A micro-current detection system

Abstract

The application relates to a micro-current detection system, which comprises a clamping current sampling unit, a current amplification conditioning unit, an analog-digital conversion unit and a controller, the clamping current sampling unit comprises a plurality of clamping sampling circuits connected in series, the first clamping sampling circuit and the last clamping sampling circuit are both used for connecting a measured sensor; the current amplification conditioning unit comprises differential amplification conditioning circuits, the number of the differential amplification conditioning circuits is associated with the number of the clamping sampling circuits, and the differential amplification conditioning circuits are electrically connected to the clamping sampling circuits in one-to-one correspondence; the analog-digital conversion unit comprises an analog-digital converter, the analog-digital converter is electrically connected to all the differential amplification conditioning circuits; and the controller is electrically connected to the analog-digital converter. The clamping current sampling unit can realize real-time, precise and continuous dynamic adaptive sampling of micro-current, and the current amplification gain does not need to be adjusted by frequently switching sampling resistors. Moreover, the system can effectively suppress acquisition noise and improve the signal-to-noise ratio.

Description

Technical Field

[0001] This invention relates to the field of sensor signal detection technology, and more specifically to a microcurrent detection system. Background Technology

[0002] Cold atom interferometry-based measurement techniques offer extremely high measurement accuracy and long-term stability. Various cold atom precision measurement systems typically employ physical measurement sensors such as photoelectric, magnetic field, vibration, and vacuum sensors to acquire atomic phase and solution information, compensate for environmental influences, and monitor equipment operation. These sensors boast high resolution, excellent accuracy, and response bandwidths exceeding the kHz level. They typically output signals in the form of microcurrents; moreover, to balance measurement accuracy and range, the output current of these sensors spans a wide range, from as low as nA to as high as mA. Therefore, there is a need to research large-range, nA-level, high-precision, and high-bandwidth microcurrent detection methods.

[0003] Traditional microcurrent detection methods can be mainly divided into the following two categories:

[0004] I. Indirect detection method using current sensors: This method uses current transformers or Hall current sensors to detect current. It uses electromagnetic induction to generate a magnetic field signal from the current signal, which is then converted into an electrical signal for detection. Although this type of current sensor is non-contact measurement, easy to install and maintain, and can be used in applications that detect large currents, it has disadvantages such as low detection accuracy, inability to distinguish weak current signals, limited response bandwidth, large size, and high cost.

[0005] II. Direct Resistance Detection Method: This method involves connecting a precision sampling resistor in series in the current loop to convert the current signal into a voltage signal, thereby directly detecting the current signal. This type of current sensor is a contact-type measurement, offering high detection accuracy, the ability to detect weak current signals, a wide response bandwidth, high reliability, small size, and low cost. Therefore, the direct resistance detection method is often used in applications requiring high-precision weak current detection. However, when detecting large-range current signals ranging from nA to mA, the conventional approach involves judging the actual current magnitude and switching sampling resistors with different resistance values ​​in real time for sampling or adjusting the gain of the amplifier circuit to match the parameters of the sampling and amplification conditioning loop. This not only introduces problems such as current surges, circuit noise, and reduced signal-to-noise ratio, but also reduces the sampling rate, limits the sampling bandwidth, and cannot accurately detect dynamic current signals during loop switching in real time.

[0006] Therefore, it can be seen from the above two micro-current detection methods that neither the indirect detection method nor the direct detection method can meet the requirements of current measurement accuracy, measurement range and response bandwidth, which restricts the application needs of photoelectric, magnetic field, vibration and vacuum degree detection in quantum precision measurement. Summary of the Invention

[0007] Based on the above description, the present invention provides a microcurrent detection system and method, which aims to solve the problem that existing indirect detection methods and direct detection methods cannot simultaneously achieve current measurement accuracy, measurement range and response bandwidth.

[0008] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0009] A microcurrent detection system, comprising:

[0010] The clamping current sampling unit includes multiple clamping sampling circuits connected in series. The first and last clamping sampling circuits are both used to connect to the sensor under test. The clamping sampling circuit is used to acquire the first voltage signal of the sensor under test.

[0011] The current amplification and conditioning unit includes a differential amplification and conditioning circuit. The number of the differential amplification and conditioning circuits is related to the number of the clamping sampling circuits. The differential amplification and conditioning circuits are electrically connected to the clamping sampling circuits in a one-to-one correspondence. The differential amplification and conditioning circuits are used to amplify the first voltage signal to obtain a second voltage signal.

[0012] An analog-to-digital conversion unit includes an analog-to-digital converter electrically connected to all of the differential amplifier conditioning circuits, the analog-to-digital converter being used to convert the second voltage signal into a digital voltage signal;

[0013] A controller, electrically connected to the analog-to-digital converter, is used to calculate the voltage of the sensor under test based on the digital voltage signal.

[0014] Based on the above technical solution, the present invention can be further improved as follows.

[0015] Furthermore, the clamping sampling circuit includes a sampling resistor and a voltage clamping sub-circuit. The voltage clamping sub-circuit includes a Zener diode and a MOSFET. The input terminal of the Zener diode and the gate of the MOSFET are both electrically connected to one end of the sampling resistor. The drain of the MOSFET is electrically connected to the output terminal of the Zener diode, and the source of the MOSFET is electrically connected to the other end of the sampling resistor. For all clamping sampling circuits, the resistance values ​​of the sampling resistors from the first clamping sampling circuit to the last clamping sampling circuit increase exponentially.

[0016] Furthermore, the voltage clamping sub-circuit includes a conducting diode, which is connected in parallel between the drain and source of the MOS transistor.

[0017] Furthermore, the clamping current sampling unit includes an operational amplifier, which is connected in parallel between the first clamping sampling circuit and the last clamping sampling circuit.

[0018] Furthermore, the differential amplifier conditioning circuit includes a differential amplifier connected in parallel between the two ends of the sampling resistor.

[0019] Furthermore, the differential amplifier conditioning circuit includes a differential amplifier, a low-pass filter, and a voltage follower connected in series.

[0020] Furthermore, the analog-to-digital conversion unit includes a voltage reference source module, which is electrically connected to the analog-to-digital converter.

[0021] Furthermore, it includes a digital isolator connected in series between the analog-to-digital converter and the controller.

[0022] Furthermore, it includes a regulated power supply, which is electrically connected to the current amplification and conditioning unit, the analog-to-digital converter, and the controller.

[0023] Furthermore, the regulated power supply includes an isolated switching power supply, a power filter, and an LDO power regulator connected in series.

[0024] Compared with the prior art, the technical solution of this application has the following beneficial technical effects: This application can perform real-time, precise, and continuous dynamic adaptive sampling of micro-currents through a clamping current sampling unit, without the need to frequently switch the sampling resistor to adjust the current amplification gain. Furthermore, it can effectively suppress acquisition noise and improve the signal-to-noise ratio. Attached Figure Description

[0025] Figure 1 This is an assembly drawing of a microcurrent detection system and method provided in an embodiment of the present invention.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1. Clamping current sampling unit; 11. Clamping sampling circuit; 111. Sampling resistor; 112. Voltage clamping sub-circuit; 1121. Zener diode; 1122. MOSFET; 1123. Turn-on diode; 12. Operational amplifier;

[0028] 2. Current amplification and conditioning unit; 21. Differential amplification and conditioning circuit; 211. Differential amplifier; 212. Low-pass filter; 213. Voltage follower;

[0029] 3. Analog-to-digital conversion unit; 31. Analog-to-digital converter; 32. Voltage reference source module;

[0030] 4. Controller;

[0031] 5. Digital isolators;

[0032] 6. Regulated power supply; 61. Isolation switching power supply; 62. Power filter; 63. LDO power regulator. Detailed Implementation

[0033] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0035] It is understood that spatial relation terms such as "below," "under," "below," "below," "above," "above," etc., can be used here to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, the element or feature described as "below" or "below" of the other element or feature will be oriented "above" the other element or feature. Therefore, the exemplary terms "below" and "below" can include both upper and lower orientations. Furthermore, the device may also include other orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptive terms used herein will be interpreted accordingly.

[0036] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” “including,” or “having,” etc., specify the presence of the stated feature, whole, step, operation, component, part, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof.

[0037] Reference Figure 1As shown, the present invention provides a technical solution: a micro-current detection system, including a clamping current sampling unit 1, a current amplification and conditioning unit 2, an analog-to-digital conversion unit 3, and a controller 4. The clamping current sampling unit 1 includes multiple clamping sampling circuits 11 connected in series. The first and last clamping sampling circuits 11 are both used to connect to the sensor under test, and the clamping sampling circuits 11 are used to acquire the first voltage signal of the sensor under test. The current amplification and conditioning unit 2 includes differential amplification and conditioning circuits 21. The number of differential amplification and conditioning circuits 21 is related to the number of clamping sampling circuits 11. The differential amplification and conditioning circuits 21 are electrically connected to the clamping sampling circuits 11 in a one-to-one correspondence. The differential amplification and conditioning circuits 21 are used to amplify the first voltage signal to obtain a second voltage signal. The analog-to-digital conversion unit 3 includes an analog-to-digital converter 31. The analog-to-digital converter 31 is electrically connected to all the differential amplification and conditioning circuits 21. The analog-to-digital converter 31 is used to convert the second voltage signal into a digital voltage signal. The controller 4 is electrically connected to the analog-to-digital converter 31. The controller 4 is used to calculate the voltage of the sensor under test based on the digital voltage signal.

[0038] For example, controller 4 can be an MCU microcontroller, FPGA controller 4, or DSP digital controller 4, etc. Analog-to-digital converter 31 can be a Σ-Δ type analog-to-digital converter 31, etc.

[0039] In this embodiment, all clamping sampling circuits 11 sample the microcurrent in real time and continuously, and can reduce their own noise to improve the signal-to-noise ratio. Therefore, there is no need to adjust the current amplification gain by switching hardware circuits, enabling adaptive detection of high-precision, large-range microcurrents from the nA to mA level. After the clamping sampling circuit 11 acquires the first voltage signal, the differential amplification and conditioning circuit 21 amplifies and conditions the first voltage signal to obtain the second voltage signal, i.e., processes it into a voltage range suitable for the analog-to-digital converter 31, thus protecting the analog-to-digital converter 31. Through the cooperation of the clamping current sampling unit 1, the current amplification and conditioning unit 2, and the analog-to-digital conversion unit 3, low sampling noise, high accuracy, and a large measurement range can be achieved, thereby improving the sampling rate and sampling bandwidth, and enhancing the reliability of the microcurrent detection system.

[0040] Reference Figure 1 As shown, in some embodiments, a control device is included, which is electrically connected to the controller 4.

[0041] For example, the control device can be a touch screen or a computer, etc.

[0042] In this embodiment, after obtaining the voltage of the sensor under test, the controller 4 can send the voltage to the control device for the operator to view and analyze. Alternatively, the control device can communicate and interact with the controller 4 to control the controller 4.

[0043] Reference Figure 1 As shown, in some embodiments, the clamping sampling circuit 11 includes a sampling resistor 111 and a voltage clamping sub-circuit 112. The voltage clamping sub-circuit 112 includes a Zener diode 1121 and a MOSFET 1122. The input terminal of the Zener diode 1121 and the gate of the MOSFET 1122 are both electrically connected to one end of the sampling resistor 111. The drain of the MOSFET 1122 is electrically connected to the output terminal of the Zener diode 1121, and the source of the MOSFET 1122 is electrically connected to the other end of the sampling resistor 111. For all clamping sampling circuits 11, the resistance values ​​of the sampling resistor 111 of the first clamping sampling circuit 11 to the sampling resistor 111 of the last clamping sampling circuit 11 increase exponentially.

[0044] In this embodiment, since there is no operational amplifier 12, the clamping sampling circuit 11 is a passive sampling circuit. Because the resistance values ​​of the sampling resistors 111 increase exponentially, their current amplification gain for the sensor under test also increases exponentially. The Zener diode 1121 clamps the voltage across the sampling resistors 111 to prevent excessive sampling voltage. Furthermore, the MOSFET 1122 prevents the Zener diode 1121 from reducing leakage current when it is not conducting, thereby improving the accuracy of micro-current sampling. When the micro-current of the sensor under test is as small as nA, the sampling resistor 111 with the largest resistance converts and amplifies the micro-current into an appropriate first voltage signal; at this time, the voltage across the other sampling resistors 111 is very small, so they are not detected. When the micro-current increases by orders of magnitude to mA, the sampling resistor 111 with the smallest resistance converts and amplifies the micro-current signal into an appropriate first voltage signal; the other sampling resistors 111, due to excessively large voltages across them and limited to the maximum clamping voltage, are also not detected. Therefore, regardless of how the microcurrent changes from nA to mA, the clamping sampling circuit 11 can convert it into an appropriate first voltage signal, thereby realizing real-time and precise sampling of a wide range of microcurrents.

[0045] Reference Figure 1 As shown, in some embodiments, the voltage clamping sub-circuit 112 includes a pass diode 1123 connected in parallel between the drain and source of the MOSFET 1122.

[0046] In this embodiment, by adding a conducting diode 1123, the conducting diode 1123 can cooperate with the MOSFET 1122 to prevent the Zener diode 1121 from further reducing the leakage current flowing through the Zener diode 1121 when it is not conducting.

[0047] Reference Figure 1 As shown, in some embodiments, the clamping current sampling unit 1 includes an operational amplifier 12, which is connected in parallel between the first clamping sampling circuit 11 and the last clamping sampling circuit 11.

[0048] In this embodiment, during actual sampling, the operational amplifier 12 performs direct resistive sampling of the micro-current of the sensor under test, and converts it into multiple first voltage signals through multiple clamping sampling circuits 11. This allows the clamping sampling circuits 11 to become active sampling circuits, thereby increasing their load-carrying capacity.

[0049] Reference Figure 1 As shown, in some embodiments, the differential amplifier conditioning circuit 21 includes a differential amplifier 212, which is connected in parallel between the two ends of the sampling resistor 111.

[0050] In this embodiment, after the clamp sampling circuit 11 acquires the first voltage signal, the second voltage signal can be obtained by amplifying the first voltage signal through the differential amplifier 212.

[0051] Reference Figure 1 As shown, in some other embodiments, the differential amplifier conditioning circuit 21 includes a differential amplifier 211, a low-pass filter 212, and a voltage follower 213 connected in series.

[0052] In this embodiment, after the clamping sampling circuit 11 acquires the first voltage signal, it can sequentially amplify, filter and impedance transform the first voltage signal through the differential amplifier 211, the low-pass filter 212 and the voltage follower 213 to obtain the second voltage signal, so that the voltage of the second voltage signal is within the voltage range suitable for the analog-to-digital converter 31.

[0053] Reference Figure 1 As shown, in some embodiments, the analog-to-digital conversion unit 3 includes a voltage reference source module 32, which is electrically connected to the analog-to-digital converter 31.

[0054] In this embodiment, during analog-to-digital conversion, the voltage reference source module 32 provides a reference voltage to the analog-to-digital converter 31, thereby greatly improving accuracy and reducing signal noise.

[0055] Reference Figure 1 As shown, in some embodiments, a digital isolator 5 is included, which is connected in series between the analog-to-digital converter 31 and the controller 4.

[0056] In this embodiment, the digital isolator 5 can not only electrically isolate the second voltage signal from the digital voltage signal to prevent the second voltage signal from interfering with the digital voltage signal, but also digitally filter the digital voltage signal to extract the effective digital voltage signal, thereby ensuring that the controller 4 can calculate the accurate voltage.

[0057] Reference Figure 1As shown, in some embodiments, a regulated power supply 6 is included, which is electrically connected to the current amplification and conditioning unit 2, the analog-to-digital converter 31, and the controller 4.

[0058] In this embodiment, the current amplification and conditioning unit 2 and the analog-to-digital converter 31 are powered by the regulated power supply 6, which can reduce the noise of the second voltage signal and the digital voltage signal and reduce the possibility of noise interference.

[0059] Reference Figure 1 As shown, in some embodiments, the regulated power supply 6 includes an isolated switching power supply 61, a power filter 62, and an LDO power regulator 63 connected in series.

[0060] In this embodiment, the regulated power supply 6 converts the external input power into a multi-channel isolated, low-ripple, high-frequency switching power supply. Power supply noise is then filtered out by the power filter 62, and further suppressed by the LDO power regulator 63. After three stages of power conversion and filtering, the low-noise linear power supply required by the current amplification and conditioning unit 2, the analog-to-digital converter 31, and the controller 4 is obtained.

[0061] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A micro-current detection system, characterized by, The application relates to a current sampling unit (1) comprising a plurality of clamping sampling circuits (11) connected in series, a first clamping sampling circuit (11) and a last clamping sampling circuit (11) are used for connecting a sensor to be measured, and the clamping sampling circuit (11) is used for collecting a first voltage signal of the sensor to be measured; the clamping sampling circuit (11) comprises a sampling resistor (111) and a voltage clamping sub-circuit (112), the voltage clamping sub-circuit (112) comprises a voltage stabilizing diode (1121) and a MOS tube (1122), an input end of the voltage stabilizing diode (1121) and a gate of the MOS tube (1122) are electrically connected to one end of the sampling resistor (111), a drain of the MOS tube (1122) is electrically connected to an output end of the voltage stabilizing diode (1121), and a source of the MOS tube (1122) is electrically connected to the other end of the sampling resistor (111); for all the clamping sampling circuits (11), the resistance values of the sampling resistors (111) of the first clamping sampling circuit (11) to the last clamping sampling circuit (11) are in a multiple increasing mode. The application further relates to a current amplification conditioning unit (2) comprising a plurality of differential amplification conditioning circuits (21), the number of the differential amplification conditioning circuits (21) is associated with the number of the clamping sampling circuits (11), the differential amplification conditioning circuits (21) are electrically connected to the clamping sampling circuits (11) in a one-to-one correspondence, and the differential amplification conditioning circuits (21) are used for amplifying the first voltage signal to obtain a second voltage signal. The application further relates to an analog-digital conversion unit (3) comprising an analog-digital converter (31), the analog-digital converter (31) is electrically connected to all the differential amplification conditioning circuits (21), and the analog-digital converter (31) is used for converting the second voltage signal into a digital voltage signal. The application further relates to a controller (4) electrically connected to the analog-digital converter (31), and the controller (4) is used for calculating the voltage of the sensor to be measured according to the digital voltage signal. The voltage clamping sub-circuit (112) comprises a conducting diode (1123) connected in parallel between the drain and the source of the MOS tube (1122).

2. The micro-current detection system of claim 1, wherein, The current sampling unit (1) comprises an operational amplifier (12) connected in parallel between the first clamping sampling circuit (11) and the last clamping sampling circuit (11).

3. A micro-current detection system according to claim 2, wherein, The differential amplification conditioning circuit (21) comprises a differential amplifier (212) connected in parallel between the two ends of the sampling resistor (111).

4. The micro-current detection system of claim 1, wherein, The differential amplification conditioning circuit (21) comprises a differential amplifier (211), a low-pass filter (212) and a voltage follower (213) connected in series.

5. The micro-current detection system of claim 1, wherein, The analog-digital conversion unit (3) comprises a voltage reference source module (32) electrically connected to the analog-digital converter (31).

6. A micro-current detection system according to claim 5, wherein, ​ 7. A micro-current detection system according to any one of claims 4 to 6, wherein, The digital isolator (5) is connected in series between the analog-to-digital converter (31) and the controller (4).

8. A micro-current detection system according to any one of claims 1 to 6, wherein, The voltage stabilizing power supply (6) is electrically connected to the current amplification conditioning unit (2), the analog-to-digital converter (31) and the controller (4).

9. A micro-current detection system according to claim 8, wherein, The voltage stabilizing power supply (6) comprises an isolation power supply (61), a power filter (62) and an LDO power stabilizer (63) connected in series.

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