CN211669350U - Eight-channel SQUID flux locking ring working point automatic regulating device - Google Patents
Eight-channel SQUID flux locking ring working point automatic regulating device Download PDFInfo
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- CN211669350U CN211669350U CN201922247660.0U CN201922247660U CN211669350U CN 211669350 U CN211669350 U CN 211669350U CN 201922247660 U CN201922247660 U CN 201922247660U CN 211669350 U CN211669350 U CN 211669350U
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Abstract
The utility model discloses an eight passageway SQUID flux locking ring operating point automatic regulating apparatus observes and controls the unit by full tension magnetic gradient probe through eight passageway SQUID readout circuits and NI and is connected, and NI observes and controls the unit and passes through the net twine and link to each other with the notebook, and NI observes and controls the unit and passes through RS485 communication bus and be connected with multichannel DAC through the singlechip, and multichannel DAC is connected with eight passageway SQUID readout circuits through the multiplexer and constitutes. The automatic adjustment of the offset current (Ib) and the offset voltage (Voff) of the DC-SQUID readout circuit is realized through an NI measurement and control unit, a single chip microcomputer, a multi-channel DAC and a multiplexer, the whole adjustment process does not need manual intervention, the Ib and the Voff are automatically adjusted through the peak value (Vpp ═ Vmax-Vmin) of a debugging voltage signal Vtune and the direct current offset (Vdc ═ Vmax + Vmin)/2), the influence of manual experience is eliminated, the operation process is simplified, the working efficiency is improved, and the field detection is greatly facilitated.
Description
The technical field is as follows:
the utility model relates to a high temperature superconducting full-tensor magnetic gradient instrument, in particular to a multichannel SQUID flux locking ring working point automatic regulating method and device in the high temperature superconducting full-tensor magnetic gradient instrument.
Background art:
superconducting Quantum Interference Device (SQUID), as a magnetic vector sensor with the highest sensitivity, has a very wide application prospect in the fields of magnetic prospecting, biomagnetic measurement, nondestructive inspection and the like. Compared with the traditional total field intensity measurement and three-component measurement technology, the high-temperature superconducting full-tensile magnetic gradient meter built by the SQUID not only improves the measurement efficiency, but also has the advantages of high positioning precision, simple positioning algorithm and the like.
When the high-temperature superconducting full-tension magnetic gradient meter adopts the classic zero-flux-locking type measuring principle to measure a magnetic field, the working point of the SQUID flux-locking ring needs to be adjusted to be in the optimal working point state, so that the SQUID in the zero-flux-locking state can work normally and stably. SQUID flux-locked loop operating point adjustment includes two parts, offset current (Ib) and offset voltage (Voff) adjustment. The traditional analog DC-SQUID measurement and control unit is characterized in that an experimenter manually adjusts Ib and Voff through a knob potentiometer according to the working state of a sensor, but in the process, a signal generator and an oscilloscope are required, so that extra equipment is required to be added in the field experiment, the output waveform is required to be observed in real time by naked eyes, and the knob potentiometer has certain limitation in the manual fine adjustment process, so that the digital DC-SQUID measurement and control unit gradually becomes a mainstream trend.
CN2473670Y discloses an automatic control interface device of a superconducting quantum interferometer, which is characterized in that a multifunctional circuit with an MCS51 microprocessor as a core is adopted, the multifunctional circuit comprises one or more than two (including two) identical branch circuits, and each branch circuit is formed by connecting a single chip microcomputer with a digital-to-analog (D/A) conversion circuit, an analog-to-digital (A/D) conversion circuit and a triangular wave generator circuit. The utility model discloses an useful part is: the operation of the measuring device of the superconducting quantum interferometer is changed from manual operation to a mode of taking a PC as master control, and meanwhile, more than two (including two) superconducting quantum interferometers can be switched and controlled by one computer. But this superconducting quantum interferometer automatic control interface arrangement output waveform on needing experimental personnel naked eye real-time observation computer display interface, judge whether reach best operating point according to the experience, cause the erroneous judgement easily, in addition whole accommodation process still needs artifical intervention, and is consuming time and wasting force, is not suitable for the regulation of multichannel SQUID flux locking ring operating point.
CN104808156A discloses a SQUID magnetic sensor and an optimal working point locking method, comprising a SQUID magnetic flux amplifying circuit which amplifies a detected magnetic flux signal and converts the signal into a response magnetic flux signal; SQUID magnetic flux detection circuit for linearly converting the response magnetic flux signal into detection voltage signal; a response voltage signal proportional to the detected magnetic flux signal is output according to the magnetic flux detection voltage signal, and the response voltage signal is converted into a magnetic flux signal and is coupled to a first SQUID magnetic flux locking loop of the SQUID magnetic flux amplifying circuit; and controlling the second SQUID magnetic flux locking loop to be stabilized at a preset working point, and then controlling the first SQUID magnetic flux locking loop to be in an optimal working point locking circuit without impact locking by a control signal. The invention has the advantages that: the automatic locking circuit is introduced, so that the whole bipolar SQUID circuit can be locked at the optimal working point, the circuit automatically completes locking, the working point and the locking time do not need to be manually selected, the operation is simple, and the high-performance bipolar SQUID magnetic sensor can be put into practical use. However, the SQUID magnetic sensor and the optimal working point locking method need to add a large number of components, the circuit design difficulty is increased, the defects are more obvious particularly when the SQUID magnetic sensor and the optimal working point locking method are applied to a multi-channel magnetometer system, and actual field experiments are not facilitated.
The invention content is as follows:
the utility model aims at providing a multichannel SQUID flux locking ring working point automatic regulating method and device suitable for high temperature superconducting full-tension magnetic gradiometer aiming at the defects of the prior art.
The utility model aims at realizing through the following technical scheme:
an eight-channel SQUID flux-locked loop working point automatic adjusting device is formed by connecting a full-tension magnetic gradient probe 1 with an NI measuring and controlling unit 3 through an eight-channel SQUID reading circuit 2, connecting the NI measuring and controlling unit 3 with a notebook computer 4 through a network cable, connecting the NI measuring and controlling unit 3 with a multi-channel DAC6 through an RS485 communication bus and a single chip microcomputer 5, and connecting a multi-channel DAC6 with the eight-channel SQUID reading circuit 2 through a multi-channel selector 7.
The readout circuit 2 of the eight-channel SQUID readout circuit 2 in a debugging state introduces a triangular wave debugging signal at a Test interface, and a feedback coil is utilized to induce a changing magnetic field at the SQUID to assist the adjustment of the working point of the SQUID magnetic flux locking ring; the SQUID magnetic sensor is connected to the positive input end of the amplifier through the low-temperature twisted pair line to amplify a weak signal, the output end of the amplifier is connected to the negative input end of the integrator through the resistor R, and the integrator outputs an amplified and integrated voltage signal of the SQUID magnetic sensor.
Has the advantages that: the utility model discloses eight passageway SQUID magnetic flux locking ring operating point automatic regulating apparatus, observe and control the unit through NI, a single chip microcomputer, multichannel DAC and multiplexer realize DC-SQUID readout circuit offset current (Ib) and offset voltage (Voff)'s automatically regulated, whole accommodation process need not artificial intervention, peak-to-peak value (Vpp ═ Vmax-Vmin) and direct current offset (Vdc ═ Vmax + Vmin)/2) through debugging voltage signal Vtune come from automatically regulated Ib, Voff, artificial experience influence has been got rid of, the operation flow has been simplified, the regulation efficiency has been improved, indoor and field experiment has been made things convenient for greatly.
Description of the drawings:
FIG. 1 is a block diagram of an automatic adjusting device for working points of an eight-channel SQUID flux-locked loop;
FIG. 2 is a circuit diagram of a single channel SQUID readout circuit;
FIG. 3 is a flow chart of a method for automatically adjusting the operating point of a SQUID flux-locked loop;
the system comprises a 1 full tensor magnetic gradient probe, a 2 eight-channel SQUID reading circuit, a 3NI measurement and control unit, a 4 notebook computer, a 5 single chip microcomputer, a 6 multi-channel DAC and a 7 multi-channel selector.
The specific implementation mode is as follows:
the invention will be described in further detail with reference to the following figures and examples:
an eight-channel SQUID flux-locked loop working point automatic adjusting device is formed by connecting a full-tension magnetic gradient probe 1 with an NI measuring and controlling unit 3 through an eight-channel SQUID reading circuit 2, connecting the NI measuring and controlling unit 3 with a notebook computer 4 through a network cable, connecting the NI measuring and controlling unit 3 with a multi-channel DAC6 through an RS485 communication bus and a single chip microcomputer 5, and connecting a multi-channel DAC6 with the eight-channel SQUID reading circuit 2 through a multi-channel selector 7.
Fig. 1 is a block diagram of the structure of the automatic adjusting device for the working point of the eight-channel SQUID flux-locked loop of the present invention, and reference numeral 2 in fig. 1 is composed of eight single-channel SQUID readout circuits shown in fig. 2. The full tensor magnetic gradient probe 1 is internally provided with 8 SQUID magnetic sensors, the number of the SQUID magnetic sensors is 3 in the x-axis direction and the y-axis direction respectively, the number of the SQUID magnetic sensors is two in the z-axis direction, and a full tensor probe coordinate system formed by three groups of mutually perpendicular SQUID magnetic sensors is used for magnetic gradient tensor measurement; because the output voltage signal of the original SQUID magnetic sensor is very weak, the full-tensor magnetic gradient probe 1 is connected with the eight-channel SQUID readout circuit 2 to carry out amplification and integration processing on the weak voltage signal; then, the output end of the integrator is connected with the NI measurement and control unit 3 to acquire, analyze and process the output voltage signal in real time; the notebook 4 is used as an upper computer part of the device to receive the voltage signal transmitted from the NI measurement and control unit 3 through a network cable and display the voltage signal in real time; the upper computer is used as a control terminal, the RS485 is used as a communication bus, the singlechip 5 is used as a control medium, and the multi-channel DAC6 and the multiplexer 7 are driven to generate corresponding triangular wave debugging signals, offset current (Ib) and compensation voltage (Voff); the output port of the multiplexer 7 is correspondingly connected to the input port of the eight-channel SQUID readout circuit 2, so that the automatic adjustment of the working point of the eight-channel SQUID flux-locked loop, namely the automatic adjustment of Ib and Voff, is realized.
As shown in fig. 2, the eight-channel SQUID readout circuit 2 in the debug state introduces a triangle wave debug signal at the Test interface, induces a changing magnetic field at the DC-SQUID by using a feedback coil built in the sensor, and the output end of the integrator outputs a debug voltage signal Vtune similar to the triangle wave under the excitation of the magnetic field, and automatically adjusts the operating point (i.e., Ib, Voff) of the SQUID flux-locked loop according to the peak-to-peak value (Vpp-Vmax-Vmin) of the debug voltage signal Vtune and the direct current offset (Vdc-Vmax + Vmin)/2).
In the automatic adjusting process of the working point of the eight-channel SQUID flux-locked loop, as shown in figure 3, a triangular wave debugging signal is firstly accessed, and a variable magnetic field is induced at the SQUID by using a feedback coil to assist in adjusting the working point of the SQUID flux-locked loop; because the peak-to-peak value Vpp of the debugging voltage signal Vtune is maximum when the bias current Ib reaches the optimal value, only the value Ib corresponding to the maximum Vpp is needed to be found, but in the process of adjusting Ib, in order to avoid the debugging voltage signal Vtune from exceeding the measurement range due to zero drift, the value Voff needs to be adjusted synchronously to ensure that the Vtune is always kept in the measurement range; taking Delta I (taking the empirical value of the Delta I to be 5 mu A) as an initial step for adjusting the Ib, continuously increasing the Ib until Vpp is not increased along with the increase of the Ib, showing that the current Ib value exceeds the optimal value, namely, overshoot occurs, inverting the Delta I and halving to reversely adjust the Ib, inverting the Delta I and halving when the overshoot occurs again so as to continuously approach the optimal bias current Ib, and finishing the adjustment of the Ib until the optimal bias current Ib is determined until the Delta I is smaller than the minimum adjustable value; finally, Voff is adjusted again, so that Vdc is equal to 0, and the value of Voff is the optimal compensation voltage at this time, so that the optimal operating points (namely Ib and Voff) of the SQUID flux-locked loop are determined.
The automatic adjusting method of the working point of the eight-channel SQUID flux-locked loop comprises the following steps:
a. assembling and connecting the eight-channel SQUID flux lock ring working point automatic adjusting device according to the mode shown in figure 1;
b. after the connection is confirmed to be correct, each module is electrified, an upper computer is started, and the device is set to be in a debugging state;
c. the NI measurement and control unit 3 collects output voltage signals of 8 paths of SQUID magnetic sensors in real time, displays the output voltage signals on the notebook 4 through a network cable, and starts a triangular wave debugging signal of a target channel (from the beginning of the channel);
d. the upper computer outputs a voltage signal Vtune according to the SQUID magnetic sensor and a peak-to-peak value V corresponding to the voltage signal Vtunepp(n)＝Vmax(n)-Vmin(n) and DC bias
Giving Ib and Voff adjusting commands of the target channel;
e. the singlechip 5 receives Ib and Voff adjusting commands sent by the upper computer through an RS485 communication bus and gives a return value;
f. the singlechip 5 drives the multi-channel DAC6 and the multi-channel selector 7 to generate a corresponding offset current value Ib and a corresponding compensation voltage value Voff to be input into the eight-channel SQUID readout circuit 2, so that the automatic adjustment of the working points (namely Ib and Voff) of the SQUID magnetic flux lock ring is realized;
g. repeating the steps d-f until the optimal working point of the SQUID flux-locked loop of the target channel is found;
h. steps c-g are repeated until the optimum operating points of the 8-way SQUID flux-locked loops in the eight-channel SQUID readout circuit 2 are all found and locked.
Claims (2)
1. The automatic adjusting device for the working point of the eight-channel SQUID flux-locked loop is characterized in that a full tensor magnetic gradient probe (1) is connected with an NI measurement and control unit (3) through an eight-channel SQUID reading circuit (2), the NI measurement and control unit (3) is connected with a notebook (4) through a network cable, the NI measurement and control unit (3) is connected with a multi-channel DAC (6) through an RS485 communication bus through a single chip microcomputer (5), and the multi-channel DAC (6) is connected with the eight-channel SQUID reading circuit (2) through a multi-channel selector (7) to form the automatic adjusting device.
2. The automatic adjusting device of working point of eight-channel SQUID flux-locked loop according to claim 1, characterized in that the readout circuit (2) of the eight-channel SQUID readout circuit (2) in the debugging state is to introduce a triangular wave debugging signal at Test interface, and to induce a changing magnetic field at SQUID by using the feedback coil to assist the adjustment of the working point of SQUID flux-locked loop; the SQUID magnetic sensor is connected to the positive input end of the amplifier through the low-temperature twisted pair line to amplify a weak signal, the output end of the amplifier is connected to the negative input end of the integrator through the resistor R, and the integrator outputs an amplified and integrated voltage signal of the SQUID magnetic sensor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922247660.0U CN211669350U (en) | 2019-12-16 | 2019-12-16 | Eight-channel SQUID flux locking ring working point automatic regulating device |
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| CN201922247660.0U CN211669350U (en) | 2019-12-16 | 2019-12-16 | Eight-channel SQUID flux locking ring working point automatic regulating device |
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| CN211669350U true CN211669350U (en) | 2020-10-13 |
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| CN201922247660.0U Expired - Fee Related CN211669350U (en) | 2019-12-16 | 2019-12-16 | Eight-channel SQUID flux locking ring working point automatic regulating device |
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Granted publication date: 20201013 Termination date: 20211216 |