A flat-top pulsed magnetic field generating device, method, medium, equipment and terminal

Abstract

The present invention belongs to the technical field of high magnetic field pulse power, and discloses a flat-top pulse magnetic field generating device, method, medium, equipment and terminal. The flat-top pulse magnetic field generating device includes a plurality of capacitor-type power supplies connected in parallel, which are composed of a capacitor bank, its protection inductor, a discharge thyristor and a freewheeling circuit; a pulse rectifier-type power supply, which is composed of a power supply and its supporting rectifier; a double-coil magnet; the positive pole of the rectifier output end of the pulse rectifier-type power supply is connected to the positive pole of the inner coil of the magnet, and the negative pole of the rectifier output end is connected to the negative pole of the inner coil of the magnet; the positive poles of the output ends of the capacitor-type power supplies are all connected to the positive pole of the outer coil of the magnet, and the negative poles of the output ends are all connected to the negative pole of the outer coil of the magnet. The flat-top pulse magnetic field generating device based on the double-coil magnet of the present invention can generate a flat-top pulse magnetic field with high stability, high field strength and long flat-top pulse width, providing a necessary high magnetic field environment for scientific experiments such as nuclear magnetic resonance and specific heat measurement.

Description

Technical Field

[0001] The present invention belongs to the technical field of high magnetic field pulse power, and particularly relates to a flat-top pulse magnetic field generating device, method, medium, equipment and terminal. Background Technique

[0002] At present, with the rapid development of science and technology, pulsed high magnetic field, as an extreme experimental environment, has become an essential research condition in basic frontier scientific research. Many scientific experiments and frontier technologies such as specific heat measurement, nuclear magnetic resonance, high-power gyrotron terahertz source, etc. not only have extremely high requirements for magnetic field strength and magnetic field stability, but also the longer the magnetic field duration, the more conducive to the realization of scientific research. The flat-top pulsed high magnetic field combines the advantages of small fluctuations in steady-state high magnetic field, long duration, high field strength of pulsed high magnetic field, and low operating cost. In summary, improving the flat-top duration of the flat-top pulsed high magnetic field and ensuring its high stability and high field strength are of great significance for the development of basic frontier scientific research and high-power gyrotron terahertz source technology.

[0003] At present, there are more than twenty scientific research institutions leading the research on flat-top magnetic field in the world, mostly distributed in developed countries and regions such as Europe, the United States, and Japan. Major high magnetic field laboratories mainly use energy storage capacitor type, battery type, and pulsed generator type as the power supply circuits for flat-top pulsed magnetic fields.

[0004] The capacitor-type power supply has a low cost, simple structure, few auxiliary facilities, is easy to realize miniaturization and modularization, and at the same time has a high output voltage, which can make the magnet current rise rapidly, reduce the heat generated by the magnet during the rising edge process, and is beneficial to extending the service life of the magnet. However, the capacitor itself has a low energy storage density, the output voltage is uncontrollable, and the output voltage drops rapidly during the discharge process, making it difficult to maintain a flat top. The WHMC in China has completed a capacitor-type power supply system composed of 22 1MJ modules and 2 0.8MJ modules, and realized a flat-top pulsed high magnetic field of 64T / 2000ppm / 6ms.

[0005] The battery-type power supply has a stable output voltage, is conducive to realizing a longer pulse width discharge, and can improve its output voltage and current capabilities through series and parallel connection methods. At present, lead-acid batteries have been widely used due to their stable performance, high-rate discharge characteristics, and strong versatility. However, limited by the output power of the battery, it is difficult to realize a flat-top pulsed high magnetic field with a high field strength.

[0006] A pulse rectifier type power supply is a power supply that supplies power to a rectifier after a pulse AC generator or AC mains power passes through a transformer, and outputs a DC voltage after rectification. It has a large output energy and an adjustable output voltage, so it can achieve long-term voltage stabilization. Taking the power supply of a pulse generator as an example, currently only LANL in the United States and WHMFC in China each have a pulse generator in the world. WHMFC uses a 100MW / 100MJ pulse generator and two sets of 67.5MW 12-pulse rectifiers to discharge a double-coil magnet to obtain a flat-top pulse strong magnetic field of 50T / 100ms / 4000ppm, but it poses very high requirements for the discharge control and timing of the magnet.

[0007] Generally speaking, there are still some deficiencies in the existing flat-top pulse strong magnetic field power supply schemes, and it is difficult to generate a flat-top pulse strong magnetic field that simultaneously has the advantages of high field strength, high stability, and long flat-top pulse width.

[0008] Through the above analysis, the problems and defects existing in the prior art are as follows:

[0009] (1) The advantage of the existing single-capacitor type power supply is that there is no limit to the output power, but its own energy storage density is low, the output voltage is uncontrollable, and the output voltage drops rapidly during the discharge process, making it difficult to maintain a flat top.

[0010] (2) The output voltage of the pulse generator type power supply is controllable, and various pulse waveforms can be generated by adjusting the output voltage when the energy storage is sufficient. However, the ripple of the pulse generator is inevitably present in nature, so it affects the stability of the final magnetic field. In addition, the control of the pulse generator is relatively complex and the application cost is high.

[0011] (3) The battery power supply combines the advantages of high energy storage of the pulse generator type power supply and no ripple of the capacitor power supply, and is more suitable for generating a long-pulse magnetic field. However, due to its low output power and long magnetic field rise time, the magnet heats up severely during the current rise process, affecting the service life of the magnet.

[0012] (4) To sum up, there are still deficiencies in the existing flat-top pulse strong magnetic field power supply schemes, and it is difficult to generate a flat-top pulse strong magnetic field that simultaneously has the advantages of high field strength, high stability, and long flat-top pulse width. Summary of the Invention

[0013] Aiming at the problems existing in the prior art, the present invention provides a flat-top pulse magnetic field generating device, method, medium, equipment and terminal, especially a flat-top pulse magnetic field generating device, method, medium, equipment and terminal based on a double-coil magnet, aiming to solve the problem that it is difficult for the existing flat-top magnetic field to take into account high field strength, high stability and long flat-top pulse width.

[0014] The present invention is implemented as follows. A flat-top pulsed magnetic field generating device includes a plurality of capacitor-type power supplies, a pulse rectifier-type power supply, and a dual-coil magnet connected in parallel.

[0015] Among them, the capacitor-type power supply consists of a capacitor bank, its protection inductor, a discharge thyristor, and a freewheeling circuit. The positive poles of the output terminals of the capacitor-type power supplies are all connected to the positive pole of the outer coil of the magnet, and the negative poles of the output terminals are all connected to the negative pole of the outer coil of the magnet.

[0016] The pulse rectifier-type power supply consists of a power supply and a supporting rectifier. The power supply is a pulse generator or the commercial power supply. The positive pole of the rectifier output terminal of the pulse rectifier-type power supply is connected to the positive pole of the inner coil of the magnet, and the negative pole of the rectifier output terminal is connected to the negative pole of the inner coil of the magnet.

[0017] Before discharging the magnet, the capacitor-type power supply is charged and stored with energy.

[0018] When discharging the magnet, the capacitor-type power supply supplies power to the outer coil of the magnet. When starting to discharge, the trigger thyristor T of the first capacitor power supply is turned on, and C starts to discharge. The magnet current rises to establish a magnetic field. After reaching the peak value, it starts to decline. Subsequently, T1 to Tn are sequentially turned on according to the calculated timing sequence, so that the subsequent capacitors are discharged in turn until the last capacitor discharges to provide a current falling edge, generating a flat-top waveform similar to a combination of multiple "m" shapes on the outer coil. The pulse rectifier power supply discharges the inner coil of the magnet. When the magnet current rises to establish a magnetic field and enters the flat-top stage, the superimposed magnetic field of the inner and outer coils obtained by sampling is compared with the target magnetic field. After passing through the logic controller, the conduction and closing of the pulse rectifier are adjusted by PI control, so that the magnetic field generated by the dual-coil magnet is consistent with the target magnetic field. After the flat-top stage ends, the remaining energy on the capacitor power supply is consumed through the freewheeling circuit, and finally the capacitor voltage drops to zero, and the output power of the pulse rectifier-type power supply gradually drops to zero. The magnet current is converted into a flat-top pulsed strong magnetic field by the magnet, and the conversion coefficient is a constant.

[0019] Furthermore, the capacitor-type power supply includes a capacitor bank, a trigger thyristor, a freewheeling diode, and a freewheeling resistor.

[0020] Among them, the positive pole of the capacitor bank is connected to the positive pole of the trigger thyristor, the negative pole of the capacitor bank is connected to the positive pole of the freewheeling diode, the negative pole of the freewheeling diode is connected to the negative pole of the trigger thyristor through the freewheeling resistor. The negative pole of the trigger thyristor is the positive pole output by the capacitor-type power supply, and the negative pole of the capacitor bank is the negative pole output by the capacitor-type power supply.

[0021] The trigger thyristor is a programmable thyristor, and the trigger timing sequence is obtained through calculation.

[0022] The capacitor bank needs to be equipped with an additional charging device, and the charging voltage is obtained through calculation.

[0023] Furthermore, when powering the pulse generator, the pulse rectifier type power supply includes a coaxial motor and generator, a phase-shifting transformer, a rectifier, and corresponding control and protection auxiliary circuits.

[0024] Among them, the motor is a wound-rotor three-phase induction motor with a rated voltage of 12 kV, a rated power of 1417 kW, and a rated frequency of 60 Hz;

[0025] The synchronous generator has a rated output voltage of 6.9 kV and a rated power of 100 MVA;

[0026] The rectifier system consists of four phase-shifting transformers with phase-shifting angles of 7.5°, -22.5°, 22.5°, and 7.5° respectively and four sets of six-pulse rectifiers. The four six-pulse rectifiers are connected in parallel in pairs to form two twelve-pulse rectifiers for use. The two twelve-pulse rectifiers can be connected in parallel or in series, and the connection method can be changed according to actual working needs;

[0027] The rated frequency of the phase-shifting transformer is 80 Hz, the working frequency range is 66 - 95 Hz, the rated capacity is 10 MVA, the short-time capacity reaches 40 MVA, and the voltage transformation ratio is 6.9 kV / 1.2 kV / 1 kV; Each rectifier arm is composed of four thyristors connected in parallel. The rated output current of the entire rectifier system is 25 kA / 3 s, the no-load voltage is 1.6 kV, and the full-load voltage is 1.35 kV.

[0028] Furthermore, the flat-top pulse magnetic field generating device further includes a controller and a current sensor.

[0029] Among them, the current sensor respectively collects the currents flowing through the inner and outer coils of the magnet;

[0030] According to the controller and the current obtained by sampling, the on and off of the twelve-pulse rectifier are controlled, so as to ensure the stability of the magnetic field in the flat-top stage of the coil.

[0031] Furthermore, the current value obtained by collection is calculated to obtain the real-time field strength obtained by superimposing the inner and outer coils;

[0032] The current determines the on and off of the pulse rectifier after passing through a series of logic control circuits;

[0033] The controller adopts a PI control strategy.

[0034] Another object of the present invention is to provide a flat-top pulse magnetic field generating method using the flat-top pulse magnetic field generating device described above. The flat-top pulse magnetic field generating method includes:

[0035] The high-voltage capacitor bank discharges the outer coil of the magnet in sequence according to a preset time sequence, causing the current to rise rapidly. Subsequently, the subsequent capacitor power supplies are turned on in sequence to keep the current in the outer coil at a certain level. The capacitor-type power supply serves as the basis for the flat-top magnetic field. The pulse rectifier-type power supply supplies power to the inner coil, superimposing the magnetic field to obtain a high-field-strength synthetic magnetic field. After entering the flat-top stage, the on-off of the pulse rectifier is controlled by PI sampling, so that the magnetic field generated by the superposition of the inner and outer coils remains unchanged. After the discharge is completed, the magnet energy is released by the freewheeling circuit.

[0036] Furthermore, the method for generating the flat-top pulse magnetic field includes the following steps:

[0037] Step 1: Use the charged capacitor-type power supply to discharge the outer coil of the magnet, causing the current in the outer coil to rise rapidly. The initial voltage and trigger time of the capacitor-type power supply are both obtained by simulation calculation;

[0038] Step 2: The pulse rectifier-type power supply starts to work after a period of time when the first group of capacitors is put in. At this time, the trigger angle is adjusted to a fixed small angle, and the pulse generator starts to discharge the inner coil of the magnet;

[0039] Step 3: When the magnetic field enters the flat-top stage, the PI controller starts to work, obtains the real-time magnetic field based on the sampled currents of the inner and outer coils, and uses the difference from the target magnetic field as the input of the PI controller;

[0040] Step 4: Adjust the trigger angle of the pulse generator. The trigger angle signal determines the closing and opening of the four sets of six-pulse rectifiers after passing through the synchronous six-pulse generator, so as to ensure the stability of the magnetic field in the flat-top stage;

[0041] Step 5: After the flat-top stage ends, the output voltage of the capacitor-type power supply drops slowly, and the energy is consumed on the freewheeling circuit. The trigger angle of the rectifier is stabilized at 140°. At this time, the output of the rectifier keeps dropping until it reaches zero.

[0042] Another object of the present invention is to provide a computer device, which includes a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, the processor performs the following steps:

[0043] At the rising edge of the flat top, the capacitor-type power supply and the pulse rectifier-type power supply discharge the outer and inner coils of the magnet respectively, and the superimposed magnetic field rises rapidly. When the discharge current of the first group of capacitor-type power supplies reaches near the peak value and the circuit enters the flat-top stage, the capacitor-type power supply discharges in sequence according to the set time sequence, and the pulse rectifier-type power supply maintains the magnetic field superimposed by the inner and outer coils to be consistent with the target magnetic field under the control of the PI controller; after the flat-top stage ends, the remaining energy in the capacitor is consumed through the freewheeling circuit, and the output power of the pulse rectifier-type power supply gradually drops to zero.

[0044] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the following steps:

[0045] For the flat-top rising edge, the capacitor-type power supply and the pulse rectifier-type power supply discharge to the outer and inner coils of the magnet respectively, and the superimposed magnetic field rises rapidly. When the discharge current of the first group of capacitor-type power supplies reaches near the peak value and the circuit enters the flat-top stage, the capacitor-type power supplies discharge in sequence according to the set time sequence, and the pulse rectifier-type power supply maintains the superimposed magnetic field of the inner and outer coils to be consistent with the target magnetic field under the control of the PI controller; after the flat-top stage ends, the remaining energy in the capacitor is consumed through the freewheeling circuit, and the output power of the pulse rectifier-type power supply gradually drops to zero.

[0046] Another object of the present invention is to provide an information data processing terminal for implementing the flat-top pulse magnetic field generating device.

[0047] Combined with the above technical solutions and the technical problems solved, please analyze the advantages and positive effects of the technical solution to be protected by the present invention from the following aspects:

[0048] First, aiming at the technical problems existing in the above-mentioned prior art and the difficulty of solving this problem, closely combining the technical solution to be protected by the present invention and the results and data in the R & D process, etc., analyze in detail and profoundly how the technical solution of the present invention solves the technical problems and the creative technical effects brought after solving the problems. The specific description is as follows:

[0049] In the present invention, the outer coil and the inner coil of the double coil are respectively powered by a capacitor-type power supply and a pulse rectifier-type power supply, which solves the problem that it is difficult for the existing flat-top magnetic field to take into account high field strength, high stability, and long flat-top pulse width.

[0050] Generally speaking, compared with the prior art solutions, the technical solutions conceived by the present invention can achieve the following beneficial effects:

[0051] (1) The present invention combines the existing time-sequence capacitor-type power supply and the pulse rectifier-type power supply, and effectively improves the magnetic field strength in the flat-top stage by using the principle of linear superposition of magnetic fields while ensuring the pulse width of the flat-top magnetic field.

[0052] (2) Aiming at the characteristic that it is difficult for the pulse rectifier to quickly respond to the output voltage, by pre-calculation, the change amount of the current flowing through the inner and outer coils of the magnet in the flat-top stage is very small, so the mutual inductance of the inner and outer coils can be ignored, which greatly simplifies the calculation process.

[0053] (3) Capacitor-type power supplies have the advantages of low cost, high power factor, and simple control. Using a capacitor power supply as the basis for synthesizing the magnetic field can shorten the magnetic field rise time, reduce the heating of the magnet during discharge, improve the efficiency of the overall system, and extend the service life of the magnet.

[0054] (4) When two twelve-pulse rectifiers are connected in series, the pulse rectifier-type power supply can provide a twenty-four-pulse waveform with small ripple, ensuring the stability of the waveform during the flat-top stage.

[0055] Second, considering the technical solution as a whole or from the perspective of the product, the technical effects and advantages of the technical solution to be protected by the present invention are specifically described as follows:

[0056] Aiming at the defects of the prior art, the present invention provides a flat-top pulse magnetic field generation device and method based on a dual-coil magnet. The flat-top pulse magnetic field generation device based on a dual-coil magnet can generate a flat-top pulse magnetic field with high stability, high field strength, and long flat-top pulse width, solving the problems that it is difficult to balance the flat-top duration and the magnetic field strength during the flat-top stage of the existing flat-top pulse magnetic field, as well as the long rise time of the flat-top waveform and the low system efficiency, and providing a necessary strong magnetic field environment for scientific experiments such as nuclear magnetic resonance and specific heat measurement. The pulse rectifier power supply of the present invention is combined with a high-voltage capacitor bank to supply power to generate a flat-top pulse magnetic field.

[0057] Third, as the creative auxiliary evidence of the claims of the present invention, it is also reflected in the following important aspects:

[0058] (1) The expected benefits and commercial value after the transformation of the technical solution of the present invention are: The application value of this solution is mainly reflected in: using a cheap high-voltage capacitor power supply as the main energy supply power, supplemented by a pulse rectifier power supply with PI control, greatly reducing the cost and control difficulty of the flat-top pulse magnetic field power supply.

[0059] (2) The technical solution of the present invention fills the technical gaps in the domestic and international industries: At present, the parameters of the flat-top pulse magnetic field obtained by simulating this solution are 60T, 110ms, and 10,000 ppm (see Supplementary Table 2). Compared with the existing solutions, it has quite obvious advantages in pulse intensity and flat-top pulse width time, and the stability can be further improved by adjusting the electrical parameters, so it has great potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments of the present invention. Obviously, the following described drawings are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings without creative efforts.

[0061] Figure 1 It is a flowchart of the method for generating a flat-top pulsed magnetic field provided by an embodiment of the present invention.

[0062] Figure 2 It is an overall schematic diagram provided by an embodiment of the present invention.

[0063] Figure 3 It is a schematic structural diagram of the device for generating a flat-top pulsed magnetic field provided by an embodiment of the present invention.

[0064] Figure 4 It is a schematic diagram of the capacitor module provided by an embodiment of the present invention.

[0065] Figure 5 It is a schematic diagram of the magnetic field waveform during actual discharge provided by an embodiment of the present invention.

[0066] Figure 6 It is a schematic diagram of the magnetic temperature rise during actual discharge provided by an embodiment of the present invention. Specific embodiments

[0067] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0068] In view of the problems existing in the prior art, the present invention provides a device, method, medium, equipment and terminal for generating a flat-top pulsed magnetic field. The following will describe the present invention in detail with reference to the accompanying drawings.

[0069] I. Explanation of the embodiments. In order to enable those skilled in the art to fully understand how the present invention is specifically implemented, this part is an explanatory embodiment that expands and explains the technical solutions of the claims.

[0070] Embodiment 1

[0071] Aiming at the defects of the prior art, the objective of the present invention is to provide a device and method for generating a flat-top pulsed magnetic field based on a dual-coil magnet. The outer coil and inner coil of the dual-coil are respectively powered by a capacitor-type power supply and a pulse rectifier-type power supply, aiming to solve the problem that it is difficult for the existing flat-top magnetic field to balance high field strength, high stability and long flat-top pulse width.

[0072] To achieve the above objective, the present invention provides a method for generating a flat-top pulsed magnetic field based on a dual-coil magnet. As Figure 1 shown, the method for generating a flat-top pulsed magnetic field provided by an embodiment of the present invention includes the following steps:

[0073] S101. Discharge the outer coil of the magnet using the charged capacitor-type power supply to rapidly increase the current in the outer coil. The initial voltage and trigger time of the capacitor-type power supply are both obtained through simulation calculation;

[0074] S102. After a period of time when the first group of capacitors is put into operation, the pulse rectifier type power supply starts to work. At this time, the firing angle is adjusted to a fixed small angle, and the pulse generator starts to discharge to the inner coil in the magnet.

[0075] S103. When the magnetic field enters the flat-top stage, the PI controller starts to work. The real-time magnetic field is obtained based on the sampled inner and outer coil currents, and the difference from the target magnetic field is used as the input of the PI controller.

[0076] S104. Adjust the firing angle of the pulse generator. The firing angle signal determines the closing and turning off of the four sets of six-pulse rectifiers after passing through the synchronous six-pulse generator, so as to ensure the stability of the magnetic field in the flat-top stage.

[0077] S105. After the flat-top stage ends, the output voltage of the capacitor type power supply slowly decreases, and the energy is consumed on the freewheeling circuit. The rectifier firing angle is stabilized at 140°, and at this time, the rectifier output continuously decreases until it reaches zero.

[0078] The overall schematic diagram provided by the embodiment of the present invention is as Figure 2 shown.

[0079] In a second aspect, the present invention provides a flat-top pulse magnetic field generating device based on a dual-coil magnet, including: a capacitor type power supply, a pulse rectifier type power supply, and a magnet;

[0080] The positive pole of the rectifier output terminal of the pulse rectifier type power supply is connected to the positive pole of the inner coil in the magnet, and the negative pole of the rectifier output terminal is connected to the negative pole of the inner coil in the magnet;

[0081] The positive poles of the output terminals of the capacitor type power supply are all connected to the positive pole of the outer coil of the magnet, and the negative poles of the output terminals are all connected to the negative pole of the outer coil of the magnet;

[0082] Before discharging to the magnet, it is necessary to charge and store energy in the capacitor type power supply;

[0083] When discharging the magnet, the capacitor-type power supply supplies power to the outer coil of the magnet. When starting the discharge, the trigger thyristor T of the first capacitor power supply is turned on, and C starts to discharge. The magnet current rises to establish a magnetic field. After reaching the peak, it starts to decline. Subsequently, T1 to Tn are turned on in sequence according to the calculated timing, so that the subsequent capacitors discharge in turn until the last capacitor discharges to provide a current falling edge, generating a flat-top waveform similar to a combination of multiple "m" shapes on the outer coil; the pulse rectifier power supply discharges the inner coil of the magnet. The magnet current rises to establish a magnetic field. After entering the flat-top stage, the superimposed magnetic field of the inner and outer coils obtained by sampling is compared with the target magnetic field. After passing through the logic controller, the conduction and closing of the pulse rectifier are adjusted by PI control, so that the magnetic field generated by the double-coil magnet is consistent with the target magnetic field; after the flat-top stage ends, the remaining energy on the capacitor power supply is consumed through the freewheeling circuit, and finally the capacitor voltage drops to zero, and the output power of the pulse rectifier-type power supply gradually drops to zero; the magnet current is converted from the magnet to a flat-top pulsed strong magnetic field, and its conversion coefficient is a constant.

[0084] Furthermore, the capacitor-type power supply includes: a capacitor bank, a trigger thyristor, a freewheeling diode, and a freewheeling resistor;

[0085] The positive pole of the capacitor bank is connected to the positive pole of the trigger thyristor. The negative pole of the capacitor bank is connected to the positive pole of the freewheeling diode. The negative pole of the freewheeling diode is connected to the negative pole of the trigger thyristor through the freewheeling resistor. The negative pole of the trigger thyristor is the positive pole output by the capacitor-type power supply, and the negative pole of the capacitor bank is the negative pole output by the capacitor-type power supply;

[0086] The trigger thyristor is a programmable thyristor, and its trigger timing is obtained through calculation;

[0087] The capacitor bank needs to be equipped with an additional charging device, and the charging voltage is obtained through calculation;

[0088] Furthermore, the pulse rectifier-type power supply includes (taking the pulse generator power supply as an example): a coaxial motor and generator, a phase-shifting transformer, a rectifier, and corresponding control and protection auxiliary circuits;

[0089] The motor is a wound-rotor three-phase induction motor with a rated voltage of 12 kV, a rated power of 1417 kW, and a rated frequency of 60 Hz;

[0090] The synchronous generator has a rated output voltage of 6.9 kV and a rated power of 100 MVA;

[0091] The rectifier system consists of four phase-shifting transformers with phase-shifting angles of 7.5°, -22.5°, 22.5°, and 7.5° respectively, and four sets of six-pulse rectifiers. Usually, the four six-pulse rectifiers are connected in parallel in pairs to form two twelve-pulse rectifiers. The two twelve-pulse rectifiers can be connected in parallel or in series, and their connection method can be changed according to actual working needs.

[0092] The rated frequency of the phase-shifting transformer is 80 Hz, the operating frequency range is 66 - 95 Hz, the rated capacity is 10 MVA, the short-time capacity can reach 40 MVA, and the voltage ratio is 6.9 kV / 1.2 kV / 1 kV. Each rectifier arm is composed of four thyristors connected in parallel. The rated output current of the entire rectifier system is 25 kA / 3 s, the no-load voltage is 1.6 kV, and the full-load voltage is 1.35 kV.

[0093] Furthermore, the device includes: a controller and current sensors;

[0094] The current sensors respectively collect the currents flowing through the inner and outer coils of the magnet.

[0095] According to the currents obtained by sampling combined with the controller, control the turn-on and turn-off of the twelve-pulse rectifier, so as to ensure the stability of the magnetic field during the flat-top stage of the coil.

[0096] Generally speaking, compared with the prior art solutions, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0097] The device of the present invention combines the existing timing capacitor-type power supply and pulse-type power supply, and effectively improves the magnetic field strength during the flat-top stage while ensuring the pulse width of the flat-top magnetic field by using the principle of linear superposition of magnetic fields.

[0098] Aiming at the characteristic that the output voltage of the pulse rectifier is difficult to respond quickly, by pre-calculation, the change amount of the current flowing through the inner and outer coils of the magnet during the flat-top stage is very small, so the mutual inductance between the inner and outer coils can be ignored, greatly simplifying the calculation process.

[0099] The capacitor-type power supply has the advantages of low cost, high power, and simple control. Using the capacitor power supply as the basis for synthesizing the magnetic field can shorten the rising time of the magnetic field, reduce the heat generation of the magnet during the discharge process, improve the efficiency of the overall system, and extend the service life of the magnet.

[0100] When the two twelve-pulse rectifiers are connected in series, the pulse rectifier-type power supply can provide a twenty-four-pulse waveform, which has small ripple and ensures the stability of the waveform during the flat-top stage.

[0101] Embodiment 2

[0102] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a flat-top pulse magnetic field generation device and method based on a dual-coil magnet, aiming to solve the problems that it is difficult to balance the flat-top duration and the magnetic field strength in the flat-top stage of the existing flat-top pulse magnetic field, as well as the long rising edge time of the flat-top waveform and the low system efficiency, and to provide a necessary strong magnetic field environment for scientific experiments such as nuclear magnetic resonance and specific heat measurement.

[0103] To generate a flat-top pulsed strong magnetic field with high field strength, high stability, and long flat-top pulse width, the present invention adopts the following technical solutions: This device uses a high-voltage capacitor-type power supply and a pulse rectifier-type power supply to supply power to the outer and inner coils of the magnet respectively. The combination of these two power supplies can greatly shorten the time required for the rising edge of the flat-top pulse magnetic field compared with the battery-type power supply, reducing it from the original 500 ms to 50 ms; during the flat-top period, the high-voltage capacitor-type power supply and the pulse rectifier-type power supply supply power simultaneously. Among them, the capacitor-type power supply provides the main part of the flat-top pulse strong field, about 40 T, and the pulse rectifier power supply provides the secondary part of the flat-top pulse strong magnetic field, about 20 T, and the trigger angle of the rectifier is adjusted in real time through PI control to ensure that the superimposed magnetic field is consistent with the target magnetic field (60 T). The advantages of the high-voltage capacitor-type power supply are high power density, simple control, high flat-top stability, controllable pulse width, low cost, etc. The pulse rectifier power supply has a large output energy, adjustable output voltage, and can achieve long-term voltage stabilization, but the system response speed is relatively slow. The present invention makes full use of the advantages of both. The capacitor-type power supply is used as the main output, and the pulse rectifier-type power supply is used as the secondary output. The discharge parameters of each capacitor are accurately obtained through simulation calculations in MATLAB / Simulink to achieve decoupling of the inner and outer coils of the magnet during the flat-top stage. Four sets of six-pulse rectifiers supporting the pulse generator are connected in parallel in pairs, equivalent to two sets of twelve-pulse rectifiers. The two sets of twelve-pulse rectifiers operate in parallel. During the flat-top stage, the currents of the inner and outer coils of the magnet are sampled in real time, and the trigger angle of the rectifier is adjusted in real time using negative feedback PI regulation to adjust the output current of the pulse rectifier power supply, compensate for the current fluctuation of the outer coil caused by the capacitor module switching process, and at the same time compensate for the current change caused by the change in the internal resistance during the magnet temperature rise process, so that the superimposed magnetic field is maintained at 60 T. In summary, a flat-top pulsed strong magnetic field with high field strength, high stability, and long flat-top pulse width is generated.

[0104] The present invention provides a flat-top pulse magnetic field generation device based on a dual-coil magnet, as Figure 3 shown, mainly including: a pulse rectifier power supply powered by a pulse generator, which consists of a 100 MW pulse generator, four phase-shifting transformers with phase-shifting angles of +7.5°, -22.5°, +22.5°, -7.5° respectively, four sets of six-pulse rectifiers, a main discharge switch, and an RC filter branch; a high-voltage capacitor-type power supply. In this example, more specifically, it includes a starting module and twelve auxiliary modules, as Figure 4As shown, each module consists of a corresponding energy storage capacitor, a trigger switch, a freewheeling diode, and a freewheeling resistor; a dual-coil magnet; a precision current sensor; and a controller.

[0105] As Figure 3 shown, the present invention is composed of a first loop and a second loop. The first loop 11 includes: the positive pole of the rectifier, a discharge diode, the inner coil of the magnet, the negative pole of the rectifier, the precision current sampler, and the negative pole of the rectifier are connected in series in turn to form a loop, and a filter loop is connected in parallel between the positive and negative poles of the rectifier; wherein the filter loop includes a resistor and a capacitor, which are used to filter out the high-frequency noise contained in the DC voltage output by the rectifier.

[0106] The second loop 12 includes thirteen capacitor power modules connected in parallel, and the positive and negative poles of its output are respectively connected to the positive and negative poles of the outer coil of the magnet.

[0107] Furthermore, as Figure 3 shown, for a specific capacitor power module, the positive pole of the capacitor, the anode of the trigger thyristor, the cathode of the trigger thyristor, the freewheeling resistor, the cathode of the freewheeling diode, the anode of the freewheeling diode, and the negative pole of the capacitor are connected in series in turn to form a loop. The cathode of the trigger thyristor serves as the positive pole of the output of the capacitor power module, and the negative pole of the capacitor serves as the negative pole of the output of the capacitor power module. Among them, the high-voltage capacitor bank is the energy storage component of the capacitor power module, and the thyristor is the control switch of the capacitor power module. The existence of the freewheeling loop enables a commutation process to occur during the switching of the capacitor power module; the magnet coil is used to convert current into a magnetic field.

[0108] Furthermore, the positions of the diode and the resistor in the freewheeling loop can be interchanged.

[0109] The precision current sensor CT respectively collects the currents ii and io of the inner and outer coils of the magnet and transmits them to the controller. The controller outputs four-way six-pulse signals to control the four sets of six-pulse rectifiers described above.

[0110] In the embodiment of the present invention, the operation of the flat-top pulsed magnetic field generating device is as follows:

[0111] The discharge process is divided into a magnet current rising stage, a magnet current flat-top stage, and a magnet current falling stage, and the start and end times of each state are determined in advance through MATLAB / Simulink calculation.

[0112] Preparation stage: Immerse the magnet in liquid nitrogen and cool it to 77K, and detect the cooling process of the magnet by measuring the change in the resistance value of the magnet; charge the capacitor modules 1-13 to the set voltage value, and the set voltage value can be obtained through simulation calculation.

[0113] During the magnet current rising stage, the start module in the capacitor-type power supply is first triggered, and the capacitor bank starts to discharge to the outer coil of the magnet, and the current in the second loop 12 gradually rises;

[0114] After the capacitor module is started, according to the set circuit trigger delay, the pulse rectifier power supply is put into operation, and the rectifier trigger angle is fixed. At this time, the current flowing through the inner coil of the magnet approximately rises linearly;

[0115] During the magnet current flat-top stage, after the magnet current provided by the start module in the capacitor-type power supply reaches the peak value and then starts to drop, the subsequent auxiliary capacitor power supply modules are started in sequence according to the set timing. It should be noted that due to reasons such as capacitor protection inductance and line inductance, the current on the previous capacitor module will not instantaneously drop to zero. At this time, two adjacent capacitor power supply modules jointly supply power to the outer coil of the magnet until the current provided by the previous module drops to zero.

[0116] This process is called commutation;

[0117] At the same time, according to the preset flat-top start time, the controller starts to work: Given the conversion coefficient of the inner and outer coils of the magnet to convert current into magnetic field, the precise current sampler transmits the measured current flowing through the inner and outer coils of the magnet to the controller. The controller calculates the difference between the current magnetic field and the target magnetic field, which is used as the input of the PI controller. Subsequently, the PI controller outputs the trigger angle of the four-way six-pulse rectifier. This trigger signal controls the closing and turning off of the thyristors of the four sets of six-pulse rectifiers described above through the six-pulse generator, so that the pulse rectifier power supply outputs current to compensate for the current drop during the commutation of the outer coil capacitor and the change in magnet current caused by the change in the internal resistance of the magnet, ensuring the stability of the current flat-top stage;

[0118] During the magnet current falling stage, at this time, the voltage across the outer coil of the magnet is negative, and the remaining magnetic field energy is consumed through the freewheeling circuit;

[0119] At this time, the PI controller stops working, the trigger angle of the pulse rectifier power supply is fixed at 90°, and then adjusted to 140°, and the output current drops to zero.

[0120] In order to further illustrate that the flat-top pulsed magnetic field provided by the embodiments of the present invention can generate a flat-top pulsed strong magnetic field with high field strength, high stability, and long flat-top pulse width, the following is detailed through an example:

[0121] The first loop 11: The operating frequency of the pulse generator is 80 Hz, the resistance value of the rectifier filter resistor is 3 Ω, the filter capacitor is 100 μF, the line inductance and line resistance are ignored, the resistance value of the inner coil of the magnet is 0.01728 Ω (77K), and the inductance is 3.6 mH;

[0122] Second loop 12: The line inductance and line resistance are negligible. The resistance of the coil in the magnet is 0.04632 Ω (77K), and the inductance is 40.6 mH. The energy storage capacitor parameters of each capacitor power supply module are the same, with a capacitance of 3.84 mF, and the internal resistance and inductance are 0.1 Ω and 1 mH respectively. The freewheeling resistance supporting each single capacitor power supply module is 6 Ω. The parallel number, initial voltage, and trigger time of the energy storage capacitors of each module capacitor power supply are shown in Table 1.

[0123] Table 1 Parallel number, initial voltage, and trigger time of the energy storage capacitors of each module capacitor power supply

[0124]

[0125] Figure 5 、 Figure 6 respectively give the flat-top magnetic field waveform and the temperature rise waveform of the coil obtained by the simulation of the embodiments of the present invention. As Figure 4 shown, B1 and B2 are the magnetic field intensities of the outer and inner coils respectively. The two magnetic fields are superimposed to obtain a 60T flat-top pulsed magnetic field, whose flat-top time is about 110 ms, and the stability of the flat-top magnetic field stage is about 1%.

[0126] II. Evidence of the related effects of the embodiments. Some positive effects have been achieved during the R & D or use of the embodiments of the present invention, and it indeed has great advantages compared with the prior art. The following content will be described in combination with the data, charts, etc. of the test process.

[0127] The simulation results of this solution are shown in Figure 5 . Comparing the obtained flat-top pulsed strong magnetic field with the prior art solutions (Table 2), it can be seen that this solution has advantages in field strength and flat-top time. In addition, its power supply type is mainly high-voltage capacitor bank and supplemented by pulse rectifier, which greatly reduces the cost and at the same time reduces the impact on the power grid. After adjusting the relevant electrical parameters, its stability can be further improved to meet the application requirements of various experiments.

[0128] Table 2 Comparison of existing flat-top pulsed magnetic field types and parameters

[0129]

[0130] In the present invention, the circuit parameters of the capacitor-type power supply and the pulse rectifier-type power supply are adjustable, and can be further optimized through simulation software to obtain a flat-top pulsed magnetic field with higher field strength and better stability.

[0131] It should be noted that the embodiments of the present invention can be implemented by hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated designed hardware. Those of ordinary skill in the art can understand that the above-mentioned devices and methods can be implemented using computer-executable instructions and / or included in processor control code, for example, such code is provided on a carrier medium such as a disk, CD, or DVD-ROM, a programmable memory such as read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The devices and their modules of the present invention can be implemented by hardware circuits of programmable hardware devices such as very large scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or field programmable gate arrays, programmable logic devices, etc., can also be implemented by software executed by various types of processors, or can be implemented by a combination of the above hardware circuits and software, such as firmware.

[0132] As described above, the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

Claims

1. A flat-top pulsed magnetic field generating device, characterized in that, The flat-top pulsed magnetic field generating device includes multiple capacitor-type power supplies, pulse rectifier-type power supplies, and double-coil magnets connected in parallel; Among them, the capacitor-type power supply consists of a capacitor bank, its protection inductor, discharge thyristor, and freewheeling circuit; the positive poles of the output terminals of the capacitor-type power supplies are all connected to the positive pole of the outer coil of the magnet, and the negative poles of the output terminals are all connected to the negative pole of the outer coil of the magnet; The pulse rectifier-type power supply consists of a power supply and a supporting rectifier. The power supply is a pulse generator or mains power; the positive pole of the rectifier output terminal of the pulse rectifier-type power supply is connected to the positive pole of the inner coil of the magnet, and the negative pole of the rectifier output terminal is connected to the negative pole of the inner coil of the magnet; Before discharging the magnet, the capacitor-type power supply is charged and stores energy; When discharging the magnet, the capacitor-type power supply supplies power to the outer coil of the magnet. When starting to discharge, the trigger thyristor T of the first capacitor power supply is turned on, and C starts to discharge. The magnet current rises to establish a magnetic field. After reaching the peak, it starts to decline. Subsequently, T1~Tn are turned on in sequence according to the calculated timing, so that the subsequent capacitors discharge in turn until the last capacitor discharges to provide a current falling edge, generating a flat-top waveform similar to a combination of multiple "m" shapes on the outer coil; the pulse rectifier power supply discharges to the inner coil of the magnet, and the magnet current rises to establish a magnetic field. After entering the flat-top stage, the superimposed magnetic field of the inner and outer coils obtained by sampling is compared with the target magnetic field. After passing through the logic controller, the PI control is used to adjust the conduction and closing of the pulse rectifier, so that the magnetic field generated by the double-coil magnet is consistent with the target magnetic field; after the flat-top stage ends, the remaining energy on the capacitor power supply is consumed through the freewheeling circuit, and finally the capacitor voltage drops to zero, and the output power of the pulse rectifier-type power supply gradually drops to zero; the magnet current is converted into a flat-top pulsed strong magnetic field by the magnet, and the conversion coefficient is a constant; The capacitor-type power supply includes a capacitor bank, a trigger thyristor, a freewheeling diode, and a freewheeling resistor; Among them, the positive pole of the capacitor bank is connected to the positive pole of the trigger thyristor, the negative pole of the capacitor bank is connected to the positive pole of the freewheeling diode, the negative pole of the freewheeling diode is connected to the negative pole of the trigger thyristor through the freewheeling resistor, the negative pole of the trigger thyristor is the positive pole output by the capacitor-type power supply, and the negative pole of the capacitor bank is the negative pole output by the capacitor-type power supply; The trigger thyristor is a programmable thyristor, and the trigger timing is obtained through calculation; The capacitor bank needs to be equipped with an additional charging device, and the charging voltage is obtained through calculation.

2. The flat-top pulsed magnetic field generating device according to claim 1, characterized in that, When powering the pulse generator, the pulse rectifier-type power supply includes a coaxial motor and generator, a phase-shifting transformer, a rectifier, and corresponding control and protection auxiliary circuits; Among them, the motor is a wound-rotor three-phase induction motor with a rated voltage of 12 kV, a rated power of 1417 kW, and a rated frequency of 60 Hz; The generator of the pulse rectifier-type power supply has a rated output voltage of 6.9 kV and a rated power of 100 MVA; The rectifier consists of four phase-shifting transformers with phase-shifting angles of 7.5°, -22.5°, 22.5° and 7.5° respectively, and four sets of six-pulse rectifiers. The four six-pulse rectifiers are connected in parallel in pairs to form two twelve-pulse rectifiers for use. The two twelve-pulse rectifiers can be connected in parallel or in series, and the connection method can be changed according to actual working needs. The rated frequency of the phase-shifting transformer is 80 Hz, the operating frequency range is 66 - 95 Hz, the rated capacity is 10 MVA, the short-time capacity reaches 40 MVA, and the voltage transformation ratio is 6.9 kV / 1.2 kV / 1 kV. Each rectifier arm is composed of four thyristors connected in parallel. The rated output current of the entire rectifier system is 25 kA / 3 s, the no-load voltage is 1.6 kV, and the full-load voltage is 1.35 kV.

3. The flat-top pulsed magnetic field generating device according to claim 1, wherein The flat-top pulsed magnetic field generating device further includes a controller and a current sensor. Among them, the current sensor respectively collects the currents flowing through the inner and outer coils of the magnet. According to the controller and the current obtained by sampling, the on and off of the twelve-pulse rectifier are controlled, so as to ensure the stability of the magnetic field during the flat-top stage of the coil.

4. The flat-top pulsed magnetic field generating device according to claim 3, wherein The collected current value is calculated to obtain the real-time field strength obtained by superimposing the inner and outer coils. The current determines the on and off of the pulsed rectifier after passing through a series of logic control circuits. The controller adopts a PI control strategy.

5. A method for generating a flat-top pulsed magnetic field using the flat-top pulsed magnetic field generating device according to any one of claims 1 to 4, characterized in that, The flat-top pulsed magnetic field generating method includes: The high-voltage capacitor bank discharges the outer coil of the magnet in sequence according to a preset time sequence, so that the current rises rapidly. Subsequently, the subsequent capacitor power supplies are conducted in sequence to keep the current of the outer coil at a certain level. The capacitor-type power supply serves as the basis for the flat-top magnetic field. The pulsed rectifier-type power supply supplies power to the inner coil to superimpose the magnetic field and obtain a high-field-strength synthetic magnetic field. After entering the flat-top stage, the on and off of the pulse rectifier are controlled by PI sampling, so that the magnetic field generated by the superposition of the inner and outer coils remains unchanged. After the discharge ends, the magnet energy is released by the freewheeling circuit.

6. The method for generating a flat-top pulsed magnetic field according to claim 5, wherein, The flat-top pulsed magnetic field generating method includes the following steps: Step 1, use the charged capacitor-type power supply to discharge the outer coil of the magnet, so that the current of the outer coil rises rapidly. The initial voltage and trigger time of the capacitor-type power supply are both obtained by simulation calculation. Step 2, the pulsed rectifier-type power supply starts to work after a period of time when the first group of capacitors is put into operation. At this time, the trigger angle is adjusted to a fixed small angle, and the pulsed generator starts to discharge the inner coil of the magnet. Step 3, when the magnetic field enters the flat-top stage, the PI controller starts to work, obtains the real-time magnetic field according to the sampled currents of the inner and outer coils, and uses the difference from the target magnetic field as the input of the PI controller. Step 4, the pulsed rectifier-type power supply includes a rectifier, which consists of four phase-shifting transformers with phase-shifting angles of 7.5°, -22.5°, 22.5° and 7.5° respectively, and four sets of six-pulse rectifiers. Adjust the trigger angle of the pulsed generator. The trigger angle signal determines the closing and opening of the four sets of six-pulse rectifiers after passing through the synchronous six-pulse generator, so as to ensure the stability of the magnetic field during the flat-top stage. Step 5: After the flat-top stage ends, the output voltage of the capacitor-type power supply drops slowly, and the energy is consumed on the freewheeling loop. The firing angle of the rectifier stabilizes at 140°, and at this time, the output of the rectifier keeps dropping until it reaches zero.

7. A computer device, characterized in that, The computer device includes a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, the processor is caused to execute the steps of the flat-top pulse magnetic field generation method according to any one of claims 5 to 6.

8. A computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the processor is caused to execute the steps of the flat-top pulse magnetic field generation method according to any one of claims 5 to 6.

9. An information data processing terminal, characterized in that, The information data processing terminal is used to implement the flat-top pulse magnetic field generation device according to any one of claims 1 to 4.

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