High-precision superconducting magnet power supply and control method

Abstract

This invention discloses a high-precision superconducting magnet power supply and control method, comprising a voltage control module, a power supply output voltage measurement module, and a diode, as well as an AC / DC primary converter module, a high-precision current-regulating power switch, an AC / DC output voltage measurement module, and a magnet current control module. The AC / DC output voltage measurement module is connected to the DC output terminals of the AC / DC primary converter module. The negative terminal of the DC output of the AC / DC primary converter module is connected to the negative busbar, which is grounded. The output Vm of the power supply output voltage measurement module and the output Im of the DC current sensor are both connected to the input of the magnet current control module, and the output Vk of the magnet current control module is connected to the control terminal of the high-precision current-regulating power switch. The current setpoint of this invention is generated by the high-precision DAC module, and the current feedback value is measured and output by the high-precision DCCT. Combined with the operation of the voltage control module and the magnet current control module, the superconducting magnet power supply output current exhibits high precision and stability.

Description

Technical Field

[0001] This invention relates to the field of power supply technology, specifically to a high-precision superconducting magnet power supply and control method. Background Technology

[0002] Superconducting magnets have been widely used in many fields such as large-scale scientific engineering, electronics, biology, and medicine. The power supply that powers a superconducting magnet is called a superconducting magnet power supply, and the accuracy of its output current determines the performance and quality of the magnetic field generated by the superconducting magnet.

[0003] For some large superconducting magnets, such as those used in large scientific facilities like steady-state strong magnetic fields, accelerators, and nuclear fusion, the power supply current sometimes needs to be as high as tens of kiloamperes. Traditionally, thyristor rectifier power supply technology is used. This type of power supply can achieve high current output and energy feedback for the superconducting magnet, but it requires the use of power frequency transformers and large LC filter circuits. The equipment is large in size, has a low power factor, and the low-frequency ripple of the output is particularly difficult to filter out.

[0004] For some small superconducting magnets, such as those used in nuclear magnetic resonance imaging, scanning electron microscopy (STM), quantum computing, quantum measurement, and superconducting particle detectors, the power supply current only needs to be a few hundred amperes. High-frequency switching power supply technology (such as DC / DC converters) is generally used. Currently, some scholars have also proposed using a three-phase PWM rectification plus H-bridge technology, or a full-bridge DC / AC-AC / DC solution. These power supplies have high power factors, and compared with thyristor rectifier power supplies, their size and weight are reduced, and their dynamic response is significantly improved.

[0005] Regardless of the power supply technology used, the pre-stage rectifier inevitably generates low-frequency voltage ripple of varying magnitudes and frequencies. The output stage uses an LC filter circuit, which has limited filtering effect on these low-frequency ripples. This is especially true in some small superconducting magnets, where the magnet inductance is small, but the power supply for the superconducting magnet has high precision requirements, necessitating a superconducting magnet power supply that can achieve extremely low ripple and high stability output. Summary of the Invention

[0006] The high-precision superconducting magnet power supply proposed in this invention can solve at least one of the above-mentioned technical problems.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A high-precision superconducting magnet power supply includes an AC / DC primary converter module, a high-precision current-regulating power switch, an AC / DC output voltage measurement module, a power supply output voltage measurement module, and a diode. The power supply is characterized by further including a voltage control module, a magnet current control module, and a DAC module.

[0009] The AC / DC output voltage measurement module is connected to the DC output terminals of the AC / DC primary converter module; the positive DC output of the AC / DC primary converter module is connected to the drain of the high-precision current-regulating power switch, the source of the high-precision current-regulating power switch and the cathode of the diode are connected together with one end of the power output voltage measurement module, and connected to one end of the superconducting magnet through the positive busbar.

[0010] The negative terminal of the DC output of the AC / DC primary converter module is connected to the negative busbar, which is grounded; the anode of the diode, the other end of the power output voltage measurement module, and the other end of the superconducting magnet are all connected to the negative busbar and grounded through the negative busbar.

[0011] The output Vdc of the AC / DC output voltage measurement module and the output Vm of the power supply output voltage measurement module are both connected to the input of the voltage control module. Vts is the set voltage difference across the high-precision current-regulating power switch, which is a fixed value. The output Vset of the voltage control module is connected to the voltage control terminal of the AC / DC primary converter module.

[0012] The output Vm of the power supply output voltage measurement module, the output Im of the DC current sensor, and the output Iref of the DAC are all connected to the input of the magnet current control module, and the output Vk of the magnet current control module is connected to the control terminal of the high-precision current regulating power switch.

[0013] The DAC module converts the current setting value, i.e., the digital quantity, into an analog voltage output Iref, which is connected to the setting value input terminal of the magnet current control module as the setting value for magnet current feedback control.

[0014] Furthermore, the AC / DC primary converter module is a controllable output voltage source, and its output voltage value can be adjusted through the control terminal. It also integrates a PFC (Power Factor Correction) function, which enables the power supply to have a high power factor on the AC input side.

[0015] Furthermore, the AC / DC primary converter module has an input of 220V or 380V AC power and an output of DC voltage with a certain voltage ripple.

[0016] Furthermore, the AC / DC output voltage measurement module is used to measure the DC output voltage Vdc of the AC / DC primary converter module, specifically by using a series voltage divider method with resistors R1 and R2 to measure the voltage.

[0017] Furthermore, a DC current sensor (DCCT) is installed on the negative busbar to measure the DC current value passing through the magnet.

[0018] It should be noted that the high-precision current-regulating power switch operates in a linear regulation state during excitation and field stabilization, and in a cutoff state during demagnetization.

[0019] In this invention, the power switch T1 is exemplified by a power MOSFET, but in practice, other power switching devices that can operate in the linear adjustment region, such as power IGBTs, can also be used. Depending on the rated output current of the superconducting magnet power supply and the current carrying capacity of the selected power switch, the high-precision current-regulating power switch T1 may actually be implemented by multiple power switching devices connected in parallel.

[0020] The diode D1 can be represented by multiple diodes in series or parallel combination according to the actual working current of the magnet and the rate requirement of the magnet during demagnetization. In this embodiment of the invention, a single diode is used only for schematic diagram purposes.

[0021] Furthermore, to meet the power supply requirements of the high-current superconducting magnet, the high-precision current-regulating power switch includes power switch T1 and power switch T2. The drains of power switch T1 and T2 are connected together. The source of power switch T1 is connected to the positive busbar via resistor R5, and the source of power switch T2 is connected to the positive busbar via resistor R6. The positive busbar is connected to one end of the superconducting magnet. Resistors R5 and R6 can be used for current sharing between high-precision current-regulating power switch T1 and T2.

[0022] The output Vk of the magnet current control module is simultaneously connected to the control terminals of the high-precision current-regulating power switches T1 and T2.

[0023] Furthermore, the diode includes two diodes D1 and D2 connected in parallel. The anodes of diodes D1 and D2 are connected to the negative busbar, the cathode of diode D1 is connected to the source of power switch T1, and the cathode of diode D2 is connected to the source of power switch T2.

[0024] Furthermore, to meet the requirement of a higher descent rate during the demagnetization of the superconducting magnet, diodes D1 and D2 can be multiple diodes connected in series.

[0025] On the other hand, the present invention also discloses a control method for a high-precision superconducting magnet power supply, which employs the aforementioned high-precision superconducting magnet power supply, and its control steps are as follows.

[0026] The voltage control module detects the output voltage Vdc of the AC / DC primary converter module and the output voltage Vm of the superconducting magnet power supply in real time. The difference Vdc-Vm is the real-time voltage value between the drain and source of the high-precision current-regulated power switch T1. This difference Vdc-Vm is used as a feedback value and compared and calculated with the set voltage Vts across the high-precision current-regulated power switch T1. That is, PID calculation is performed on Vts-(Vdc-Vm). The output value Vset after PID calculation is the control voltage of the AC / DC primary converter module. The output value Vset can adjust the rise and fall of the output voltage Vdc of the AC / DC primary converter module to ensure that the voltage between the drain and source of the high-precision current-regulated power switch T1 remains constant, that is, Vdc-Vm=Vset;

[0027] The magnet current control module uses the real-time detection of the superconducting magnet power supply output current Im as the feedback current value and the superconducting magnet power supply output voltage Vm as the feedback voltage value. It compares and calculates Im with the magnet current setpoint Iref output by the high-precision DAC, that is, it performs PID calculation on Iref-Im, and then compares the calculation result with Vm and performs PID calculation. The calculated output value Vk is the control voltage of the high-precision current regulating power switch T1.

[0028] Furthermore, during the excitation and stable operation phases of the superconducting magnet, the voltage control module adjusts the output voltage Vdc of the AC / DC primary converter module to keep the drain-source voltage of the high-precision current-regulating power switch T1 constant. As a result, the control voltage Vk output by the magnet current control module enables the high-precision current-regulating power switch T1 to operate in a linear adjustment state. At this time, the high-precision current-regulating power switch T1 can be equivalent to a rapidly adjustable variable resistor. Due to the rapid adjustment of the magnet current control module and the high-precision current-regulating power switch T1, the superconducting magnet power supply output current has extremely low current ripple and very stable output.

[0029] Furthermore, during the demagnetization phase of the superconducting magnet, the magnet current control module controls its output voltage Vset to be negative, the high-precision current regulating power switch T1 is turned off, and the superconducting magnet current freewheels and decreases through diode D1. The rate of current decrease is determined by the forward voltage drop of the diode and the magnet inductance, i.e., di / dt=-Vm / L, where Vm is the forward voltage drop of diode D1 and L is the magnet inductance.

[0030] As can be seen from the above technical solution, the high-precision superconducting magnet power supply and control method proposed in this invention can achieve extremely low ripple and high stability output of the superconducting magnet power supply, while also having a small size and weight. The current setpoint is generated by a high-precision DAC module, and the current feedback value is measured and output by a high-precision DCCT. Combined with the operation of the voltage control module and the magnet current control module, the superconducting magnet power supply of this invention achieves high stability of the output current.

[0031] The high-precision superconducting magnet power supply of the present invention has the following beneficial effects:

[0032] (1) The high-precision superconducting magnet power supply of the present invention adopts a conventional AC / DC adjustable voltage source module and uses the high-precision current-regulating power switch and its control method described in the present invention. By adjusting the voltage control module and the current control module, the voltage across the power switch is kept constant and operates in a linear regulation state, so that the power supply has low output current ripple and high output current stability. The main circuit and control circuit of the high-precision superconducting magnet power supply of the present invention are simple and easy to implement. By simply connecting the high-precision current-regulating power switch and the diode, the power supply of high-current superconducting magnets can also be realized. The present invention meets the high-performance application requirements of superconducting magnets with a simple topology and extremely low cost.

[0033] (2) The high-precision superconducting magnet power supply described in this invention has a conventional AC / DC adjustable voltage source module at the input end. This power supply module can be a common switching power supply module with adjustable output voltage on the market. Compared with the traditional thyristor rectifier power supply, the AC side has a high power factor, does not require a large power frequency transformer and filter inductor, and the power supply has a small size and weight. Attached Figure Description

[0034] Figure 1 This is a circuit diagram of a high-precision superconducting magnet power supply according to Embodiment 1 of the present invention;

[0035] Figure 2 This is a circuit diagram of a high-precision superconducting magnet power supply according to Embodiment 2 of the present invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0037] Implementation Example 1:

[0038] See Figure 1A high-precision superconducting magnet power supply is composed of an AC / DC primary converter module 1, a high-precision current-regulating power switch T1, an AC / DC output voltage measurement module 5, a power supply output voltage measurement module 6, a DC current sensor DCCT, a diode D1, a voltage control module 3, a magnet current control module 4, and a high-precision DAC module 7.

[0039] The AC / DC primary converter module is an adjustable output voltage source, with an input of 220V or 380V AC and an output of DC voltage with a certain voltage ripple. The AC / DC output voltage measurement module is connected to the DC output terminals of the AC / DC primary converter module. The positive terminal of the DC output of the AC / DC primary converter module is connected to the drain of the high-precision current-regulating power switch T1. The source of the high-precision current-regulating power switch T1, the cathode of diode D1, and one end of the power output voltage measurement module are connected together and connected to one end of the superconducting magnet through the positive busbar. The negative terminal of the DC output of the AC / DC primary converter module is connected to the negative busbar, which is grounded. The anode of diode D1, the other end of the power output voltage measurement module, and the other end of the superconducting magnet are all connected to the negative busbar and grounded through the negative busbar. A DC current sensor (DCCT) is installed on the negative busbar to measure the DC current value passing through the magnet.

[0040] The output Vdc of the AC / DC output voltage measurement module and the output Vm of the power supply output voltage measurement module are both connected to the input of the voltage control module. Vts is the set voltage difference across the high-precision current-regulating power switch T1, which is a fixed value. The output Vset of the voltage control module is connected to the voltage control terminal of the AC / DC primary converter module.

[0041] The output Vm of the power supply output voltage measurement module, the output Im of the DC current sensor, and the output Iref of the high-precision DAC are all connected to the input of the magnet current control module. The output Vk of the magnet current control module is connected to the control terminal of the high-precision current-regulating power switch T1, which in this example is the gate-source control terminal of the power MOSFET.

[0042] The high-precision DAC module converts the current setpoint (digital quantity) into a high-precision analog voltage output Iref, which is connected to the setpoint input terminal of the magnet current control module as the setpoint for magnet current feedback control.

[0043] The AC / DC primary converter module is a controllable output voltage source and integrates PFC function, which enables the power supply to have a high power factor on the AC side.

[0044] The AC / DC output voltage measurement module is used to measure the DC output voltage Vdc of the AC / DC primary converter module. In this embodiment, the voltage is measured by series voltage divider using resistors R1 and R2.

[0045] It should be noted that the high-precision current-regulating power switch T1 operates in a linear regulation state during excitation and field stabilization, and operates in a cutoff state during demagnetization.

[0046] In this invention, the high-precision current-regulating power switch T1 is exemplified by a power MOSFET. In practice, other power switching devices that can operate in the linear adjustment region, such as power IGBTs, can also be used. Depending on the rated output current of the superconducting magnet power supply and the current-carrying capacity of the selected high-precision current-regulating power switch, the high-precision current-regulating power switch T1 may actually be implemented by multiple power switching devices connected in parallel.

[0047] The diode D1 can be represented by multiple diodes in series or parallel combination according to the actual working current of the magnet and the rate requirement of the magnet during demagnetization. In this embodiment of the invention, a single diode is used only for schematic diagram purposes.

[0048] The power output voltage measurement module is used to measure the DC voltage Vm output by the superconducting magnet power supply of the present invention, that is, the voltage across the superconducting magnet. In this embodiment, the voltage is measured by series voltage divider method using resistors R3 and R4.

[0049] The DC current sensor is used to measure the DC current Im output by the superconducting magnet power supply of the present invention, that is, the current flowing through the superconducting magnet. In this embodiment, a DC current sensor current measurement scheme is used, which can realize the isolation between the measured signal and the output signal. The current sensor should also have high accuracy and low temperature drift.

[0050] The high-precision DAC module consists of a 16-bit or higher analog-to-digital converter chip and its peripheral circuits. It should have high precision and low temperature drift and is used to control the power supply output current setting value.

[0051] The voltage control module is used to control and adjust the DC output voltage Vdc of the AC / DC primary converter module;

[0052] The magnet current control module is used to control and adjust the output DC current Im of the high-precision superconducting magnet power supply described in this invention.

[0053] The high-precision superconducting magnet power supply described in this invention employs the following control scheme:

[0054] The voltage control module detects the output voltage Vdc of the AC / DC primary converter module and the output voltage Vm of the superconducting magnet power supply in real time. The difference (Vdc-Vm) is the real-time voltage value between the drain and source of the high-precision current-regulated power switch T1. This difference (Vdc-Vm) is used as a feedback value and compared and calculated with the set voltage Vts across the high-precision current-regulated power switch (which should be a fixed value for a given high-precision current-regulated power switch). That is, PID calculation is performed on Vts-(Vdc-Vm). The output value Vset after PID calculation is the control voltage of the AC / DC primary converter module. Vset can adjust the rise and fall of the output voltage Vdc of the AC / DC primary converter module to ensure that the voltage between the drain and source of the high-precision current-regulated power switch T1 remains constant, i.e., Vdc-Vm=Vset.

[0055] The magnet current control module uses the real-time detection of the superconducting magnet power supply output current Im as the feedback current value and the superconducting magnet power supply output voltage Vm as the feedback voltage value. It compares and calculates Im with the magnet current set value Iref output by the high-precision DAC, that is, it performs PID calculation on (Iref-Im), and then compares the calculation result with Vm and performs PID calculation. The calculated output value Vk is the control voltage of the high-precision current regulating power switch T1.

[0056] During the excitation and steady-state operation of the superconducting magnet, the voltage control module can adjust the output voltage Vdc of the AC / DC primary converter module to keep the drain-source voltage of the high-precision current-regulating power switch T1 constant. Thus, the control voltage Vk output by the magnet current control module can make the high-precision current-regulating power switch T1 work in a linear adjustment state. At this time, the high-precision current-regulating power switch T1 can be equivalent to a rapidly adjustable variable resistor. Due to the rapid adjustment of the magnet current control module and the high-precision current-regulating power switch T1, the superconducting magnet power supply of the present invention has extremely low current ripple and very stable output.

[0057] During the demagnetization phase of the superconducting magnet, the magnet current control module controls its output voltage Vset to be negative, the high-precision current regulating power switch T1 is turned off, and the superconducting magnet current freewheels and decreases through diode D1. The rate of current decrease is determined by the forward voltage drop of the diode and the magnet inductance, i.e., di / dt=-Vm / L, where Vm is the forward voltage drop of diode D1 (as mentioned above, it can actually be a series-parallel combination of multiple diodes), and L is the magnet inductance.

[0058] As mentioned above, the current setting value of the present invention is generated by a high-precision DAC module, and the current feedback value is measured and output by a high-precision DCCT. Combined with the operation of the voltage control module and the magnet current control module, the superconducting magnet power supply output current of the present invention has high stability.

[0059] Implementation Example 2:

[0060] The working principle and control scheme of the main circuit in this implementation example are the same as those in Implementation Example 1, but the difference is:

[0061] When the rated output current of the superconducting magnet power supply is large, and a single high-precision current-regulating power switch T1 cannot meet the power supply output current requirements, multiple switches need to be connected in parallel to meet the power supply needs of the superconducting magnet.

[0062] See Figure 2 In this embodiment, two switching transistors T1 and T2 connected in parallel are used as an example. The high-precision current-regulating power switching transistors T1 and T2 are exemplified as power MOSFETs in this invention, but in practice, other power switching devices that can operate in the linear adjustment region, such as power IGBTs, can also be used.

[0063] The drains of the high-precision current-regulated power switches T1 and T2 are connected together. The source of the high-precision current-regulated power switch T1 is connected to the positive busbar via resistor R5, and the source of the high-precision current-regulated power switch T2 is connected to the positive busbar via resistor R6. The positive busbar is connected to one end of the superconducting magnet. Resistors R5 and R6 can be used for current sharing of the high-precision current-regulated power switches T1 and T2.

[0064] To meet the current carrying capacity requirements during magnet demagnetization or protection, multiple diodes D1 need to be connected in parallel. In this embodiment, two diodes D1 and D2 connected in parallel are used as an example. The anodes of diodes D1 and D2 are connected to the negative busbar. The cathode of diode D1 cuts off the source of the high-precision current regulating power switch T1, and the cathode of diode D2 cuts off the source of the high-precision current regulating power switch T2.

[0065] The output Vk of the magnet current control module needs to be connected to the control terminals of the high-precision current-regulating power switching transistors T1 and T2 simultaneously. In the example of this invention, this is the gate-source control terminal of the power MOSFETs T1 and T2.

[0066] The circuit connections and working principles of the other parts are the same as in Scheme 1, and will not be repeated here.

[0067] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-precision superconducting magnet power supply comprising an AC / DC primary conversion module, an AC / DC output voltage measurement module, a power supply output voltage measurement module, and a diode, characterized by, The high-precision superconducting magnet power supply further comprises a current-regulating power switch tube, a voltage control module and a magnet current control module. The AC / DC output voltage measurement module is connected at both ends of the DC output of the AC / DC primary conversion module; the positive pole of the DC output of the AC / DC primary conversion module is connected to the drain of the current-regulating power switch tube, the source of the current-regulating power switch tube and the cathode of the diode, and one end of the power output voltage measurement module is connected together and connected to one end of the superconducting magnet through a positive pole bus. The negative pole of the DC output of the AC / DC primary conversion module is connected to a negative pole bus, and the negative pole bus is grounded; the anode of the diode, the other end of the power output voltage measurement module and the other end of the superconducting magnet are all connected to the negative pole bus and grounded through the negative pole bus. The output Vdc of the AC / DC output voltage measurement module and the output Vm of the power output voltage measurement module are both connected to the input of the voltage control module, Vts is the set voltage difference between the current-regulating power switch tube, which is a fixed value, i.e. Vts=Vdc-Vm, and the output Vset of the voltage control module is connected to the voltage control end of the AC / DC primary conversion module. The output Vm of the power output voltage measurement module and the output Im of the DC current sensor are both connected to the input of the magnet current control module, and the output Vk of the magnet current control module is connected to the control end of the current-regulating power switch tube. The high-precision superconducting magnet power supply further comprises that, in the superconducting magnet excitation and field stabilization operation stage, the voltage control module adjusts the output voltage Vdc of the AC / DC primary conversion module so as to keep the voltage between the drain and the source of the current-regulating power switch tube constant, so that the control voltage Vk output by the magnet current control module can make the current-regulating power switch tube T1 work in a linear adjustment state, at this time, the current-regulating power switch tube T1 can be equivalent to a variable resistor which can be quickly adjusted, due to the quick adjustment of the magnet current control module and the current-regulating power switch tube T1, the output current of the superconducting magnet power supply has very low current ripple and very stable output; The high-precision superconducting magnet power supply further comprises that, in the superconducting magnet demagnetization stage, the magnet current control module controls the output voltage Vset to be negative, the current-regulating power switch tube T1 is cut off, the superconducting magnet current flows through the diode D1 and drops, and the current drop rate is determined by the conduction voltage drop of the diode and the magnet inductance, i.e. di / dt=-Vm / L, Vm is the conduction voltage drop of the diode D1, and L is the magnet inductance.

2. The high-precision superconducting magnet power supply according to claim 1, characterized in that: The high-precision superconducting magnet power supply further comprises a DAC module, and the output Iref of the DAC is connected to the input of the magnet current control module; The DAC module converts the current set value, i.e. digital quantity, into an analog voltage output Iref, which is connected to the set value input end of the magnet current control module as the set value of the magnet current feedback control.

3. The high-precision superconducting magnet power supply of claim 1, wherein: The AC / DC primary conversion module is a controllable output voltage source and is integrated with a PFC function, so that the power supply has a high power factor at the AC input side. The AC / DC primary conversion module has an input of 220V or 380V AC power and an output of DC voltage with a certain voltage ripple.

4. The high-precision superconducting magnet power supply of claim 1, wherein: The AC / DC output voltage measurement module is configured to measure the DC output voltage Vdc of the AC / DC primary conversion module, and specifically, the voltage is measured by using a series connection of resistors R1 and R2.

5. The high-precision superconducting magnet power supply of claim 1, wherein: A DC current sensor DCCT is mounted on the negative bus bar to measure the DC current value passing through the magnet.

6. The high-precision superconducting magnet power supply of claim 1, wherein: The current-regulating power switch tube includes power switch tubes T1 and T2, the drains of the power switch tubes T1 and T2 are connected together, the source of the power switch tube T1 is connected to the positive bus bar through a resistor R5, the source of the power switch tube T2 is connected to the positive bus bar through a resistor R6, and the positive bus bar is connected to one end of the superconducting magnet, and the resistors R5 and R6 are used for current sharing of the power switch tubes T1 and T2; The output Vk of the magnet current control module is connected to the control terminals of the current-regulating power switch tubes T1 and T2.

7. The high-precision superconducting magnet power supply of claim 1, wherein: The diode includes two diodes D1 and D2 connected in parallel, the anodes of the diodes D1 and D2 are connected to the negative bus bar, the cathode of the diode D1 is connected to the source of the current-regulating power switch tube T1, and the cathode of the diode D2 is connected to the source of the current-regulating power switch tube T2.

8. A control method of a high-precision superconducting magnet power supply using the high-precision superconducting magnet power supply according to any one of claims 1 to 7, characterized by: The control steps are as follows, The voltage control module detects the output voltage Vdc of the AC / DC primary conversion module and the output voltage Vm of the superconducting magnet power supply in real time, the difference Vdc-Vm is the real-time voltage value between the drain and the source of the current-regulating power switch tube T1, the difference Vdc-Vm is used as a feedback value to compare and operate with the set voltage Vts between the current-regulating power switch tubes, i.e., PID operation is performed on Vts-(Vdc-Vm), and the output value Vset of the PID operation is the control voltage of the AC / DC primary conversion module, and the output value Vset can adjust the output voltage Vdc of the AC / DC primary conversion module to rise and fall, so as to ensure that the voltage between the drain and the source of the current-regulating power switch tube T1 remains constant, i.e., Vdc-Vm=Vset; The magnet current control module detects the output current Im of the superconducting magnet power supply in real time as a feedback current value, and detects the output voltage Vm of the superconducting magnet power supply as a feedback voltage value, compares and operates Im with the magnet current set value Iref output by the DAC, i.e., PID operation is performed on Iref-Im, and then compares and operates the operation result with Vm, and the output value Vk of the operation is the control voltage of the current-regulating power switch tube T1. The control method of the high-precision superconducting magnet power supply further comprises, in the superconducting magnet excitation and field stabilization operation stage, adjusting the output voltage Vdc of the AC / DC primary conversion module by the voltage control module, so that the voltage between the drain and the source of the current-regulating power switch tube T1 is kept constant, thereby the control voltage Vk output by the magnet current control module can make the current-regulating power switch tube T1 work in a linear adjustment state, at this time the current-regulating power switch tube T1 can be equivalent to a variable resistor which can be quickly adjusted, and due to the quick adjustment of the magnet current control module and the current-regulating power switch tube T1, the output current of the superconducting magnet power supply has very low current ripple and very stable output; The control method of the high-precision superconducting magnet power supply further comprises, in the superconducting magnet excitation and field stabilization operation stage, adjusting the output voltage Vdc of the AC / DC primary conversion module by the voltage control module, so that the voltage between the drain and the source of the current-regulating power switch tube T1 is kept constant, thereby the control voltage Vk output by the magnet current control module can make the current-regulating power switch tube T1 work in a linear adjustment state, at this time the current-regulating power switch tube T1 can be equivalent to a variable resistor which can be quickly adjusted, and due to the quick adjustment of the magnet current control module and the current-regulating power switch tube T1, the output current of the superconducting magnet power supply has very low current ripple and very stable output;

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