Magnetic field control device

Abstract

A magnetic field control device, the magnetic field control device comprises a load coil, a sampling module, a programmed reference voltage module and a controller module; the programmed reference voltage module can generate an instruction digital signal, the programmed reference voltage module comprises a trigger input end and a reset input end, the trigger input end and the reset input end are used for receiving a digital signal trigger, the programmed reference voltage module outputs a reference analog voltage signal according to the instruction digital signal and the digital signal triggers received by the trigger input end and the reset input end respectively; the sampling module is used for acquiring a sampling voltage signal of the load coil; the controller module is used for receiving the reference analog voltage signal and the sampling voltage signal, and performing a difference proportional integral operation according to the reference analog voltage signal and the sampling voltage signal to acquire a target voltage signal, and transmitting the target voltage signal to the load coil.

Description

Technical Field

[0001] This application relates to the fields of cold atom physics and quantum precision measurement technology, specifically to a magnetic field control device. Background Technology

[0002] Precise control of magnetic fields is crucial for cold atom physics and quantum precision measurements, and energized coils are an important means of generating and controlling magnetic fields. To precisely manipulate atomic energy levels, the required magnetic field typically needs to vary from milligauss to hundreds of gauss and achieve a stability of 1 ppm. This necessitates precise control of the current in the coil to generate a stable magnetic field that changes abruptly with the experimental process. Current conventional current sources can meet the stability requirements, but they are difficult to directly integrate into experimental systems to meet the need for precise control during the experiment. Summary of the Invention

[0003] This application provides a magnetic field control device, which at least solves the problem that traditional current sources cannot meet the requirements for precise control of the experimental process.

[0004] This application provides a magnetic field control device, which includes a load coil, a sampling module, a programmable reference voltage module, and a controller module. The programmable reference voltage module is capable of generating a command digital signal and includes a trigger input terminal and a reset input terminal. The trigger input terminal and the reset input terminal are used to receive digital signal triggers. The programmable reference voltage module outputs a reference analog voltage signal based on the command digital signal and the digital signal received by the trigger input terminal and the reset input terminal, respectively. The sampling module is used to acquire the sampled voltage signal of the load coil. The controller module is used to receive the reference analog voltage signal and the sampled voltage signal, and perform differential proportional integral operation on the reference analog voltage signal and the sampled voltage signal to obtain a target voltage signal, so as to transmit the target voltage signal to the load coil.

[0005] In one embodiment, the programmable reference voltage module further includes a computer program, a field programmable gate array (FPGA), and a digital-analog converter (DAC). The computer program is communicatively connected to the FPGA, and the FPGA is communicatively connected to the DAC. The computer program inputs the instruction digital signal to the FPGA via serial communication. The digital signal triggers the DAC to output the reference analog voltage signal through the FPGA.

[0006] In one embodiment, the instruction digital signal includes a cyclic switching instruction and an analog voltage value group, the analog voltage value group including multiple different analog voltage values, and the cyclic switching instruction is used to control the FPGA to cyclically output the analog voltage value group; the FPGA is used to control the DAC to cyclically output multiple reference analog voltage signals corresponding to the different analog voltage values ​​according to the digital signal trigger, the cyclic switching instruction and the analog voltage value group.

[0007] In one embodiment, the FPGA includes a trigger input terminal and a reset input terminal. The digital signal triggering includes a reset trigger input to the reset input terminal and a timing trigger input to the trigger input terminal. When the FPGA receives the instruction digital signal containing the cyclic switching instruction and the analog voltage value group, after receiving the reset trigger at the reset input terminal, the FPGA controls the DAC to sequentially output the reference analog voltage signals corresponding to different analog voltage values ​​in the analog voltage value group according to the timing trigger received at the trigger input terminal.

[0008] In one embodiment, the instruction digital signal includes a single output instruction and an analog voltage value. The FPGA is used to control the DAC to output a constant reference analog voltage signal that corresponds to the analog voltage value, based on the digital signal trigger, the single output instruction, and the analog voltage value.

[0009] In one embodiment, the FPGA includes a trigger input terminal and a reset input terminal; when the FPGA receives the single output command, the digital signal triggering further includes a low-level triggering. When both the trigger input terminal and the reset input terminal receive the low-level triggering, the FPGA controls the DAC to output a constant reference analog voltage signal to the controller module, which corresponds to the analog voltage value.

[0010] In one embodiment, the magnetic field control device further includes a voltage-controlled current drive module, which includes a control terminal, a current input terminal, and a current output terminal. The current input terminal is connected to the load coil, and the control terminal is connected to the controller module. The voltage-controlled current drive module receives the target voltage signal output by the controller module and converts the target voltage signal into a target current, and transmits the target current to the load coil through the current output terminal.

[0011] In one embodiment, the sampling module includes a first sampling resistor, a gain resistor, and an operational amplifier. The voltage-controlled current drive module further includes a current output terminal. The first sampling resistor includes a first terminal, a second terminal, a first output terminal, and a second output terminal. The first terminal is connected to the current output terminal, and the second terminal is connected to the load coil. The operational amplifier includes a first positive input terminal, a first negative input terminal, and a third output terminal. The first output terminal is connected to the first positive input terminal, the second output terminal is connected to the first negative input terminal, and the third output terminal is connected to the controller module to output the sampled voltage signal to the controller module. The operational amplifier is used to amplify the voltage flowing through the first sampling resistor. The gain resistor is connected to the operational amplifier and is used to adjust the amplification factor of the operational amplifier.

[0012] In one embodiment, the magnetic field control device further includes a detection module connected between the load coil and the voltage-controlled current drive module. The detection module is used to detect the current flowing through the load coil and transmit the current flowing through the load coil to the voltage-controlled current drive module.

[0013] In one embodiment, the detection module includes a multimeter and a second sampling resistor. The second sampling resistor includes a third terminal and a fourth terminal. The third terminal is connected to the current input terminal of the voltage-controlled current drive module, and the fourth terminal is connected to the load coil. The multimeter is used to detect the voltage flowing through the second sampling resistor.

[0014] In the magnetic field control device of this application, by setting a trigger input terminal and a reset input terminal, the programmable reference voltage module is triggered according to the digital signals received by the trigger input terminal and the reset input terminal. In conjunction with the command digital signal, the command digital signal can be set according to the experimental process, and the triggering of the digital signal received by the trigger input terminal and the reset input terminal can also be controlled according to the experimental process. Compared with the magnetic field generation method based on commercial precision power supply, the magnetic field control device of this application can remotely control the magnitude of the magnetic field generated by the load coil to change with the command digital signal set according to the experimental process. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below.

[0016] Figure 1 This is a schematic diagram of the magnetic field control device provided in the embodiments of this application;

[0017] Figure 2 This is a schematic diagram of the specific structure of the magnetic field control device provided in the embodiments of this application. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] The following descriptions of the embodiments are based on the accompanying illustrations and are used to illustrate specific embodiments in which this application can be implemented. Directional terms used herein, such as "up," "down," "front," "back," "left," "right," "inner," "outer," and "side," are merely for reference to the accompanying illustrations. Therefore, the use of directional terms is for better and clearer explanation and understanding of this application, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation; therefore, it should not be construed as a limitation of this application.

[0020] Furthermore, the serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. Unless otherwise specified, the terms "connection" and "linkage" used in this application include both direct and indirect connections (linkages).

[0021] Please see Figure 1 , Figure 1 This is a schematic diagram of the magnetic field control device 100 provided in the embodiments of this application, as shown below. Figure 1 As shown, the magnetic field control device 100 includes a programmable reference voltage module 10, a load coil 20, a sampling module 30, and a controller module 40. The programmable reference voltage module 10 can generate command digital signals. The programmable reference voltage module 10 includes a trigger input terminal and a reset input terminal. The trigger input terminal and the reset input terminal are used to receive digital signals for triggering. The programmable reference voltage module 10 is triggered according to the command digital signals and the digital signals received by the trigger input terminal and the reset input terminal respectively, and outputs a reference analog voltage signal. The sampling module 30 is used to acquire the sampled voltage signal of the load coil 20. The controller module 40 is used to receive the reference digital signal and the sampled voltage signal, and perform differential proportional integral calculation according to the reference analog voltage signal and the sampled voltage signal to obtain the target voltage signal, so as to transmit the target voltage signal to the load coil 20.

[0022] In the magnetic field control device 100 of this application, by setting a trigger input terminal and a reset input terminal, the programmable reference voltage module 10 is triggered according to the digital signals received by the trigger input terminal and the reset input terminal. In conjunction with the command digital signal, the command digital signal can be set according to the experimental process, and the triggering of the digital signal received by the trigger input terminal and the reset input terminal can also be controlled according to the experimental process. Compared with the magnetic field generation method based on commercial precision power supply, the magnetic field control device 100 of this application can remotely control the change of the magnetic field generated by the load coil 20 according to the command digital signal set according to the experimental process.

[0023] The instruction digital signal can be a signal controlled and output by the computer program 11, which includes mode selection information (cyclic switching and single output) and voltage value information. One instruction digital signal can correspond to one instruction.

[0024] Digital signal triggering is divided into timing triggering and reset triggering. Timing triggering is used to control the timing of the switching of the reference analog voltage output by the programmable reference voltage module, while reset triggering is used to achieve the repetition of the switching output.

[0025] The sampling module 30 acquires the current signal flowing through the load coil 20, converts the acquired current signal into a voltage signal to obtain a sampling voltage signal corresponding to the acquired current signal, and feeds the sampling voltage signal back to the controller module 40.

[0026] The controller module 40 performs differential proportional-integral calculations on the sampled voltage signal transmitted from the sampling module 30 and the reference analog voltage signal transmitted from the DAC13, and outputs the target voltage signal.

[0027] The magnetic field control device 100 of this application can be used for precise control of the magnetic field in cold atom experiments. It realizes remote and precise control of the coil magnetic field by computer through a programmable voltage module, and realizes the convenient function of cooperating with digital signal triggering to control the experimental process.

[0028] For example, the programmable reference voltage module 10 also includes a computer program 11, an FPGA 12, and a DAC 13. The computer program 11 is communicatively connected to the FPGA 12, and the FPGA 12 is communicatively connected to the DAC 13. The computer program 11 inputs instruction digital signals to the FPGA 12 via serial communication. The digital signals trigger the switching of the output of the DAC 13 to be controlled by the FPGA 12.

[0029] Computer program 11 can be a LabVIEW program or other program input module used to generate voltage value information and mode selection information.

[0030] FPGA12 can be configured with serial communication input terminals and a series of data input, reset input terminals, trigger input terminals, and data output (I / O) interfaces for a Serial Peripheral Interface (SPI) communication system. DAC13 can be configured with SPI communication I / O, a reference signal input terminal, and a first voltage output terminal. Computer program 11 can communicate with FPGA12 through the serial communication input terminals. Specific voltage values ​​can be input into computer program 11, which converts them into instruction digital signals recognizable by FPGA12. Computer program 11 then communicates with FPGA12 via the serial communication input terminals. The SPI communication I / O of FPGA12 is connected to the SPI communication I / O of DAC13 to realize SPI communication between FPGA12 and DAC13, allowing FPGA12 to control DAC13 to output a reference analog voltage signal. Both the trigger input terminal and the reset input terminal are connected to ports controlling the experimental process, allowing FPGA12 to receive digital signals for triggering the experimental process. In addition, the precision reference voltage is connected to the reference signal input terminal of DAC13, and the first voltage output terminal of DAC13 is connected to the controller module 40 so that the first voltage output terminal of DAC13 outputs a reference analog voltage signal to the controller module 40.

[0031] By setting a trigger input terminal and a reset input terminal in the programmable reference voltage module 10, the digital signals received by the trigger input terminal and the reset input terminal are connected to the FPGA 12. This allows the FPGA 12 to combine the digital signal trigger for controlling the experimental process and the instruction digital signal to control the DAC 13 to output a reference analog voltage signal controlled according to the experimental process. This allows the load coil 20 to be connected to the voltage set according to the experimental process, thereby precisely controlling the current in the load coil 20 and enabling the load coil 20 to generate a stable magnetic field that jumps with the experimental process.

[0032] In one embodiment, the instruction digital signal includes a cyclic switching instruction and an analog voltage value group. The analog voltage value group includes multiple different analog voltage values. The cyclic switching instruction is used to control the FPGA 12 to cyclically output the analog voltage value group. The computer program 11 is used to output the instruction digital signal containing the cyclic switching instruction and the analog voltage value group. The FPGA 12 is used to control the DAC 13 to cyclically output multiple reference analog voltage signals corresponding to the different analog voltage values ​​according to the digital signal trigger, the cyclic switching instruction and the analog voltage value group.

[0033] The computer program 11 includes a cyclic switching instruction and an analog voltage value group. When the computer program 11 transmits the cyclic switching instruction to the FPGA 12, the computer program 11 can bind the output analog voltage value group. The analog voltage value group includes multiple different analog voltage values. Each analog voltage value corresponds to a reference analog voltage signal after passing through the DAC 13. The FPGA 12 controls the DAC 13 to cyclically switch out the reference analog voltage signals corresponding to the multiple analog voltage values ​​in the analog voltage value group according to the digital signal received at the trigger input terminal and the digital signal received at the reset input terminal, as well as the cyclic switching instruction. This allows the load coil 20 to cyclically switch out the current corresponding to the reference analog voltage signal, thereby causing the load coil 20 to generate a magnetic field that switches with the experimental process.

[0034] When PFGA12 receives a cyclic switching command, it triggers and controls DAC13 to cyclically output a group of analog voltage values ​​based on the digital signal received at the reset input terminal, and triggers and controls DAC13 to output reference analog voltage signals corresponding to multiple different analog voltage values ​​in the group of analog voltage values ​​in a cyclic switching manner based on the digital signal received at the trigger input terminal.

[0035] For example, FPGA12 includes a trigger input and a reset input. The digital signal triggering includes a reset trigger input to the reset input and a timing trigger input to the trigger input. When FPGA12 receives a command digital signal containing a cyclic switching instruction and an analog voltage value group, after receiving the reset trigger at the reset input, FPGA12 controls DAC13 to sequentially output reference analog voltage signals corresponding to different analog voltage values ​​in the analog voltage value group according to the timing trigger received at the trigger input.

[0036] The trigger input and reset input are located on FPGA12. FPGA12 determines whether to cyclically output the analog voltage value group based on whether the reset input receives a reset trigger. If the reset input receives a reset trigger, it further controls DAC13 to output reference analog voltage signals corresponding to different analog voltage values ​​in the analog voltage value group based on whether the trigger input receives a timing trigger and based on the multiple timing triggers received by the trigger input. This allows the reference analog voltage signal output by DAC13 to change with the experimental process, thereby controlling the current output by the load coil 20 to change according to the experimental process, thus obtaining a precise magnetic field that changes with the experimental process.

[0037] When it is necessary to control the load coil 20 to generate different magnetic field magnitudes in cyclic transitions to match the experimental process, the trigger input and reset input of the FPGA will be connected to digital signal triggers that match the experimental process. The computer program 11 will output a cyclic transition instruction. The computer program 11 will sequentially number the N analog voltage values ​​in the analog voltage value group from 0 to N-1, where N is a positive integer greater than 0. At this time, the FPGA 12 receives a set of analog voltage values ​​including N analog voltage values, the cyclic transition instruction, the timing trigger, and the reset trigger. The experimental process can then control the trigger input to receive multiple timing triggers. When the FPGA 12 receives a cyclic transition instruction, the FPGA 12 will, upon receiving the first timing trigger at the trigger input, communicate with the DAC. 13 converts the analog voltage value with the sequence number "0" in the analog voltage value group into a corresponding reference analog voltage signal and transmits the reference analog voltage signal to the controller module 40; when the trigger input receives a timing trigger again, the communication DAC13 converts the analog voltage value with the sequence number "1" in the analog voltage signal value group into a corresponding reference analog voltage signal. Before outputting the reference analog voltage signal corresponding to the analog voltage value with the sequence number "N-1" in the analog voltage value group, the FPGA12 outputs the reference analog voltage signal corresponding to the next sequence number of the analog voltage value every time it receives a timing trigger at the trigger input, thereby realizing the switching output of the reference analog voltage signals corresponding to different analog voltage values ​​in the analog voltage value group.

[0038] If the reset input receives a reset trigger during the above process, then when the trigger input receives another timing trigger, the FPGA12 will output the reference analog voltage signal corresponding to the analog voltage value with the sequence number "0" in the analog voltage value group from the communication DAC13. This allows the DAC13 to cycle through multiple reference analog voltage signals corresponding to multiple different analog voltage values ​​in the same group of analog voltage values, thereby controlling the current of the load coil 20 to change with the experimental process and obtaining a precise magnetic field that jumps with the experimental process.

[0039] In this embodiment, a reset trigger can be connected to the reset input terminal, and a timing trigger can be input to the trigger input terminal at the moment when the magnetic field needs to change. When the trigger input terminal receives a timing trigger that changes to the last analog voltage value in the analog voltage value group in the current cycle, and between the timing trigger that changes to the first analog voltage value in the same analog voltage value in the next cycle, a reset trigger is connected to the reset input terminal, so that the magnetic field control device can generate the same magnetic field in each cycle and provide a precision magnetic field of different magnitudes at different times in a cycle.

[0040] In one embodiment, the instruction digital signal includes a single output instruction and an analog voltage value. The FPGA12 is used to control the DAC13 to output a constant reference analog voltage signal that corresponds to the analog voltage value, based on the digital signal trigger, the single output instruction, and the analog voltage value.

[0041] In this embodiment, when FPGA12 receives a single output command, FPGA12 receives an analog voltage value. For example, when computer program 11 transmits a single output command to FPGA12, computer program 11 can bind an analog voltage value.

[0042] When the FPGA12 receives a single output command, the digital signal triggering also includes low-level triggering. When both the trigger input and reset input receive low-level triggering, the FPGA12 controls the DAC to output a constant reference analog voltage signal to the controller module 40, which corresponds to the analog voltage value.

[0043] When computer program 11 transmits a single output instruction to FPGA 12, computer program 11 can bind an analog voltage value. At this time, the reset input and trigger input of FPGA are connected to a 50-ohm load, that is, both the trigger input and reset input are connected to a low-level trigger. After receiving the instruction digital signal, FPGA immediately controls DAC 13 to output a constant reference digital signal, so that the load coil 20 can receive a stable target voltage signal, thereby generating a stable precision magnetic field.

[0044] For example, the magnetic field control device 100 also includes a voltage-controlled current drive module 50. The voltage-controlled current drive module 50 includes a control terminal, a current input terminal, and a current output terminal. The current input terminal of the voltage-controlled current drive module 50 is connected to the load coil 20, and the control terminal of the voltage-controlled current drive module 50 is connected to the controller module 40. The voltage-controlled current drive module 50 receives the target voltage signal output by the controller module 40 and is used to convert the target voltage signal into a target current and transmit the target current to the load coil 20.

[0045] The controller module 40 may include a second voltage output terminal, which is connected to the control terminal of the voltage-controlled current drive module 50. The target voltage signal generated by the controller module 40 is input to the voltage-controlled current drive module 50 through the second voltage output terminal and the control terminal.

[0046] The voltage-controlled current drive module 50 receives the current signal flowing through the load coil 20 and the target voltage signal output by the controller module 40. The voltage-controlled current drive module 50 provides feedback control to the target current input to the circuit of the load coil 20 in order to control the magnitude of the magnetic field generated by the load coil 20.

[0047] In this application, the voltage-controlled current drive module 50 realizes the linear relationship between the target voltage signal set by the computer program 11 and the current of the load coil 20, and uses the negative feedback regulation mechanism to adjust the target current in the circuit where the load coil 20 is located, while suppressing circuit noise, so that the stability of the target current received by the load coil 20 follows the target voltage signal, thereby obtaining a stable precision DC magnetic field.

[0048] Please see Figure 2 , Figure 2 This is a schematic diagram of the specific structure of the magnetic field control device 100 provided in the embodiments of this application. For example, the sampling module 30 includes a first sampling resistor 31, a gain resistor 32, and an operational amplifier 33. The voltage-controlled current drive module 50 also includes a current output terminal. The first sampling resistor 31 includes a first terminal, a second terminal, a first output terminal, and a second output terminal. The first terminal is connected to the current output terminal of the voltage-controlled current drive module 50, and the second terminal is connected to the load coil 20. The operational amplifier 33 includes a first positive input terminal, a first negative input terminal, and a third output terminal. The first output terminal is connected to the first positive input terminal, the second output terminal is connected to the first negative input terminal, and the third output terminal is connected to the controller module 40 to output the sampled voltage signal to the controller module 40. The operational amplifier 33 is used to amplify the voltage flowing through the first sampling resistor 31. The gain resistor 32 is connected to the operational amplifier 33 and is used to adjust the amplification factor of the operational amplifier 33.

[0049] The magnetic field control device 100 also includes a power supply 60. One end of the load coil 20 is connected to the positive terminal of the power supply 60, and the other end of the load coil 20 is connected to the current input terminal of the voltage-controlled current drive module 50. The first terminal of the first sampling resistor 31 is connected to the current output terminal of the voltage-controlled current drive module 50, and the second terminal of the first sampling resistor 31 is connected to the negative terminal of the power supply 60. The second terminal is connected to the load coil 20 through the power supply 60. Both the negative terminal of the power supply 60 and the second terminal of the first sampling resistor 31 are grounded. The current flowing through the load coil 20 is the same as the current flowing through the first sampling resistor 31. The first output terminal of the first sampling resistor 31 is connected to the first positive input terminal of the operational amplifier 33, and the second output terminal of the first sampling resistor 31 is connected to the first negative input terminal of the operational amplifier 33. The operational amplifier 33 is connected to a gain resistor 32. The gain resistor 32 adjusts the amplification factor of the operational amplifier 33, amplifying the voltage corresponding to the current flowing through the load coil 20, facilitating the subsequent comparison and calculation of the sampled voltage signal with the reference analog voltage signal by the controller module 40.

[0050] The controller module 40 includes a second positive input terminal and a second negative input terminal. The second positive input terminal is connected to the first voltage output terminal of the DAC13, and the second negative input terminal is connected to the third output terminal of the operational amplifier 33. The voltage amplified by the operational amplifier 33 is output from the third output terminal and input to the controller module 40 from the second negative input terminal.

[0051] The power supply terminal of operational amplifier 33 is connected to a power supply circuit, such as the positive power supply terminal of operational amplifier 33 (e.g., Figure 2 The +Vs and negative power supply terminals (as shown) are shown. Figure 2 The -Vs shown is used to connect to the power supply circuit, which is used to power the operational amplifier 33.

[0052] In this application, the first sampling resistor 31 is connected to the circuit containing the load coil 20. The current in the first sampling resistor 31 and the load coil 20 are the same. The voltage of the first sampling resistor 31 is amplified by the operational amplifier 33 and fed back to the controller module 40. The current value on the load coil 20 and the reference analog voltage signal output by the DAC 13 determine the amplification factor selected by the operational amplifier 33.

[0053] Both the first sampling resistor 31 and the gain resistor 32 can be four-wire resistors, high-precision sampling resistors, or Hall elements, etc., and this application does not impose any restrictions on them.

[0054] For example, the magnetic field control device 100 also includes a detection module 70, which is connected between the load coil 20 and the voltage-controlled current drive module 50. The detection module 70 is used to detect the current flowing through the load coil 20 and transmit the current flowing through the load coil 20 to the voltage-controlled current drive module 50.

[0055] In this application, one end of the load coil 20 is connected to the positive terminal of the power supply 60, and the other end of the load coil 20 is connected to one end of the detection module 70. The other end of the detection module 70 is connected to the voltage-controlled current drive module 50. The detection module 70 is used to detect the current flowing through the load coil 20 and input the current to the voltage-controlled current drive module 50. The current is then output to the sampling module 30 via the current output terminal of the voltage-controlled current drive module 50. The current transmitted from the detection module 70 to the voltage-controlled current drive module 50 is unstable. After the current flows through the sampling module 30 and is converted into a sampling voltage signal, the controller module 40 performs differential proportional integral calculation on the sampling voltage signal and the reference digital signal to output a target voltage signal. The voltage-controlled current drive module 50 then converts the target voltage signal into a stable target current. This target current is transmitted from the current output terminal of the voltage-controlled current drive module 50 through the first terminal, the second terminal, and the power supply current of the sampling module 30 to the load coil 20, thereby causing the load coil 20 to generate a stable magnetic field.

[0056] Once the current stability generated by the load coil 20 reaches the preset requirement, the detection module 70 can be removed, and the current input terminal of the voltage-controlled current drive module 50 can be directly connected to the load coil 20.

[0057] For example, the detection module 70 includes a multimeter 71 and a second sampling resistor 72. The second sampling resistor 72 includes a third terminal and a fourth terminal. The third terminal is connected to the current input terminal of the voltage-controlled current drive module 50, and the fourth terminal is connected to the load coil 20. The multimeter 71 is used to detect the voltage flowing through the second sampling resistor 72.

[0058] In this application, the multimeter 71 is set to voltmeter mode and kept floating to avoid the influence of environmental noise on voltage measurement when the multimeter 71 is grounded. Keeping the multimeter 71 floating can reduce the influence of environmental noise on voltage measurement, which is beneficial to improving the accuracy of the target voltage signal output by the controller module 40, and thus beneficial to improving the accuracy of the magnetic field generated by the load coil 20 to follow the experimental process.

[0059] The second sampling resistor 72 is connected in the same circuit as the load coil 20. The current value of the load coil 20 can be detected by measuring the voltage value of the second sampling resistor 72 using the multimeter 71.

[0060] In this application, the load coil 20 can be a pair of Helmholtz coils or other coils connected in series, composed of rectangular coils made of enameled copper wire; the FPGA 12 can be an ALINX development board AX301; the DAC 13 can be a 20-bit high-precision DAC 13 evaluation board, capable of generating analog voltages from -10V to 10V, with a reference voltage of 1ppm high-precision 5V; the voltage-controlled current drive module 50 is an enhancement-mode N-channel MOSFET, for example, an enhancement-mode N-channel MOSFET of model IRLR3636PbF; the operational amplifier 33 can be an AD8429, with a gain set to 10, and the corresponding gain resistor 32 can have a resistance of 665Ω; the first sampling resistor 31 can be a low-noise, low-temperature drift resistor with a resistance of 0.5Ω and a power of 8W; the second sampling resistor 72 can be a low-temperature drift, low-noise resistor with a resistance of 1Ω.

[0061] It should be noted that the first sampling resistor 31 limits the maximum current of the load coil 20 (e.g., 4A), while the current of the load coil 20 in the magnetic field control device 100 can be in the range of 0.01A to 1A, and the corresponding reference digital signal output by the DAC13 can be in the range of 0.05V to 5V.

[0062] This application utilizes FPGA12 to add trigger input and reset input, enabling FPGA12 to remotely control the voltage of load coil 20, thus realizing program-controlled cyclic switching precision magnetic field control. In the magnetic field control device 100 of this application, when the target current output controlled by the voltage-controlled current drive module 50 flows through the load coil 20, the current stability of the load coil 20 can reach 1ppm, enabling the load coil 20 to generate a stable DC magnetic field. Furthermore, FPGA12 can remotely and precisely control the magnetic field to maintain a stable magnetic field magnitude, and can also remotely control the precision magnetic field to switch according to digital signal triggers, which is convenient for coordinating with the cold atom experiment process to generate a DC magnetic field that changes with time.

[0063] The above are some embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications are also considered to be within the scope of protection of this application.

Claims

1. A magnetic field control device, characterized by, Includes a load coil, a sampling module, a programmable reference voltage module, and a controller module; The programmable reference voltage module generates instruction digital signals. It includes a trigger input and a reset input, which are used to receive digital signal triggers. The programmable reference voltage module outputs a reference analog voltage signal based on the instruction digital signal and the digital signals received by the trigger and reset inputs. The programmable reference voltage module also includes a computer program, a field-programmable gate array (FPGA), and a digital-to-analog converter (DAC). The computer program is communicatively connected to the FPGA, and the FPGA is communicatively connected to the DAC. The computer program inputs the instruction digital signal to the FPGA via serial communication. The digital signal triggers the DAC to output the reference analog voltage signal through the FPGA. The sampling module is used to acquire the sampled voltage signal of the load coil; The controller module is used to receive the reference analog voltage signal and the sampled voltage signal, and perform differential proportional integral operation based on the reference analog voltage signal and the sampled voltage signal to obtain the target voltage signal, so as to transmit the target voltage signal to the load coil; The magnetic field control device further includes a voltage-controlled current drive module, which includes a control terminal, a current input terminal, and a current output terminal. The current input terminal is connected to the load coil, and the control terminal is connected to the controller module. The voltage-controlled current drive module receives the target voltage signal output by the controller module and converts the target voltage signal into a target current, and transmits the target current to the load coil through the current output terminal.

2. The magnetic field control device of claim 1, wherein, The instruction digital signal includes a cyclic switching instruction and an analog voltage value group. The analog voltage value group includes multiple different analog voltage values. The cyclic switching instruction is used to control the FPGA to cyclically output the analog voltage value group. The FPGA is used to control the DAC to cyclically output multiple reference analog voltage signals corresponding to the different analog voltage values ​​according to the digital signal trigger, the cyclic switching instruction and the analog voltage value group.

3. The magnetic field control device of claim 2, wherein, The FPGA includes a trigger input terminal and a reset input terminal. The digital signal triggering includes a reset trigger input to the reset input terminal and a timing trigger input to the trigger input terminal. When the FPGA receives the instruction digital signal containing the cyclic switching instruction and the analog voltage value group, after receiving the reset trigger at the reset input terminal, the FPGA controls the DAC to sequentially output the reference analog voltage signals corresponding to different analog voltage values ​​in the analog voltage value group according to the timing trigger received at the trigger input terminal.

4. The magnetic field control device according to claim 1, characterized in that, The instruction digital signal includes a single output instruction and an analog voltage value. The FPGA is used to control the DAC to output a constant reference analog voltage signal that corresponds to the analog voltage value, based on the digital signal trigger, the single output instruction, and the analog voltage value.

5. The magnetic field control device according to claim 4, characterized in that, The FPGA includes the trigger input terminal and the reset input terminal; when the FPGA receives the single output command, the digital signal triggering also includes low-level triggering. When both the trigger input terminal and the reset input terminal receive the low-level triggering, the FPGA controls the DAC to output a constant reference analog voltage signal to the controller module, which corresponds to the analog voltage value.

6. The magnetic field control device according to claim 1, characterized in that, The sampling module includes a first sampling resistor, a gain resistor, and an operational amplifier. The first sampling resistor includes a first terminal, a second terminal, a first output terminal, and a second output terminal. The first terminal is connected to the current output terminal, and the second terminal is connected to the load coil. The operational amplifier includes a first positive input terminal, a first negative input terminal, and a third output terminal. The first output terminal is connected to the first positive input terminal, the second output terminal is connected to the first negative input terminal, and the third output terminal is connected to the controller module to output the sampled voltage signal to the controller module. The operational amplifier is used to amplify the voltage flowing through the first sampling resistor. The gain resistor is connected to the operational amplifier and is used to adjust the amplification factor of the operational amplifier.

7. The magnetic field control device according to claim 6, characterized in that, The magnetic field control device further includes a detection module connected between the load coil and the voltage-controlled current drive module. The detection module is used to detect the current flowing through the load coil and transmit the current flowing through the load coil to the voltage-controlled current drive module.

8. The magnetic field control device according to claim 7, characterized in that, The detection module includes a multimeter and a second sampling resistor. The second sampling resistor includes a third terminal and a fourth terminal. The third terminal is connected to the current input terminal of the voltage-controlled current drive module, and the fourth terminal is connected to the load coil. The multimeter is used to detect the voltage flowing through the second sampling resistor.

Images