SQUID working parameter regulation and control device and method

Abstract

The invention provides an SQUID working parameter regulation and control device and method. The SQUID working parameter regulation and control device comprises an SQUID reading circuit used for detecting a magnetic signal; the reference magnetic sensor is used for collecting working environment magnetic field data and providing a modulation signal for an SQUID device in the SQUID reading circuit; the control module is connected to the output end of the SQUID reading circuit and the output end of the reference magnetic sensor, when parameters are regulated and controlled, a relation curve of the output voltage and the input magnetic flux is constructed based on the influence of modulation signals on the SQUID device, the working point slope of the relation curve of the output voltage and the input magnetic flux is calculated, and the working point slope of the relation curve of the output voltage and the input magnetic flux is calculated. And a control signal of the SQUID reading circuit is generated, so that the slope of the working point reaches the maximum value. According to the invention, the working point can be intelligently adjusted in application, and high-reliability and high-accuracy magnetic detection can be realized in a complex working environment.

Description

Technical Field

[0001] The present invention relates to the field of magnetic field detection, and in particular to a SQUID working parameter control device and method. Background Art

[0002] Superconducting quantum interference device (SQUID) is the most sensitive magnetic / electromagnetic sensor in practical use so far. Its noise level can reach the fT level. It has important application significance in biomedicine, geophysics and basic research. When the bias current of SQUID is constant, the voltage at both ends of SQUID will change periodically with the external magnetic flux, with a period of φ0 (magnetic flux quantum, h is Planck's constant, e is the basic charge), thus forming a flux-voltage conversion device. Ideally, the SQUID operating point is locked at the maximum slope W of the V-Φ curve (i.e. At this point, the SQUID flux-voltage transfer rate is at its maximum, the magnetic flux inside the superconducting Josephson ring remains unchanged, and the linear amplification of the external magnetic flux can be achieved, so that the SQUID can be used as a sensor for linear readout of magnetic field signals.

[0003] However, the accuracy of SQUID is poor in practical applications, mainly because the basic parameters of superconducting sensors (such as critical current, etc.) change with environmental background interference, which makes the practical performance of the sensor affected by environmental background interference and cannot be manually adjusted to the optimal working point, reducing the observation accuracy. In order to solve this problem, current technologies either use metal-containing shielding devices to effectively suppress environmental interference, but simultaneously introduce strong eddy current interference; or use direct reading of chip calibration parameters, but only realize intelligent regulation based on the amplitude of the modulation signal, and cannot make fine adjustments to the working parameters, which is difficult to be practical in complex environments; or use a two-stage SQUID circuit to improve the flux-voltage transmission rate and design a locking scheme for the optimal working point, but the design is relatively complex and more suitable for calibration of chips and sensors in the laboratory.

[0004] Therefore, how to provide a device that enables a superconducting magnetic sensor to work in a complex environment, with high reliability, simple structure, high accuracy and strong practicality, has become one of the problems that need to be solved urgently by those skilled in the art.

[0005] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present invention and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because these solutions are described in the background technology section of the present invention. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a SQUID working parameter control device and method, which is used to solve the problem in the prior art that the basic parameters of the SQUID are easily affected by the environmental background and change.

[0007] To achieve the above-mentioned and other related purposes, the present invention provides a SQUID operating parameter control device, the SQUID operating parameter control device at least comprising:

[0008] SQUID readout circuit, reference magnetic sensor and control module;

[0009] The SQUID readout circuit is used to detect magnetic signals;

[0010] The reference magnetic sensor is used to collect working environment magnetic field data and provide a modulation signal for the SQUID device in the SQUID readout circuit;

[0011] The control module is connected to the output end of the SQUID readout circuit and the reference magnetic sensor. When adjusting parameters, a relationship curve between output voltage and input magnetic flux is constructed based on the influence of the modulation signal on the SQUID device, the operating point slope of the relationship curve between output voltage and input magnetic flux is calculated, and a control signal of the SQUID readout circuit is generated so that the operating point slope reaches a maximum value.

[0012] Optionally, the SQUID readout circuit includes: a SQUID device, a bias resistor, an offset resistor, an amplifier, an integrator, a feedback resistor array, a feedback coil, an adjustment unit and a switch control unit;

[0013] The first input end of the amplifier is connected to the output end of the SQUID device and the first end of the bias resistor, and the second input end is connected to the first end of the offset resistor, for amplifying the output signal of the SQUID device;

[0014] The adjustment module is controlled by the control module, the first output end is connected to the second end of the bias resistor to adjust the bias current of the SQUID device, and the second output end is connected to the second end of the offset resistor to adjust the offset voltage;

[0015] The integrator is connected to the output end of the amplifier and integrates the output signal of the amplifier;

[0016] A first end of the feedback resistor array is connected to the output end of the integrator, and the other end is grounded via the feedback coil;

[0017] The output end of the switch control unit is connected to the control end of the integrator and the feedback resistor array respectively, and is used to adjust the resistance value of the feedback resistor and / or the time integration constant.

[0018] More optionally, the switch control unit is also connected to the output end of the amplifier to adjust the amplification factor of the amplifier.

[0019] Optionally, the reference magnetic sensor is a fluxgate, a magnetoresistive sensor or a SQUID sensor.

[0020] More optionally, the control module includes a switch, an analog-to-digital converter and a microcontroller unit;

[0021] A first end of the switch is connected to the output end of the reference magnetic sensor, and a second end is connected to the analog-to-digital converter;

[0022] The analog-to-digital converter performs digital-to-analog conversion on the output signal of the reference magnetic sensor and performs analog-to-digital conversion on the output signal of the SQUID readout circuit;

[0023] The microcontroller unit is connected to the output end of the analog-to-digital converter, constructs a relationship curve between the output voltage and the input magnetic flux based on the output signals of the reference magnetic sensor and the SQUID readout circuit, calculates the operating point slope, and generates a corresponding control signal.

[0024] To achieve the above-mentioned purpose and other related purposes, the present invention further provides a SQUID working parameter control method, which is implemented based on the above-mentioned SQUID working parameter control device, and the SQUID working parameter control method at least includes:

[0025] Detect whether the reference magnetic sensor provides a modulation signal for the SQUID readout circuit based on the working environment magnetic field. If not, configure the parameters in the SQUID readout circuit with preset values ​​and lock the working point; if yes, adjust the parameters in the SQUID readout circuit based on the modulation signal, and lock the working point when the working point slope of the relationship curve between the output voltage and the input magnetic flux reaches a maximum value.

[0026] Optionally, the parameters to be adjusted in the SQUID readout circuit include: at least one of a bias current, an offset voltage, a feedback resistor value, a time integration constant and an amplification factor.

[0027] More optionally, when the modulation signal is connected to the SQUID readout circuit, the relationship curve between the output voltage and the input magnetic flux is constructed based on the modulation signal, and the bias current of the SQUID device and / or the offset voltage of the amplifier in the SQUID readout circuit are first adjusted so that the peak-to-peak value of the relationship curve between the output voltage and the input magnetic flux is maximized, and the relationship curve between the output voltage and the input magnetic flux is symmetrical about the zero voltage value; then the resistance value and / or the integration time constant of the feedback resistor in the SQUID readout circuit are further adjusted so that the operating point slope of the relationship curve between the output voltage and the input magnetic flux reaches a maximum value.

[0028] More optionally, after adjusting various parameters in the SQUID readout circuit based on the modulation signal, the reference magnetic sensor is disconnected from the SQUID readout circuit.

[0029] More optionally, when the slope of the operating point of the relationship curve between the output voltage and the input magnetic flux is adjusted to a maximum value, the values ​​of each parameter to be adjusted in the SQUID readout circuit are stored.

[0030] As described above, the SQUID operating parameter control device and method of the present invention have the following beneficial effects:

[0031] The SQUID working parameter control device and method of the present invention introduces a reference magnetic measurement channel, records the magnetic field waveform in real time, and accurately measures the parameters of the working point slope of the SQUID magnetic sensor based on the magnetic field data and the open-loop output of the SQUID readout circuit. By switching the electronic switch, the parameters such as the bias resistor value, the offset resistor value, the feedback resistor value and the integral time constant in the SQUID readout circuit are intelligently adjusted, thereby ensuring that the main parameters of the SQUID readout circuit are stable and reliable in a complex working environment, and realizing high-reliability observation of magnetic field / electromagnetic signals. On the one hand, the present invention can realize intelligent automatic control of working parameters in practical applications, avoid errors caused by manual adjustment caused by magnetic field environment interference in actual application scenarios, and improve work efficiency; on the other hand, the working point is accurately locked, so that the high-sensitivity SQUID sensor can simultaneously achieve high-precision observation, thereby giving full play to the advantages of low-noise and high-sensitivity signal observation in the fields of biological imaging, geophysics and basic research. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Shown is a schematic structural diagram of the SQUID working parameter control device of the present invention.

[0033] Figure 2 It shows a schematic diagram of the V-Φ curve of the SQUID working parameter control device of the present invention in the open-loop state.

[0034] Figure 3Shown is a structural schematic diagram of the control module of the present invention.

[0035] Figure 4 Shown is a schematic flow chart of the SQUID working parameter control method of the present invention.

[0036] Component number description

[0037] 1 SQUID working parameter control device

[0038] 11 SQUID readout circuit

[0039] 111 SQUID Device

[0040] 112 Amplifier

[0041] 113 Integrator

[0042] 114 Feedback Resistor Array

[0043] 115 Adjustment unit

[0044] 116 Switch control unit

[0045] 12 Reference magnetic sensor

[0046] 13 Control Module

[0047] 131 Switch

[0048] 132 Analog-to-digital converter

[0049] 133 Microcontroller unit DETAILED DESCRIPTION

[0050] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0051] See also Figure 1 to Figure 4 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0052] In the actual working environment, due to the interference of the external magnetic field environment, manual adjustment often cannot be adjusted to the optimal working point. In order to solve this problem, the present invention uses the magnetic field in the actual environment as modulation in the open-loop state of the SQUID readout circuit, and automatically adjusts and accurately calculates and locks the working point at the maximum flux-voltage transfer rate, that is, the working point slope of the V-Φ curve. The biggest point.

[0053] like Figure 1 As shown, the present invention provides a SQUID operating parameter control device 1, and the SQUID operating parameter control device 1 includes:

[0054] SQUID readout circuit 11 , reference magnetic sensor 12 and control module 13 .

[0055] like Figure 1 As shown, the SQUID readout circuit 11 is used to detect magnetic signals.

[0056] Specifically, the SQUID readout circuit 11 is a flux locked loop (FLL), which detects the external magnetic field and generates a corresponding electrical signal. As an example, the SQUID readout circuit 11 includes a SQUID device 111, a bias resistor R1, an offset resistor R2, an amplifier 112, an integrator 113, a feedback resistor array 114, a feedback coil Lf, an adjustment unit 115 and a switch control unit 116. In this embodiment, the SQUID device 111 is a superconducting ring composed of two Josephson junctions, one connection node of the two Josephson junctions is grounded, and the other connection node is used as an output terminal; the SQUID device 111 is set in a low temperature environment (liquid nitrogen or liquid helium) for sensing magnetic signals. The first end of the bias resistor R1 is connected to the connection node of the two Josephson junctions to provide a bias current for the superconducting ring to ensure that the SQUID device 111 works normally. The first input end of the amplifier 112 is connected to the output end of the SQUID device 111 (and the first end of the bias resistor R1), and the second input end is connected to the first end of the offset resistor R2, for amplifying the output voltage (or current) of the SQUID device 111; in this example, the amplifier 112 adopts a low-noise preamplifier structure. The adjustment module 115 is controlled by the control module 13, and the first output end is connected to the second end of the bias resistor R1. By changing the voltage applied to the second end of the bias resistor R1, the current flowing through the bias resistor R1 is adjusted, thereby adjusting the bias current of the SQUID device 111; at the same time, the second output end of the adjustment module 115 is connected to the second end of the offset resistor R2, and the voltage at the first end of the offset resistor R2 is adjusted by changing the voltage applied to the second end of the offset resistor R2, thereby adjusting the offset voltage; in this example, an electronic switch is provided in the adjustment module 115, and the voltage is adjusted by the electronic switch, and the control signal of the electronic switch is provided by the switch control unit 116. The integrator 113 is connected to the output end of the amplifier 112, and integrates the output signal of the amplifier 112 to suppress self-oscillation, eliminate the offset voltage of the amplifier 112, and perform integral compensation in feedback control when measuring the magnetic field; in this example, the integrator 113 has an amplification function in the open-loop mode, and forms a two-stage amplification ratio amplification structure with the amplifier 112. The first end of the feedback resistor array 114 is connected to the output end of the integrator 113, and the other end is grounded via the feedback coil Lf; the output voltage of the integrator 113 is converted into a feedback current via the feedback resistor array 114, and is converted into a feedback magnetic flux acting on the feedback coil Lf, and the feedback magnetic flux has a corresponding effect on the output voltage (or current) of the SQUID device 111.The output end of the switch control unit 116 is respectively connected to the control end of the integrator 113 and the feedback resistor array 114, and is used to adjust the resistance value of the feedback resistor and / or the time integration constant; in this example, a capacitor array is provided in the integrator 113, and the time integration constant can be adjusted by controlling the electronic switch in the capacitor array to adjust the capacitance value of the capacitor array; similarly, the feedback current can be adjusted by controlling the switch in the feedback resistor array to adjust the resistance value of the feedback resistor, and the feedback current and the matching relationship with the integration capacitor in the integrator 113 can also be adjusted (i.e., the time integration constant can be adjusted). As another implementation of the present invention, the output end of the switch control unit 116 is also connected to the amplifier 112, which is used to adjust the amplification factor of the amplifier 112, so as to observe the V-Φ curve and ensure that the V-Φ curve is within the range, so as to be suitable for different application scenarios.

[0057] It should be noted that any structure capable of detecting a magnetic field signal and reading out a corresponding electrical signal is applicable to the SQUID readout circuit 11 of the present invention, and is not limited to this embodiment.

[0058] like Figure 1 As shown, the reference magnetic sensor 12 is used to collect magnetic field data of the working environment and provide a modulation signal for the SQUID device 111 in the SQUID readout circuit 11.

[0059] Specifically, any device that can convert the working environment magnetic field into a corresponding electrical signal is suitable for the reference magnetic sensor 12 of the present invention, including but not limited to a fluxgate, a magnetoresistive sensor or a SQUID sensor, which are not described in detail here.

[0060] like Figure 1 As shown, the control module 13 is connected to the output end of the SQUID readout circuit 11 and the reference magnetic sensor 12. When adjusting the parameters, a relationship curve between the output voltage and the input magnetic flux (i.e., a V-Φ curve) is constructed based on the influence of the modulation signal on the SQUID device, and the slope of the working point of the V-Φ curve is calculated. And generate a control signal for the SQUID readout circuit 11 so that the operating point slope Reached maximum value.

[0061] Specifically, when adjusting parameters, the SQUID working parameter control device 1 is in an open-loop mode. The electrical signal corresponding to the working environment magnetic field detected by the reference magnetic sensor 12 is sent to the input end of the feedback resistor array 114 (i.e., the connection node between the integrator 113 and the feedback resistor array 114) by the control module 13, and is fed back to the SQUID device 111 through the feedback resistor array 114 and the feedback coil Lf to affect the output signal of the integrator 113 as a modulation signal. In addition, the output signal of the integrator 113 and the output signal of the reference magnetic sensor 12 are received by the control module 13 and a V-Φ curve is constructed, such as Figure 2 The V-Φ curve in the open loop state is shown. Based on the constructed V-Φ curve, the control module 13 generates a control signal to adjust the parameters in the SQUID readout circuit 11, and the V-Φ curve changes accordingly. When the slope of the operating point When the maximum value is reached, the control ends, the SQUID working parameter control device 1 switches to the closed-loop mode, and the working point of the SQUID readout circuit 11 is locked at the slope of the V-Φ curve. At the maximum value (optimal operating point); at this time, the SQUID readout circuit 11 works based on the parameters at the time of locking (the parameters at the time of locking are stored in the MCU of the control module 13), and the output voltage of the SQUID device 111 is amplified and integrated, and then the feedback loop feeds the signal back to the SQUID device 111 in the form of magnetic flux, maintaining the net magnetic field in the SQUID device 111 unchanged, and the external magnetic field is measured in this state; the reference magnetic sensor 12 does not work, or the reference magnetic sensor 12 detects that the signal is not connected to the SQUID readout circuit 11.

[0062] More specifically, if Figure 3 As shown, as an example, the control module 13 includes a switching switch, an analog-to-digital converter 132 and a microcontroller unit 133. The first end of the switching switch 131 is connected to the output end of the reference magnetic sensor 12, and the second end is connected to the input end of the analog-to-digital converter 132; the control signal of the switching switch 131 can be provided by an external controller or by the switch control unit 116, and is not limited to this embodiment. The analog-to-digital converter 133 obtains the output signal of the reference magnetic sensor 12 and the output signal of the SQUID readout circuit 11, performs digital-to-analog conversion on the output signal of the reference magnetic sensor 12 and introduces it to the input end of the feedback resistor array 114, performs analog-to-digital conversion on the output signal of the SQUID readout circuit 11, and transmits the output signal of the reference magnetic sensor 12 and the output signal of the SQUID readout circuit 11 after analog-to-digital conversion to the lower-level digital circuit for further processing by the subsequent digital circuit. The microcontroller unit 133 is connected to the output terminal of the analog-to-digital converter 132, and constructs a V-Φ curve based on the output signal of the analog-to-digital converter 132 (the output signal of the reference magnetic sensor 12 in digital form and the output signal of the SQUID readout circuit 11), and calculates the slope of the working point of the V-Φ curve. And generate corresponding control signals. Any structure that can realize the above functions is applicable to the control module of the present invention, and will not be described in detail here.

[0063] The present invention further provides a SQUID operating parameter control method, which is implemented based on the SQUID operating parameter control device 1 of the present invention, and the method comprises:

[0064] Detect whether the reference magnetic sensor 12 provides a modulation signal to the SQUID readout circuit 11 based on the working environment magnetic field. If not, configure the parameters in the SQUID readout circuit 11 with preset values ​​and lock the working point; if yes, adjust the parameters in the SQUID readout circuit 11 based on the modulation signal. When the slope of the working point of the V-Φ curve is The operating point is locked when the maximum value is reached.

[0065] Specifically, the parameters to be adjusted in the SQUID readout circuit 11 include but are not limited to at least one of the bias current, offset voltage, feedback resistor value and time integral constant. Any parameters that can affect the operating point are applicable to the present invention and will not be described in detail here.

[0066] Specifically, when the parameters in the SQUID readout circuit 11 are adjusted based on the modulation signal, a curve of the relationship between the output voltage and the input magnetic flux (V-Φ curve) is constructed based on the modulation signal. First, a rough adjustment is performed to adjust the bias current of the SQUID device 111 in the SQUID readout circuit 11 so that the peak-to-peak value of the V-Φ curve is maximized; the offset voltage of the amplifier 112 is adjusted so that the V-Φ curve is symmetrical about the zero voltage value; in actual use, the peak-to-peak value may have reached the maximum value or the V-Φ curve may have been symmetrical about the zero voltage value. At this time, only the corresponding resistance (bias resistance or offset resistance) needs to be adjusted, and finally the peak-to-peak value of the V-Φ curve is maximized and the V-Φ curve is symmetrical about the zero voltage value. Then fine-tune and calculate the operating point slope of the V-Φ curve in real time. Further adjusting the resistance value and the integral time constant of the feedback resistor in the SQUID readout circuit 11, adjusting the resistance value and the integral time constant of the feedback resistor (the integral time constant is related to the resistance value of the feedback resistor and the capacitance value) can change the slope of the operating point. The slope of the operating point of the V-Φ curve is finely adjusted by continuously adjusting the resistance value of the feedback resistor and / or the integral time constant. Reached maximum value.

[0067] Specifically, when the operating point slope of the V-Φ curve is adjusted to the maximum value, the values ​​of the parameters to be adjusted in the SQUID readout circuit 11 (including but not limited to the bias resistor, the offset resistor and the feedback resistor, and the time integration constant) are stored, and the connection between the reference magnetic sensor 12 and the SQUID readout circuit 11 is disconnected, so that the SQUID readout circuit 11 enters a closed-loop locked state.

[0068] In actual applications, when the SQUID working parameter control device 1 is in an open-loop state (not receiving the output signal of the reference magnetic sensor 12), the default configuration is read, and each parameter is automatically fine-tuned based on the preset value, and the working point is locked and the work is directly started. In a complex working environment, the reference magnetic sensor 12 is first connected as the flux modulation signal input, and the slope of the V-Φ curve is searched through fine adjustment. The maximum value is then adjusted to a closed-loop locking state through an electronic switch (switching switch 131), forming a negative feedback loop, locking the optimal working point to measure the magnetic signal. The specific process is as follows Figure 4 As shown:

[0069] S1) First, the SQUID operating parameter control device 1 is turned on, and the SQUID device 111 is defaulted to operate in an open-loop state. It is determined whether a reference magnetic sensor 12 is connected.

[0070] S2) If no reference magnetic sensor 12 is connected, the stored preset parameters are directly read, and the default memory chip is the parameters calibrated when leaving the factory. The control module 13 generates a control signal to enter the switch control unit 116 to generate a switch control signal for each electronic switch, so as to control the electronic switch in the adjustment unit 115 to adjust the bias resistor so that the output voltage in the V-Φ curve is the maximum within the adjustable range (the peak-to-peak value is the maximum), and the offset resistor is adjusted so that the V-Φ curve is symmetrical about the zero voltage value, and the adjustment is ended. If a reference magnetic sensor 12 is connected, the data collected by the reference magnetic sensor 12 is converted into digital-to-analog data, and used as the input modulation signal; the control module 13 optimizes the working point through an algorithm, adjusts the bias resistor R1 so that the output voltage in the V-Φ curve is the maximum within the adjustable range, adjusts the offset resistor R2 so that the V-Φ curve is symmetrical about the zero voltage value, adjusts the feedback resistor and the capacitance value in the integrator 113 to change the time integral constant, and calculates the working point slope. Compare with the factory calibration parameters, and repeatedly adjust the feedback resistance and time integration constant until the operating point slope It is the maximum under current conditions, and the adjustment is ended.

[0071] S3) End the adjustment process, store and update the working parameters at the optimal working point W, including but not limited to the bias resistor value, offset resistor value, feedback resistor value, integral time constant, Numeric value.

[0072] S4) The control module 13 controls the switch to disconnect the external reference magnetic sensor 12 circuit, the closed loop is locked to enter the working mode, and the magnetic field measurement begins.

[0073] S5) After the work is completed, the working mode is switched back to the open-loop mode, and then the device is turned off.

[0074] In summary, the present invention provides a SQUID working parameter control device and method, including: a SQUID readout circuit, a reference magnetic sensor and a control module; the SQUID readout circuit is used to detect magnetic signals; the reference magnetic sensor is used to collect working environment magnetic field data and provide a modulation signal for the SQUID device in the SQUID readout circuit; the control module is connected to the output end of the SQUID readout circuit and the reference magnetic sensor, and when adjusting the parameters, a relationship curve between the output voltage and the input magnetic flux is constructed based on the influence of the modulation signal on the SQUID device, the working point slope of the relationship curve between the output voltage and the input magnetic flux is calculated, and a control signal of the SQUID readout circuit is generated so that the working point slope reaches the maximum value. The present invention can realize intelligent adjustment of the working point in the application, and can realize high reliability and high accuracy magnetic detection in a complex working environment. Therefore, the present invention effectively overcomes the various shortcomings in the prior art and has a high industrial utilization value.

[0075] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A SQUID operating parameter control device, characterized in that: The SQUID operating parameter control device at least comprises: SQUID readout circuit, reference magnetic sensor and control module; The SQUID readout circuit is used to detect magnetic signals; The reference magnetic sensor is used to collect working environment magnetic field data and provide a modulation signal for the SQUID device in the SQUID readout circuit; The control module is connected to the output end of the SQUID readout circuit and the reference magnetic sensor. When adjusting parameters, a relationship curve between output voltage and input magnetic flux is constructed based on the influence of the modulation signal on the SQUID device, the operating point slope of the relationship curve between output voltage and input magnetic flux is calculated, and a control signal of the SQUID readout circuit is generated so that the operating point slope reaches a maximum value.

2. The SQUID operating parameter control device according to claim 1, characterized in that: The SQUID readout circuit includes: a SQUID device, a bias resistor, an offset resistor, an amplifier, an integrator, a feedback resistor array, a feedback coil, an adjustment unit and a switch control unit; The first input end of the amplifier is connected to the output end of the SQUID device and the first end of the bias resistor, and the second input end is connected to the first end of the offset resistor, for amplifying the output signal of the SQUID device; The adjustment module is controlled by the control module, the first output end is connected to the second end of the bias resistor to adjust the bias current of the SQUID device, and the second output end is connected to the second end of the offset resistor to adjust the offset voltage; The integrator is connected to the output end of the amplifier and integrates the output signal of the amplifier; A first end of the feedback resistor array is connected to the output end of the integrator, and the other end is grounded via the feedback coil; The output end of the switch control unit is connected to the control end of the integrator and the feedback resistor array respectively, and is used to adjust the resistance value of the feedback resistor and / or the time integration constant.

3. The SQUID operating parameter control device according to claim 2, characterized in that: The switch control unit is also connected to the output end of the amplifier and is used to adjust the gain of the amplifier.

4. The SQUID operating parameter control device according to claim 1, characterized in that: The reference magnetic sensor is a fluxgate, a magnetoresistive sensor or a SQUID sensor.

5. The SQUID operating parameter control device according to any one of claims 1 to 4, characterized in that: The control module includes a switch, an analog-to-digital converter and a microcontroller unit; A first end of the switch is connected to the output end of the reference magnetic sensor, and a second end is connected to the analog-to-digital converter; The analog-to-digital converter performs digital-to-analog conversion on the output signal of the reference magnetic sensor and performs analog-to-digital conversion on the output signal of the SQUID readout circuit; The microcontroller unit is connected to the output end of the analog-to-digital converter, constructs a relationship curve between the output voltage and the input magnetic flux based on the output signals of the reference magnetic sensor and the SQUID readout circuit, calculates the operating point slope, and generates a corresponding control signal.

6. A method for controlling SQUID working parameters, implemented based on the SQUID working parameter control device according to any one of claims 1 to 5, characterized in that: The SQUID working parameter control method at least comprises: Detect whether the reference magnetic sensor provides a modulation signal for the SQUID readout circuit based on the working environment magnetic field. If not, configure the parameters in the SQUID readout circuit with preset values ​​and lock the working point; if yes, adjust the parameters in the SQUID readout circuit based on the modulation signal, and lock the working point when the working point slope of the relationship curve between the output voltage and the input magnetic flux reaches a maximum value.

7. The SQUID operating parameter control method according to claim 6, characterized in that: The parameters to be adjusted in the SQUID readout circuit include: at least one of bias current, offset voltage, feedback resistor value, time integration constant and amplification factor.

8. The SQUID operating parameter control method according to claim 6 or 7, characterized in that: When the modulation signal is connected to the SQUID readout circuit, the relationship curve between the output voltage and the input magnetic flux is constructed based on the modulation signal. First, the bias current of the SQUID device and / or the offset voltage of the amplifier in the SQUID readout circuit are adjusted to maximize the peak-to-peak value of the relationship curve between the output voltage and the input magnetic flux, and the relationship curve between the output voltage and the input magnetic flux is symmetrical about the zero voltage value above and below; then, the resistance value of the feedback resistor and / or the integration time constant in the SQUID readout circuit are further adjusted to make the operating point slope of the relationship curve between the output voltage and the input magnetic flux reach a maximum value.

9. The SQUID operating parameter control method according to claim 8, characterized in that: After adjusting various parameters in the SQUID readout circuit based on the modulation signal, the reference magnetic sensor is disconnected from the SQUID readout circuit.

10. The SQUID operating parameter control method according to claim 8, characterized in that: When the slope of the working point of the relationship curve between the output voltage and the input magnetic flux is adjusted to a maximum value, the values ​​of the parameters to be adjusted in the SQUID readout circuit are stored.

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