A control system for a superconducting magnet and a superconducting magnet

Abstract

The utility model provides a kind of control system and superconducting magnet of superconducting magnet, and the intermediate node of the current drop resistor in its current drop circuit is connected to one end of the current drop resistor by second switch, and the resistance in current drop circuit can be adjusted by controlling the state of second switch, when quench protection, open second switch, maximize current drop power;When the current of coil is current drop adjusted, control second switch is closed, reduce current drop power, adapt current drop adjustment demand, and response is fast.The superconducting magnet of the utility model can provide a variety of different current drop power, increase the regulation and control precision when superconducting magnet coil is abnormal or quench, can effectively improve work stability and monocrystalline silicon crystal pulling quality.

Description

Technical Field

[0001] This utility model relates to the field of superconducting magnet technology, and in particular to a control system for a superconducting magnet and a superconducting magnet. Background Technology

[0002] In the field of large-size single-crystal silicon wafer fabrication, the novel magnetron-controlled Czochralski (CZ) silicon single-crystal technology has become the mainstream technology due to its advantages such as no growth streaks, fewer secondary defects in single-crystal silicon, and low impurity content. Among these technologies, superconducting magnets are widely recognized as the best solution for single-crystal silicon fabrication due to their advantages such as low energy consumption, high magnetic field strength, and good uniformity of the horizontal magnetic field in suppressing melt convection.

[0003] In the magnetron Czochralski (MCS) production technology of monocrystalline silicon, different magnetic field strengths are required at different growth stages, which corresponds to adjusting the coil current of the superconducting magnet. When it is necessary to enhance the magnetic field, it is often achieved by increasing the power supply output. When it is necessary to reduce the magnetic field strength, it is achieved by reducing the power supply output, and the electrical energy is quickly consumed through electrothermal conversion by the resistive element in the current reduction circuit.

[0004] However, the current reduction circuit is mainly used for quench protection. Its current reduction power is large and relatively fixed, which makes it difficult to match the variable requirements in actual current reduction. For example, when the current rise is too large and a small current reduction is required, the current reduction speed of the current reduction circuit is too fast, which leads to a sudden change in the magnetic field and has an adverse effect on the growth of monocrystalline silicon. Utility Model Content

[0005] Based on this, the purpose of this utility model is to provide a control system for a superconducting magnet and a superconducting magnet, so as to solve the problem that the existing technology is difficult to match with the variable requirements in actual current reduction.

[0006] This utility model provides a control system for a superconducting magnet, comprising:

[0007] Turn on the switch, which is connected in series between the positive terminal of the power supply and the positive terminal of the superconducting magnet coil;

[0008] A current-reducing circuit is connected in parallel across the two ends of the superconducting magnet coil;

[0009] A state detection module is set in the working environment of the superconducting magnet coil. The state detection module includes a current sensor, a vacuum sensor, and a temperature sensor.

[0010] The main controller is connected to the sampling data output terminal of the status detection module, and the first control port of the main controller is connected to the control terminal of the start switch;

[0011] The current-reducing circuit includes a first current-reducing diode and a current-reducing resistor. The cathode of the first current-reducing diode is connected to the positive terminal of the superconducting magnet coil, and the anode of the first current-reducing diode is connected to the negative terminal of the superconducting magnet coil through the current-reducing resistor. The intermediate node of the current-reducing resistor is also connected to the negative terminal of the superconducting magnet coil through a second switch.

[0012] The second control port of the main controller is connected to the control terminal of the second switch.

[0013] Optionally, at least two current reduction circuits are connected in parallel, and the main controller has multiple second control ports, each corresponding to one of the second switches.

[0014] Optionally, the current-reducing resistor is a variable resistor, and the variable node of the variable resistor is connected to the negative terminal of the superconducting magnet coil through the second switch.

[0015] Optionally, it also includes a primary current-reducing circuit, which is connected in parallel with the start switch. The primary current-reducing circuit includes a second current-reducing diode and a third switch connected in forward series between the positive terminal of the power supply and the positive terminal of the superconducting magnet coil. The third control port of the main controller is connected to the control terminal of the third switch.

[0016] Optionally, at least two of the second current-reducing diodes are connected in parallel.

[0017] Optionally, it also includes a negative voltage protection diode, the anode of which is connected to the negative terminal of the power supply, and the cathode of which is connected to the positive terminal of the power supply.

[0018] Optionally, the main controller includes a programmable logic controller (PLC), which is also connected to a human-machine interface.

[0019] Another aspect of this invention provides a superconducting magnet, including a control system for the superconducting magnet described above.

[0020] Optionally, the upper and lower coils of the superconducting magnet are connected in series.

[0021] The control system of this invention for a superconducting magnet collects the operating status of the superconducting magnet coil through a status detection module. The collected data is fed back to the main controller, which controls the start switch and the second switch of the current-reducing circuit. During current increase or stabilization, the start switch is closed, directly connecting the power supply to the coil, increasing or stabilizing the current. During current reduction, the start switch is opened, disconnecting the power supply circuit, and the current-reducing circuit connected in parallel with the coil is converted to a series structure, consuming electrical energy through the current-reducing circuit. The intermediate node of the current-reducing resistor in the current-reducing circuit is connected to one end of the current-reducing resistor through the second switch. By controlling the state of the second switch, the resistance value in the current-reducing circuit can be adjusted, thereby maximizing the current-reducing power by opening the second switch during quench protection. During coil current reduction adjustment, the second switch is closed to reduce the current-reducing power, adapting to current reduction adjustment requirements with a fast response. This invention's superconducting magnet can provide various different current-reducing powers, increasing the control accuracy when the superconducting magnet coil is abnormal or quenched, and effectively improving operational stability and the quality of single-crystal silicon crystal pulling. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the module structure of the control system of the superconducting magnet in this embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the control circuit of the superconducting magnet in the embodiment of this utility model.

[0024] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this utility model. Detailed Implementation

[0025] To facilitate understanding of this utility model, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of this utility model are shown in the drawings. However, this utility model can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this utility model will be more thorough and complete.

[0026] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0028] To address the issue that current superconducting magnet control is primarily achieved at the power supply end, which results in slow control response and insufficient quality of produced monocrystalline silicon, this invention provides a control system for a superconducting magnet. A state detection module collects the operating status of the superconducting magnet coil, enabling quench detection and current reduction monitoring. The collected data is fed back to the main controller to control the start switch and the second switch of the current reduction circuit. During current increase or stabilization, the start switch is closed, directly connecting the power supply to the coil, increasing or stabilizing the current. During current reduction, the start switch is opened, forming a parallel structure between the coil and the current reduction circuit or a series structure with the primary current reduction circuit. Electrical energy is consumed through the current reduction circuit or the primary current reduction circuit. The intermediate node of the current reduction resistor in the current reduction circuit is connected to one end of the resistor via the second switch. By controlling the state of the second switch, the resistance value in the current reduction circuit can be adjusted. Therefore, in case of quench protection, the second switch can be opened to maximize the current reduction power. During coil current reduction adjustment, the second switch is closed to reduce the current reduction power, adapting to current reduction adjustment requirements with a fast response.

[0029] Specifically, please refer to Figure 1 and Figure 2 In this embodiment, the control system for the superconducting magnet is located between the power supply 110 and the superconducting magnet coil 120, and is situated outside the cryogenic container containing the superconducting magnet coil 120, i.e., the superconducting magnet. The control system mainly includes a main controller 10, a control circuit 20, and a status monitoring module 30. The main controller 10 controls the control circuit 20 according to preset parameters or user input parameters to adjust the current on the superconducting magnet coil 120, thereby adjusting the magnetic field excited by the current.

[0030] The status monitoring module 30 is matched with the superconducting magnet coil 120 and includes a voltage sensor, a current sensor, a vacuum sensor, and a temperature sensor, etc., to monitor the voltage and current on the circuit of the superconducting magnet coil 120, as well as the vacuum and temperature of the environment in which the coil is located. The main controller 10 is pre-input with corresponding safety values, and can judge whether the superconducting environment is abnormal by comparing the actual values ​​with the safety values. When the superconducting environment is abnormal, the control and regulation circuit 20 disconnects from the power supply 110, and the current-reducing circuit connected in reverse parallel with the superconducting magnet coil 120 is converted to be connected in series with the superconducting magnet coil 120. The electrical energy on the superconducting magnet coil 120 is converted into heat energy dissipation through the current-reducing resistor of the current-reducing circuit, so as to avoid damage to the superconducting magnet coil 120 in the quenching state by the large current.

[0031] The types of sensors configured in the status monitoring module 30 need to be determined according to actual monitoring requirements. For example, if the current or voltage value exceeds the limit or the short-term fluctuation exceeds the limit, it can be determined that the superconducting magnet is at risk of quenching. At the same time, the current data can be used to monitor and control the excitation current to achieve monitoring and control of the magnetic field. The vacuum degree and temperature are used to directly monitor the state of the environment in which the superconducting magnet coil is located. If the vacuum degree or temperature exceeds the alarm value, it can be determined that the superconducting magnet is at risk of quenching, thereby realizing multi-directional quenching judgment and improving the accuracy of quenching judgment.

[0032] The first control port and the second control port of the main controller 10 are respectively connected to the control terminals of the start switch K1 and the second switch K2, and control the state of the start switch K1 and the second switch K2 respectively.

[0033] The control circuit 20 includes a start switch K1 connected in series between the positive terminal of the power supply 110 and the positive terminal of the superconducting magnet coil 120. When the power supply 110 is working, the start switch K1 is closed and the second switch K2 is opened, and the superconducting magnet coil 120 is connected to current, which can generate a magnetic field. In this embodiment, the upper coil L1 and the lower coil L2 of the superconducting magnet coil 120 are connected in series, synchronously controlled, and excited by the same power supply, which can fully ensure the consistency of the current in the upper and lower coils, thereby avoiding the magnetic field from shifting. This can reduce the oxygen content of the single crystal silicon rod in the magnetic field and ensure the temperature stability of the solid-liquid interface of the silicon solution, thereby improving the uniformity of the radial distribution of impurities in the single crystal silicon rod, that is, improving the crystal pulling quality of single crystal silicon.

[0034] A current-reducing circuit is connected in parallel across the superconducting magnet coil 120, including a first current-reducing diode D1 and a current-reducing resistor R1. The cathode of the first current-reducing diode D1 is connected to the positive terminal of the superconducting magnet coil 120, and the anode of the first current-reducing diode D1 is connected to the negative terminal of the superconducting magnet coil 120 through the current-reducing resistor R1. The intermediate node of the current-reducing resistor R1 is also connected to the negative terminal of the superconducting magnet coil 120 through a second switch K2. By adjusting the switching state of the second switch K2, the resistance value in the current-reducing circuit can be adjusted to match different current-reducing power requirements. Furthermore, the current-reducing circuit is located outside the superconducting magnet and the superconducting magnet coil 120. Compared with the conventional technology of connecting a protection diode in parallel across the superconducting magnet coil inside the superconducting magnet, this design ensures that the internal temperature rise of the superconducting magnet is not too large, the temperature drops quickly, and the superconducting magnet can quickly regain current and be energized again after rapid current reduction.

[0035] In this embodiment, closing the start switch K1 and opening the second switch K2 can be used for linear current boosting and current stabilization of the superconducting magnet coil 120. At the same time, in the current boosting circuit, only the start switch K1 is provided, and no resistors and / or diodes or other impedance devices are provided. At this time, the current reduction circuit is connected in reverse parallel and is not conducting. This can not only fully reduce unnecessary energy consumption during the current boosting process, but also quickly switch the connection mode of the current reduction circuit and the coil when current reduction is needed, thereby improving the rapid current reduction rate.

[0036] In this embodiment, disconnecting the start switch K1 allows for rapid current reduction in the superconducting magnet coil 120. Simultaneously, to avoid heat concentration and reduce thermal management pressure, at least two current reduction circuits can be connected in parallel; for example, three are provided in this embodiment. The main controller 10 has multiple second control ports, each corresponding to a second switch. The parallel connection of multiple current reduction circuits enables current shunting, improves the stability and reliability of quench protection, reduces the heat buildup pressure of a single current reduction resistor, and increases the options for current reduction power, adapting to various current reduction power requirements and improving practicality.

[0037] To further improve the controllability of the current reduction power, in an optional embodiment, the current reduction resistor R1 is a variable resistor. The variable node of the variable resistor is connected to the negative terminal of the superconducting magnet coil 120 through a second switch K2. When the current reduction power requirement is low, the second switch K2 can be closed to reduce the input resistance in the current reduction circuit and reduce the current reduction power. Depending on the specific requirements, the variable resistor can be an automatic adjustment type, which can provide more precise current reduction power control.

[0038] A current-reducing resistor R1 is connected in series in the current-reducing circuit, resulting in a relatively large current-reducing power. To further adapt to the control precision, this embodiment also includes a primary current-reducing circuit, which is connected in parallel with the start switch. The current-reducing power of the primary current-reducing circuit is less than that of the current-reducing circuit, which can further increase the selectivity of the current-reducing power and increase the linearity of the current-reducing power control. The primary current-reducing circuit includes a second current-reducing diode D2 and a third switch K3 connected in series in the forward direction between the positive terminal of the power supply 110 and the positive terminal of the superconducting magnet coil 120. The third control port of the main controller 10 is connected to the control terminal of the third switch K3. When the current-reducing power requirement is small, the start switch K1 can be opened and the third switch K3 can be closed, reducing the coil current through the impedance of the second current-reducing diode D2.

[0039] In this embodiment, the primary current-reducing circuit is set on the main circuit of the superconducting magnet coil 120. When the current is large, in order to avoid concentrated heat generation, two second current-reducing diodes D2 are connected in parallel. In optional embodiments, multiple diodes can be connected in parallel, and the specific selection can be made according to actual needs.

[0040] To prevent high negative voltage from appearing at both ends of the coil and damaging the power supply, a negative voltage protection diode D3 is also provided in this embodiment. The anode of the negative voltage protection diode D3 is connected to the negative terminal of the power supply 110, and the cathode of the negative voltage protection diode D3 is connected to the positive terminal of the power supply 110. When a negative voltage occurs, the magnitude of the negative voltage is consistent with the forward voltage drop of the negative voltage protection diode D3, which can prevent excessive negative voltage from damaging the power supply.

[0041] To facilitate the operation of the main controller 10, the main controller 10 includes a programmable logic controller (PLC), which is also connected to a human-machine interface.

[0042] This invention also provides a superconducting magnet, including a control system for the superconducting magnet described above. The superconducting magnet has multiple options for current reduction power, which increases the control accuracy when the superconducting magnet coil malfunctions or loses quench, and can effectively improve working stability and the quality of single-crystal silicon crystal pulling.

[0043] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0044] The embodiments described above are merely illustrative of several specific implementations of this utility model, and while the descriptions are detailed, they should not be construed as limiting the scope of protection of this utility model. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these modifications and improvements all fall within the scope of protection of this utility model. Therefore, the scope of protection of this utility model patent should be determined by the appended claims.

Claims

1. A control system for a superconducting magnet, characterized in that, include: Turn on the switch, which is connected in series between the positive terminal of the power supply and the positive terminal of the superconducting magnet coil; A current-reducing circuit is connected in parallel across the two ends of the superconducting magnet coil; A state detection module is set in the working environment of the superconducting magnet coil, and the state detection module includes a current sensor; The main controller is connected to the sampling data output terminal of the status detection module, and the first control port of the main controller is connected to the control terminal of the start switch; The current-reducing circuit includes a first current-reducing diode and a current-reducing resistor. The cathode of the first current-reducing diode is connected to the positive terminal of the superconducting magnet coil, and the anode of the first current-reducing diode is connected to the negative terminal of the superconducting magnet coil through the current-reducing resistor. The intermediate node of the current-reducing resistor is also connected to the negative terminal of the superconducting magnet coil through a second switch. The second control port of the main controller is connected to the control terminal of the second switch.

2. The control system for the superconducting magnet according to claim 1, characterized in that, At least two current reduction circuits are connected in parallel, and the main controller has multiple second control ports, each corresponding to a second switch.

3. The control system for the superconducting magnet according to claim 1 or 2, characterized in that, The current-reducing resistor is a variable resistor, and the variable node of the variable resistor is connected to the negative terminal of the superconducting magnet coil through the second switch.

4. The control system for the superconducting magnet according to claim 1, characterized in that, It also includes a primary current-reducing circuit, which is connected in parallel with the start switch. The primary current-reducing circuit includes a second current-reducing diode and a third switch connected in forward series between the positive terminal of the power supply and the positive terminal of the superconducting magnet coil. The third control port of the main controller is connected to the control terminal of the third switch.

5. The control system for the superconducting magnet according to claim 4, characterized in that, At least two of the second current-reducing diodes are connected in parallel.

6. The control system for the superconducting magnet according to claim 1, characterized in that, It also includes a negative voltage protection diode, the anode of which is connected to the negative terminal of the power supply, and the cathode of which is connected to the positive terminal of the power supply.

7. The control system for the superconducting magnet according to claim 1, characterized in that, The main controller includes a programmable logic controller (PLC), which is also connected to a human-machine interface.

8. A superconducting magnet, characterized in that, A control system including the superconducting magnet as described in any one of claims 1 to 7.

9. The superconducting magnet according to claim 8, characterized in that, The upper and lower coils of the superconducting magnet are connected in series.

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