and the size of the control setting data exceeds the size of one memory area 221-j (the fixed length described above), the control setting data of that model (hereinafter also referred to as oversized data) is stored in memory area 221-j with the size of the control setting data set to be equal to or less than the size of memory area 221-j, with one of the control setting values in the two directions omitted for items for which the control setting values in the two directions are the same, as described above.

For normal size data, the data setting unit 212b reads out the control setting values for both of the two directions described above that are stored in the memory area 221-i, and sets them in the control circuit 211.

For oversized data, the data setting unit 212b reads out the control setting value for one of the two directions for any of the above-mentioned multiple items for which the control setting values for the above-mentioned two directions are the same, and identifies the control setting value for the other of the above-mentioned two directions from the read control setting value. The data setting unit 212b then sets in the control circuit 211 the control setting value read out from the memory unit 212a for that item (e.g., the control setting value for the X-axis direction) and the identified control setting value (e.g., the control setting value for the Y-axis direction).

In this embodiment, as shown in FIG. 6, for example, the control setting data 231 includes a flag 231a. The flag 231a indicates whether the control setting data 231 exceeds the size of the memory area 221-i if it includes control setting values in both of the two directions described above. In other words, the flag 231a indicates whether the control setting data is normal size data or oversized data.

The data setting unit 212b refers to this flag 231a to determine whether the control setting data 231 exceeds the size of the memory area 221-i when it includes the control setting values for both of the two directions described above. In other words, the data setting unit 212b refers to this flag 231a to determine whether the control setting data 231 is normal size data or oversized data.

When flag 231a is a certain value (i.e., the control setting data is normal size data), the control setting values of both of the above-mentioned two directions are read from memory unit 212a and set in control circuit 211. On the other hand, when flag 231a is a different value (i.e., the control setting data is oversized data), the control setting value of only one of the above-mentioned two directions is read from memory unit 212a, the control setting value of the other of the above-mentioned two directions is set to the same value as the read control setting value, and the control setting values of the above-mentioned two directions are set in control circuit 211.

Next, the operation of the control device 200 will be described. Figure 7 is a flowchart explaining the operation of the control device 200 shown in Figures 1 and 5.

When the control device 200 is connected to the above-mentioned magnetic bearing device and the control circuit 211 is started (step S1), the control circuit 211 identifies the model of the connected magnetic bearing device and notifies the data setting unit 212b of the identified model (step S2). For example, the magnetic bearing device has one or more identification resistors having a resistance value specific to the model, and the control circuit 211 measures the resistance value of one or more identification resistors of the connected magnetic bearing device, and identifies the model of the connected magnetic bearing device based on the measured resistance value or values.

Next, the data setting unit 212b reads out the control setting data corresponding to the notified model from the memory unit 212a, and judges whether the control setting data of the notified model is compressed (i.e., whether the control setting data is oversized data) by referring to the above-mentioned flag 231a (step S3). Note that here, for example, the data setting unit 212b refers to a table showing the correspondence between multiple models and memory areas 221-1 to 221-N, identifies the memory area 221-i corresponding to the notified model, and reads out the control setting data of the notified model from the identified memory area 221-i.

If it is determined that the control setting data of the notified model is compressed (i.e., the control setting data is oversized data), the data setting unit 212b reproduces the control setting value for the specific item from the control setting value for one of the above-mentioned two directions to the control setting value for the other, as described above, thereby decompressing (expanding) the control setting data (step S4). The data setting unit 212b then sets the control setting data including the control setting values for both of the above-mentioned two directions in the control circuit 211 (step S5).

On the other hand, if it is determined that the control setting data for the notified model is not compressed (i.e., the control setting data is normal size data), the data setting unit 212b sets the control setting data read from the memory unit 212a as is in the control circuit 211 for all items, including the specific item, as described above (step S5).

After the control setting data specific to the model of the magnetic bearing device is set in the control circuit 211 in this manner, the motor unit 6 starts operating according to a command from the control device 200, and the control circuit 211 starts controlling the magnetic bearing device (step S6).

This causes the vacuum pump to start operating. In the vacuum pump, the rotor shaft 113 rotates due to the operation of the motor unit 6, and the rotor also rotates. When the rotor rotates, the sensors 107 and 108 detect the radial displacement of the rotor shaft 113, and the control circuit 211 generates a drive current according to the detected displacement according to the set control setting data and supplies it to the electromagnets 104 and 105 of the magnetic bearing device, suppressing the radial displacement of the rotor shaft 113. This allows the rotor to rotate stably, and the gas molecules that fly in through the intake port 101 are guided by the rotor 102 and fixed blades 123 into the flow path and exhausted from the exhaust port 133.

As described above, according to the above embodiment, the control circuit 211 controls a magnetic bearing device that supports a rotor shaft in at least two directions. The memory unit 212a stores control setting data for multiple models of magnetic bearing devices. The data setting unit 212b selects the control setting data for the magnetic bearing device to be controlled from the control setting data for multiple models of magnetic bearing devices and sets it in the control circuit 211. The control setting data includes control setting values for multiple items, and for items in the control setting data for a certain model where the control setting values for the above-mentioned two directions are the same, the control setting value for only one of the two directions is included. Then, for items where the control setting values for the above-mentioned two directions are the same, the data setting unit 212b identifies the control setting value for the other from the control setting value for one, and sets the control setting values for the two directions in the control circuit 211.

As a result, for items where the control setting values for the two directions of magnetic bearing control are common, one of the control setting values is omitted, so the size of the control setting data stored in memory unit 212a can be small. Furthermore, when updating the control setting values stored in memory unit 212a, by updating one control setting value for that item, the update of the control setting value is reflected in the control setting values for both directions, simplifying maintenance work such as updating the control setting values.

It should be noted that various changes and modifications to the above-described embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the subject matter and without diminishing its intended advantages. In other words, such changes and modifications are intended to be included within the scope of the claims.

The present invention can be applied, for example, to a magnetic bearing control device for a vacuum pump.

100 Turbo molecular pump (an example of a vacuum pump)
104 Upper radial electromagnet (part of an example of a magnetic bearing device)
105 Lower radial electromagnet (part of an example of a magnetic bearing device)
107 Upper radial sensor (part of an example of a magnetic bearing device)
108 Lower radial sensor (part of an example of a magnetic bearing device)
200 Control device (an example of a magnetic bearing control device)
211 Control circuit 212a Memory section 212b Data setting section 221-1 to 221-N Storage area 231 Control setting data 231a Flag

Claims (5)

a magnetic bearing device that supports the rotor shaft in at least two directions;
a magnetic bearing control device for controlling the magnetic bearing device,
The magnetic bearing control device includes:
A control circuit for controlling the magnetic bearing device;
A memory unit that stores control setting data for a plurality of types of magnetic bearing devices;
a data setting unit that selects control setting data of a magnetic bearing device to be controlled by the magnetic bearing control device from the control setting data of the multiple models of magnetic bearing devices and sets the control setting data in the control circuit;
The control setting data includes control setting values of a plurality of items,
In the control setting data for a certain model among the plurality of models, for an item among the plurality of items for which the control setting values for the two directions are the same, the control setting value for one of the two directions is included, but the control setting value for the other of the two directions is not included;
the data setting unit (a) for an item among the plurality of items for which control setting values for the two directions are the same, specifies a control setting value for the other of the two directions from a control setting value for one of the two directions, and (b) sets the two control setting values for the two directions in the control circuit;
A vacuum pump characterized by: the memory unit includes a plurality of storage areas of the same fixed length in which the control setting data of the plurality of models of magnetic bearings are respectively stored,
The control setting data, which does not exceed the size of the storage area even when the control setting values of both of the two directions are included, is stored in the storage area in a state including the control setting values of both of the two directions,
The control setting data, which would exceed the size of the storage area when control setting values of both of the two directions are included, is stored in the storage area with a size of the control setting data set equal to or less than the size of the storage area, in a state in which the control setting values for one of the two directions are included but not the control setting value for the other of the two directions, for an item for which the control setting values for the two directions are the same;
the data setting unit: (a) for control setting data that does not exceed the size of the storage area even when control setting values of both of the two directions are included, reads out the control setting values of both of the two directions stored in the storage area and sets them in the control circuit; (b) for control setting data that exceeds the size of the storage area when control setting values of both of the two directions are included, (b1) for items among the plurality of items for which control setting values for the two directions are the same, identifies a control setting value of the other of the two directions from the control setting value of one of the two directions; and (b2) sets the one control setting value and the identified control setting value of the other of the two directions in the control circuit;
2. The vacuum pump according to claim 1, the control setting data includes a flag indicating whether or not the control setting data would exceed the size of the storage area if it included control setting values in both of the two directions;
the data setting unit refers to the flag to determine whether or not the control setting data will exceed the size of the storage area when it includes control setting values for both of the two directions;
3. The vacuum pump according to claim 2, A magnetic bearing control device for controlling a magnetic bearing device that supports a rotor shaft in at least two directions in a vacuum pump, comprising:
A control circuit for controlling the magnetic bearing device;
A memory unit that stores control setting data for a plurality of types of magnetic bearing devices;
a data setting unit that selects control setting data of a magnetic bearing device to be controlled by the magnetic bearing control device from the control setting data of the multiple models of magnetic bearing devices and sets the control setting data in the control circuit;
The control setting data includes control setting values of a plurality of items,
In the control setting data for a certain model among the plurality of models, for an item among the plurality of items for which the control setting values for the two directions are the same, the control setting value for one of the two directions is included, but the control setting value for the other of the two directions is not included;
the data setting unit (a) for an item among the plurality of items for which control setting values for the two directions are the same, specifies a control setting value for the other of the two directions from a control setting value for one of the two directions, and (b) sets the two control setting values for the two directions in the control circuit;
A magnetic bearing control device comprising: 1. A method for compressing and decompressing control setting data for controlling a magnetic bearing device that supports a rotor shaft in at least two directions in a vacuum pump, comprising:
The memory unit stores control setting data for a plurality of models of magnetic bearing devices,
The control setting data includes control setting values of a plurality of items,
In the control setting data for a certain model among the plurality of models, for an item among the plurality of items for which the control setting values for the two directions are the same, the control setting value for one of the two directions is included, and the control setting value for the other of the two directions is not included, thereby compressing the control setting data;
for an item among the plurality of items having the same control setting values in the two directions, specifying a control setting value in the other of the two directions from a control setting value in one of the two directions, thereby decompressing the compressed control setting data;
A compression/decompression method comprising:

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