CN114325060A - A current sensor system - Google Patents

Abstract

The invention provides a current sensor system, which belongs to the technical field of current sensors. The system includes an electromagnetic coil and a Rogowski coil, and the electromagnetic coil and the Rogowski coil are used to pass through the line to be tested; the Rogowski coil is connected to a signal processing module, and is used to send the sensed signal to the signal processing module, The signal processing module is used to amplify and integrate the induced current; the electromagnetic coil is connected to the battery management module, and is used to convert the electric energy obtained by the battery management module, and give the signal through the converted electric energy The processing module and the main control module supply power; the main control module is used for processing and outputting the signal output by the signal processing module. The invention adopts the electromagnetic coil to take electricity and the Rogowski coil for current detection, which can appropriately reduce the volume of the electromagnetic coil, optimize the size of the current sensor, avoid the problems that the magnetic field of the electromagnetic coil is easy to be saturated and the frequency band is narrow, and improve the current measurement precision.

Description

A current sensor system

technical field

The invention relates to a current sensor system, which belongs to the technical field of current sensors.

Background technique

As a device for detecting electrical energy in a power system, the current sensor has gradually increased with the development of power electronics technology, and the requirements for the detection accuracy of the current sensor are also gradually increasing. In the prior art, electromagnetic transformers are mainly used for current detection. At the same time, the electromagnetic transformers can both detect current and take electricity. In the patent of "Method and System for Obtaining Power Data", the current signal and voltage signal of the power system are collected through the electromagnetic induction wireless transmission transformer, and the required power supply is provided by the secondary winding of the electromagnetic voltage transformer. This electromagnetic current transformer consists of a closed iron core and a winding wound on the iron core. The thickness of the iron core and the number of turns of the winding directly affect the measurement accuracy. When the thickness of the iron core and the number of turns of the winding meet certain requirements, the measurement accuracy is high, but it will take up a large space. In order to meet the measurement accuracy, the volume of the electromagnetic coil is generally large, and the electromagnetic frequency band is narrow, and the magnetic circuit of the iron core is easily saturated under high current, which will cause a large error in the measurement result.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a current sensor system to solve the problems of large volume and low measurement accuracy of the existing electromagnetic current sensor.

The present invention provides a current sensor system, comprising an electromagnetic coil and a Rogowski coil, wherein the electromagnetic coil and the Rogowski coil are used to pass through a line to be measured; the Rogowski coil is connected to a signal processing module and is used to The signal transmission signal processing module is used for amplifying and integrating the induced current; the electromagnetic coil is connected with the battery management module, and is used for converting the electric energy obtained by the battery management module, The signal processing module and the main control module are powered by the converted electric energy; the main control module is used for processing and outputting the signal output by the signal processing module.

The current sensor system provided by the present invention includes an electromagnetic coil and a Rogowski coil. The electromagnetic coil is used to obtain electricity, and the Rogowski coil is used for current detection. The volume of the electromagnetic coil can be appropriately reduced, the size of the current sensor is optimized, and the electromagnetic coil is avoided. The magnetic field is easy to saturate and the frequency band is narrow, which improves the current measurement accuracy, and realizes the signal processing and digitization functions through the signal processing module and the main control module.

Further, in order to improve the power supply performance of the battery management module, the sensor system further includes a rectifier, the AC side of the rectifier is connected to the electromagnetic coil, and the DC side of the rectifier is connected to the battery management module, for the electromagnetic coil to sense the AC power. converted to direct current.

Further, in order to realize the conversion of analog signals and digital signals, the sensor system also includes an analog-to-digital conversion module, the input end of the analog-to-digital conversion module is connected with the output end of the signal processing module, and the output end is connected with the main control module, for The analog signal output by the signal processing module is converted into a digital signal, and the analog-to-digital conversion module is powered by the power management module.

Further, in order to realize signal amplification and integration processing, the signal processing module includes a first amplifying circuit and an integrating circuit, the amplifying circuit includes a second amplifier for amplifying the current signal, and the integrating circuit includes an amplifier , which is used to perform integral reduction processing on the current amplified signal to obtain the current reduction signal.

Further, in order to realize flexible output of signals, the main control module is also connected with a signal transformation module, and the signal is output through the signal transformation module.

Further, in order to improve the anti-electromagnetic interference capability of the output signal, the signal conversion module is an optocoupler, the input side of the optocoupler is connected to the output end of the main control module, and the output side is used to connect the interface module to realize the main control module. Electromagnetic isolation from the interface module.

Further, the signal conversion module includes a digital-to-analog conversion circuit, a signal amplification circuit and an emitter-level follower circuit connected in sequence, wherein the input end of the digital-to-analog conversion circuit is connected with the output end of the main control module, and the output end of the digital-to-analog conversion circuit is connected. The terminal outputs the corresponding voltage signal after amplification and follow-up by the signal amplifying circuit and the emitter-level follower circuit.

Further, the signal conversion module is a digital-to-analog conversion circuit, the input end of the digital-to-analog conversion circuit is connected with the output end of the main control module, and the output end of the digital-to-analog conversion circuit is used to connect the interface module, so that the main control module outputs a digital signal. The signal is converted into an analog current signal and sent to the interface module.

The signal transformation module can select different output modes according to different use environments, so as to avoid the interference of the external environment on the signal as much as possible, and ensure that the output signal is better detected by the subsequent modules.

Further, in order to realize the switching of different output signals, the signal transformation module further includes a switch, which is used to realize the switching of different signal output modes of the signal transformation module.

Further, the electromagnetic coil and the Rogowski coil are stacked in concentric circles.

Description of drawings

Fig. 1 is the circuit diagram of the current sensor system of the present invention;

FIG. 2 is a schematic structural diagram of a current sensor system;

Figure 3 is a schematic diagram of the installation of the electromagnetic coil and the Rogowski coil;

4 is a schematic diagram of a signal processing module;

Figure 5 is a waveform diagram of a Rogowski coil sampling signal;

FIG. 6 is a structural diagram of a power management module.

Detailed ways

The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

The present invention proposes a current sensor system, as shown in FIG. 1 and FIG. 2 , the current sensor includes an electromagnetic coil and a Rogowski coil. As shown in Figure 1, the dark circle represents the electromagnetic coil, the light circle represents the Rogowski coil, and the wire to be tested passes through the axis of the electromagnetic coil and the Rogowski coil; the Rogowski coil and the signal processing module (Singal Condition) connected to the signal processing module to amplify and integrate the acquired signal; the electromagnetic coil is connected to the battery management module (Power Management), and the battery management module supplies power to the signal processing module and the main control module (Processor); the main control module uses It is used to process and output the signal output by the signal processing module.

Existing electromagnetic coils can both take electricity and detect current signals. In the present invention, only electromagnetic coils are used to take electricity, and Rogowski coils are used to detect current signals. In this case, the thickness of the iron core of the electromagnetic coil can be appropriately reduced. , The number of turns to reduce the volume of the electromagnetic coil, thereby optimizing the size of the current sensor, while avoiding the problem of low measurement accuracy caused by the narrow frequency band of the electromagnetic coil and easy saturation under high current.

In this embodiment, a total of three electromagnetic coils and three Rogowski coils are arranged. The electromagnetic coils and the Rogowski coils are both insulated and packaged, and are stacked in concentric circles. As shown in Figure 3, the Rogowski coil is on the top and the electromagnetic coil It is lowered to the groove set in the integrated base for integral pouring and fixing. The poured electromagnetic coil and Rogowski coil can form a measuring and power-taking module. In this embodiment, three groups of measuring and power-taking modules are formed. B, C three-way circuit to measure and get electricity.

As shown in FIG. 1 , the sensor system further includes a rectifier, wherein the AC side of the rectifier is connected to the electromagnetic coil, and the DC side of the rectifier is connected to the battery management module, so as to convert the alternating current induced by the electromagnetic coil into direct current. Depending on the voltage requirements of different modules, as shown in Figure 1 and Figure 2, the signal processing module, the main control module, and the signal conversion module can output the corresponding voltage to supply power to each module through the battery management module. The battery management module is also connected with a battery as a backup power source. The current sensor system also includes an analog-to-digital conversion module (ADC), the input end of the analog-to-digital conversion module (ADC) is connected to the output end of the signal processing module, and the output end is connected to the main control module, for converting the output end of the signal processing module The analog signal is converted to a digital signal, and the analog-to-digital conversion module is also powered by the power management module.

The structure of the power management module is shown in Figure 6. The power management module includes an input circuit, a power management chip and peripherals, a backup super capacitor and a battery. When a large current flows through the primary side of the input circuit, due to the maximum peak current limit of the entire power management module (PMU) input, the excess current needs to be discharged through a suitable discharge path to ensure the reliability and stability of the entire current design. Therefore, it is necessary to connect several diodes with low leakage current, high conduction voltage drop in parallel at the input end of the power management module (PMU), and at the same time, the forward conduction peak current is large. When the input generates a large current, it is discharged. In the circuit, D5 -D8 plays the role of high current discharge, among which R28-R30 plays the function of equalizing voltage. Secondly, after that, the VIN voltage is input into the power management chip U1. The power management chip adopts the chip of the model ADP5091. The capacitors C13, R13, R18, R23, and R24 jointly determine the maximum power tracking point (MPPT) of the power management module. The specific It is the U1 chip that periodically samples the input open-circuit voltage and divides the voltage, and then uses this voltage as the maximum power tracking point for constant voltage and maximum power point tracking, and then stores the voltage of the maximum power point through the C13 capacitor of the CBP pin for use. To adjust the input voltage of the U1 chip in real time. The maximum tracking point voltage is determined by the ratio of the sum of R13 and R18 to the sum of R13, R18, R23 and R24. The peripheral devices R25, R26 and R27 of the U1 chip jointly determine the working mode in U1. The PGOOD pin connected to the micro-control pin can also monitor the power management chip U1. When the voltage output exceeds the adjustment range, it controls the voltage regulator output; VID The R3 resistor of the pin is used to set the output voltage of the U1 chip, the inductor L1 is used to set the switching node of the inductive boost regulator of U1, and the resistors R4-R12, R14-R17, R19-R22, R31 are used to set U1. Power path switch. U1 connects the R2 resistor on the MINOP pin to set the minimum operating voltage of the power management module. Specifically, U1 outputs a bias current of 2uA on R2, and the minimum operating voltage of the system is determined by the resistance value of R2; C9, C10, C11 and C12 are backup supercapacitors, some of which are used to stabilize voltage and eliminate glitches. C12 and BT1 form a backup battery (the battery is not rechargeable), the BACK_UP pin is connected to the backup battery, and C12 acts as a voltage regulator. The output voltage of U1 is regulated by C7 and C8 and the burr is eliminated for the entire system.

As shown in FIG. 4 , the signal processing module includes an amplifier circuit and an integrating circuit, and the current signal detected by the Rogowski coil is amplified and integrated through the signal processing module, wherein the amplifier circuit includes a first amplifier, and one input end of the first amplifier is connected to The current signal sensed by the Rogowski coil, the other input terminal is used to connect the standard signal, the input terminal and the output terminal of the first amplifier are also connected with different resistors, the first amplifier is also connected in parallel with another resistor, and the current signal is processed by the amplifier circuit. Amplification processing to obtain a current amplified signal; the integrating circuit includes a second amplifier, one input end of the second amplifier is connected to the output end of the first amplifier, the other input end is connected to a standard signal, and the input end of the second amplifier is also connected with a resistor, The integrating circuit also includes a capacitor, the second amplifier is connected in parallel with the capacitor and the other resistor, and the current amplified signal is integrated and restored through the integrating circuit to obtain the current restored signal; the signal processing module also includes a filter circuit, which is used for the amplified signal. The integrated signal is filtered to make the processed waveform smoother, and the filtered signal is sent to the analog-to-digital conversion module, and the output analog signal device is converted into a digital signal through the analog-to-digital conversion module; wherein the filter circuit can Conventional filter circuits such as RC and LC are used. In this embodiment, the result obtained after the current signal detected by the Rogowski coil is processed by the signal processing module is shown in FIG. 5 . In Figure 5, the "Roche coil" marked curve represents the amplified and integrated waveform of the Roche coil signal, and the "A current" marked curve is the waveform of the primary current signal. It can be seen that the current signal collected by the Roche coil can correctly reflect the current change, including the amplitude value, phase and other information, the current signal waveform processed by the signal processing module is basically the same as the primary current waveform and frequency.

As shown in FIG. 1 , the main control module is also connected with a signal transformation module, which outputs signals to the interface module through the signal transformation module. The signal transformation module can set the corresponding output mode according to the environment where the interface module is used, and the different requirements of the interface module. The signal transformation module includes the following three structures, corresponding to the three output modes. First, the signal conversion module is an optocoupler, the input side of the optocoupler is connected to the output end of the main control module, and the output side is used to connect the interface module, so as to realize the electromagnetic isolation between the main control module and the interface module, and improve the electromagnetic resistance. Interference ability, output digital signal to interface module through photoelectric coupler; can meet the requirements of complex electromagnetic environment where interface module is located. Second, the signal conversion module includes a digital-to-analog conversion circuit (DAC), a signal amplification circuit, and an emitter-level follower circuit connected in sequence, wherein the input end of the digital-to-analog conversion circuit is connected to the output end of the main control module, and the digital-to-analog conversion circuit is connected to the output end of the main control module. The output terminal outputs the corresponding voltage signal after the amplification and follow-up of the signal amplifier circuit and the emitter follower circuit. Through the amplification and follow-up, the subsequent voltage signal can be better detected; it can meet the requirements of low signal detection accuracy of the interface module. Third, the signal conversion module is a digital-to-analog conversion circuit, the input end of the digital-to-analog conversion circuit is connected to the output end of the main control module, and the output end of the digital-to-analog conversion circuit is used to connect the interface module to convert the digital signal output from the main control module. The analog current signal is sent to the interface module, which can meet the requirements of high detection accuracy of the interface module. In order to better realize the selection of different modes, at the same time, the signal conversion module also includes a switch to realize the switching of different signal output modes of the signal conversion module. The switch switches the signal conversion module to the photoelectric coupler, and the photoelectric coupler is used to transmit the digital signal input through the main control module to the interface module. The toggle switch can be a DIP switch.

The present invention collects the current signal through the Rogowski coil, amplifies and integrates the collected current signal through the amplifying circuit and the integrating circuit in the signal processing module, and then converts the processed analog signal into a digital signal through the analog-to-digital conversion module; Then the output digital signal is processed by the main control module, and then output to the signal conversion module. According to the different use environments, select the appropriate signal output mode, and send the output signal to the interface module. According to the voltage requirements of different modules, the corresponding voltage can be output to supply power to each module through the battery management module. The invention avoids the problems that the electromagnetic coil magnetic field is easy to be saturated and the frequency band is narrow, can improve the current measurement accuracy, and realize the signal processing and digitization functions through the signal processing module and the main control module; according to the different use environments, the appropriate signal output mode is selected , as far as possible to avoid environmental interference.

Claims (10)

1. A current sensor system, characterized in that it comprises an electromagnetic coil and a Rogowski coil, and the electromagnetic coil and the Rogowski coil are used to be worn on the circuit to be measured; the Rogowski coil is connected to a signal processing module for Send the sensed signal to a signal processing module, and the signal processing module is used to amplify and integrate the sensed current; the electromagnetic coil is connected to the battery management module, and is used to convert the electric energy obtained by the battery management module The conversion is performed, and the signal processing module and the main control module are powered by the converted electric energy; the main control module is used for processing and outputting the signal output by the signal processing module. 2 . The current sensor system according to claim 1 , wherein the sensor system further comprises a rectifier, the AC side of the rectifier is connected to the electromagnetic coil, and the DC side of the rectifier is connected to the battery management module for connecting the electromagnetic coil. 3 . The alternating current sensed by the coil is converted into direct current. 3 . The current sensor system according to claim 1 , wherein the sensor system further comprises an analog-to-digital conversion module, the input end of the analog-to-digital conversion module is connected to the output end of the signal processing module, and the output end is connected to the main control module. 4 . connected to the analog-digital conversion module for converting the analog signal output by the signal processing module into a digital signal, and the analog-digital conversion module is powered by the power management module. 4 . The current sensor system according to claim 1 , wherein the signal processing module comprises an amplifier circuit and an integrating circuit, the amplifying circuit includes a first amplifier for amplifying the current signal, and the integrating circuit The circuit includes a second amplifier, which is used for integrating and restoring the current amplified signal to obtain a current restoring signal. 5 . The current sensor system according to claim 1 , wherein the output end of the main control module is further connected with a signal conversion module, and the signal is output through the signal conversion module. 6 . 6 . The current sensor system according to claim 5 , wherein the signal conversion module is a photocoupler, the input side of the photocoupler is connected to the output end of the main control module, and the output side is used to connect the interface module to To achieve electromagnetic isolation between the main control module and the interface module. 7 . The current sensor system according to claim 5 , wherein the signal conversion module comprises a digital-to-analog conversion circuit, a signal amplification circuit and an emitter-level follower circuit connected in sequence, wherein the input end of the digital-to-analog conversion circuit is connected to The output end of the main control module is connected, and the output end of the digital-to-analog conversion circuit outputs a corresponding voltage signal after being amplified and followed by the signal amplifying circuit and the emitter-level follower circuit. 8 . The current sensor system according to claim 5 , wherein the signal conversion module is a digital-to-analog conversion circuit, the input end of the digital-to-analog conversion circuit is connected to the output end of the main control module, and the output end of the digital-to-analog conversion circuit is connected to the output end of the main control module. 9 . The terminal is used to connect the interface module, so as to convert the output digital signal of the main control module into an analog current signal and send it to the interface module. 9 . The current sensor system according to claim 6 , wherein the signal conversion module further comprises a switch for switching between different signal output modes of the signal conversion module. 10 . 10 . The current sensor system according to claim 1 , wherein the electromagnetic coil and the Rogowski coil are stacked in concentric circles. 11 .

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