Superconducting equipment cooling device and method for operating the superconducting equipment cooling device

Abstract

To improve the usability of a superconductive apparatus cooling device.SOLUTION: A superconductive apparatus cooling device comprises a cryogenic refrigerator 10 for cooling a superconductive apparatus, an interface 110 which is constituted so as to accept the selection of a plurality of performance parameters of the cryogenic refrigerator 10 by a user, and creating an operation mode setting S1 indicating the plurality of selected performance parameters, and a controller 120 for receiving the operation mode setting S1 from the interface 110, and controlling the plurality of operation parameters of the cryogenic refrigerator 10 exerted on the plurality of selected performance parameters.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a superconducting equipment cooling device and a method for operating a superconducting equipment cooling device. [Background technology]

[0002] Superconducting devices such as superconducting coils need to be cooled to cryogenic temperatures in order to exhibit superconductivity. Cryogenic refrigerators are often used to cool superconducting devices to cryogenic temperatures. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2016-052225 Summary of the Invention [Problem to be solved by the invention]

[0004] Existing superconducting equipment cooling systems are typically designed to operate at preset operating conditions defined by their manufacturers, leaving users of superconducting equipment with little room to adjust the operating conditions of the cooling system at their own discretion.

[0005] One exemplary object of certain aspects of the present invention is to improve the usability of superconducting equipment cooling systems. [Means for solving the problem]

[0006] According to one aspect of the present invention, a superconducting equipment cooling system includes a cryogenic refrigerator for cooling a superconducting equipment; an interface configured to accept a user's selection of a plurality of performance parameters of the cryogenic refrigerator and generate an operating mode setting representative of the selected plurality of performance parameters; and a controller configured to receive the operating mode setting from the interface and control a plurality of operating parameters of the cryogenic refrigerator that affect the selected plurality of performance parameters.

[0007] According to one aspect of the present invention, there is provided a method of operating a superconducting equipment cooling system including a cryogenic refrigerator for cooling a superconducting equipment, the method comprising: accepting a user selection of a plurality of performance parameters of the cryogenic refrigerator; and controlling a plurality of operating parameters of the cryogenic refrigerator that affect the selected performance parameters. [Effects of the Invention]

[0008] According to the present invention, the usability of a superconducting equipment cooling device can be improved. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram schematically illustrating a superconducting magnet device according to an embodiment. [Figure 2] 1 is a diagram illustrating a cryogenic refrigerator according to an embodiment; [Figure 3] 1 is a diagram illustrating a cryogenic refrigerator according to an embodiment; [Figure 4] 3 is a flowchart illustrating an example of a method for operating a superconducting equipment cooling device according to an embodiment. [Figure 5] 4 is a flowchart showing an example of a control algorithm used in a method for operating a superconducting equipment cooling device according to an embodiment. [Figure 6] 6(a) and 6(b) are graphs showing the dependence of the first-stage temperature and the second-stage temperature of a cryogenic refrigerator on the operating frequency, respectively. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the description and drawings, identical or equivalent components, parts, and processes are designated by the same reference numerals, and redundant explanations will be omitted as appropriate. The scale and shape of each part shown in the drawings are set for convenience to facilitate explanation, and should not be interpreted as limiting unless otherwise specified. The embodiments are merely examples and do not limit the scope of the present invention in any way. All features and combinations thereof described in the embodiments are not necessarily essential to the invention.

[0011] 1 is a diagram schematically illustrating a superconducting device according to an embodiment, for example, a superconducting magnet device 100. The superconducting magnet device 100 is installed in high-magnetic-field devices as a magnetic field source for, for example, a single-crystal pulling device, an NMR (Nuclear Magnetic Resonance) system, an MRI (Magnetic Resonance Imaging) system, an accelerator such as a cyclotron, a high-energy physics system such as a nuclear fusion system, or other high-magnetic-field devices (not shown), and can generate the high magnetic field required for the devices.

[0012] The superconducting magnet device 100 includes a cryogenic refrigerator 10, a superconducting coil 102, a vacuum vessel 104, a radiation shield 106, and a magnetic shield 108. An exemplary configuration of the cryogenic refrigerator 10 will be described later with reference to FIGS.

[0013] The superconducting coil 102 is placed in a vacuum vessel 104. The superconducting coil 102 is thermally coupled to a cryogenic refrigerator 10 installed in the vacuum vessel 104, and is used in a state cooled to a cryogenic temperature below the superconducting transition temperature. In this embodiment, the superconducting magnet device 100 is configured as a so-called conduction-cooled type in which the superconducting coil 102 is directly cooled by the cryogenic refrigerator 10.

[0014] In another embodiment, the superconducting magnet device 100 may be configured as an immersion-cooled type in which the superconducting coil 102 is immersed in a cryogenic liquid refrigerant such as liquid helium. In this case, the cryogenic refrigerator 10 is used to cool, i.e., re-condense, the liquid refrigerant. The cryogenic refrigerator 10 can cool the superconducting coil 102 via the liquid refrigerant.

[0015] The vacuum vessel 104 is an insulated vacuum vessel, also called a cryostat, that provides a cryogenic vacuum environment suitable for bringing the superconducting coil 102 into a superconducting state. Typically, the vacuum vessel 104 has a cylindrical shape or a hollow cylindrical shape with a central cavity. The vacuum vessel 104 thus has a generally flat, circular or annular top plate 104a and bottom plate 104b, and a cylindrical side wall (a cylindrical outer wall, or coaxially arranged cylindrical outer and inner walls) connecting them. The cryogenic refrigerator 10 may be mounted on the top plate 104a of the vacuum vessel 104. The vacuum vessel 104 is formed of a metallic material, such as stainless steel, or other suitable high-strength material to withstand ambient pressure (e.g., atmospheric pressure).

[0016] The radiation shield 106 is disposed within the vacuum vessel 104 to surround the superconducting coil 102. The radiation shield 106 has a top plate 106a and a bottom plate 106b that face the top plate 104a and bottom plate 104b of the vacuum vessel 104, respectively. The top plate 106a and the bottom plate 106b of the radiation shield 106 have a generally flat circular or annular shape, similar to the vacuum vessel 104. The radiation shield 106 also has a cylindrical side wall (a cylindrical outer peripheral wall, or coaxially arranged cylindrical outer and inner peripheral walls) that connects the top plate 106a and the bottom plate 106b. The radiation shield 106 is formed, for example, from pure copper (e.g., oxygen-free copper, tough pitch copper, etc.) or another highly thermally conductive metal. The radiation shield 106 blocks radiant heat from the vacuum vessel 104 and can thermally protect low-temperature parts such as the superconducting coil 102, which is placed inside the radiation shield 106 and cooled to a lower temperature than the radiation shield 106, from the radiant heat.

[0017] The magnetic shield 108 covers the top plate 104a, the bottom plate 104b, and the cylindrical side wall (at least the outer peripheral wall) connecting them of the vacuum vessel 104 in order to prevent the magnetic field generated by the superconducting coil 102 from leaking to the outside. The magnetic shield 108 is formed of a magnetic material such as iron. In this embodiment, the magnetic shield 108 is provided as a separate member from the vacuum vessel 104 and is fixed to the outside of the vacuum vessel 104. However, in other embodiments, at least a portion of the magnetic shield 108 may be integrated with the vacuum vessel 104. For example, at least a portion of the top plate 104a, the bottom plate 104b, and the side wall connecting them of the vacuum vessel 104 may be formed of a magnetic material so as to function as the magnetic shield 108.

[0018] The first cooling stage 33 of the cryocooler 10 is thermally coupled to a top plate 106a of the radiation shield 106, and the second cooling stage 35 of the cryocooler 10 is thermally coupled to the superconducting coil 102 inside the radiation shield 106. During operation of the superconducting magnet device 100, the radiation shield 106 is cooled to a first cooling temperature, for example, 30 K to 70 K, by the first cooling stage 33 of the cryocooler 10, and the superconducting coil 102 is cooled to a second cooling temperature lower than the first cooling temperature, for example, a temperature less than 10 K (for example, about 1 K to about 4 K), by the second cooling stage 35 of the cryocooler 10. The superconducting coil 102 cooled to a cryogenic temperature in this manner is supplied with power from a coil power supply (not shown) arranged outside the vacuum vessel 104, thereby generating a desired high magnetic field.

[0019] 2 and 3 are diagrams that schematically show a cryogenic refrigerator 10 according to an embodiment. Fig. 2 shows the external appearance of the cryogenic refrigerator 10, and Fig. 3 shows the internal structure of the cryogenic refrigerator 10. The cryogenic refrigerator 10 is, for example, a two-stage Gifford-McMahon (GM) refrigerator.

[0020] The cryogenic refrigerator 10 includes a compressor 12 and an expander 14. As will be described in detail later, an interface 110 and a controller 120 are provided, which, together with the cryogenic refrigerator 10, constitute a superconducting equipment cooling device according to the embodiment, as shown in FIG.

[0021] The compressor 12 is configured to recover the working gas of the cryogenic refrigerator 10 from the expander 14, increase the pressure of the recovered working gas, and supply the working gas again to the expander 14. The working gas, also called a refrigerant gas, is typically helium gas, but other suitable gases may also be used.

[0022] Generally, the pressure of the working gas supplied from the compressor 12 to the expander 14 and the pressure of the working gas recovered from the expander 14 to the compressor 12 are both significantly higher than atmospheric pressure and can be referred to as the first high pressure and the second high pressure, respectively. For ease of explanation, the first high pressure and the second high pressure are also simply referred to as the high pressure and the low pressure, respectively. Typically, the high pressure is, for example, 2 to 3 MPa. The low pressure is, for example, 0.5 to 1.5 MPa, e.g., approximately 0.8 MPa. For ease of understanding, the flow direction of the working gas is indicated by an arrow.

[0023] The compressor 12 includes a compressor body 22 and a compressor housing 23 that houses the compressor body 22. The compressor 12 is also referred to as a compressor unit.

[0024] The compressor body 22 is configured to compress the working gas drawn in through its intake port and discharge it from its discharge port. The compressor body 22 may be, for example, a scroll type, a rotary type, or any other pump that pressurizes the working gas. The compressor body 22 may be configured to discharge a fixed, constant flow rate of the working gas. Alternatively, the compressor body 22 may be configured to vary the flow rate of the working gas it discharges. The compressor body 22 is sometimes referred to as a compression capsule.

[0025] The compressor 12 also includes a compressor motor 24 and a compressor inverter 25 that controls the operating frequency, i.e., the rotation speed, of the compressor motor 24 based on a compressor control signal C1 from the controller 120. The compressor motor 24 is a drive source that drives the compressor main body 22 and is, for example, an electric motor driven by three-phase AC. The compressor inverter 25 is configured to convert AC input from a power source 46 to AC with a different frequency and supply the converted AC to the compressor motor 24. The power source 46 may be an external power source such as a commercial power source (three-phase AC power source). The operating frequency of the compressor motor 24 may be controlled by the compressor inverter 25 within a range of 30 Hz to 100 Hz or a range of 40 Hz to 70 Hz.

[0026] A first meter 50 may be provided to measure the power consumption of the compressor motor 24. The first meter 50 may be installed on the power supply wiring connecting the compressor inverter 25 to the compressor motor 24. As an example, the first meter 50 may be a three-phase power meter based on the two-wattmeter method, or may be any other type of power sensor that measures the power consumption of the compressor motor 24. The first meter 50 may be communicatively connected to the controller 120 by wire or wirelessly. A compressor power signal E1 indicating the power consumption of the compressor motor 24 measured by the first meter 50 may be input from the first meter 50 to the controller 120.

[0027] Note that the controller 120 may obtain the power consumption of the compressor motor 24 by other known methods, in which case the cryogenic refrigerator 10 does not need to include the above-mentioned first measuring device 50. For example, the compressor inverter 25 may be configured to detect the power consumption of the compressor motor 24 from the current and voltage supplied to the compressor motor 24, and the controller 120 may obtain the power consumption of the compressor motor 24 from the compressor inverter 25. Alternatively, the controller 120 may obtain a signal indicating the magnitude of the current and voltage supplied to the compressor motor 24 from the compressor inverter 25, and obtain the power consumption of the compressor motor 24.

[0028] As is known, the compressor 12 may have various other components not shown. For example, an oil separator, an absorber, etc. may be provided in the working gas flow path on the discharge side. A storage tank and other components may be provided in the working gas flow path on the suction side. The compressor 12 may also be provided with an oil circulation system that cools the compressor body 22 with oil, a cooling system that cools the oil with cooling water, etc.

[0029] The expander 14 includes a refrigerator cylinder 16 and a displacer assembly 18. The refrigerator cylinder 16 guides the linear reciprocating motion of the displacer assembly 18, and forms expansion chambers (32, 34) for the working gas between the refrigerator cylinder 16 and the displacer assembly 18. The expander 14 also includes a pressure switching valve 40 that determines the timing at which the working gas starts to be drawn into the expansion chamber and the timing at which the working gas starts to be exhausted from the expansion chamber.

[0030] In this document, for convenience in explaining the positional relationships between the components of the cryocooler 10, the side closer to the top dead center of the displacer's axial reciprocating motion will be referred to as "top" and the side closer to the bottom dead center as "bottom." The top dead center is the position of the displacer where the volume of the expansion space is maximum, and the bottom dead center is the position of the displacer where the volume of the expansion space is minimum. During operation of the cryocooler 10, a temperature gradient occurs in which the temperature decreases from top to bottom in the axial direction, so the top side can also be referred to as the high-temperature side and the bottom side as the low-temperature side.

[0031] The refrigerator cylinder 16 has a first cylinder 16a and a second cylinder 16b. The first cylinder 16a and the second cylinder 16b are, for example, cylindrical members, and the second cylinder 16b has a smaller diameter than the first cylinder 16a. The first cylinder 16a and the second cylinder 16b are arranged coaxially, and the lower end of the first cylinder 16a is rigidly connected to the upper end of the second cylinder 16b.

[0032] The displacer assembly 18 includes a first displacer 18a and a second displacer 18b that are connected to each other and move together. The first displacer 18a and the second displacer 18b are, for example, cylindrical members, and the second displacer 18b has a smaller diameter than the first displacer 18a. The first displacer 18a and the second displacer 18b are arranged coaxially.

[0033] The first displacer 18a is accommodated in the first cylinder 16a, and the second displacer 18b is accommodated in the second cylinder 16b. The first displacer 18a is capable of reciprocating in the axial direction along the first cylinder 16a, and the second displacer 18b is capable of reciprocating in the axial direction along the second cylinder 16b.

[0034] 3, the first displacer 18a accommodates the first regenerator 26. The first regenerator 26 is formed by filling a cylindrical main body of the first displacer 18a with a wire mesh such as copper or other suitable first regenerator material. The upper and lower lids of the first displacer 18a may be provided as separate members from the main body of the first displacer 18a, and the upper and lower lids of the first displacer 18a may be fixed to the main body by suitable means such as fastening or welding, thereby accommodating the first regenerator material in the first displacer 18a.

[0035] Similarly, the second displacer 18b accommodates the second regenerator 28. The second regenerator 28 is formed by filling the cylindrical main body of the second displacer 18b with a non-magnetic regenerator material such as bismuth, a magnetic regenerator material such as HoCu2, or another suitable second regenerator material. The second regenerator material may be formed in a granular form. The upper and lower covers of the second displacer 18b may be provided as separate members from the main body of the second displacer 18b, and the upper and lower covers of the second displacer 18b may be fixed to the main body by suitable means such as fastening or welding, thereby accommodating the second regenerator material in the second displacer 18b.

[0036] The displacer assembly 18 defines a room-temperature chamber 30, a first expansion chamber 32, and a second expansion chamber 34 inside the refrigerator cylinder 16. The expander 14 includes a first cooling stage 33 and a second cooling stage 35 for heat exchange with the desired object or medium to be cooled by the cryogenic refrigerator 10. The room-temperature chamber 30 is defined between the top cover of the first displacer 18a and the top of the first cylinder 16a. The first expansion chamber 32 is defined between the bottom cover of the first displacer 18a and the first cooling stage 33. The second expansion chamber 34 is defined between the bottom cover of the second displacer 18b and the second cooling stage 35. The first cooling stage 33 is fixed to the bottom of the first cylinder 16a to surround the first expansion chamber 32, and the second cooling stage 35 is fixed to the bottom of the second cylinder 16b to surround the second expansion chamber 34. The first cooling stage 33 and the second cooling stage 35 are formed of, for example, pure copper (for example, oxygen-free copper, tough pitch copper, etc.) or other highly thermally conductive metal.

[0037] The first regenerator 26 is connected to the room-temperature chamber 30 through a working gas passage 36a formed in the upper lid of the first displacer 18a, and is connected to the first expansion chamber 32 through a working gas passage 36b formed in the lower lid of the first displacer 18a. The second regenerator 28 is connected to the first regenerator 26 through a working gas passage 36c formed from the lower lid of the first displacer 18a to the upper lid of the second displacer 18b. The second regenerator 28 is also connected to the second expansion chamber 34 through a working gas passage 36d formed in the lower lid of the second displacer 18b.

[0038] A first seal 38a and a second seal 38b may be provided so that the flow of working gas between the first expansion chamber 32, the second expansion chamber 34 and the room temperature chamber 30 is guided to the first regenerator 26 and the second regenerator 28, rather than through the clearance between the refrigerator cylinder 16 and the displacer assembly 18. The first seal 38a may be attached to an upper cover of the first displacer 18a so as to be positioned between the first displacer 18a and the first cylinder 16a. The second seal 38b may be attached to an upper cover of the second displacer 18b so as to be positioned between the second displacer 18b and the second cylinder 16b.

[0039] 2, the expander 14 includes a refrigerator housing 20 that houses a pressure switching valve 40. The refrigerator housing 20 is coupled to the refrigerator cylinder 16, thereby forming an airtight container that houses the pressure switching valve 40 and the displacer assembly 18. The refrigerator housing 20 and the refrigerator cylinder 16 are formed of a metal material, such as stainless steel, or other suitable high-strength material so that the airtight container can withstand the pressure difference between the inside and outside.

[0040] 3, the pressure switching valve 40 includes a high-pressure valve 40a and a low-pressure valve 40b, and is configured to generate periodic pressure fluctuations in the refrigerator cylinder 16. The working gas discharge port of the compressor 12 is connected to the room-temperature chamber 30 via the high-pressure valve 40a, and the working gas inlet port of the compressor 12 is connected to the room-temperature chamber 30 via the low-pressure valve 40b. The high-pressure valve 40a and the low-pressure valve 40b are configured to open and close selectively and alternately (i.e., when one is open, the other is closed).

[0041] The pressure switching valve 40 may take the form of a rotary valve. That is, the pressure switching valve 40 may be configured so that the high-pressure valve 40a and the low-pressure valve 40b are alternately opened and closed by the rotational sliding of a valve disc relative to a stationary valve body. In this case, the expander motor 42 may be connected to the pressure switching valve 40 so as to rotate the valve disc of the pressure switching valve 40. For example, the pressure switching valve 40 is arranged so that the valve rotation axis is coaxial with the rotation axis of the expander motor 42.

[0042] Alternatively, the high pressure valve 40a and the low pressure valve 40b may be valves that can be controlled individually, in which case the pressure switching valve 40 does not need to be connected to the expander motor .

[0043] The expander 14 includes an expander motor 42 and a motion conversion mechanism 43. The expander motor 42 is a drive source that drives the expander 14, and is, for example, an electric motor driven by three-phase AC. The expander motor 42 is attached to the refrigerator housing 20. The motion conversion mechanism 43, like the pressure switching valve 40, is housed in the refrigerator housing 20.

[0044] The expander motor 42 is connected to a displacer drive shaft 44 via a motion conversion mechanism 43, such as a Scotch yoke mechanism. The motion conversion mechanism 43 converts the rotational motion output by the expander motor 42 into linear reciprocating motion of the displacer drive shaft 44. The displacer drive shaft 44 extends from the motion conversion mechanism 43 into the room-temperature chamber 30 and is fixed to the upper lid of the first displacer 18a. The rotation of the expander motor 42 is converted into axial reciprocating motion of the displacer drive shaft 44 by the motion conversion mechanism 43, and the displacer assembly 18 reciprocates linearly in the axial direction within the refrigerator cylinder 16.

[0045] The cryogenic refrigerator 10 is also provided with an expander inverter 45 that controls the operating frequency, i.e., the rotation speed, of the expander motor 42 based on an expander control signal C2 from the controller 120. In this example, the expander inverter 45 is mounted on the compressor 12, but is not limited to this and may be mounted on the expander 14. The expander inverter 45 is configured to convert AC input from a power source 46 to the expander inverter 45 into AC having a different frequency, and supply the converted AC to the compressor motor 24. The operating frequency of the expander motor 42 may be controlled by the expander inverter 45 within a range of 30 Hz to 100 Hz or a range of 40 Hz to 70 Hz.

[0046] A second measuring instrument 51 may be provided to measure the power consumption of the expander motor 42. The second measuring instrument 51 may be installed on a power supply wiring that connects the expander inverter 45 to the expander motor 42. As an example, the second measuring instrument 51 may be a three-phase power meter based on the two-wattmeter method, or may be any other type of power sensor that measures the power consumption of the expander motor 42. The second measuring instrument 51 may be communicatively connected to the controller 120 by wire or wirelessly. An expander power signal E2 indicating the power consumption of the expander motor 42 measured by the second measuring instrument 51 may be input from the second measuring instrument 51 to the controller 120.

[0047] The controller 120 may obtain the power consumption of the expander motor 42 by other known methods, in which case the cryogenic refrigerator 10 does not need to include the above-mentioned second measuring device 51. For example, the expander inverter 45 may be configured to detect the power consumption of the expander motor 42 from the current and voltage supplied to the expander motor 42, and the controller 120 may obtain the power consumption of the expander motor 42 from the expander inverter 45. Alternatively, the controller 120 may obtain signals indicating the magnitude of the current and voltage supplied to the expander motor 42 from the expander inverter 45, and obtain the power consumption of the expander motor 42.

[0048] Furthermore, a first temperature sensor 52 for measuring the temperature of the first cooling stage 33 and a second temperature sensor 53 for measuring the temperature of the second cooling stage 35 may be provided. The first temperature sensor 52 may be attached to the first cooling stage 33. The second temperature sensor 53 may be attached to the second cooling stage 35. The first temperature sensor 52 and the second temperature sensor 53 may be communicatively connected to the controller 120 via wire or wirelessly. A first-stage temperature signal T1 indicating the first cooling temperature measured by the first temperature sensor 52 may be input from the first temperature sensor 52 to the controller 120. A second-stage temperature signal T2 indicating the second cooling temperature measured by the second temperature sensor 53 may be input from the second temperature sensor 53 to the controller 120.

[0049] It is not essential that the cryogenic refrigerator 10 includes the first temperature sensor 52 and the second temperature sensor 53. Instead of attaching the first temperature sensor 52 and the second temperature sensor 53 to the first cooling stage 33 and the second cooling stage 35, respectively, the first temperature sensor 52 and the second temperature sensor 53 may be provided in the superconducting magnet device 100. In this case, the first temperature sensor 52 may be attached to the radiation shield 106 shown in FIG. 1 and provide a first-stage temperature signal T1 to the controller 120. The second temperature sensor 53 may be attached to the superconducting coil 102 shown in FIG. 1 and provide a second-stage temperature signal T2 to the controller 120.

[0050] In this embodiment, an interface 110 is provided for a user to input settings for controlling the cryogenic refrigerator 10 into the controller 120. In an exemplary configuration, the interface 110 may be an operation panel mounted on the compressor 12 or attached to the compressor housing 23. The interface 110 is provided with input means, such as operation buttons, a keyboard, or a touch screen, for accepting inputs from the user. Data representing the settings input by the user is transmitted from the interface 110 to the controller 120. The interface 110 may also have notification means, such as a display, a warning light, or a speaker, for presenting the settings input by the user or other information related to the cryogenic refrigerator 10 to the user.

[0051] As described below, the interface 110 may be configured to accept a user selection of performance parameters of the cryogenic refrigerator 10 and to generate an operating mode setting S1 representative of the selected performance parameters.

[0052] The controller 120 is configured to control the cryogenic refrigerator 10. In this embodiment, as described below, the controller 120 may be configured to receive an operational mode setting S1 from the interface 110 and to control a number of operational parameters of the cryogenic refrigerator 10 that affect a number of selected performance parameters.

[0053] The internal configuration of the controller 120 is realized as a hardware configuration by elements and circuits such as a computer CPU and memory, and as a software configuration by a computer program, etc., but in the figure it is depicted as appropriate as functional blocks realized by the cooperation of these. Those skilled in the art will understand that these functional blocks can be realized in various ways by combining hardware and software.

[0054] For example, the controller 120 can be implemented as a combination of a processor (hardware) such as a CPU (Central Processing Unit) or a microcomputer, and a software program executed by the processor (hardware). Such a hardware processor may be configured, for example, as a programmable logic device such as an FPGA (Field Programmable Gate Array), or may be a control circuit such as a programmable logic controller (PLC). The software program may be a computer program that causes the controller 120 to control the cryogenic refrigerator 10.

[0055] It should be noted that the interface 110 and the controller 120 do not necessarily have to be mounted on the compressor 12 as described above, and other arrangements are also possible. For example, the interface 110 and the controller 120 may be mounted on the expander 14. Alternatively, the interface 110 and the controller 120 may be located remotely from the cryogenic refrigerator 10 and communicatively connected to the cryogenic refrigerator 10.

[0056] With the above configuration, when the compressor 12 and the expander motor 42 are operated, the cryogenic refrigerator 10 generates periodic volume fluctuations and synchronized pressure fluctuations of the working gas in the first expansion chamber 32 and the second expansion chamber 34. Typically, during the intake stroke, the low-pressure valve 40b closes and the high-pressure valve 40a opens, causing high-pressure working gas to flow from the compressor 12 through the high-pressure valve 40a into the room-temperature chamber 30, be supplied to the first expansion chamber 32 through the first regenerator 26, and be supplied to the second expansion chamber 34 through the second regenerator 28. In this way, the pressures of the first expansion chamber 32 and the second expansion chamber 34 are increased from low to high. At this time, the displacer assembly 18 is moved upward from bottom dead center to top dead center, increasing the volumes of the first expansion chamber 32 and the second expansion chamber 34. The intake stroke ends when the high-pressure valve 40a closes.

[0057] During the exhaust stroke, the high-pressure valve 40a closes and the low-pressure valve 40b opens, opening the high-pressure first and second expansion chambers 32 and 34 to the low-pressure working gas inlet of the compressor 12. This causes the working gas to expand in the first and second expansion chambers 32 and 34, resulting in the low-pressure working gas being discharged from the first and second expansion chambers 32 and 34 through the first and second regenerators 26 and 28 into the room-temperature chamber 30. At this time, the displacer assembly 18 is moved downward from top dead center to bottom dead center, reducing the volumes of the first and second expansion chambers 32 and 34. The working gas is recovered from the expander 14 through the low-pressure valve 40b and returned to the compressor 12. The exhaust stroke ends when the low-pressure valve 40b closes.

[0058] In this manner, a refrigeration cycle such as a GM cycle is configured, and the first cooling stage 33 and the second cooling stage 35 are cooled to a desired cryogenic temperature. The first cooling stage 33 can be cooled to a first cooling temperature, for example, in the range of about 30 K to about 70 K. The second cooling stage 35 can be cooled to a second cooling temperature (for example, about 1 K to about 4 K) lower than the first cooling temperature. Therefore, the superconducting coil 102 can be cooled to a temperature below the critical temperature, and the superconducting magnet device 100 can be operated.

[0059] 4 is a flowchart showing an example of a method for operating a superconducting equipment cooling apparatus according to an embodiment. The method includes a step (S10) in which the interface 110 accepts a user's selection of a plurality of performance parameters of the cryocooler 10, and a step (S20) in which the controller 120 controls a plurality of operating parameters of the cryocooler 10 that affect the selected performance parameters.

[0060] The interface 110 may be configured to present various performance parameters of the cryogenic refrigerator 10 as candidates for selection to the user. For example, the interface 110 may display these candidate performance parameters on a display. The user can refer to this display and select the performance parameter of interest on the interface 110, thereby inputting the performance parameter selection into the interface 110.

[0061] The multiple performance parameters of the cryogenic refrigerator 10 presented to the user may be at least three parameters that represent the performance of the cryogenic refrigerator 10. The at least three parameters may include a first-stage temperature of the cryogenic refrigerator 10, a second-stage temperature of the cryogenic refrigerator 10, and power consumption of the cryogenic refrigerator 10. The first-stage temperature, second-stage temperature, and power consumption of the cryogenic refrigerator 10 affect the operation of the superconducting equipment cooled by the cryogenic refrigerator 10, and are therefore representative performance parameters of the cryogenic refrigerator 10 that are of great interest to users.

[0062] The interface 110 may be configured to accept a selection of up to two performance parameters from among the selectable candidate performance parameters. The selected performance parameters may be one or two of the first stage temperature of the cryocooler 10, the second stage temperature of the cryocooler 10, and the power consumption of the cryocooler 10.

[0063] The user's selection of the performance parameters of the cryogenic refrigerator 10 may include prioritizing the performance parameters. Thus, the selected performance parameters may include a first performance parameter having a first priority and a second performance parameter having a second priority. The first priority and the second priority are based on the user's prioritization. The first priority represents a higher priority than the second priority. The controller 120 may be configured to control the operating parameters to preferentially improve the first performance parameter relative to the second performance parameter.

[0064] When up to two performance parameters are selected with prioritization, the interface 110 can generate nine different operation mode settings S1. That is, there are three cases where only one performance parameter is selected (operation modes 1 to 3), and there are six cases where two performance parameters are selected with prioritization (operation modes 4 to 9). Note that operation modes 4 to 9 are listed below in order of priority, that is, from the left, the first performance parameter has the first priority, followed by the second performance parameter with the second priority. Operation mode 1: 2-stage temperature Operation mode 2: 1-stage temperature Operation mode 3: Power consumption Operation mode 4: 2-stage temperature, 1-stage temperature Operation mode 5: 1st temperature, 2nd temperature Operation mode 6: 2-stage temperature, power consumption Operation mode 7: Power consumption, two-stage temperature Operation mode 8: 1-stage temperature, power consumption Operation mode 9: Power consumption, 1st temperature

[0065] Instead of presenting the performance parameters themselves to the user as candidates for selection, the interface 110 may present all or some of the driving modes 1 to 9 to the user as candidates for selection.

[0066] For ease of selection, names may be assigned to these operation modes in advance, and the interface 110 may present such operation mode names for selection. For example, operation modes 3, 7, and 9, in which power consumption is prioritized, may be assigned operation mode names such as power consumption mode 1, power consumption mode 2, and power consumption mode 3, respectively (or, if the superconducting magnet device 100 is an MRI device, the user may prioritize reducing power consumption when operating at night compared to during the day, and so the modes may be named night mode 1, night mode 2, and night mode 3).

[0067] Operation mode 4 may be called the standard operation mode. Operation mode 1 and operation mode 6 may be called emergency mode 1 and emergency mode 2, respectively. Operation mode 1 prioritizes only maintaining the second-stage temperature, and therefore may be useful for delaying the occurrence of a quench (loss of superconductivity) as much as possible in situations where it may occur. Operation mode 6 prioritizes maintaining the second-stage temperature, with power consumption being a secondary priority, and therefore may be useful for extending the life of the auxiliary power supply in situations where superconducting equipment is operated using an auxiliary power supply as a backup power source in case of a power outage. Operation mode 5, in which priority is given to maintaining the first-stage temperature, may be called the aging degradation countermeasure mode. Because aging degradation of the cryogenic refrigerator 10 is often manifested as an increase in the first-stage temperature, operation mode 5 may be useful for mitigating the effects of aging degradation.

[0068] The interface 110 may be configured to accept target values ​​for the selected performance parameters from the user. This allows the user to not only select a performance parameter but also set a target value that the performance parameter must satisfy. The operation mode setting S1 may include the target value for the performance parameter set by the user.

[0069] 2, when the interface 110 receives a user's selection of multiple performance parameters of the cryogenic refrigerator 10, the interface 110 generates an operation mode setting S1 representing the selected multiple performance parameters and outputs the operation mode setting S1 to the controller 120. The operation mode setting S1 is stored in the controller 120.

[0070] The controller 120 may include multiple control algorithms 122, each corresponding to a different operation mode setting S1 (e.g., the controller 120 may include nine control algorithms 122 corresponding to operation modes 1 to 9, respectively). Each control algorithm 122 may be configured to control multiple operation parameters of the cryogenic refrigerator 10 so as to improve at least one performance parameter selected in the corresponding operation mode setting S1.

[0071] Therefore, the controller 120 may be configured to receive an operation mode setting S1 from the interface 110, select a control algorithm 122 corresponding to this operation mode setting S1 from a plurality of control algorithms 122, and control a plurality of operation parameters of the cryogenic refrigerator 10 in accordance with the selected control algorithm 122.

[0072] 5 is a flowchart showing an example of a control algorithm 122 used in the method for operating a superconducting equipment cooling device according to the embodiment. The control algorithm 122 is executed in a step (S20 in FIG. 4) of controlling a plurality of operating parameters of the cryogenic refrigerator 10. As shown in the figure, the control algorithm 122 includes a step (S21) of acquiring current values ​​of performance parameters selected in a corresponding operating mode setting S1, a step (S22) of comparing the acquired current values ​​of the performance parameters with target values, and a step (S23) of controlling the operating parameters of the cryogenic refrigerator 10 based on the comparison result.

[0073] If the selected performance parameter is the first stage temperature of the cryogenic refrigerator 10, the controller 120 can obtain the current value of the first stage temperature from the first stage temperature signal T1 from the first temperature sensor 52. Similarly, if the selected performance parameter is the second stage temperature of the cryogenic refrigerator 10, the controller 120 can obtain the current value of the second stage temperature from the second stage temperature signal T2 from the second temperature sensor 53.

[0074] If the selected performance parameter is the power consumption of the cryogenic refrigerator 10, the controller 120 can obtain the current value of the power consumption of the cryogenic refrigerator 10 from the compressor power signal E1 from the first measuring instrument 50 and the expander power signal E2 from the second measuring instrument 51. The power consumption of the cryogenic refrigerator 10 can be calculated as the sum of the power consumption of the compressor motor 24 and the power consumption of the expander motor 42. As described above, the controller 120 may obtain the current and voltage supplied to the compressor motor 24 and the expander motor 42, respectively, and calculate the power consumption of the cryogenic refrigerator 10 from these.

[0075] The target value of a performance parameter against which the current value of the obtained performance parameter is compared may be a value set by the user, as described above, or, if a target value is not set by the user, the controller 120 may use a default target value for the individual performance parameter or a target value set by the controller 120.

[0076] The controller 120 compares the current value of the acquired performance parameter with the target value and generates a comparison result. The comparison result can take one of the following three states, State A to State C, depending on the magnitude relationship between the current value and the target value. State A: The current value is smaller (lower) than the target value. State B: Current value equals target value. State C: The current value is greater than (higher than) the target value.

[0077] Note that "the current value is equal to the target value" in state B does not necessarily mean that the current value exactly matches the target value, but may also mean that the current value is within an acceptable range that includes the target value. This acceptable range may be a predetermined ratio or amount relative to the target value (for example, within ±5% of the target value). State A (or state C) may mean that the current value exceeds (or falls below) the acceptable range.

[0078] When the selected performance parameter is the first stage temperature, second stage temperature, or power consumption of the cryogenic refrigerator 10, the performance parameter can be considered to satisfy the target value if the comparison result is state A or state B. On the other hand, when the comparison result is state C, the performance parameter is considered to not satisfy the target value.

[0079] Based on the comparison result, the controller 120 may operate the interface 110 to present information to the user indicating that the performance parameter meets the target value, or to present information (i.e., a warning) indicating that the performance parameter does not meet the target value. For example, the controller 120 may turn on a warning light provided on the interface 110 to warn the user.

[0080] In addition to or instead of presenting the information to the user, the controller 120 may control the operating parameters of the cryogenic refrigerator 10 so as to reduce the deviation between the current value of the acquired performance parameter and the target value. For example, when the current value of the acquired performance parameter does not satisfy the target value (i.e., when the comparison result is state C), the controller 120 may control the operating parameters of the cryogenic refrigerator 10 so as to change the value of the performance parameter toward the target value (e.g., reduce the value of the performance parameter).

[0081] The controller 120 may select at least one of the plurality of operating parameters of the cryogenic refrigerator 10 based on the comparison result, and control the selected operating parameter. In this case, the control algorithm 122 may predefine which operating parameter to control depending on the comparison result (i.e., for each of the plurality of states). Therefore, the controller 120 can select the operating parameter to be controlled by referring to the comparison result.

[0082] The controller 120 may be configured to determine the value of the operating parameter to be controlled. The controller 120 may determine a new value of the operating parameter by adding a change amount to the current value of the operating parameter. The change amount may be a positive or negative value, thereby increasing or decreasing the value of the operating parameter. The change amount may be a fixed value or a variable value that is changed depending on the situation.

[0083] An operating parameter of the cryogenic refrigerator 10 is a manipulable parameter that affects the performance parameters of the cryogenic refrigerator 10 and may be, for example, the operating frequency of the compressor motor 24 or the operating frequency of the expander motor 42 .

[0084] FIG. 6(a) shows the relationship between the first stage temperature and the operating frequency of the expander motor 42 for four operating frequencies of the compressor motor 24: 40 Hz, 50 Hz, 60 Hz, and 70 Hz. As shown in FIG. 6(a), the first stage temperature of the cryogenic refrigerator 10 tends to decrease monotonically as the operating frequency of the compressor motor 24 increases. Therefore, by changing (e.g., increasing) the operating frequency of the compressor motor 24, the first stage temperature can be adjusted (e.g., decreased).

[0085] Similarly, the first stage temperature tends to decrease monotonically as the operating frequency of the expander motor 42 increases. By changing (e.g., increasing) the operating frequency of the expander motor 42, the first stage temperature can be adjusted (e.g., decreased).

[0086] Typically, the first-stage temperature can be adjusted more significantly when the operating frequency of the compressor motor 24 is changed by a certain amount compared to when the operating frequency of the expander motor 42 is changed by the same amount. As can be seen from Figure 6(a), this tendency is significant when the operating frequency of the compressor motor 24 is 60 Hz or less. Therefore, when the first-stage temperature of the cryogenic refrigerator 10 is selected as a performance parameter in the operation mode setting S1, it can be more effective to select the operating frequency of the compressor motor 24 as an operation parameter.

[0087] FIG. 6(b) shows the relationship between the second stage temperature and the operating frequency of the expander motor 42 for each of four operating frequencies of the compressor motor 24: 40 Hz, 50 Hz, 60 Hz, and 70 Hz. As shown in FIG. 6(b), the second stage temperature of the cryogenic refrigerator 10 tends to decrease monotonically as the operating frequency of the compressor motor 24 increases. Therefore, by changing (for example, increasing) the operating frequency of the compressor motor 24, 2 The stage temperature can be adjusted (eg, decreased).

[0088] On the other hand, the second-stage temperature has a different tendency than the first-stage temperature with respect to the operating frequency of the expander motor 42. Specifically, when the operating frequency of the compressor motor 24 is kept constant and the operating frequency of the expander motor 42 is changed, the second-stage temperature is lowest when the operating frequency of the expander motor 42 takes a certain value. (For example, as shown in FIG. 6(b), when the operating frequency of the compressor motor 24 is 50 Hz, the second-stage temperature is lowest when the operating frequency of the expander motor 42 is 50 Hz.) In other words, when the operating frequency of the expander motor 42 is lower than this value, the second-stage temperature decreases as the operating frequency of the expander motor 42 increases. However, when the operating frequency of the expander motor 42 is higher than this value, the second-stage temperature increases as the operating frequency of the expander motor 42 increases. Therefore, it is difficult to say whether an increase or decrease in the operating frequency of the expander motor 42 is necessary to decrease the second-stage temperature. This operating frequency dependency of the second-stage temperature is particularly evident when the second-stage temperature is approximately 4 K or lower.

[0089] Therefore, when the second-stage temperature of the cryogenic refrigerator 10 is selected as a performance parameter in the operation mode setting S1, in order to lower the second-stage temperature, it is desirable to control both the operating frequency of the compressor motor 24 and the operating frequency of the expander motor 42 as operation parameters.

[0090] The power consumption of the cryogenic refrigerator 10 is basically in a trade-off relationship with the cooling temperature. Power consumption tends to increase monotonically as the operating frequency of the compressor motor 24 increases. Therefore, power consumption can be adjusted (e.g., reduced) by changing (e.g., reducing) the operating frequency of the compressor motor 24. Furthermore, power consumption can increase or decrease by changing the operating frequency of the expander motor 42. Therefore, power consumption can be adjusted by changing the operating frequency of the expander motor 42. When the power consumption of the cryogenic refrigerator 10 is selected as a performance parameter in the operation mode setting S1, it may be more effective to select the operating frequency of the compressor motor 24 as an operating parameter.

[0091] When the operating frequency of the compressor motor 24 is controlled, the controller 120 generates a compressor control signal C1 representing the determined value of the operating frequency of the compressor motor 24 and transmits the compressor control signal C1 to the compressor inverter 25. The compressor inverter 25 receives the compressor control signal C1 and operates to drive the compressor motor 24 at the determined operating frequency.

[0092] Similarly, when the operating frequency of the expander motor 42 is controlled, the controller 120 generates an expander control signal C2 that represents the determined value of the operating frequency of the expander motor 42, and transmits the expander control signal C2 to the expander inverter 45. The expander inverter 45 receives the expander control signal C2 and operates to drive the expander motor 42 at the determined operating frequency.

[0093] Since it takes some time for the effects of changing the operating parameters to appear in the performance parameters, the controller 120 may wait a predetermined time after changing the operating parameters. When this waiting time has elapsed, the controller 120 may execute the control algorithm 122 (S21 to S23) again.

[0094] When two performance parameters are selected in the operation mode setting S1, the controller 120 acquires the current value of the first performance parameter and the current value of the second performance parameter, compares the current value of the first performance parameter with a first target value, and compares the current value of the second performance parameter with a second target value. The first target value and the second target value are the target values ​​of the first performance parameter and the second performance parameter, respectively. When the operation mode setting S1 includes prioritization of the performance parameters, the first performance parameter may have the first priority and the second performance parameter may have the second priority, as described above. The comparison result can take one of the following nine states, State Aa to State Cc. State Aa: The current value of the first performance parameter is smaller than the first target value, and the current value of the second performance parameter is smaller than the second target value. State Ab: The current value of the first performance parameter is smaller than the first target value, and the current value of the second performance parameter is equal to the second target value. State Ac: The current value of the first performance parameter is smaller than the first target value, and the current value of the second performance parameter is larger than the second target value. State Ba: The current value of the first performance parameter is equal to the first target value, and the current value of the second performance parameter is smaller than the second target value. State Bb: The current value of the first performance parameter is equal to the first target value, and the current value of the second performance parameter is equal to the second target value. State Bc: The current value of the first performance parameter is equal to the first target value, and the current value of the second performance parameter is greater than the second target value. State Ca: The current value of the first performance parameter is greater than the first target value, and the current value of the second performance parameter is less than the second target value. State Cb: The current value of the first performance parameter is greater than the first target value, and the current value of the second performance parameter is equal to the second target value. State Cc: The current value of the first performance parameter is greater than the first target value, and the current value of the second performance parameter is greater than the second target value.

[0095] The controller 120 may operate the interface 110 based on the comparison result to present information indicating whether the performance parameters satisfy the target values ​​to the user. For example, if the first performance parameter does not satisfy the first target value, the controller 120 may issue a first warning regardless of whether the second performance parameter satisfies the second target value (states Ca, Cb, and Cc). This ensures that the user is informed that the first performance parameter, which has a higher priority than the second performance parameter, does not satisfy its target value. The controller 120 may issue a second warning if the first performance parameter satisfies the first target value and the second performance parameter does not satisfy the second target value (states Ac and Bc). The controller 120 may also issue a normal notification if the first performance parameter satisfies the first target value and the second performance parameter satisfies the second target value. The first warning, second warning, and normal notification may be presented to the user via the interface 110.

[0096] In addition to or instead of presenting information to the user, the controller 120 may control the plurality of operating parameters of the cryogenic refrigerator 10 to preferentially improve the first performance parameter over the second performance parameter. In this case, if the first performance parameter does not satisfy the first target value, the controller 120 may control a first operating parameter of the plurality of operating parameters that affects the first performance parameter, regardless of whether the second performance parameter satisfies the second target value. The first operating parameter may be controlled to reduce the deviation between the current value of the first performance parameter and the first target value.

[0097] When the first performance parameter satisfies the first target value and the second performance parameter does not satisfy the second target value, the controller 120 may control a second operating parameter of the plurality of operating parameters that affects the second performance parameter. The second operating parameter may be controlled so as to reduce the deviation between the current value of the second performance parameter and the second target value. The second operating parameter may be different from the first operating parameter. The first operating parameter may be the operating frequency of the compressor motor 24 (or the operating frequency of the expander motor 42), and the second operating parameter may be controlled so as to reduce the deviation between the current value of the second performance parameter and the second target value. 2. Luck The operating parameter may be the operating frequency of the expander motor 42 (or the operating frequency of the compressor motor 24).

[0098] Below are some examples of the control algorithm 122. The first example is the above-mentioned operation mode 4 (where the first performance parameter is the second-stage temperature and the second performance parameter is the first-stage temperature). In one example of the control algorithm 122 corresponding to operation mode 4, the operation parameters are controlled as follows for each of the nine states from state Aa to state Cc. State Aa: Maintain operating parameters. State Ab: Maintain operating parameters. State Ac: The operating frequency of the compressor motor 24 is increased. State Ba: Maintain operating parameters. State Bb: Maintain operating parameters. State Bc: The operating frequency of the compressor motor 24 is increased. State Ca: The operating frequency of the expander motor 42 is changed. State Cb: The operating frequency of the expander motor 42 is changed. State Cc: The operating frequency of the compressor motor 24 is increased.

[0099] In six states from state Aa to state Bc, the second stage temperature, which is the first performance parameter, meets its target value. In states Aa, Ab, Ba, and Bb, the first stage temperature, which is the second performance parameter, also meets its target value, so there is no need to change the operating parameters and they are maintained.

[0100] In states Ac and Bc, the operating parameters are controlled so that the first stage temperature, which is the second performance parameter, satisfies a target value while the second stage temperature, which is the first performance parameter, satisfies a target value. State Ac is expected to transition to state Ab as a result of an increase in the operating frequency of the compressor motor 24, resulting in a decrease in the first stage temperature (and second stage temperature). If the operating frequency of the compressor motor 24 has already reached the highest value (e.g., 70 Hz) in the adjustable range, the operating frequency of the expander motor 42 may be increased instead of increasing the operating frequency of the compressor motor 24 (in this case, a transition to state Ab or state Bb is expected. In the unlikely event of a transition to state Cb, a warning is issued). State Bc is also expected to transition to state Ab or state Ac as a result of an increase in the operating frequency of the compressor motor 24, resulting in a decrease in the first stage temperature (and second stage temperature).

[0101] From state Ca to state Cc, the operating parameters are controlled so that the second-stage temperature, which is the first performance parameter, satisfies the target value. States Ca and Cb are expected to transition to either state Ba or state Bc as a result of increasing (or decreasing) the operating frequency of the expander motor 42. If state Ca is maintained despite this optimization of the operating frequency of the expander motor 42, the operating frequency of the compressor motor 24 may be increased (in this case, a transition to either state Ba or state Bc is expected. If state Ca is still maintained, a warning is issued). State Cc is expected to transition to state Bc or state Cb as a result of the increase in the operating frequency of the compressor motor 24. If state Cc is still maintained, the operating frequency of the expander motor 42 may be decreased (in this case, a transition to state Bc is expected. If state Cc is still maintained, a warning is issued).

[0102] The second example is operation mode 6 (where the first performance parameter is second-stage temperature and the second performance parameter is power consumption). In one example of control algorithm 122 corresponding to operation mode 6, the operation parameters are controlled as follows for each of the nine states from state Aa to state Cc. State Aa: Maintain operating parameters. State Ab: Maintain operating parameters. State Ac: The operating frequency of the compressor motor 24 is reduced. State Ba: Maintain operating parameters. State Bb: Maintain operating parameters. State Bc: The operating frequency of the expander motor 42 is changed. State Ca: The operating frequency of the compressor motor 24 is increased. State Cb: The operating frequency of the compressor motor 24 is increased. State Cc: The operating frequency of the compressor motor 24 is increased.

[0103] In six states from state Aa to state Bc, the second-stage temperature, which is the first performance parameter, meets its target value. Among these, states Aa, Ab, Ba, and Bb also meet the target value for power consumption, which is the second performance parameter, so there is no need to change the operating parameters and they are maintained. In states Aa and Ab, the operating frequency of the compressor motor 24 may be lowered to further reduce power consumption (in this case, a transition to state Ba may occur).

[0104] In states Ac and Bc, the operating parameters are controlled so that the second performance parameter, power consumption, meets a target value while the second performance parameter, second-stage temperature, meets a target value. State Ac is expected to transition to state Ab or Bb as a result of a decrease in the operating frequency of the compressor motor 24. State Bc is expected to transition to state Ab or Bb as a result of a change in the operating frequency of the expander motor 42 (if state Bc is still maintained, a warning is issued).

[0105] From state Ca to state Cc, the operating parameters are controlled so that the second-stage temperature, which is the first performance parameter, meets the target value. State Ca can transition to state Ba or Cb as a result of an increase in the operating frequency of the compressor motor 24. State Cb can transition to state Bc or Cc as a result of an increase in the operating frequency of the compressor motor 24. State Cc can transition to state Bc as a result of an increase in the operating frequency of the compressor motor 24 (if no transition occurs, the operating frequency of the expander motor 42 can be changed to transition to state Bc. If state Cc is still maintained, a warning is issued).

[0106] A third example is operation mode 7 (where the first performance parameter is power consumption and the second performance parameter is two-stage temperature). In one example of control algorithm 122 corresponding to operation mode 7, the operation parameters are controlled as follows for each of the nine states from state Aa to state Cc. State Aa: Maintain operating parameters. State Ab: Maintain operating parameters. State Ac: The operating frequency of the expander motor 42 is changed. State Ba: Maintain operating parameters. State Bb: Maintain operating parameters. State Bc: The operating frequency of the expander motor 42 is changed. State Ca: The operating frequency of the compressor motor 24 is reduced. State Cb: The operating frequency of the compressor motor 24 is reduced. State Cc: The operating frequency of the compressor motor 24 is reduced.

[0107] In the six states from state Aa to state Bc, the power consumption, which is the first performance parameter, meets its target value. Among these, in states Aa, Ab, Ba, and Bb, the second-stage temperature, which is the second performance parameter, also meets its target value, so there is no need to change the operating parameters and they are maintained. Note that in state Aa, it is possible to aim for further reduction in power consumption by lowering the operating frequency of the compressor motor 24 (in this case, a transition to state Ab may occur).

[0108] In states Ac and Bc, the operating parameters are controlled so that the first performance parameter, power consumption, satisfies a target value, while the second performance parameter, second-stage temperature, satisfies a target value. State Ac is expected to transition to state Ab or Bc as a result of an increase (or decrease) in the operating frequency of the expander motor 42. If state Ac is maintained despite such optimization of the operating frequency of the expander motor 42, the operating frequency of the compressor motor 24 may be increased, resulting in a transition to state Ab or Bc. State Bc is expected to transition to state Ab or Bb as a result of an increase (or decrease) in the operating frequency of the expander motor 42 (if state Bc is still maintained, a warning is issued).

[0109] From state Ca to state Cc, the operating parameters are controlled so that the power consumption, which is the first performance parameter, meets the target value. State Ca can transition to state Ba or Cb as a result of a reduction in the operating frequency of the compressor motor 24. State Cb can transition to state Bb or Bc as a result of a reduction in the operating frequency of the compressor motor 24. State Cc can transition to state Bc as a result of a reduction in the operating frequency of the compressor motor 24.

[0110] As mentioned at the beginning of this book, existing superconducting equipment cooling systems are often operated under the default operating conditions set by their manufacturers. For example, the cooling system can be operated with sufficient reserve capacity. This is advantageous because it allows stable operation of the superconducting equipment even in the event of various anticipated emergencies or other unforeseen circumstances. However, the reality is that users of superconducting equipment have little room to adjust the operating conditions of the cooling system at their own discretion, for example, from other perspectives such as energy conservation.

[0111] In contrast, with the superconducting equipment cooling device according to the embodiment, the user can select the performance parameters of the cryogenic refrigerator 10 to achieve the operating state that the user considers desirable. The cryogenic refrigerator 10 controls the operating parameters so that the selected performance parameters meet the target values, thereby achieving the operating state that the user desires. Furthermore, if the desired operating state is not achieved, a warning can be issued to notify the user. Therefore, the usability of the superconducting equipment cooling device can be improved.

[0112] The present invention has been described above based on examples. It will be understood by those skilled in the art that the present invention is not limited to the above-described embodiments, and that various design changes and modifications are possible, and that such modifications are also within the scope of the present invention. Various features described in relation to one embodiment can also be applied to other embodiments. A new embodiment created by combining embodiments will have the combined effects of the respective combined embodiments.

[0113] In the above-described embodiment, the first-stage temperature, second-stage temperature, and power consumption are exemplified as performance parameters of the cryocooler 10, but other performance parameters may be used. For example, if the superconducting magnet device 100 is an immersion-cooled type, the pressure of a liquid refrigerant tank (e.g., a liquid helium tank) in the vacuum vessel 104 may be used as a performance parameter. Because the liquid refrigerant in the liquid refrigerant tank is cooled by the second cooling stage 35, the pressure of the liquid refrigerant tank correlates with the second-stage temperature. Therefore, the pressure of the liquid refrigerant tank may be used as a performance parameter instead of the second-stage temperature.

[0114] In the above-described embodiment, the operating frequencies of the compressor motor 24 and the expander motor 42 are exemplified as the operating parameters of the cryogenic refrigerator 10, but other operating parameters may be used. For example, if a first heater for heating the first cooling stage 33 and / or a second heater for heating the second cooling stage 35 are provided, the heater output may be used as the operating parameter.

[0115] Although the above-described embodiment has been described as an example of a two-stage GM refrigerator, the present invention is not limited thereto. In some embodiments, the cryocooler 10 may be a single-stage GM refrigerator. In some embodiments, the cryocooler 10 may be another type of cryocooler, such as a Solvay refrigerator, a Stirling refrigerator, or a pulse tube refrigerator.

[0116] In the above embodiment, the cryocooler 10 is used to cool the superconducting magnet device 100, but the present invention is not limited to this. In some embodiments, the cryocooler 10 may provide cryogenic cooling for other superconducting devices, such as devices for power transmission using superconductivity and sensor devices using superconductivity.

[0117] The present invention has been described using specific terms based on the embodiments, but the embodiments merely illustrate one aspect of the principles and applications of the present invention, and many modifications and changes in arrangement are permitted to the embodiments as long as they do not deviate from the concept of the present invention as defined in the claims. [Explanation of symbols]

[0118] 10 cryogenic refrigerator, 12 compressor, 14 expander, 24 compressor motor, 25 compressor inverter, 42 expander motor, 45 expander inverter, 1 10 Interface, 120 Controller, 122 Control Algorithm.

Claims

1. A cryogenic refrigerator that cools superconducting equipment, an interface configured to accept a user selection of a plurality of performance parameters of the cryogenic refrigerator and generate an operational mode configuration representative of the selected performance parameters; a controller configured to receive the operating mode setting from the interface and to control a plurality of operating parameters of the cryogenic refrigerator that affect the selected plurality of performance parameters.

2. The setting of the operating mode includes a user prioritizing a plurality of performance parameters of the cryogenic refrigerator; the selected plurality of performance parameters include a first performance parameter having a first priority and a second performance parameter having a second priority based on the prioritization, the first priority representing a higher priority than the second priority; 2. The superconducting equipment cooling system of claim 1, wherein the controller is configured to control the plurality of operating parameters to preferentially improve the first performance parameter relative to the second performance parameter.

3. The controller comparing a current value of the first performance parameter to a first target value; 3. The superconducting equipment cooling device according to claim 2, wherein when the first performance parameter does not satisfy the first target value, a first operating parameter of the plurality of operating parameters that affects the first performance parameter is controlled regardless of whether the second performance parameter satisfies a second target value.

4. The controller comparing the current value of the second performance parameter to the second target value; 4. The superconducting equipment cooling device according to claim 3, wherein, when the first performance parameter satisfies the first target value and the second performance parameter does not satisfy the second target value, a second operating parameter of the plurality of operating parameters that affects the second performance parameter is controlled.

5. The controller issuing a first warning when the first performance parameter does not satisfy the first target value, regardless of whether the second performance parameter satisfies a second target value; 5. The superconducting equipment cooling device according to claim 4, wherein a second warning is issued when the first performance parameter satisfies the first target value and the second performance parameter does not satisfy the second target value.

6. the controller includes a plurality of control algorithms, each corresponding to a different operating mode setting; 10. The superconducting equipment cooling system of claim 1, wherein each control algorithm is configured to control the plurality of operating parameters to improve at least one performance parameter of the plurality of selected performance parameters in a corresponding operating mode setting.

7. 2. The superconducting equipment cooling device according to claim 1, wherein the selected performance parameters are two of a first-stage temperature of the cryogenic refrigerator, a second-stage temperature of the cryogenic refrigerator, and power consumption of the cryogenic refrigerator.

8. The cryogenic refrigerator includes an expander and a compressor that supplies refrigerant gas to the expander, The expander includes an expander motor that drives the expander, and an expander inverter that controls an operating frequency of the expander motor, the compressor includes a compressor motor that drives the compressor and a compressor inverter that controls an operating frequency of the compressor motor; 2. The superconducting equipment cooling device according to claim 1, wherein the plurality of operating parameters include an operating frequency of the compressor motor and an operating frequency of the expander motor.

9. A method of operating a superconducting equipment cooling apparatus, the superconducting equipment cooling apparatus including a cryogenic refrigerator for cooling a superconducting equipment, the method comprising: accepting a user selection of a plurality of performance parameters of the cryogenic refrigerator; generating an operating mode configuration representative of a selected plurality of performance parameters; and controlling a plurality of operating parameters of the cryogenic refrigerator that affect the selected plurality of performance parameters in accordance with the operating mode setting.

Images