Micro-current detection system

Abstract

The invention relates to a micro-current detection system, which comprises a clamping current sampling unit, a current amplification conditioning unit, an analog-to-digital conversion unit and a controller, and is characterized in that the clamping current sampling unit comprises a plurality of clamping sampling circuits which are sequentially connected in series, and the first clamping sampling circuit and the last clamping sampling circuit are both used for being connected to a detected 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 a one-to-one correspondence manner; the analog-to-digital conversion unit comprises an analog-to-digital converter, and the analog-to-digital converter is electrically connected to all the differential amplification conditioning circuits; the controller is electrically connected to the analog-to-digital converter. According to the invention, real-time, precise, continuous and dynamic self-adaptive sampling can be carried out on the micro-current through the clamping current sampling unit, and the current amplification gain does not need to be adjusted by frequently switching a sampling resistor. Moreover, the collection noise can be effectively suppressed, and the signal-to-noise ratio is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sensor signal detection, and in particular to a micro-current detection system. Background Art

[0002] The measurement technology based on cold atom interference has extremely high measurement accuracy and long-term stability. In various cold atom precision measurement systems, physical measurement sensors such as photoelectric, magnetic field, vibration and vacuum are usually required to obtain atomic phase and its solution information, compensate for the influence of environmental factors, and monitor the operation status of equipment. These measurement sensors have high resolution and excellent accuracy, and the response bandwidth is above the kHz level. They usually output signals in the form of microcurrents; and in order to take into account both measurement accuracy and measurement range, the output current span of these measurement sensors is large, such as from as low as nA level to as high as mA level. Therefore, it is necessary to study a large-range, nA-level, high-precision, high-bandwidth microcurrent detection method.

[0003] Traditional micro-current detection methods are mainly divided into the following two categories: 1. Indirect detection method using current sensor. This method uses current transformer or Hall current sensor to detect current. It uses electromagnetic induction to make the current signal generate a magnetic field 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 for detecting large current applications, it has disadvantages such as low detection accuracy, inability to distinguish weak current signals, limited response bandwidth, large size and high cost.

[0004] Second, the direct detection method of resistance. This method is to connect 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 measurement with high detection accuracy, capable of detecting weak current signals, wide response bandwidth, high reliability, small size and low cost. Therefore, in situations where high-precision weak current detection is required, the direct detection method of resistance is often used. However, when detecting a large range of current signals ranging from nA level to mA level, the conventional method is to judge the actual current size, switch sampling resistors of different resistance values ​​in real time for sampling or adjust the gain of the amplifier circuit, so that the sampling and amplification conditioning loops are parameter-adapted. This not only brings about current shock, circuit noise and reduced signal-to-noise ratio, but also reduces the sampling rate, limits the sampling bandwidth, and cannot detect the dynamic current signal in the loop switching process in real time and accurately.

[0005] 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 take into account the requirements of current measurement accuracy, measurement range and response bandwidth, which restricts the application needs of photoelectric, magnetic field, vibration and vacuum detection in quantum precision measurement. Summary of the invention

[0006] Based on the above description, the present invention provides a micro-current detection system and method thereof, aiming to solve the problem that the existing indirect detection method and direct detection method cannot take into account the current measurement accuracy, measurement range and response bandwidth.

[0007] The technical solution of the present invention to solve the above technical problems is as follows: A micro-current detection system, comprising: A clamp current sampling unit, comprising a plurality of clamp sampling circuits connected in series, wherein the first clamp sampling circuit and the last clamp sampling circuit are both used to access the sensor under test, and the clamp sampling circuit is used to collect a first voltage signal of the sensor under test; A current amplification and conditioning unit, comprising a differential amplification and conditioning circuit, the number of the differential amplification and conditioning circuits is associated with the number of the clamp sampling circuits, the differential amplification and conditioning circuits are electrically connected to the clamp sampling circuits one by one, and the differential amplification and conditioning circuits are used to amplify the first voltage signal to obtain a second voltage signal; an analog-to-digital conversion unit, comprising an analog-to-digital converter, the analog-to-digital converter being electrically connected to all of the differential amplification and conditioning circuits, and the analog-to-digital converter being used to convert the second voltage signal into a digital voltage signal; A controller is electrically connected to the analog-to-digital converter, and is used to calculate the voltage of the sensor under test according to the digital voltage signal.

[0008] Based on the above technical solution, the present invention can also be improved as follows.

[0009] Furthermore, the clamp sampling circuit includes a sampling resistor and a voltage clamp sub-circuit, the voltage clamp sub-circuit includes a voltage stabilizing diode and a MOS tube, the input end of the voltage stabilizing diode and the gate of the MOS tube are electrically connected to one end of the sampling resistor, the drain of the MOS tube is electrically connected to the output end of the voltage stabilizing diode, and the source of the MOS tube is electrically connected to the other end of the sampling resistor; for all the clamp sampling circuits, the resistance values ​​of the sampling resistors from the first clamp sampling circuit to the last clamp sampling circuit increase in multiples.

[0010] Furthermore, the voltage clamping sub-circuit includes a conducting diode, and the conducting diode is connected in parallel between the drain and the source of the MOS tube.

[0011] Furthermore, the clamp current sampling unit comprises an operational amplifier, and the operational amplifier is connected in parallel between the first clamp sampling circuit and the last clamp sampling circuit.

[0012] Furthermore, the differential amplification and conditioning circuit includes a differential amplifier, and the differential amplifier is connected in parallel between two ends of the sampling resistor.

[0013] Furthermore, the differential amplification and conditioning circuit includes a differential amplifier, a low-pass filter and a voltage follower connected in series in sequence.

[0014] Furthermore, the analog-to-digital conversion unit includes a voltage reference source module, and the voltage reference source module is electrically connected to the analog-to-digital converter.

[0015] Furthermore, a digital isolator is included, and the digital isolator is connected in series between the analog-to-digital converter and the controller.

[0016] Furthermore, it includes a voltage-stabilized power supply, which is electrically connected to the current amplification and conditioning unit, the analog-to-digital converter and the controller.

[0017] Furthermore, the voltage-stabilized power supply comprises an isolation switch power supply, a power filter and an LDO power regulator which are sequentially connected in series.

[0018] Compared with the prior art, the technical solution of the present application has the following beneficial technical effects: the present application can perform real-time, precise, continuous and dynamic adaptive sampling of microcurrents through the clamped current sampling unit, without the need to frequently switch the sampling resistor to adjust the current amplification gain. It can also effectively suppress the acquisition noise and improve the signal-to-noise ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is an assembly diagram of a micro-current detection system and method provided in an embodiment of the present invention.

[0020] Description of reference numerals: 1. Clamp current sampling unit; 11. Clamp sampling circuit; 111. Sampling resistor; 112. Voltage clamp subcircuit; 1121. Zener diode; 1122. MOS tube; 1123. Conducting diode; 12. Operational amplifier; 2. Current amplification and conditioning unit; 21. Differential amplification and conditioning circuit; 211. Differential amplifier; 212. Low-pass filter; 213. Voltage follower; 3. Analog-to-digital conversion unit; 31. Analog-to-digital converter; 32. Voltage reference source module; 4. Controller; 5. Digital isolator; 6. Regulated power supply; 61. Isolating switch power supply; 62. Power filter; 63. LDO power regulator. DETAILED DESCRIPTION

[0021] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0023] It will be appreciated that spatial relationship terms such as "under," "beneath," "below," "under," "above," "above," etc., may be used herein to describe the relationship of an element or feature shown in the figures to other elements or features. It will be appreciated that, in addition to the orientations shown in the figures, spatial relationship terms also include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is flipped, an element or feature described as "under other elements" or "under it" or "under it" will be oriented as being "above" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. In addition, the device may also include additional orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptors used herein are interpreted accordingly.

[0024] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" etc. specify the presence of stated features, wholes, steps, operations, components, parts or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof.

[0025] Reference Figure 1As shown, the present invention provides a technical solution: a micro-current detection system, comprising a clamp current sampling unit 1, a current amplification and conditioning unit 2, an analog-to-digital conversion unit 3 and a controller 4, wherein the clamp current sampling unit 1 comprises a plurality of clamp sampling circuits 11 connected in series in sequence, wherein the first clamp sampling circuit 11 and the last clamp sampling circuit 11 are both used to access the sensor under test, and the clamp sampling circuit 11 is used to collect a first voltage signal of the sensor under test; the current amplification and conditioning unit 2 comprises a differential amplification and conditioning circuit 21, wherein the number of the differential amplification and conditioning circuits 21 is associated with the number of the clamp sampling circuits 11, and the differential amplification and conditioning circuits 21 are electrically connected to the clamp sampling circuits 11 one by one, and 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 comprises an analog-to-digital converter 31, wherein the analog-to-digital converter 31 is electrically connected to all the differential amplification and conditioning circuits 21, and 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, and the controller 4 is used to calculate the voltage of the sensor under test according to the digital voltage signal.

[0026] Exemplarily, the controller 4 may be an MCU single chip microcomputer, an FPGA controller 4 or a DSP digital controller 4, etc. The analog-to-digital converter 31 may be a Σ-Δ type analog-to-digital converter 31, etc.

[0027] In this embodiment, all clamp sampling circuits 11 sample microcurrents 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 the hardware circuit mode, and adaptive detection of high-precision and large-range microcurrents from nA level to mA level can be achieved. After the clamp sampling circuit 11 collects the first voltage signal, the differential amplifier and conditioning circuit 21 amplifies and conditions the first voltage signal to obtain a second voltage signal, that is, it is processed into a voltage range suitable for the analog-to-digital converter 31, so as to protect the analog-to-digital converter 31. Through the cooperation of the clamp current sampling unit 1, the current amplification and conditioning unit 2 and the analog-to-digital conversion unit 3, low sampling noise, high precision and large measurement range can be achieved, thereby improving the sampling rate and sampling bandwidth, and improving the reliability of the microcurrent detection system.

[0028] Reference Figure 1 As shown, in some embodiments, a control device is included, and the control device is electrically connected to the controller 4.

[0029] Exemplarily, the control device may be a touch screen or a computer.

[0030] In this embodiment, after the controller 4 obtains the voltage of the sensor under test, it can send the voltage to the control device for the operator to check and analyze. In addition, the control device can also communicate and interact with the controller 4 to control the controller 4.

[0031] Reference Figure 1 As shown, in some embodiments, the clamp sampling circuit 11 includes a sampling resistor 111 and a voltage clamp sub-circuit 112, the voltage clamp sub-circuit 112 includes a voltage zener diode 1121 and a MOS transistor 1122, the input end of the voltage zener diode 1121 and the gate of the MOS transistor 1122 are both electrically connected to one end of the sampling resistor 111, the drain of the MOS transistor 1122 is electrically connected to the output end of the voltage zener diode 1121, and the source of the MOS transistor 1122 is electrically connected to the other end of the sampling resistor 111; for all the clamp sampling circuits 11, the resistance values ​​of the sampling resistors 111 from the first clamp sampling circuit 11 to the last clamp sampling circuit 11 increase in multiples.

[0032] In this embodiment, since there is no operational amplifier 12, the clamp sampling circuit 11 is a passive sampling circuit. Since the resistance between the sampling resistors 111 increases exponentially, their current amplification gain for the sensor under test also increases exponentially. The voltage regulator diode 1121 clamps the voltage across the sampling resistor 111 to prevent the sampling voltage from being too large. And the MOS tube 1122 can prevent the voltage regulator diode 1121 from reducing the leakage current flowing through the voltage regulator diode 1121 when it is not turned on, thereby improving the accuracy of micro-current sampling. When the micro-current of the sensor under test is as small as nA level, 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 no detection is performed. When the micro-current increases to mA across orders of magnitude, the sampling resistor 111 with the smallest resistance converts and amplifies the micro-current signal into an appropriate first voltage signal; other sampling resistors 111 are not detected because the voltage across the two ends is too large and limited to the maximum clamping voltage. Therefore, no matter how the microcurrent changes from nA level to mA level, the clamp sampling circuit 11 can convert it into an appropriate first voltage signal, thereby achieving real-time and precise sampling of a wide range of microcurrents.

[0033] Reference Figure 1 As shown, in some embodiments, the voltage clamping sub-circuit 112 includes a conducting diode 1123 , which is connected in parallel between the drain and the source of the MOS transistor 1122 .

[0034] In this embodiment, by adding the conducting diode 1123, the conducting diode 1123 cooperates with the MOS transistor 1122 to prevent the Zener diode 1121 from further reducing the leakage current flowing through the Zener diode 1121 when the Zener diode 1121 is not conducting.

[0035] Reference Figure 1 As shown, in some embodiments, the clamp current sampling unit 1 includes an operational amplifier 12 , and the operational amplifier 12 is connected in parallel between the first clamp sampling circuit 11 and the last clamp sampling circuit 11 .

[0036] In this embodiment, during actual sampling, the operational amplifier 12 performs direct resistance sampling on the micro-current of the sensor under test, and converts it into multiple first voltage signals through multiple clamp sampling circuits 11. Thus, the clamp sampling circuit 11 can become an active sampling circuit to increase the load capacity of the clamp sampling circuit 11.

[0037] Reference Figure 1 As shown, in some embodiments, the differential amplifier conditioning circuit 21 includes a differential amplifier 212 , and the differential amplifier 212 is connected in parallel between two ends of the sampling resistor 111 .

[0038] In this embodiment, after the clamp sampling circuit 11 collects the first voltage signal, the differential amplifier 212 amplifies the first voltage signal to obtain a second voltage signal.

[0039] Reference Figure 1 As shown, in some other embodiments, the differential amplification and conditioning circuit 21 includes a differential amplifier 211, a low-pass filter 212 and a voltage follower 213 connected in series in sequence.

[0040] In this embodiment, after the clamp sampling circuit 11 collects the first voltage signal, the first voltage signal can be amplified, filtered and impedance transformed in sequence through the differential amplifier 211, the low-pass filter 212, and the voltage follower 213 to obtain a 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.

[0041] Reference Figure 1 As shown, in some embodiments, the analog-to-digital conversion unit 3 includes a voltage reference source module 32 , and the voltage reference source module 32 is electrically connected to the analog-to-digital converter 31 .

[0042] In this embodiment, during the analog-to-digital conversion of the analog-to-digital converter 31 , the voltage reference source module 32 provides a reference voltage to the analog-to-digital converter 31 , thereby greatly improving the accuracy and reducing the signal noise.

[0043] Reference Figure 1 As shown, in some embodiments, a digital isolator 5 is included, and the digital isolator 5 is connected in series between the analog-to-digital converter 31 and the controller 4 .

[0044] 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.

[0045] Reference Figure 1As shown, in some embodiments, a regulated power supply 6 is included, and the regulated power supply 6 is electrically connected to the current amplification and conditioning unit 2 , the analog-to-digital converter 31 and the controller 4 .

[0046] In this embodiment, the current amplification and conditioning unit 2 and the analog-to-digital converter 31 are powered by the voltage-stabilized power supply 6, so that the noise of the second voltage signal and the digital voltage signal can be reduced, and the possibility of being interfered by noise can be reduced.

[0047] 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 which are connected in series in sequence.

[0048] In this embodiment, the voltage stabilizer 6 converts the external input power into a multi-channel isolated low-ripple high-frequency switching power supply, and then filters the power noise through the power filter 62, and further suppresses the power noise interference through the LDO power regulator 63. After three-stage 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.

[0049] The above are only 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 in the protection scope of the present invention.

Claims

1. A micro-current detection system, characterized in that: include: A clamp current sampling unit (1) comprises a plurality of clamp sampling circuits (11) connected in series, wherein the first clamp sampling circuit (11) and the last clamp sampling circuit (11) are both used to connect to a sensor under test, and the clamp sampling circuit (11) is used to collect a first voltage signal of the sensor under test; A current amplifying and conditioning unit (2), comprising a differential amplifying and conditioning circuit (21), the number of the differential amplifying and conditioning circuits (21) being associated with the number of the clamping sampling circuits (11), the differential amplifying and conditioning circuits (21) being electrically connected to the clamping sampling circuits (11) in a one-to-one correspondence, and the differential amplifying and conditioning circuits (21) being used to amplify the first voltage signal to obtain a second voltage signal; An analog-to-digital conversion unit (3), comprising an analog-to-digital converter (31), wherein the analog-to-digital converter (31) is electrically connected to all of the differential amplification and conditioning circuits (21), and the analog-to-digital converter (31) is used to convert the second voltage signal into a digital voltage signal; A controller (4) is electrically connected to the analog-to-digital converter (31), and the controller (4) is used to calculate the voltage of the sensor under test according to the digital voltage signal.

2. A micro-current detection system according to claim 1, characterized in that: The clamp sampling circuit (11) comprises a sampling resistor (111) and a voltage clamp sub-circuit (112); the voltage clamp sub-circuit (112) comprises a voltage stabilizing diode (1121) and a MOS transistor (1122); the input end of the voltage stabilizing diode (1121) and the gate of the MOS transistor (1122) are both electrically connected to one end of the sampling resistor (111); the drain of the MOS transistor (1122) is electrically connected to the output end of the voltage stabilizing diode (1121); and the source of the MOS transistor (1122) is electrically connected to the other end of the sampling resistor (111); for all the clamp sampling circuits (11), the resistance values ​​of the sampling resistors (111) from the first clamp sampling circuit (11) to the last clamp sampling circuit (11) are increased in multiples.

3. A micro-current detection system according to claim 2, characterized in that: The voltage clamping subcircuit (112) comprises a conducting diode (1123), and the conducting diode (1123) is connected in parallel between the drain and the source of the MOS tube (1122).

4. A micro-current detection system according to claim 3, characterized in that: The clamp current sampling unit (1) comprises an operational amplifier (12), wherein the operational amplifier (12) is connected in parallel between the first clamp sampling circuit (11) and the last clamp sampling circuit (11).

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

6. A micro-current detection system according to claim 2, characterized in that: The differential amplification and conditioning circuit (21) comprises a differential amplifier (211), a low-pass filter (212), and a voltage follower (213) which are sequentially connected in series.

7. A micro-current detection system according to claim 6, characterized in that: The analog-to-digital conversion unit (3) comprises a voltage reference source module (32), and the voltage reference source module (32) is electrically connected to the analog-to-digital converter (31).

8. A micro-current detection system according to any one of claims 5 to 7, characterized in that: It comprises a digital isolator (5), wherein the digital isolator (5) is connected in series between the analog-to-digital converter (31) and the controller (4).

9. A micro-current detection system according to any one of claims 1 to 7, characterized in that: It comprises a voltage-stabilized power supply (6), wherein the voltage-stabilized power supply (6) is electrically connected to the current amplification and conditioning unit (2), the analog-to-digital converter (31) and the controller (4).

10. A micro-current detection system according to claim 9, characterized in that: The voltage-stabilized power supply (6) comprises an isolation switch power supply (61), a power filter (62) and an LDO power supply stabilizer (63) which are sequentially connected in series.

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