DC magnetic field superconducting coil power supply unit

Abstract

A current ripple is reduced in a DC magnetic field superconducting coil power supply device used in a DC magnetic field generator using a superconducting coil. [Solution] The device comprises a superconducting coil, a power supply device capable of supplying DC voltage, a plurality of chopper circuits connected in parallel between one end of the power supply device and one end of the superconducting coil, a resistor connected in parallel with the superconducting coil, and a control unit that controls the chopper circuits, and the control unit operates the plurality of chopper circuits in a time-division manner when the superconducting coil is being charged.

Description

[Technical Field]

[0001] The present disclosure relates to a DC magnetic field superconducting coil power supply device. [Background technology]

[0002] Conventionally, a DC magnetic field generator using a superconducting coil has been known. In order to generate a high magnetic field using a DC magnetic field generator using a superconducting coil, it is usually necessary to pass a large current through the superconducting coil.

[0003] Patent Document 1 discloses a technique for reducing the average current supplied by the power supply current and reducing costs by operating the plurality of chopper circuits in a time-division manner when charging a superconducting coil. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2022 / 249514 Summary of the Invention [Problem to be solved by the invention]

[0005] In the configuration disclosed in Patent Document 1, the voltage of the superconducting coil is a square wave, which causes a slight ripple in the current flowing through the superconducting coil. As a result, no voltage is applied to the superconducting coil during the zero voltage period of the square wave, which lengthens the charging time.

[0006] An object of the present disclosure is to reduce current ripple in a DC magnetic field superconducting coil power supply device used in a DC magnetic field generating device using a superconducting coil. [Means for solving the problem]

[0007] The DC magnetic field superconducting coil power supply device according to the present disclosure comprises: a superconducting coil; a power supply device capable of supplying DC voltage; a plurality of chopper circuits connected in parallel between one end of the power supply device and one end of the superconducting coil; a resistor connected in parallel with the superconducting coil; a control unit that controls the chopper circuit, The control unit operates the plurality of chopper circuits in a time-division manner when the superconducting coil is being charged.

[0008] In the DC magnetic field superconducting coil power supply device according to the present disclosure, the resistor is switchable between a superconducting state and a non-superconducting state; The control unit controls the resistor to the non-superconducting state during charging, and controls the resistor to the superconducting state when charging of the superconducting coil is completed and the state transitions to the non-charging state.

[0009] In the DC magnetic field superconducting coil power supply device according to the present disclosure, further comprising a low resistance switch capable of short-circuiting both ends of the superconducting coil; When the current flowing through the superconducting coil reaches or exceeds a predetermined threshold, the control unit controls the low resistance switch to turn on, thereby short-circuiting both ends of the superconducting coil.

[0010] In the DC magnetic field superconducting coil power supply device according to the present disclosure, The power supply further includes a diode connected in parallel with the superconducting coil and the resistor. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to reduce current ripples in a DC magnetic field superconducting coil power supply device used in a DC magnetic field generator using a superconducting coil. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing the configuration of a DC magnetic field superconducting coil power supply device according to an embodiment of the present disclosure. [Figure 2]FIG. 2 is a diagram illustrating an example of the configuration of a chopper circuit. [Figure 3] FIG. 1 is a diagram illustrating an example of the configuration of a low-resistance switch. [Figure 4] 10 is a timing chart showing an example of the on / off timing of a switch of a chopper circuit. [Figure 5] 10 is a flowchart illustrating an example of the operation of a DC magnetic field superconducting coil power supply device according to an embodiment of the present disclosure. [Figure 6] FIG. 10 is a diagram showing the configuration of a DC magnetic field superconducting coil power supply device according to a first modified example of the present disclosure. [Figure 7] FIG. 10 is a diagram showing the configuration of a DC magnetic field superconducting coil power supply device according to a second modified example of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0014] FIG. 1 is a diagram showing the configuration of a DC magnetic field superconducting coil power supply device 1 according to an embodiment of the present disclosure.

[0015] The DC magnetic field superconducting coil power supply device 1 includes a power supply device 11, first leads 12-1 to 12-2, chopper circuits 13-1 to 13-8, a low resistance switch 14, a current sensor 15, second leads 16-1 to 16-2, a superconducting coil 17, a control unit 18, and a resistor 19.

[0016] Hereinafter, the first leads 12-1 and 12-2 may be simply referred to as "first leads 12" when there is no particular need to distinguish between them.

[0017] Hereinafter, when there is no particular need to distinguish between the chopper circuits 13-1 to 13-8, they may be simply referred to as "chopper circuits 13."

[0018] Hereinafter, the second leads 16-1 to 16-2 may be simply referred to as "second leads 16" when there is no particular need to distinguish between them.

[0019] The first lead 12 , chopper circuit 13 , low resistance switch 14 , current sensor 15 , second lead 16 , superconducting coil 17 , control unit 18 and resistor 19 are installed inside the cooling vessel 5 .

[0020] The cooling vessel 5 is a device capable of cooling the inside to a low temperature. For example, the cooling vessel 5 is capable of cooling the inside to about 20K.

[0021] The power supply device 11 is a device capable of supplying a DC voltage. The power supply device 11 may include, for example, an AC / DC converter that converts an AC voltage supplied from a commercial power source or the like into a DC voltage. The DC voltage supplied by the power supply device 11 may be, for example, about 6 V.

[0022] A first lead 12-1 and a first lead 12-2 are connected to two output terminals of the power supply device 11. One output terminal of the power supply device 11 is connected to a plurality of chopper circuits 13-1 to 13-8 via the first lead 12-1. In this embodiment, the term "connected" means not only direct connection but also indirect connection. The other output terminal of the power supply device 11 is connected to a resistor 19, a low-resistance switch 14, and a second lead 16-2 via the first lead 12-2. In addition, the first lead 12-2, the second lead 16-2, the low-resistance switch 14, and the resistor 19 are connected to the ground of each chopper circuit 13.

[0023] The first lead 12 is a conductor capable of passing an electric current.

[0024] The plurality of chopper circuits 13-1 to 13-8 are connected in parallel between one end of the power supply device 11 and one end of the superconducting coil 17.

[0025] One of the plurality of chopper circuits 13-1 to 13-8 connected in parallel is connected to one end of power supply device 11 via first lead 12-1. The other of the plurality of chopper circuits 13-1 to 13-8 connected in parallel is connected to one end of superconducting coil 17 via current sensor 15 and second lead 16-1. The ground of each chopper circuit 13 is connected to low resistance switch 14 and resistor 19, and is connected to the other end of power supply device 11 via first lead 12-2 and the other end of superconducting coil 17 via second lead 16-2.

[0026] In this embodiment, a configuration in which eight chopper circuits 13-1 to 13-8 are connected in parallel will be described as an example, but the number of chopper circuits 13 connected in parallel is not limited to 8. The number of chopper circuits 13 connected in parallel may be any number equal to or greater than two.

[0027] The chopper circuit 13-1 includes a first switch SA1, a second switch SB1, and an inductor L1. Similarly, the chopper circuit 13-2 includes a first switch SA2, a second switch SB2, and an inductor L2. Similarly, the chopper circuit 13-8 includes a first switch SA8, a second switch SB8, and an inductor L8. The chopper circuits 13-3 to 13-7 are not shown in FIG.

[0028] Since the chopper circuits 13-1 to 13-8 have the same configuration, the chopper circuit 13-1 will be taken as an example for explanation.

[0029] The first switch SA1 and inductor L1 of the chopper circuit 13-1 connect in series one end of the power supply device 11 and one end of the superconducting coil 17. The second switch SB1 connects a node between the first switch SA1 and the inductor L1 to ground.

[0030] Chopper circuit 13-1 charges superconducting coil 17 and inductor L1 with a current supplied from power supply device 11 when first switch SA1 is on and second switch SB1 is off.

[0031] The first switch SA1 and the second switch SB1 of the chopper circuit 13-1 are controlled by the control unit 18.

[0032] 2 shows an example of the circuit configuration of the chopper circuit 13-1. As shown in FIG. 2, the first switch SA1 and the second switch SB1 may be MOSFETs. The first switch SA1 may be a P-channel MOSFET. The second switch SB1 may be an N-channel MOSFET.

[0033] When the first switch SA1 and the second switch SB1 are MOSFETs, the gates of the MOSFETs are controlled by the control unit 18.

[0034] By using MOSFETs as the first switch SA1 and the second switch SB1, the operation speed of the first switch SA1 and the second switch SB1 can be increased. Furthermore, by using MOSFETs as the first switch SA1 and the second switch SB1, the on-resistance of the MOSFETs is small, so that the conduction loss of the first switch SA1 and the second switch SB1 can be reduced.

[0035] Since the chopper circuit 13-1 is installed inside the cooling container 5, the on-resistance of the first switch SA1 and the second switch SB1 is smaller than when they are installed at room temperature. Also, since the chopper circuit 13-1 is installed inside the cooling container 5, the series resistance value of the inductor L1 is smaller than when they are installed at room temperature.

[0036] Low-resistance switch 14 is a switch that can short-circuit both ends of superconducting coil 17. One end of low-resistance switch 14 is connected to one end of superconducting coil 17 via current sensor 15 and second lead 16-1. The other end of low-resistance switch 14 is connected to the other end of superconducting coil 17 via second lead 16-2.

[0037] It should be noted that low resistance switch 14 short-circuiting both ends of superconducting coil 17 does not mean a complete short circuit, but means that low resistance switch 14 connects both ends of superconducting coil 17 with a resistance value equal to or less than a predetermined resistance value. The predetermined resistance value may be, for example, about 0.01 to 0.1 mΩ.

[0038] The on / off of low-resistance switch 14 is controlled by control unit 18. While superconducting coil 17 is being charged, low-resistance switch 14 is off. That is, while superconducting coil 17 is being charged, low-resistance switch 14 does not short-circuit both ends of superconducting coil 17. When charging of superconducting coil 17 is complete, low-resistance switch 14 is turned on. That is, when charging of superconducting coil 17 is complete, low-resistance switch 14 short-circuits both ends of superconducting coil 17 and transitions to a non-charging state.

[0039] When charging of the superconducting coil 17 is completed and the low resistance switch 14 is turned on, a current flows through the closed loop connecting the low resistance switch 14, the current sensor 15, the second lead 16-1, the superconducting coil 17 and the second lead 16-2.

[0040] 3 shows an example of the circuit configuration of the low-resistance switch 14. The low-resistance switch 14 may have a configuration in which a plurality of parallel circuits, each of which is made up of a MOSFET 141 and a diode 142, are connected in parallel. The low-resistance switch 14 may also have a configuration including a MOSFET 141 having a plurality of parasitic diodes connected in parallel. The low-resistance switch 14 may have a configuration in which, for example, ten parallel circuits, each of which is made up of a MOSFET 141 and a diode 142, are connected in parallel. Note that the MOSFET 141 may be a type of circuit element other than a MOSFET, as long as it can function as a switch.

[0041] Since the low resistance switch 14 is installed inside the cooling vessel 5, the on-resistance of the MOSFET 141 is smaller than when it is installed at room temperature.

[0042] In this way, by configuring low resistance switch 14 to include low loss MOSFET 141, it is possible to reduce loss when current is passed through superconducting coil 17 in a closed loop.

[0043] The current sensor 15 detects the current flowing through the superconducting coil 17. The current sensor 15 may be, for example, a CT (Current Transformer).

[0044] The second lead 16 is a conductor capable of passing a current. The second lead 16 may be, for example, a superconducting current lead. Since the resistance value of a superconducting current lead is approximately zero, the cross-sectional area of ​​the lead can be reduced. Therefore, the superconducting current lead has high thermal insulation properties, and can suppress the transfer of heat to the superconducting coil 17.

[0045] The superconducting coil 17 may include a coil formed from high-temperature superconducting wire. The superconducting coil 17 may be, for example, an uninsulated coil in which a metal tape of a relatively high-resistance normal-conducting material is sandwiched between coil-shaped high-temperature superconducting wire. If the superconducting coil 17 is an uninsulated coil, deterioration of the mechanical properties of the superconducting coil 17 can be prevented. Furthermore, if the superconducting coil 17 is an uninsulated coil, thermal runaway of the superconducting coil 17 can be suppressed, improving stability.

[0046] The control unit 18 controls the operation of the chopper circuit 13. The control unit 18 controls the operations of the chopper circuits 13-1 to 13-8 by controlling the first switches SA1 to SA8 and the second switches SB1 to SB8.

[0047] Control unit 18 operates multiple chopper circuits 13-1 to 13-8 in a time-division manner when charging superconducting coil 17. Details of the control of multiple chopper circuits 13-1 to 13-8 by control unit 18 will be described later.

[0048] The control unit 18 may have a configuration including a logic IC without including a processor such as a CPU (Central Processing Unit), or may have a configuration including a processor such as a CPU.

[0049] If the control unit 18 is configured not to include a processor such as a CPU, it is possible to improve the reliability of the control unit 18. Alternatively, if the control unit 18 is configured to include a processor such as a CPU, the control unit 18 can perform advanced processing.

[0050] Resistor 19 smoothes the voltage applied to superconducting coil 17. Current ripple is reduced by smoothing the voltage applied to superconducting coil 17. Resistor 19 is connected in parallel with superconducting coil 17.

[0051] Next, the operation of the DC magnetic field superconducting coil power supply device 1 to charge the superconducting coil 17 will be described in detail.

[0052] When charging of superconducting coil 17 starts, control unit 18 controls low resistance switch 14 to be turned off.

[0053] Subsequently, the control unit 18 operates the plurality of chopper circuits 13 in a time-division manner to charge the superconducting coil 17 .

[0054] Operating the multiple chopper circuits 13 in a time-division manner means dividing the time of one cycle by the number of chopper circuits 13 and operating one chopper circuit 13 during each divided time. In other words, the control unit 18 operates each chopper circuit 13 once during one cycle.

[0055] 1, the number of chopper circuits 13 is eight. Control of chopper circuits 13-1 to 13-8 by control unit 18 when the number of chopper circuits 13 is eight will be described with reference to the timing chart shown in FIG.

[0056] The control unit 18 divides one cycle into eight parts, and in the example shown in FIG. 4, operates each chopper circuit 13 in turn for each 1 / 8 cycle. One cycle is the time from t1 to t17. The control unit 18 operates chopper circuit 13-1 from t1 to t3. The control unit 18 operates chopper circuit 13-2 from t3 to t5. The control unit 18 operates chopper circuit 13-8 from t15 to t17. Note that in the timing chart shown in FIG. 4, the control of chopper circuits 13-3 to 13-7 is omitted.

[0057] Between t1 and t2, the control unit 18 controls the first switch SA1 of the chopper circuit 13-1 to be on and the second switch SB1 to be off. At this time, the control unit 18 controls the first switches SA2 to SA8 of the other chopper circuits 13-2 to 13-8 to be off and the second switches SB2 to SB8 to be on.

[0058] By this control, the inductor L1 and the superconducting coil 17 of the chopper circuit 13-1 are charged by the current supplied from the power supply device 11 between t1 and t2.

[0059] Subsequently, from t2 to t3, the control unit 18 controls the first switch SA1 of the chopper circuit 13-1 to be off and the second switch SB1 to be on. At this time, the control unit 18 controls the first switches SA2 to SA8 of the other chopper circuits 13-2 to 13-8 to be off and the second switches SB2 to SB8 to be on.

[0060] Subsequently, from t3 to t4, the control unit 18 controls the first switch SA2 of the chopper circuit 13-2 to be on and the second switch SB2 to be off. At this time, the control unit 18 controls the first switches SA1 and SA3 to SA8 of the other chopper circuits 13-1 and 13-3 to 13-8 to be off and the second switches SB1 and SB3 to SB8 to be on.

[0061] By this control, the inductor L2 and the superconducting coil 17 of the chopper circuit 13-2 are charged by the current supplied from the power supply device 11 from t3 to t4.

[0062] Subsequently, from t4 to t5, the control unit 18 controls the first switch SA2 of the chopper circuit 13-2 to be off and the second switch SB2 to be on. At this time, the control unit 18 controls the first switches SA1 and SA3 to SA8 of the other chopper circuits 13-1 and 13-3 to 13-8 to be off and the second switches SB1 and SB3 to SB8 to be on.

[0063] The control unit 18 repeats this process sequentially for the chopper circuits 13-3 to 13-8. When the operation of the chopper circuit 13-8 ends, that is, when t17 shown in Fig. 4 is reached, the control unit 18 returns to the process of operating the chopper circuit 13-1, and repeats the same process.

[0064] In this manner, control unit 18 charges superconducting coil 17 by repeating the processes shown in t1 to t17 of FIG.

[0065] While superconducting coil 17 is being charged, control unit 18 acquires the value of the current flowing through superconducting coil 17 from current sensor 15, which detects the current through superconducting coil 17. When control unit 18 determines that the current flowing through superconducting coil 17 has reached a predetermined threshold or greater, it terminates the charging process for superconducting coil 17. Furthermore, when control unit 18 determines that the current flowing through superconducting coil 17 has reached a predetermined threshold or greater, it controls low resistance switch 14 to turn on, shorting both ends of superconducting coil 17 and transitioning to a non-charging state.

[0066] The predetermined threshold may be the value of the current that needs to be passed through superconducting coil 17 in order to generate a predetermined DC magnetic field. The predetermined threshold may be, for example, about 300A.

[0067] When the low resistance switch 14 is turned on, a current flows through a closed loop that connects the low resistance switch 14, the current sensor 15, the second lead 16-1, the superconducting coil 17, and the second lead 16-2.

[0068] In this way, the DC magnetic field superconducting coil power supply device 1 according to this embodiment charges the superconducting coil 17 using eight chopper circuits 13 connected in parallel. Therefore, when charging the superconducting coil 17 so that a current of 300 A flows through the superconducting coil 17, the average current flowing through one chopper circuit 13 is 300 A / 8=37.5 A.

[0069] Because chopper circuits 13-1 to 13-8 operate in a time-division manner, power supply device 11 only needs to be able to supply an average current of about 37.5 A. Therefore, power supply device 11 can be a low-cost power supply device compared to a power supply device that can supply 300 A.

[0070] Furthermore, when charging superconducting coil 17 so that a current of 300 A flows through superconducting coil 17, first lead 12 only needs to be able to pass a current of about 37.5 A on average. Therefore, the cross-sectional area of ​​first lead 12 can be made smaller than that of a current lead that can pass 300 A. By making the cross-sectional area of ​​first lead 12 smaller, the amount of heat that enters cooling vessel 5 from the outside through first lead 12 can be reduced.

[0071] Furthermore, each chopper circuit 13 only needs to be able to pass an average current of about 37.5 A. Therefore, the chopper circuit 13 can be made smaller than a chopper circuit that can pass 300 A. This makes it easier to install the chopper circuit 13 inside the cooling vessel 5.

[0072] When the charging process of superconducting coil 17 is completed, control unit 18 may control first switches SA1 to SA8 and second switches SB1 to SB8 of chopper circuits 13-1 to 13-8 to be turned off.

[0073] Alternatively, when the charging process of superconducting coil 17 is completed, control unit 18 may control first switches SA1 to SA8 of chopper circuits 13-1 to 13-8 to be turned off, and control second switches SB1 to SB8 of chopper circuits 13-1 to 13-8 to be turned on.

[0074] When the second switches SB1 to SB8 of the chopper circuits 13-1 to 13-8 are controlled to be turned on, a series configuration of the inductor L1 and the second switch SB1, a series configuration of the inductor L2 and the second switch SB2, and a series configuration of the inductor L8 and the second switch SB8 are connected in parallel to the low-resistance switch 14, and the resistance value across the low-resistance switch 14 when the low-resistance switch 14 is turned on can be further reduced. For example, when the resistance value of the series-parallel configuration of the inductors L1 to L8 and the second switches SB1 to SB8 when they are on is small, such as when the inductors L1 to L8 are superconducting coils, the low-resistance switch 14 may be omitted.

[0075] The control unit 18 can adjust the duty ratio when operating the chopper circuit 13. Taking the chopper circuit 13-1 as an example, the duty ratio is the ratio of the time during which the first switch SA1 is on to the time during which the chopper circuit 13-1 is operating. That is, in FIG. 4, if the time from t1 to t3 during which the chopper circuit 13-1 is operating is defined as TA, and the time from t1 to t2 during which the first switch SA1 is on is defined as TB, the duty ratio is expressed as TB / TA.

[0076] Control unit 18 can adjust the duty ratio to adjust the charging capacity for superconducting coil 17. Control unit 18 can maximize the charging capacity for superconducting coil 17 by setting the duty ratio close to 100%, for example.

[0077] When superconducting coil 17 is being charged, the voltage applied to superconducting coil 17 temporarily becomes 0 when the first switches of all chopper circuits are turned off, for example, from t2 to t3, due to the operation of chopper circuit 13. When the applied voltage becomes 0, a ripple occurs in the current flowing through superconducting coil 17.

[0078] By connecting resistor 19 in parallel with superconducting coil 17, the voltage applied to superconducting coil 17 is smoothed even when the first switches of all chopper circuits are turned off, thereby preventing the generation of ripple current.

[0079] The control unit 18 may control the power supply device 11 to slightly increase the voltage output from the power supply device 11 in order to compensate for the voltage drop while the first switches of all chopper circuits 13 are off.

[0080] The operation of the DC magnetic field superconducting coil power supply device 1 will be described with reference to the flowchart shown in FIG.

[0081] Control unit 18 controls low resistance switch 14 to be turned off (step S101). Thereafter, control unit 18 controls first switches SA1 to SA8 and second switches SB1 to SB8 of chopper circuits 13-1 to 13-8 as shown in the timing chart of FIG. 4, thereby charging superconducting coil 17 (step S102).

[0082] While superconducting coil 17 is being charged, control unit 18 acquires from current sensor 15 the value of the current flowing through superconducting coil 17 detected by current sensor 15 (step S103).

[0083] Control unit 18 determines whether the current flowing through superconducting coil 17 is equal to or greater than a predetermined threshold value (step S104).

[0084] If the current flowing through superconducting coil 17 is less than the predetermined threshold value (No in step S104), control unit 18 returns to step S103.

[0085] If the current flowing through superconducting coil 17 is equal to or greater than the predetermined threshold (Yes in step S104), control unit 18 stops charging superconducting coil 17 (step S105). After stopping charging, control unit 18 controls low-resistance switch 14 to turn on (step S106).

[0086] (First Modification) A DC magnetic field superconducting coil power supply device 1a according to a first modified example of the present disclosure will be described below with reference to Fig. 6. Fig. 6 is a diagram showing the configuration of a DC magnetic field superconducting coil power supply device 1a according to a first modified example of the present disclosure. The DC magnetic field superconducting coil power supply device 1a is the same as the DC magnetic field superconducting coil power supply device 1 shown in Fig. 1 except that it includes a resistor 20 connected in parallel with the superconducting coil 17 instead of resistor 19.

[0087] Resistor 20 is a resistor that can be switched between a superconducting state and a non-superconducting state. Control unit 18 controls the state of resistor 20 so that resistor 20 is in the non-superconducting state when superconducting coil 17 is being charged, and is in the superconducting state when charging of superconducting coil 17 is completed.

[0088] In order for resistor 20 to transition from a non-superconducting state to a superconducting state, it is necessary to cool resistor 20. Therefore, after charging of superconducting coil 17 is completed, a certain amount of time is required for resistor 20 to transition from a non-superconducting state to a superconducting state.

[0089] Therefore, after the charging of the superconducting coil 17 is completed, the control unit 18 turns on the low-resistance switch 14 until the resistor 20 transitions to a superconducting state, causing a current to flow through a closed loop connecting the low-resistance switch 14, the current sensor 15, the second lead 16-1, the superconducting coil 17, and the second lead 16-2.

[0090] When resistor 20 transitions to the superconducting state, control unit 18 turns off low-resistance switch 14. This causes current to flow through a closed loop connecting current sensor 15, second lead 16-1, superconducting coil 17, second lead 16-2, and resistor 20. Alternatively, control unit 18 may keep low-resistance switch 14 on.

[0091] With this configuration, when charging superconducting coil 17, resistor 20 serves as a significant resistance and can smooth the voltage applied to superconducting coil 17. Furthermore, when charging of superconducting coil 17 is completed, resistor 20 enters a superconducting state with zero resistance, so that the loss of the current flowing through superconducting coil 17 can be reduced to almost zero.

[0092] (Second Modification) A DC magnetic field superconducting coil power supply device 1b according to a second modified example of the present disclosure will be described below with reference to Fig. 7. Fig. 7 is a diagram showing the configuration of DC magnetic field superconducting coil power supply device 1b according to the second modified example of the present disclosure. DC magnetic field superconducting coil power supply device 1b is the same as DC magnetic field superconducting coil power supply device 1a shown in Fig. 6 except that it includes a diode 21 connected in parallel with superconducting coil 17 instead of low resistance switch 14.

[0093] In the second modification, by connecting resistor 20 in parallel with superconducting coil 17, resistor 20 in a non-superconducting state serves as a significant resistance to smooth the voltage applied to superconducting coil 17 during charging of superconducting coil 17. Furthermore, by connecting diode 21 in parallel with superconducting coil 17, a closed loop can be formed that connects current sensor 15, second lead 16-1, superconducting coil 17, second lead 16-2, and diode 21 until resistor 20 transitions to a superconducting state after charging of superconducting coil 17 is completed. This prevents resistor 20 from generating a voltage as a significant resistance. Furthermore, the number of parts can be reduced compared to when low-resistance switch 14 is used, thereby reducing costs.

[0094] The present disclosure is not limited to the above-described embodiments. For example, multiple blocks shown in the block diagrams may be integrated, or a single block may be divided. Other modifications may be made without departing from the spirit of the present disclosure.

[0095] For example, in the above embodiment, an example was described in which eight chopper circuits 13 are connected in parallel, but the number of chopper circuits 13 connected in parallel may be any number equal to or greater than two. [Industrial Applicability]

[0096] The DC magnetic field superconducting coil power supply device of the present disclosure is suitable for applications in which a DC magnetic field is generated using a superconducting coil. [Explanation of symbols]

[0097] 1, 1a, 1b Superconducting coil power supply for DC magnetic field 5 Cooling container 11 Power supply 12 First Lead 13 Chopper Circuit 14 Low resistance switch 15 Current Sensor 16 Second Lead 17 Superconducting coil 18 Control Unit 19 Resistance 20 Resistance 21 Diode L1~L8 inductors SA1~SA8 1st switch SB1~SB8 Second switch

Claims

1. a superconducting coil; a power supply device capable of supplying DC voltage; a plurality of chopper circuits connected in parallel between one end of the power supply device and one end of the superconducting coil; a resistor connected in parallel with the superconducting coil; a control unit that controls the chopper circuit, The control unit operates the plurality of chopper circuits in a time-division manner when charging the superconducting coil.

2. 2. The DC magnetic field superconducting coil power supply device according to claim 1, the resistor is switchable between a superconducting state and a non-superconducting state; The control unit controls the resistor to the non-superconducting state during charging, and controls the resistor to the superconducting state when charging of the superconducting coil is completed and the superconducting coil transitions to the non-charging state.

3. 3. The DC magnetic field superconducting coil power supply device according to claim 1, further comprising a low resistance switch capable of short-circuiting both ends of the superconducting coil; The control unit controls the low resistance switch to turn on when the current flowing through the superconducting coil reaches or exceeds a predetermined threshold, thereby short-circuiting both ends of the superconducting coil.

4. 3. The DC magnetic field superconducting coil power supply device according to claim 2, The DC magnetic field superconducting coil power supply device further comprises a diode connected in parallel with the superconducting coil and the resistor.

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