Direct current measurement sensing device capable of reducing microwave interference and measurement method

Abstract

The invention provides a direct current measurement sensing device and measurement method for reducing microwave interference, and the device comprises a plurality of front-end modules located at a high-voltage side, a rear-end module located at a low-voltage side, and an optical fiber used for optical transmission between the high-voltage side and the low-voltage side. Each front-end module comprises a solid-state spinning color center detection module, a light emitting module and an optical carrier microwave receiving module; each solid-state spinning color center detection module is used for sensing a magnetic field generated by high-voltage side current, receiving laser transmitted by the rear-end module, receiving a modulated microwave electric signal transmitted by the optical microwave receiving module, collecting and converting generated fluorescence into a first analog electric signal, and outputting the first analog electric signal to the light emitting module; the modulation frequencies of the microwaves transmitted to every two solid-state spinning color center detection modules are different; and the back-end module converts the optical signal into a second analog electric signal, and demodulates the second analog electric signal by using a reference signal with a corresponding modulation frequency. Interference caused by other microwaves in a short distance can be reduced, and accuracy is improved.

Description

Technical Field

[0001] This invention relates to the field of quantum precision measurement, and in particular to a DC measurement sensing device and method for reducing microwave interference. Background Technology

[0002] Current sensors are indispensable and important measuring devices in power systems. Solid-state spin color center systems are important physical systems for realizing quantum precision measurement. Taking diamond NV color centers as an example, magnetic field measurements using them have advantages such as wide temperature range, high precision, and large range, providing a new and effective way to solve the current measurement problem in power systems.

[0003] To improve the signal-to-noise ratio and avoid 1 / f noise, existing quantum current sensors employ a modulation signal of a certain frequency added to the microwave. Since the microwave frequency oscillates in a sinusoidal or square wave manner, the fluorescence generated by the NV color center near the resonance absorption peak will also oscillate at a corresponding frequency. After demodulation, the first-order differential spectrum, i.e., the demodulation curve, can be obtained. The modulated microwave frequency can be expressed by the following formula: ,in, It is an unmodulated frequency. It is the modulation depth. It is the modulation frequency. This is the modulation phase. The AC signal used for demodulation in the fluorescence signal generated by this modulated microwave is... , The oscillation amplitude of the fluorescence signal. For fluorescence phase. Using a reference signal. Mixing with the fluorescence signal, since the frequency of the reference signal is the same as that of the fluorescence signal, the result after mixing is: Then, through low-pass filtering, we can obtain: ,adjust , making ,get: ,because If it is known, then it can be extracted. .

[0004] In practical applications, multiple solid-state spin center quantum probes are often placed on the outer circumference of the conductor under test. When these quantum probes are close together and operating simultaneously, the microwaves radiated by the antennas of adjacent probes can interfere with each other. For example... Figure 2 As shown, when the resonant frequency of quantum probe A is At that time, the microwaves generated by the adjacent quantum probe B... The oscillations occur in the vicinity, and the oscillation frequency is the modulation frequency. The fluctuation range is ,when and When the difference is not significant, such as Figure 2 If both frequencies are within the same resonance peak, or within two different resonance peaks, the microwaves generated by the quantum probe B antenna will cause a change in the fluorescence signal on the quantum probe A. In the fluorescence signal generated by the same quantum probe, the AC signal used for demodulation is superimposed. Finally, the demodulation result is Mixed with Interference with other quantum probes can introduce more interference signals, leading to errors in the acquisition of the resonant frequency and consequently introducing errors into the measurement. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a DC current measurement sensing device and measurement method that reduces microwave interference, in order to solve the problem in the prior art that when multiple quantum probes located on the high-voltage side are close to each other and work simultaneously, microwave interference occurs, which introduces errors into the measurement.

[0006] To achieve the above and other related objectives, a first aspect of the present invention provides a DC current measurement and sensing device for reducing microwave interference, comprising: a plurality of front-end modules located on the high-voltage side, a back-end module located on the low-voltage side, and an optical fiber for optical transmission between the high-voltage side and the low-voltage side. Each front-end module includes a solid-state spin center detection module, an optical emission module, and an optically-carried microwave receiving module. Each solid-state spin center detection module is used to sense the magnetic field generated by the current on the high-voltage side, receive laser light transmitted from the back-end module, and receive modulated microwave electrical signals transmitted from the optically-carried microwave receiving module, and to convert the solid-state spin center into a signal transmitted from the laser light, modulated microwave light, and optically-carried microwave signal. The fluorescence generated under the action of the magnetic field is collected, converted into a first analog electrical signal, and then output to the optical emission module. The optical emission module converts the first analog electrical signal into an optical signal and transmits it to the back-end module. The optical microwave receiving module receives the optical modulated microwave signal from the back-end module, converts it into a modulated microwave electrical signal, and outputs it. The modulation frequency of the microwaves transmitted to each of the two solid-state spin center detection modules is different. The back-end module converts the optical signal into a second analog electrical signal, and demodulates the AC signal in it using a reference signal with a corresponding modulation frequency to obtain demodulated data. The magnetic field strength value and / or current value are calculated based on the demodulated data.

[0007] Furthermore, each solid-state spin center detection module includes a quantum probe containing a solid-state spin center, a microwave antenna, and a detection module; the microwave antenna receives modulated microwave electrical signals transmitted from the optical microwave receiving module and radiates them to the quantum probe, which is also used to sense magnetic fields and receive laser irradiation; the detection module is used to collect and detect fluorescence and output a first analog electrical signal to the light emitting module.

[0008] Furthermore, the distance between any two adjacent quantum probes is no more than 10 cm.

[0009] Furthermore, the modulation frequency difference of the microwaves transmitted to each of the two adjacent solid-state spin center detection modules is not less than 1 kHz, and each modulation frequency is not greater than the maximum modulation frequency that the spin center can accept.

[0010] Furthermore, multiple solid-state spin center detection modules are arranged at intervals on a circle centered on the cross-section of the conductor under test, or located on one or both sides of the conductor under test.

[0011] Furthermore, the optical emission module converts the first analog electrical signal into an analog optical signal.

[0012] Furthermore, the optical emission module employs a laser, which is driven by an analog electrical signal to output a corresponding analog optical signal.

[0013] Furthermore, each front-end module also includes an auxiliary magnetic sensor, a data acquisition module, and a digital optical emission module. The auxiliary magnetic sensor is used to sense the magnetic field generated by the high-voltage side current and output an auxiliary electrical signal. The data acquisition module is used to acquire the auxiliary electrical signal, and the digital optical emission module converts the auxiliary electrical signal into a digital optical signal for transmission to the back-end module.

[0014] Furthermore, the back-end module includes a laser module, multiple optical receiving modules corresponding one-to-one with multiple optical emitting modules, multiple optical microwave emitting modules corresponding one-to-one with multiple optical microwave receiving modules, a microwave source, and a control module. The laser module is used to deliver laser light to each solid-state spin center detection module. Each optical microwave emitting module is used to convert the modulated microwave electrical signal from the microwave source into an optical modulated microwave signal and output it. Each optical receiving module is used to receive the optical signal transmitted by the corresponding optical emitting module, perform photoelectric conversion on it, output a second analog electrical signal, and transmit it to the control module. The control module acquires the second analog electrical signal, demodulates the second analog electrical signal using a reference signal with a corresponding modulation frequency to obtain demodulated data, and then calculates the magnetic field strength and / or current value based on the demodulated data.

[0015] To achieve the above and other related objectives, a second aspect of the present invention provides a DC measurement method for reducing microwave interference, comprising: placing a plurality of quantum probes containing solid-state spin centers in a magnetic field generated by a current to be measured on a high-voltage side; transmitting laser light and modulated microwaves from a low-voltage side to the quantum probes on the high-voltage side, wherein the modulation frequency of the microwaves transmitted to each pair of quantum probes is different; collecting the fluorescence generated by the quantum probes to obtain a first analog electrical signal, converting it into an optical signal and transmitting it to the low-voltage side; performing photoelectric conversion on the low-voltage side to obtain a second analog electrical signal; demodulating the AC signal therein using a reference signal with a corresponding modulation frequency to obtain demodulated data; and calculating the magnetic field strength value and / or current value based on the demodulated data.

[0016] As described above, the DC measurement sensing device and method for reducing microwave interference of the present invention have the following beneficial effects: For multiple solid-state spin center detection modules located on the high-voltage side, the modulation frequency of the microwaves transmitted to each pair of solid-state spin center detection modules is different. By using a reference signal with a corresponding modulation frequency for demodulation on the low-voltage side, the correct fluorescence signal can be demodulated, which can reduce the microwave mutual interference generated when multiple solid-state spin center detection modules work simultaneously at close range, thereby improving the accuracy of measurement. Attached Figure Description

[0017] Figure 1 The diagram shown is a schematic representation of the overall structure of the sensing device of the present invention.

[0018] Figure 2 The diagram shows the fluorescence changes caused by microwave interference between two probes at close range;

[0019] Figure 3 The diagram shown is an exemplary structural schematic of the sensing device of the present invention.

[0020] Figure 4 The diagram shown is a structural schematic of a solid-state spin center detection module of the present invention.

[0021] Figure 5 The diagram shown is a structural schematic of the front-end module of the present invention.

[0022] Figure 6 The graph shown is the demodulation curve obtained by ODMR measurement using microwave sweep frequency method for diamond NV color centers.

[0023] Component labeling: 1—Front-end module; 11—Solid-state spin center detection module; 111—Quantum probe; 112—Microwave antenna; 113—Detection module; 1131—Filter; 1132—First photodetector; 1133—First voltage converter circuit; 1134—Differential circuit; 1135—Second photodetector; 1136—Second voltage converter circuit; 12—Optical emission module; 13—Optical microwave receiver module; 14—Photovoltaic cell; 15—Auxiliary magnetic sensor; 16—Acquisition module; 17—Digital optical emission module; 18—Digital merging circuit; 2—Back-end module; 21—Optical receiver module; 22—Control module; 221—Fifth ADC; 222—Controller; 23—Optical microwave emission module; 24—Microwave source; 25—First laser; 26—Second laser; 3—Fiber optic cable; 4—Insulator; 5—Conductor under test. Detailed Implementation

[0024] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0025] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0026] Example 1: As Figure 1 , Figure 3 As shown, this embodiment provides a DC measurement and sensing device for reducing microwave interference, including multiple front-end modules 1 located on the high-voltage side, a back-end module 2 located on the low-voltage side, and an optical fiber 3 for optical transmission between the high-voltage side and the low-voltage side. Each front-end module includes a solid-state spin center detection module 11, an optical emission module 12, and an optical microwave receiving module 13.

[0027] Each solid-state spin center detection module 11 is used to sense the magnetic field generated by the high-voltage side current, receive the laser transmitted from the back-end module 2, and receive the modulated microwave electrical signal transmitted from the optical microwave receiving module 13. It collects the fluorescence generated by the solid-state spin center under the action of laser, modulated microwave, and magnetic field, converts it into a first analog electrical signal, and outputs it to the optical emitting module 12. The optical emitting module 12 converts the first analog electrical signal into an optical signal and transmits it to the back-end module 2. The optical microwave receiving module 13 is used to receive the optical modulated microwave signal from the back-end module 2, convert it into a modulated microwave electrical signal, and output it. The modulation frequency of the microwaves transmitted to each pair of solid-state spin center detection modules 11 is different. The back-end module 2 converts the optical signal into a second analog electrical signal, demodulates it with a reference signal with a corresponding modulation frequency, obtains demodulated data, and calculates the magnetic field strength value and / or current value based on the demodulated data.

[0028] In this embodiment, microwaves with different modulation frequencies are delivered to multiple solid-state spin center detection modules. Taking two solid-state spin center detection modules as an example, the applied microwave frequencies are as follows: and The AC signals generated by two microwaves with different modulation frequencies on the same solid-state spin center detection module are superimposed as follows: For the superimposed signal generated by the first solid-state spin center detection module, using Demodulating the signal as a reference signal can yield the demodulated signal. For the superimposed signal generated by the second solid-state spin center detection module, using Demodulating the signal as a reference signal can yield the demodulated signal. Similarly, this can be applied to the superposition of fluorescence signals generated by more than two microwaves with different modulation frequencies on the same solid-state spin center detection module. Therefore, it is evident that using a reference signal with the corresponding modulation frequency for demodulation can correctly demodulate the fluorescence signal, reducing microwave interference caused by multiple solid-state spin center detection modules operating simultaneously at close range, thereby improving measurement accuracy.

[0029] It is important to note that for modulated signals The fluorescence it produces can be expressed by the formula This indicates that, since demodulation is performed on AC signals and specifically on the first harmonic, the DC term V must be filtered out first during demodulation, which can be achieved, for example, through AC coupling. When performing low-pass filtering after mixing, multiple solid-state spin center detection modules can share a single cutoff frequency filter, or different cutoff frequencies can be set. The cutoff frequency is determined based on the minimum frequency of the AC term to be filtered out.

[0030] like Figure 4As shown, each solid-state spin center detection module 11 includes a quantum probe 111 containing a solid-state spin center, a microwave antenna 112, and a detection module 113. The microwave antenna 112 receives the modulated microwave signal transmitted from the optical microwave receiving module 13 and radiates the modulated microwave signal to the quantum probe 111. The quantum probe 111 is also used to sense magnetic fields and receive laser irradiation.

[0031] The detection module 113 includes a fluorescence detection module for collecting the fluorescence generated by the quantum probe 111, outputting a fluorescence electrical signal, and outputting the fluorescence electrical signal as a first analog electrical signal to the light emission module 12. The fluorescence detection module includes a filter 1131, a first photodetector 1132, and a first voltage conversion circuit 1133. When using fiber optic laser transmission and placing the quantum probe 111 on the end face of the fiber, the fluorescence detection module is located on the side of the diamond detector opposite to the fiber end face. The fluorescence generated by the quantum probe 111 is filtered out by the filter 1131, collected by the first photodetector 1132, converted into a current signal, and then converted into a voltage signal by the first voltage conversion circuit 1133, which is then output to the light emission module 12. The voltage conversion circuit can be a transimpedance amplifier.

[0032] In this embodiment, the optical emitting module 12 can convert the first analog electrical signal into a digital optical signal or an analog optical signal. When converting to a digital optical signal, the optical emitting module 12 uses a digital optical transmitter; when converting to an analog optical signal, the optical emitting module 12 uses a laser, and the laser is driven by the first analog electrical signal to output the corresponding analog optical signal. A 1550nm or 1310nm laser is preferably used, as it has superior performance and low loss.

[0033] In this embodiment, the first analog electrical signal detected is converted into an analog optical signal by the optical emission module 12 and then transmitted to the low-voltage side. This achieves the high signal transmission rate required to improve phase accuracy when using modulated microwaves. Preferably, after converting the received analog optical signal into an analog electrical signal on the low-voltage side, the sampling rate of this analog electrical signal is not less than 10MHz. For example, in this embodiment, when applied to the measurement of ultra-high voltage electricity in the power grid, since the magnetic measurement sampling rate needs to reach 10kHz, the microwave modulation frequency is at least 40kHz. During demodulation, in order to better restore the modulated signal, a 10MHz ADC is used to collect the fluorescent electrical signal, which can achieve 250 sampling points per modulation cycle, thereby improving the phase accuracy to close to 1°. In this embodiment, after significantly improving the phase accuracy, it is possible to ensure that the difference between the initial phase of the reference signal and the initial phase of the signal under test is zero as much as possible, so as to maximize the output signal amplitude, improve the signal-to-noise ratio, and improve the sensitivity, accuracy, and reliability of weak signal detection.

[0034] Optical microwave transmission is a technology that loads microwave signals onto light waves for transmission. Microwave electrical signals can be modulated onto an optical carrier using modulation techniques. In this embodiment, the microwaves are frequency-modulated microwaves. On the low-voltage side, the modulated microwave electrical signal is loaded onto the light wave and converted into an optically modulated microwave signal, which is then transmitted to the optical microwave receiving module 13 on the high-voltage side. The microwave antenna 112 can be a microstrip antenna, located close to the quantum probe 111, for example, on one side of the quantum probe 111.

[0035] like Figure 1 As shown, multiple solid-state spin center detection modules 11 are arranged at intervals on a circle with the center of the cross section of the conductor 5 under test as the center. They can also all be located on one side of the conductor 5 under test, or they can be divided into two arrays located on both sides of the conductor 5 under test. When the distance between two adjacent quantum probes is no more than 10cm, microwave interference will occur. Here, the distance refers to the straight-line distance between the opposite surfaces of the two probes. Using the sensing device of this embodiment, even if two adjacent probes are brought close to each other with a distance of 1cm, the mutual interference of microwaves can be reduced. Figure 1 The example provides four solid-state spin color center detection modules 11, but other numbers are also possible, preferably 2n, where n is an integer. The solid-state spin color center is one of the following: diamond nitrogen-vacancy color center, diamond germanium-vacancy color center, diamond silicon-vacancy color center, silicon carbide silicon-carbon double-vacancy color center, silicon carbide silicon-vacancy color center, or hexagonal boron nitride boron-vacancy color center. All of them are based on the principle of photoluminescence and fluorescence response to changes in magnetic field. In this embodiment, diamond NV color center is used as an example. The quantum probe 111 is composed of diamond containing nitrogen-vacancy color centers and has a nano- or micro-scale granular structure or a rectangular block structure.

[0036] The wavelength of the excitation light may differ for different solid-state spin color centers. For example, 532 nm green excitation light is generally used for diamond nitrogen-vacancy color centers and hexagonal boron nitride boron-vacancy color centers; 900-940 nm excitation light is used for silicon carbide double-vacancy color centers; and other color centers can be excited using corresponding excitation light. The placement of the quantum probe 111 in the magnetic field can be selected such that the direction of the magnetic field acting on the solid-state spin color center is parallel to the axis of one of the color centers. Therefore, when calculating the magnetic field component along this single axis, it is the magnetic field strength generated by the conductor under test along its circumference.

[0037] For example Figure 3As shown, the backend module 2 includes a laser module, multiple optical receiving modules 21 corresponding to multiple optical emitting modules 12, a control module 22, multiple optical microwave emitting modules 23 corresponding to multiple optical microwave receiving modules 13, and a microwave source 24. The laser module is used to deliver laser light to the quantum probe 111 to excite the solid-state spin center to generate fluorescence. Each optical microwave emitting module 23 is used to convert the modulated microwave signal from the microwave source 24 into an optical microwave signal and output it to the corresponding optical microwave receiving module 13. Each optical receiving module 21 is used to receive the optical signal transmitted by the corresponding optical emitting module 12, perform photoelectric conversion on it, output a second analog electrical signal, and transmit it to the control module 22. The control module 22 collects the second analog electrical signal, demodulates it with a reference signal with a corresponding modulation frequency to obtain demodulated data, and then calculates the magnetic field strength value and / or current value based on the demodulated data.

[0038] The optical receiving module 21 is a photodetector that receives the optical signal transmitted from the high-voltage side, performs photoelectric conversion on it, and outputs a second analog electrical signal.

[0039] The control module 22 calculates the current based on the demodulated data. Specifically, this involves first obtaining the resonant frequency from the demodulated data, then calculating the magnetic field strength value based on the resonant frequency, and finally calculating the current value based on the relationship between the magnetic field strength value and the current value. The control module 22 also provides a modulation signal to the microwave source 24, which includes multiple different modulation frequencies.

[0040] In this embodiment, the control module 22 may include, for example, multiple fifth ADCs (i.e., analog-to-digital converters) 221 and a controller 222. Each fifth ADC 221 is used to acquire the second analog electrical signal transmitted by the corresponding optical receiving module 21 and transmit it to the controller 222. The controller 222 demodulates the signal to obtain demodulated data and then calculates the magnetic field strength and / or current value based on the demodulated data. Figure 5 In the case of a single optical receiver module 21, an example of a fifth ADC is provided. The controller 222 can be, for example, an FPGA. After converting the first analog electrical signal into analog light on the high-voltage side and transmitting it to the low-voltage side, and then converting the analog light into a second analog electrical signal on the low-voltage side, the fifth ADC 221 can achieve a sampling rate of at least 10MHz for the second analog electrical signal. This will help improve the phase accuracy in demodulation, maximize the output signal amplitude, improve the signal-to-noise ratio, and enhance the sensitivity, accuracy, and reliability of weak signal detection. The sampling rate of the fifth ADC 221 for the second analog electrical signal is preferably 10MHz.

[0041] For a fixed sensing device, different modulation frequencies will result in a corresponding fixed phase in the fluorescence response. This phase can be obtained experimentally under the influence of a single modulation frequency. This embodiment uses biphase demodulation technology, employing two reference signals, namely... , After mixing the two reference signals with the fluorescence signal and performing low-pass filtering, two components can be obtained. , By adjusting the phase so that one component, for example X, approaches zero, the other component Y becomes the desired value. Figure 6 The demodulation curves shown are for the case of the eight resonant frequencies of the diamond NV color center.

[0042] One method to obtain the resonant frequency is to plot the demodulated data as a function of frequency by sweeping the frequency curve and finding the resonant frequency point on the curve. Another method is to obtain the resonant frequency point through the first sweep and then use a closed-loop control algorithm to adjust the frequency of the modulated microwave radiated by the microwave source to obtain the resonant frequency corresponding to the magnetic field. This method is called frequency tracking and can improve efficiency. The closed-loop control algorithm used is, for example, the PID algorithm. When using the frequency sweep method, if there are errors in the demodulated data, it may lead to the absence of a zero-crossing point or an incorrect zero-crossing point in the demodulation curve, resulting in an incorrect resonant frequency. It should be noted that if multiple probes operating simultaneously have the same microwave frequency, the multiple probes will affect the fluorescence in terms of microwave power. Whether the superimposed power weakens or enhances is uncertain, which may also lead to errors in the obtained zero-crossing point. When using the PID algorithm for control, for each demodulated data, the slope of the curve segment where the zero-crossing point is located in the initial demodulation curve is usually used to calculate the microwave offset to be adjusted each time to calculate the new resonant frequency. If there are errors in the demodulated data, the calculated resonant frequency will be incorrect. In this embodiment, after the correct fluorescence signal is demodulated, the above errors can be reduced.

[0043] The controller 222 can be demodulated by programming, for example using FPGA programming, or it can be demodulated and transmitted to the microwave source by a quadrature digital lock-in amplifier.

[0044] The modulation frequency difference between the microwaves supplied to each pair of adjacent solid-state spin center detection modules is no less than 1 kHz, ensuring efficient low-pass filtering during demodulation and improving the signal-to-noise ratio. Furthermore, each modulation frequency is no greater than the maximum modulation frequency acceptable to the spin center, achieving optimal center response. The maximum modulation frequency can be determined experimentally; for example, the acceptable modulation frequency for diamond NV centers is 10-100 kHz.

[0045] Multiple optical fibers (fiber 3) are used, depending on the specific application requirements. It may also include, for example... Figure 1The insulator 4 shown includes an insulating channel for mounting the optical fiber 3, which makes the line connection between the high-voltage side and the low-voltage side safer and more reliable. The insulator can be made of ceramic, glass, or composite materials.

[0046] The front-end module also includes a photovoltaic cell 14, which receives laser energy from the back-end module 2 and converts the light energy into electrical energy to power the high-voltage side circuit. The laser module in the back-end module 2 supplies power to the photovoltaic cell 14, such as... Figure 3 As shown, the laser module includes two lasers. The first laser 25 is used to provide excitation laser to the high-voltage side, and the second laser 26 is used to provide power laser to the photovoltaic cell 14. The transmission method is fiber optic transmission.

[0047] Example 2: Based on Example 1, as follows Figure 5 As shown (exemplary example of a front-end module), this embodiment also includes an auxiliary magnetic sensor 15 in the front-end module 1 to sense the magnetic field generated by the high-voltage side current and output an auxiliary electrical signal. This auxiliary electrical signal includes a signal characterizing the magnetic field strength and a signal characterizing the magnetic field direction. A data acquisition module 16 and a digital optical emission module 17 are also included. The data acquisition module 16 acquires the auxiliary electrical signal, and the digital optical emission module 17 converts the auxiliary electrical signal into a digital optical signal for transmission to the low-voltage side. Multiple digital optical receiving modules 27, each corresponding to a digital optical emission module 17, are also included in the back-end module. These modules receive the digital optical signals transmitted by the digital optical emission modules 17, convert them into digital electrical signals, and transmit them to the control module 22. The control module 22 then reads the magnetic field strength and magnetic field direction signals. The auxiliary magnetic sensor 15 can be a magnetoresistive sensor, such as a tunnel magnetoresistive sensor (TMR), an anisotropic magnetoresistive sensor (AMR), or a giant magnetoresistive sensor (GMR).

[0048] On the one hand, when the back-end module tracks the resonant frequency using a closed-loop control algorithm, if an anomaly occurs in frequency tracking, the control module 22 can convert the magnetic field strength signal into the corresponding resonant frequency based on the relationship between the magnetic field strength signal measured by the auxiliary magnetic sensor 15 and the resonant frequency measured by the quantum probe 111. This resonant frequency is then used as the initial frequency for frequency tracking, and closed-loop control is executed to track the accurate resonant frequency corresponding to the external magnetic field. While the auxiliary magnetic sensor performs a rough measurement of the magnetic field and converts it into the resonant frequency of the quantum probe through calibration, this resonant frequency, although containing errors and not precise enough, can be used as the initial microwave frequency for frequency tracking to quickly and accurately lock onto the accurate resonant frequency corresponding to the external magnetic field, thereby calculating the precise magnetic field strength value.

[0049] On the other hand, the signal representing the direction of the magnetic field in the auxiliary electrical signal can supplement the determination of the magnetic field direction and reduce the complexity of direction measurement. In this embodiment, the number of auxiliary magnetic sensors 15 is the same as that of quantum probes 111, and they are placed in a one-to-one correspondence with quantum probes 111; preferably, the circumference of the auxiliary magnetic sensor is the same as the circumference of the corresponding quantum probe, so that the measured magnetic field magnitude is consistent; of course, the relationship between the magnetic field magnitudes of the two can also be determined by calibration on different circumferences.

[0050] The relationship between the magnetic field measurement value of the calibrated auxiliary magnetic sensor and the microwave resonant frequency measured by the solid-state spin center detection module is as follows: The external magnetic field strength is varied sequentially, and for each magnetic field strength, the magnetic field measurement value B measured by the auxiliary magnetic sensor is read. i And the microwave resonance frequency f along the axis of each specified color center obtained by ODMR measurement using a solid-state spin color center detection module. n1i f n2i For each color center axis, establish the magnetic field measurement value B. i With microwave resonant frequency f n1i The correspondence between them, and the magnetic field measurement value B i with f n2i The correspondence between them is given, where n refers to the nth color center axis, which is an integer from 1 to 4 depending on the specified color center axis; i refers to the i-th measurement value, which is an integer.

[0051] The aforementioned correspondence can be a fitting formula, such as f=aB+b, or a discrete mapping relationship. The resonant frequency corresponding to any magnetic field measurement value is then calculated using interpolation. The magnetic field measurement value can be an electrical signal value output by an auxiliary sensor, such as a voltage value, or a magnetic field strength value calculated based on the relationship between the electrical signal and the magnetic field strength.

[0052] The acquisition module 16 can use an analog-to-digital converter, such as... Figure 5 The first ADC in the system acquires the auxiliary electrical signal and converts it into a digital electrical signal. The digital optical transmitter module 17 and the digital optical receiver module 27 use existing digital optical transmitters and receivers to complete the electro-optical conversion.

[0053] To achieve further fluorescence noise reduction, in this embodiment, as follows Figure 5As shown, the detection module includes a fluorescence detection module, a laser detection module, and a differential circuit 1134. The fluorescence detection module includes a filter 1131, a first photodetector 1132, and a first voltage conversion circuit 1133. The laser detection module includes a second photodetector 1135 and a second voltage conversion circuit 1136. Furthermore, the laser transmitted from the first laser 25 to each solid-state spin center detection module 11 is split into two paths. One path is transmitted to the quantum probe 111, where the fluorescence detection module collects the fluorescence generated by the quantum probe and outputs a fluorescence electrical signal. The other path serves as a reference laser, transmitted to the second photodetector 1135 in the laser detection module, where it is converted into a laser electrical signal. The differential circuit 1134 receives the fluorescence and laser electrical signals, performs differential processing on them, and outputs the resulting differential electrical signal as the first analog electrical signal to the light emission module 12. Using differential electrical signals from fluorescence and co-source lasers reduces the influence of common-mode noise and improves the signal-to-noise ratio and accuracy of the measurement. The laser can be split using a beam splitter.

[0054] The photovoltaic cell 14 converts the laser energy transmitted from the low-voltage side into electrical energy, which is existing technology and can be implemented using existing products. The photovoltaic cell module supplies power to the high-voltage side circuits, including the differential circuit 1134, the optical emitting module 12, the optical microwave receiving module 13, the related circuits in the auxiliary magnetic sensor 15, the acquisition module 16, and the digital optical emitting module 17.

[0055] The acquisition module 16 is also used to acquire the laser electrical signal, the voltage signal, and the current signal of the photovoltaic cell output by the laser detection module. Figure 5 Multiple ADCs are provided as an example for sampling. A digital combining circuit 18 is also provided to combine the laser electrical signal, the photovoltaic cell voltage signal, the photovoltaic cell current signal, and the auxiliary electrical signal into a single digital electrical signal. This digital electrical signal is then converted into a digital optical signal by the digital optical transmitting module 17. After this digital optical signal is transmitted to the digital optical receiving module 27 and converted back into a digital electrical signal, the control module 22 can read the laser intensity signal, photovoltaic cell voltage signal, and photovoltaic cell current signal from the digital electrical signal to monitor whether there are any abnormalities in the laser intensity and photovoltaic cell power, facilitating real-time judgment of the operating status and ensuring the reliability of the measurement data. The digital combining circuit 18 can be a digital combining FPGA, and the photovoltaic cell 14 also supplies power to the digital combining circuit.

[0056] Example 3: This example provides a DC measurement method to reduce microwave interference, comprising: placing multiple quantum probes containing solid-state spin centers in the magnetic field generated by the current to be measured on the high-voltage side; transmitting laser light and modulated microwaves from the low-voltage side to the quantum probes on the high-voltage side, wherein the modulation frequency of the microwaves transmitted to each pair of quantum probes is different; collecting the fluorescence generated by the detection quantum probes to obtain a first analog electrical signal, converting it into an optical signal and transmitting it to the low-voltage side; performing photoelectric conversion on the low-voltage side to obtain a second analog electrical signal; demodulating the AC signal therein using a reference signal with a corresponding modulation frequency to obtain demodulated data; and calculating the magnetic field strength value and / or current value based on the demodulated data.

[0057] This embodiment can be applied to situations where multiple quantum probes are placed close together. By applying microwaves with different modulation frequencies to each probe and demodulating them with the corresponding modulation frequency, fluorescence interference caused by microwaves from nearby probes can be reduced, and the correct fluorescence can be demodulated to improve accuracy.

[0058] The method for calculating the current based on demodulated data in this embodiment can be found in the description in Embodiment 1. Furthermore, the method in this embodiment can also be implemented using the DC current measurement and sensing device for reducing microwave interference as described in Embodiment 1 or 2, which will not be elaborated here. Other related devices can also be used, as long as they can implement the method in this embodiment.

[0059] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can 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 those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A DC current measurement and sensing device for reducing microwave interference, characterized in that, The sensing device includes: multiple front-end modules located on the high-voltage side, a back-end module located on the low-voltage side, and an optical fiber for optical transmission between the high-voltage side and the low-voltage side. Each front-end module includes a solid-state spin center detection module, an optical emission module, and an optical microwave receiving module. Each solid-state spin center detection module is used to sense the magnetic field generated by the high-voltage side current, receive the laser transmitted from the back-end module, and receive the modulated microwave electrical signal transmitted from the optical microwave receiving module. It collects the fluorescence generated by the solid-state spin center under the action of laser, modulated microwave, and magnetic field, converts it into a first analog electrical signal, and outputs it to the optical emitting module. The optical emitting module converts the first analog electrical signal into an optical signal and transmits it to the back-end module. The optical microwave receiving module receives the optical modulated microwave signal from the back-end module, converts it into a modulated microwave electrical signal, and outputs it. The modulation frequency of the microwaves transmitted to each pair of solid-state spin center detection modules is different. The back-end module converts the optical signal into a second analog electrical signal, and demodulates the AC signal in it using a reference signal with a corresponding modulation frequency to obtain demodulated data. The magnetic field strength value and / or current value are calculated based on the demodulated data.

2. The DC current measurement and sensing device for reducing microwave interference according to claim 1, characterized in that: Each solid-state spin center detection module includes a quantum probe containing a solid-state spin center, a microwave antenna, and a detection module. The microwave antenna receives modulated microwave signals transmitted from the optical microwave receiving module and radiates them to the quantum probe. The quantum probe is also used to sense magnetic fields and receive laser irradiation. The detection module is used to collect and detect fluorescence and outputs a first analog electrical signal to the light emitting module.

3. The DC current measurement and sensing device for reducing microwave interference according to claim 2, characterized in that: The distance between any two adjacent quantum probes shall not exceed 10cm.

4. The DC current measurement and sensing device for reducing microwave interference according to claim 1, characterized in that: The modulation frequency difference of the microwaves transmitted to each of the two adjacent solid-state spin center detection modules is not less than 1 kHz, and each modulation frequency is not greater than the maximum modulation frequency that the spin center can accept.

5. The DC current measurement and sensing device for reducing microwave interference according to claim 1, characterized in that: Multiple solid-state spin color center detection modules are arranged at intervals on a circle with the center of the cross section of the conductor under test as the center, or located on one or both sides of the conductor under test.

6. The DC current measurement and sensing device for reducing microwave interference according to claim 1, characterized in that: The optical emission module converts the first analog electrical signal into an analog optical signal.

7. The DC current measurement and sensing device for reducing microwave interference according to claim 6, characterized in that: The optical emission module uses a laser and drives the laser with analog electrical signals to output corresponding analog optical signals.

8. The DC current measurement and sensing device for reducing microwave interference according to claim 1, characterized in that: Each front-end module also includes an auxiliary magnetic sensor, a data acquisition module, and a digital light emission module. The auxiliary magnetic sensor is used to sense the magnetic field generated by the high-voltage side current and output an auxiliary electrical signal. The acquisition module is used to acquire auxiliary electrical signals, and the digital optical transmission module converts the auxiliary electrical signals into digital optical signals for transmission to the back-end module.

9. The DC current measurement and sensing device for reducing microwave interference according to any one of claims 1-8, characterized in that: The backend module includes a laser module, multiple optical receiving modules corresponding to multiple optical emitting modules, multiple optical microwave emitting modules corresponding to multiple optical microwave receiving modules, a microwave source, and a control module. The laser module is used to deliver laser light to each solid-state spin center detection module. Each optical microwave emitting module is used to convert the modulated microwave electrical signal from the microwave source into an optical modulated microwave signal and output it. Each optical receiving module is used to receive the optical signal transmitted by the corresponding optical emitting module, perform photoelectric conversion on it, output a second analog electrical signal, and transmit it to the control module. The control module acquires the second analog electrical signal, demodulates the second analog electrical signal using a reference signal with a corresponding modulation frequency to obtain demodulated data, and then calculates the magnetic field strength and / or current value based on the demodulated data.

10. A method for reducing microwave interference in DC current measurement, characterized in that, The method includes: placing multiple quantum probes containing solid-state spin centers in the magnetic field generated by the current to be measured on the high-voltage side; transmitting laser light and modulated microwaves from the low-voltage side to the quantum probes on the high-voltage side, wherein the modulation frequency of the microwaves transmitted to each pair of quantum probes is different; collecting the fluorescence generated by the quantum probes to obtain a first analog electrical signal, converting it into an optical signal and transmitting it to the low-voltage side; performing photoelectric conversion on the low-voltage side to obtain a second analog electrical signal; demodulating the AC signal therein using a reference signal with a corresponding modulation frequency to obtain demodulated data; and calculating the magnetic field strength value and / or current value based on the demodulated data.

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