Multi-gear current measuring device and method based on TVS (Transient Voltage Suppressor) multi-path impedance

Abstract

The invention relates to the technical field of current measurement, and provides a multi-gear current measurement device and method based on TVS (Transient Voltage Suppressor) multi-path impedance, the multi-gear current measurement device is formed by connecting a plurality of TVS connected in series with a corresponding impedance network in parallel, a wide current measurement range is realized on the premise of ensuring the measurement precision, and the measurement accuracy is improved. Therefore, the problem of narrow measurement range caused by limitation of a protection circuit and detection impedance in the prior art is effectively solved. A proper measurement gear can be automatically selected according to an input signal, so that a high-precision measurement result can be kept under different current conditions, when the current is increased to the degree that a circuit is possibly damaged, a corresponding TVS tube acts, an output voltage signal is reduced by changing the impedance value of the current, and the measurement accuracy is improved. Or the input current is directly grounded under extreme conditions, so that the circuit is protected from being influenced by overcurrent.

Description

Technical Field

[0001] The present invention relates to the technical field of current measurement, and in particular to a multi-level current measurement device and method based on TVS tube multi-path impedance. Background Art

[0002] In modern society, daily life, industrial production and scientific research, accurate measurement of current is one of the key links to ensure safe operation of equipment, improve process quality and promote technological progress. In order to achieve high-precision current measurement, current comparators are traditionally relied on. Current comparators are based on the principle of electromagnetic balance and have extremely high measurement accuracy. However, current comparators are expensive, bulky, complex to operate, and require high maintenance. They are subject to many restrictions in practical applications and are difficult to be widely popularized.

[0003] Other current measurement technologies in the prior art have problems such as small measurement range, low accuracy in measuring small currents, and potential overcurrent hazards. On the one hand, the protection circuit and detection impedance of the current measurement circuit in the prior art have corresponding action values ​​or characteristic ranges, which are subject to the performance and parameters of the original components and have limited applicable measurement ranges; on the other hand, there are application scenarios where it is difficult to predict the measured current value. If the parameters of the measurement circuit used are improperly set, it is difficult to ensure measurement accuracy when the current on the line is very small due to the small potential difference, and the measurement circuit may be burned out when the current on the line is very large due to the large potential difference.

[0004] In summary, the existing current measurement technology has deficiencies in measurement accuracy, range and safety of use. It is necessary to propose a multi-level current measurement device with high accuracy based on the multi-path impedance of the TVS tube. Summary of the invention

[0005] The purpose of the present invention is to solve the deficiencies of the prior art and provide a multi-level current measuring device based on the multi-path impedance of a TVS tube to improve the measurement accuracy, range and safety of use.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A multi-level current measurement device based on TVS tube multi-path impedance, comprising: a signal acquisition module, a multi-level current measurement module and a control processing module;

[0008] The signal acquisition module uses an active differential probe to directly connect to the current source to be measured, and is used to collect the current signal of the current source, and transmit the differential voltage signal after the signal is amplified and optimized to the multi-speed current measurement module;

[0009] The input end of the multi-speed current measurement module is electrically connected to the output end of the signal acquisition module, and the output end of the multi-speed current measurement module is electrically connected to the input end of the control processing module. The multi-speed current measurement module is composed of multiple TVS tubes connected in series and corresponding impedance networks in parallel. The end of the last TVS tube is grounded. The voltage signal of each stage of the TVS tube is input into the control processing module through the signal line. The multi-speed current measurement module is used to dynamically select the conduction state of the appropriate TVS tube according to the size of the input differential voltage signal, and transmit the measured analog voltage signal to the control processing module, so as to realize the measurement of currents of different sizes using different gears, and realize overcurrent protection at the same time;

[0010] The control processing module adopts a single chip microcomputer to control a multi-speed current measurement module, which is used to read the on / off state of the TVS tube, perform signal processing, measure the output voltage, and calculate the output current value.

[0011] Preferably, in the multi-speed current measuring device, when the current is small, no TVS tube is activated, and the current signal can form an output voltage signal through all impedances; when the current increases, the lowest-level TVS tube is activated, the impedance value through which the current passes decreases, and the output voltage signal is also relatively reduced; the end of the last-level TVS tube is grounded, and when the current value is greater than the action current of the highest-level TVS tube, all TVS tubes are activated, the input current is directly connected to the ground, and the output voltage is 0, so as to ensure that the current signal is within a safe range, thereby achieving overcurrent protection.

[0012] Preferably, the multi-stage current measurement module is connected in series in n stages, wherein the first stage TVS tube is TVS1, the breakdown voltage is U1, TVS1 is connected in parallel with the resistor R1, and the i-th stage TVS tube is TVS i , the breakdown voltage is U i , TVS i With resistor R i In parallel, the nth TVS tube is TVS n , the breakdown voltage is U n , TVS n With resistor R n In parallel, the operating current of each level of TVS tube is given by the following formula:

[0013]

[0014] Among them, 0 <I1<I2……<I i … n , I n This is the maximum current value that the circuit can measure, I i is the operating current of the i-th TVS tube, U i is the breakdown voltage of the i-th TVS tube, R i is the resistance value connected in parallel with the i-th TVS tube.​

[0015] Preferably, the control processing unit comprises: an analog-to-digital conversion module, a state monitoring module, a main operation module, a data output module and a data storage module;

[0016] The analog-to-digital conversion module is used to obtain the analog voltage signal from the multi-speed current measurement module and convert it into a digital signal, and at the same time input the numerical signal into the main operation module;

[0017] The status monitoring module is used to monitor the conduction status of the TVS tubes at each gear in real time and input the conduction status signal of the TVS tubes into the main operation module;

[0018] The main operation module combines the input data of the status monitoring module and the analog-to-digital conversion module to calculate and measure the current value;

[0019] The data output module outputs the actual current data output by the main operation module to the display module through the serial port, I2C or other interfaces;

[0020] Data storage module, used to store measurement configuration and historical data.

[0021] Preferably, the control processing unit monitors the conduction state of the TVS tubes at each gear in real time by measuring the voltage across each TVS tube through the state monitoring module, and informs the main operation module through the output signal IO that the number of TVS tubes that have not been operated is m (0≤m≤n). The main operation module calculates the current value I according to the total voltage value U output by the analog-to-digital conversion module, and the calculation formula is:

[0022]

[0023] Among them, U is the total voltage value measured, R i is the resistance value of the i-th TVS tube in parallel.

[0024] Preferably, the multi-speed current measurement module includes at least three stages of TVS tubes connected in series and corresponding impedance networks connected in parallel to form three current measurement gears.

[0025] Preferably, in the multi-speed current measurement module, the first-stage TVS tube is TVS1, the breakdown voltage is 10V, and it is connected in parallel with the resistor R1; the second-stage TVS tube is TVS2, the breakdown voltage is 10V, and it is connected in parallel with the resistor R2; the third-stage TVS tube is TVS3, the breakdown voltage is 10V, and it is connected in parallel with the resistor R3 to form a small current measurement path; the resistance of R1 is 10kΩ, the resistance of R2 is 100Ω, and the resistance of R3 is 1Ω.

[0026] Preferably, the signal acquisition module adopts Pico TA041 active differential probe.

[0027] Preferably, the control processing unit adopts a STM32F103C8T6 single chip microcomputer.

[0028] Another object of the present invention is to provide a method for current measurement using the multi-stage current measurement device based on TVS tube multi-path impedance, comprising the following steps:

[0029] S1. Connect the input terminal of the signal acquisition module to the current measured point;

[0030] S2, connecting the output end of the control processing unit to the display module or the data recording device;

[0031] S3, energize the current point to be measured, and start signal acquisition and processing;

[0032] S4, the control processing module calculates and measures the current value through the signals input by the analog-to-digital conversion module and the status monitoring module;

[0033] S4.1, the control processing module reads the monitoring result of the state monitoring module, obtains the conduction state of the TVS tube, thereby obtains the m value in the current value calculation formula, and calls the resistance value of the m resistors connected in parallel with the unactuated TVS tube;

[0034] S4.2, substituting the voltage value data input by the analog-to-digital conversion module and the resistance values ​​of the m resistors into the calculation formula to calculate the measured current value;

[0035] S4.3, input the measured current value into the data output module and the data storage module;

[0036] S5. Output the calculated current value to the display module through the data output module, or transmit it to an external device through other interfaces.

[0037] The present invention discloses a multi-level current measuring device based on TVS tube multi-path impedance, which has the following beneficial effects.

[0038] First, the present invention forms a multi-level current measurement device by using multiple series-connected transient suppression diodes (TVS tubes) and corresponding impedance networks in parallel, which achieves a wide current measurement range while ensuring measurement accuracy, thereby effectively solving the problem of narrow measurement range caused by the limitation of protection circuits and detection impedance in traditional technologies. And it can automatically select the appropriate measurement level according to the input signal, so as to maintain high-precision measurement results under different current conditions.

[0039] Secondly, when the current increases to a level that may damage the circuit, the corresponding TVS tube will be activated to reduce the output voltage signal by changing the impedance value through which the current passes, or in extreme cases directly connect the input current to ground, thereby protecting the circuit from the influence of overcurrent. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a structural schematic diagram of a multi-level current measuring device based on multi-path impedance of a TVS tube of the present invention.

[0041] Figure 2 The circuit diagram of the multi-speed current measurement module of the present invention is shown in FIG.

[0042] Figure 3 This is a gradation state diagram of the multi-grade current measurement module of the present invention.

[0043] Figure 4 It is a schematic diagram of the composition framework of the control processing unit of the present invention.

[0044] Figure 5 The present invention is a schematic flow chart of a multi-speed current measurement method based on multi-path impedance of a TVS tube.

[0045] In the attached figure: 1. Signal acquisition module; 2. Multi-speed current measurement module; 3. Control processing module. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0047] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0048] Example 1

[0049] Please refer to Figure 1 A multi-speed current measurement device based on TVS tube multi-path impedance includes: a signal acquisition module 1, a multi-speed current measurement module 2 and a control processing module 3; the signal acquisition module 1 adopts a Pico TA041 active differential probe to be directly connected to a current source to be measured, and is used to collect the current signal of the current source, and transmit the differential voltage signal after amplification and optimization to the multi-speed current measurement module 2; in this embodiment, the signal acquisition module 1 adopts the Pico TA041 active differential probe with the advantages of low load effect, high signal fidelity, wide dynamic range and small temperature drift.

[0050] like Figure 2As shown, the input end of the multi-speed current measurement module 2 is electrically connected to the output end of the signal acquisition module 1, and the output end of the multi-speed current measurement module 2 is electrically connected to the input end of the control processing module 3. The multi-speed current measurement module 2 is composed of multiple series-connected transient suppression diodes (TVS tubes) and corresponding impedance networks in parallel. The last TVS tube end is grounded. The multi-speed current measurement module 2 is used to dynamically select the conduction state of the appropriate TVS tube according to the size of the input differential voltage signal, and transmit the measured analog voltage signal to the control processing module 3, so as to achieve different sizes of currents using different gears for measurement, and at the same time achieve overcurrent protection; in this embodiment, the TVS tube adopts a bidirectional TVS tube in SMBJ packaging.

[0051] The control processing module 3 uses a single-chip microcomputer to control the multi-speed current measurement module 2, which is used to read the on-off state of the TVS tube, perform signal processing, measure the output voltage, and calculate the output current value. The control processing module 3 uses STM32F103C8T6, which has a built-in Cortex-M3 core, 64K Flash memory, 20KSRAM, and 37 GPIO pins. Figure 4 As shown, the control processing unit includes: an analog-to-digital conversion module, a state monitoring module, a main operation module, a data output module and a data storage module; the analog-to-digital conversion module is used to obtain the analog voltage signal from the multi-speed current measurement module 2, and convert it into a digital signal, and input the numerical signal into the main operation module; the state monitoring module is used to monitor the conduction state of the TVS tube in each gear in real time, and input the conduction state signal of the TVS tube into the main operation module; the main operation module combines the input data of the state monitoring module and the analog-to-digital conversion module to calculate and measure the current value; the data output module outputs the actual current data output by the main operation module to the display module through the serial port, I2C or other interfaces; the data storage module is used to store measurement configurations and historical data.

[0052] Example 2

[0053] Please refer to Figure 1 and Figure 2 , a multi-speed current measuring device based on multi-path impedance of TVS tube, a multi-speed current measuring device, when the current is small, no TVS tube is activated, and the current signal can form an output voltage signal through all impedances; when the current increases, the lowest level TVS tube is activated, the impedance value of the current is reduced, and the output voltage signal is also relatively reduced; the end of the last level TVS tube is grounded, when the current value is greater than the action current of the highest level TVS tube, all TVS tubes are activated, the input current is directly connected to the ground, and the output voltage is 0, to ensure that the current signal is within a safe range, thereby achieving overcurrent protection. The specific multi-speed current measurement module 2 is n-level series, in which the first-level TVS tube is TVS1, the breakdown voltage is U1, TVS1 is connected in parallel with the resistor R1, and the i-th level TVS tube is TVSi , the breakdown voltage is U i , TVS i With resistor R i In parallel, the nth TVS tube is TVS n , the breakdown voltage is U n , TVS n With resistor R n In parallel, the operating current of each level of TVS tube is given by the following formula:

[0054]

[0055] Among them, 0 <I1<I2……<I i … n , I n This is the maximum current value that the circuit can measure, I i is the operating current of the i-th TVS tube, U i is the breakdown voltage of the i-th TVS tube, R i is the resistance value connected in parallel with the i-th TVS tube.

[0056] The single-chip microcomputer monitors the conduction state of each TVS tube in real time through the state monitoring module by measuring the voltage across each TVS tube. The output signal IO informs the main operation module that the number of unactuated TVS tubes is m (0≤m≤n). The main operation module calculates the current value I according to the total voltage value U output by the analog-to-digital conversion module. The calculation formula is:

[0057]

[0058] Among them, U is the total voltage value measured, R i is the resistance value of the i-th TVS tube in parallel.

[0059] like Figure 1 and 2 The single chip microcomputer shown in the figure measures the voltage across each TVS tube through the state monitoring module to obtain the conduction state of each TVS tube. Specifically, in the multi-level current measurement module 2, both ends of each TVS tube are connected with wiring terminals, such as Figure 2 As shown, there are four terminals N0 to N3 in the multi-speed current measurement module 2. The N3 terminal is directly grounded, while the N0 to N2 terminals are connected to the state monitoring module and analog-to-digital conversion module of the single-chip microcomputer to transmit voltage signals.

[0060] Example 3

[0061] Please refer to Figure 3 ​In this embodiment, the multi-stage current measurement module 2 includes at least three TVS tubes connected in series and corresponding impedance networks connected in parallel to form three current measurement gears. Specifically, the first-stage TVS tube in the multi-stage current measurement module 2 is TVS1, with a breakdown voltage of 10V, connected in parallel with the resistor R1; the second-stage TVS tube is TVS2, with a breakdown voltage of 10V, connected in parallel with the resistor R2; the third-stage TVS tube is TVS3, with a breakdown voltage of 10V, connected in parallel with the resistor R3 to form a small current measurement path; R1, resistance value is 10kΩ, R2, resistance value is 100Ω, R3, resistance value is 1Ω, correspondingly, the first-stage TVS tube action current I1 is 1mA, the second-stage TVS tube action current I2 is 100mA, and the third-stage TVS tube action current I3 is 10A. When the measured current is 0≤I<I1, TVS1, TVS2, and TVS3 are all inactive, and it is the small current measurement gear at this time; when the measured current is I1≤I<I2, TVS1 is active, and TVS2 and TVS3 are all inactive, and it is the medium current measurement gear at this time; when the measured current is I2≤I<I3, TVS1 and TVS2 are active, and TVS3 is inactive, and it is the large current measurement gear at this time; when the measured current is I3≤I, TVS1, TVS2, and TVS3 are all inactive, and the input current is directly connected to the ground, and the output voltage is 0.

[0062] Example 4

[0063] Please refer to Figure 5 A multi-level current measurement method based on multi-path impedance of a TVS tube comprises the following steps:

[0064] S1, connect the input end of the signal acquisition module 1 to the current measured point;

[0065] S2, connecting the output end of the control processing unit to the display module or the data recording device;

[0066] S3, energize the current point to be measured, and start signal acquisition and processing;

[0067] S4, the control processing module 3 calculates and measures the current value through the signal input by the analog-to-digital conversion module and the status monitoring module;

[0068] S4.1, the control processing module 3 reads the monitoring result of the state monitoring module, obtains the conduction state of the TVS tube, thereby obtains the m value in the current value calculation formula, and retrieves the resistance values ​​of the m resistors connected in parallel with the unactuated TVS tube;

[0069] S4.2, substituting the voltage value data input by the analog-to-digital conversion module and the resistance values ​​of the m resistors into the calculation formula to calculate the measured current value;

[0070] S4.3, input the measured current value into the data output module and the data storage module;

[0071] S5. Output the calculated current value to the display module through the data output module, or transmit it to an external device through other interfaces.

[0072] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The substitution may be a substitution of a part of the structure, device, method step, or a complete technical solution. The equivalent replacement or change according to the technical solution and the inventive concept of the present invention shall be covered within the protection scope of the present invention.

Claims

1. A multi-level current measuring device based on TVS tube multi-path impedance, characterized in that: include: Signal acquisition module, multi-speed current measurement module and control processing module; The signal acquisition module uses an active differential probe to directly connect to the current source to be measured, and is used to collect the current signal of the current source, and transmit the differential voltage signal after the signal is amplified and optimized to the multi-speed current measurement module; The input end of the multi-speed current measurement module is electrically connected to the output end of the signal acquisition module, and the output end of the multi-speed current measurement module is electrically connected to the input end of the control processing module. The multi-speed current measurement module is composed of multiple TVS tubes connected in series and corresponding impedance networks in parallel. The end of the last TVS tube is grounded. The voltage signal of each stage of the TVS tube is input into the control processing module through the signal line. The multi-speed current measurement module is used to dynamically select the conduction state of the appropriate TVS tube according to the size of the input differential voltage signal, and transmit the measured analog voltage signal to the control processing module, so as to realize the measurement of currents of different sizes using different gears, and realize overcurrent protection at the same time; The control processing module adopts a single chip microcomputer to control a multi-speed current measurement module, which is used to read the on / off state of the TVS tube, perform signal processing, measure the output voltage, and calculate the output current value.

2. The multi-level current measuring device based on TVS tube multi-path impedance as claimed in claim 1, characterized in that: In the multi-level current measuring device, when the current is small, no TVS tube is activated, and the current signal can form an output voltage signal through all impedances; when the current increases, the lowest-level TVS tube is activated, the impedance value through which the current passes decreases, and the output voltage signal is also relatively reduced; the terminal of the last-level TVS tube is grounded, and when the current value is greater than the action current of the highest-level TVS tube, all TVS tubes are activated, the input current is directly connected to the ground, and the output voltage is 0, so as to ensure that the current signal is within a safe range, thereby realizing overcurrent protection.

3. The multi-level current measuring device based on TVS tube multi-path impedance as claimed in claim 2, characterized in that: The multi-level current measurement module is connected in series in n stages, wherein the first-stage TVS tube is TVS1, the breakdown voltage is U1, TVS1 is connected in parallel with the resistor R1, and the i-th-stage TVS tube is TVS i , the breakdown voltage is U i , TVS i With resistor R i In parallel, the nth TVS tube is TVS n , the breakdown voltage is U n , TVS n With resistor R n In parallel, the operating current of each level of TVS tube is given by the following formula: Among them, 0 <I1<I2……<I i … n , I n This is the maximum current value that the circuit can measure, I i is the operating current of the i-th TVS tube, U i is the breakdown voltage of the i-th TVS tube, R i is the resistance value connected in parallel with the i-th TVS tube.​ 4. The multi-level current measuring device based on TVS tube multi-path impedance as claimed in claim 1, characterized in that: The control processing unit includes: an analog-to-digital conversion module, a state monitoring module, a main operation module, a data output module and a data storage module; The analog-to-digital conversion module is used to obtain the analog voltage signal from the multi-speed current measurement module and convert it into a digital signal, and at the same time input the numerical signal into the main operation module; The status monitoring module is used to monitor the conduction status of the TVS tubes at each gear in real time and input the conduction status signal of the TVS tubes into the main operation module; The main operation module combines the input data of the status monitoring module and the analog-to-digital conversion module to calculate and measure the current value; The data output module outputs the actual current data output by the main operation module to the display module through the serial port, I2C or other interfaces; Data storage module, used to store measurement configuration and historical data.

5. The multi-level current measuring device based on TVS tube multi-path impedance as claimed in claim 4, characterized in that: The control processing unit monitors the conduction state of the TVS tubes at each level in real time through the state monitoring module by measuring the voltage across each TVS tube, and informs the main operation module through the output signal IO that the number of TVS tubes that are not in action is m (0≤m≤n). The main operation module calculates the current value I according to the total voltage value U output by the analog-to-digital conversion module. The calculation formula is: Among them, U is the total voltage value measured, R i is the resistance value of the i-th TVS tube in parallel.

6. The multi-level current measuring device based on TVS tube multi-path impedance as claimed in claim 3, characterized in that: The multi-level current measurement module includes at least three TVS tubes connected in series and corresponding impedance networks connected in parallel to form three current measurement levels.

7. The multi-level current measuring device based on TVS tube multi-path impedance as claimed in claim 6, characterized in that: In the multi-speed current measurement module, the first-stage TVS tube is TVS1, the breakdown voltage is 10V, and it is connected in parallel with the resistor R1; the second-stage TVS tube is TVS2, the breakdown voltage is 10V, and it is connected in parallel with the resistor R2; the third-stage TVS tube is TVS3, the breakdown voltage is 10V, and it is connected in parallel with the resistor R3 to form a small current measurement path; the resistance of R1 is 10kΩ, the resistance of R2 is 100Ω, and the resistance of R3 is 1Ω.

8. The multi-level current measuring device based on TVS tube multi-path impedance as claimed in claim 1, characterized in that: The signal acquisition module adopts Pico TA041 active differential probe.

9. The multi-level current measuring device based on TVS tube multi-path impedance according to claim 1, characterized in that: The control processing unit adopts STM32F103C8T6 single chip microcomputer.

10. A method for measuring multi-speed current based on TVS tube multi-path impedance, using the multi-speed current measuring device based on TVS tube multi-path impedance according to any one of claims 1 to 9, characterized in that: The steps include: S1. Connect the input terminal of the signal acquisition module to the current measured point; S2, connecting the output end of the control processing unit to the display module or the data recording device; S3, energize the current point to be measured, and start signal acquisition and processing; S4, the control processing module calculates and measures the current value through the signals input by the analog-to-digital conversion module and the status monitoring module; S4.1, the control processing module reads the monitoring result of the state monitoring module, obtains the conduction state of the TVS tube, thereby obtains the m value in the current value calculation formula, and calls the resistance value of the m resistors connected in parallel with the unactuated TVS tube; S4.2, substituting the voltage value data input by the analog-to-digital conversion module and the resistance values ​​of the m resistors into the calculation formula to calculate the measured current value; S4.3, input the measured current value into the data output module and the data storage module; S5. Output the calculated current value to the display module through the data output module, or transmit it to an external device through other interfaces.

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