Batteryless adaptive dual-mode wire current sensor system

Abstract

The present application relates to the technical field of current sensing without battery, in particular to a self-adaptive dual-mode wire current sensor system without battery, comprising a current collection unit, a collection switching unit, an active sampling unit, a passive sampling unit and a current calculation unit; the measured wire is connected to the input end of the collection switching unit through the current collection unit, the first output end and the second output end of the collection switching unit are connected to the active sampling unit and the passive sampling unit respectively, and the output ends of the active sampling unit and the passive sampling unit are connected to the current calculation unit; the present application can start the active sampling unit or the passive sampling unit according to the energy signal amplitude output by the current collection unit, and then calculate the current value of the measured wire by the sampling data. The present application can solve the technical problems of the low current measurement blind area, low energy utilization efficiency, poor weak signal anti-interference ability and inability to work continuously and stably under wide dynamic range current of the traditional passive current sensor.

Description

Technical Field

[0001] This invention relates to the field of battery-free current sensing technology, and more particularly to a battery-free adaptive dual-mode wire current sensor system. Background Technology

[0002] Traditional battery-free conductor current sensors rely on current transformers as their core energy extraction and sensing components, which inherently limits their ability to measure currents over a wide dynamic range. When the current in the conductor being measured is large, the induced energy is sufficient, enabling the system to activate active sampling circuits such as ADCs for high-precision measurement. However, when the current is small, the induced energy is weak and insufficient to meet the startup and operating energy requirements of the active measurement unit, resulting in a measurement blind zone in the low-current range and hindering continuous monitoring across the entire range. Current technologies lack an effective mechanism for seamlessly switching measurements from high to extremely low currents under conditions of drastic energy supply fluctuations, making it difficult to meet the demands for maintenance-free, long-cycle, and wide-range current monitoring. Summary of the Invention

[0003] The purpose of this invention is to propose a battery-free adaptive dual-mode wire current sensor system to solve the technical problems of traditional passive current sensors, such as low current measurement blind zone, low energy utilization efficiency, poor anti-interference ability of weak signals, and inability to work continuously and stably under wide dynamic range current.

[0004] To achieve this objective, the present invention adopts the following technical solution: A battery-free adaptive dual-mode conductor current sensor system includes a current acquisition unit, an acquisition switching unit, an active sampling unit, a passive sampling unit, and a current calculation unit. The input terminal of the current acquisition unit is connected to the conductor under test, the output terminal of the current acquisition unit is connected to the input terminal of the acquisition switching unit, the first output terminal of the acquisition switching unit is connected to the active sampling unit, and the second output terminal of the acquisition switching unit is connected to the passive sampling unit. The acquisition switching unit is used to select either the active sampling unit or the passive sampling unit to start based on the amplitude of the energy signal output by the current acquisition unit; The output terminals of both the active sampling unit and the passive sampling unit are connected to the current calculation unit, which is used to calculate the current value of the conductor under test based on the sampling data.

[0005] Preferably, the current acquisition unit includes a current transformer (CT) and an AC-DC module; The sensing end of the current transformer (CT) surrounds the conductor being measured, and the output end of the current transformer (CT) is connected to the input end of the AC-DC module. The AC-DC module is used to convert the AC signal output by the current transformer (CT) into a DC voltage signal and output it to the acquisition and switching unit.

[0006] Preferably, the acquisition switching unit includes an input voltage comparison module, switch S1, and switch S2; The input terminal of the input voltage comparison module is connected to the output terminal of the AC-DC module, the first output terminal of the input voltage comparison module is connected to the active sampling unit through the switch S1, and the second output terminal of the input voltage comparison module is connected to the passive sampling unit through the switch S2. The output terminal of switch S1 serves as the first output terminal of the acquisition switching unit, and the output terminal of switch S2 serves as the second output terminal of the acquisition switching unit. The input voltage comparison module is set with a threshold voltage Vs. The input voltage comparison module is used to receive the DC voltage output by the AC-DC module and compare it with the threshold voltage Vs. When the DC voltage signal is greater than the threshold voltage Vs, a first control signal is output to control the switch S1 to close and the switch S2 to open. When the DC voltage signal is less than the threshold voltage Vs, a second control signal is output to control the switch S2 to close and the switch S1 to open.

[0007] Preferably, the active sampling unit includes an active sampling module, an undervoltage lockout module, a Buck conversion module, an output voltage comparison module, an input storage capacitor C0, an output storage capacitor C1, and a switch S3; The two ends of the active sampling module are respectively connected to the first output terminal of the acquisition switching unit and the ADC sampling terminal of the MCU. The active sampling module is used to output the sensing signal to the MCU. The two ends of the input storage capacitor C0 are respectively connected to the first output terminal of the acquisition switching unit and the input terminal of the switch S3. The output terminal of the switch S3 is connected to the input terminal of the Buck conversion module. The output terminal of the Buck conversion module is connected to the power supply terminal of the MCU through the output storage capacitor C1. The output storage capacitor C1 is used to supply power to the MCU. The detection terminal of the output voltage comparison module is connected to the output storage capacitor C1, and the output terminal of the output voltage comparison module is connected to the input terminal of the undervoltage lockout module and the operating terminal of the MCU respectively. The detection terminal of the undervoltage lockout module is connected to the input storage capacitor C0, and the output terminal of the undervoltage lockout module is connected to the control terminal of the switch S3. The undervoltage lockout module is configured with a start-up threshold voltage Vstart and a stop-down threshold voltage Vstop. The undervoltage lockout module receives the capacitor voltage VC0 of the input storage capacitor C0 and compares it with the start-up threshold voltage Vstart and the stop-down threshold voltage Vstop, respectively. When the capacitor voltage VC0 is greater than the start-up threshold voltage Vstart, the output control signal drives the switch S3 to close, and the Buck conversion module is powered on and put into operation. When the capacitor voltage VCO is less than the turn-off threshold voltage Vstop, the output control signal drives the switch S3 to open, and the Buck conversion module stops working; The output voltage comparison module is set with the turn-off threshold voltage Vstop. The output voltage comparison module is used to receive the capacitor voltage VC1 of the output storage capacitor C1 and compare it with the turn-off threshold voltage Vstop respectively. When the capacitor voltage VC1 is lower than the shutdown threshold voltage Vstop, the output voltage comparison module shuts down the MCU's operation and outputs a prompt signal to the undervoltage lockout module to open the switch S3.

[0008] Preferably, the passive sampling unit includes a voltage doubler rectifier module, a Schmitt trigger oscillator switch module, and switch S4; The input terminals of the voltage doubler rectifier modules are all connected to the second output terminal of the acquisition switching unit. The first output terminal of the voltage doubler rectifier module is connected to the input terminal of the switch S4. The second output terminal of the voltage doubler rectifier module is connected to the input terminal of the Schmitt oscillator switch module. The output terminal of the Schmitt oscillator switch module is connected to the control terminal of the switch S4. The output terminal of the switch S4 is connected to the sampling terminal of the RFID chip to output a sensing signal. The Schmitt oscillator switch module is used to drive the switch S4 to switch on and off at a fixed period and duty cycle, periodically applying a DC voltage signal to the RFID chip.

[0009] Preferably, the current calculation unit includes a current calculation module, the MCU, and the RFID; The MCU writes the sampled current data into the storage area of ​​the RFID chip via the SPI interface.

[0010] Preferably, the MCU is model MSP430FR2433.

[0011] Preferably, the RFID chip is model EM4320.

[0012] Preferably, the backscatter signal of the RFID chip includes a received signal strength indication and a phase, wherein the received signal strength indication changes positively correlated with the supply voltage, and the phase changes negatively correlated with the supply voltage.

[0013] Preferably, the RFID chip performs differential processing on the backscattered signals under both the on and off states of the sensing signal to extract the change in received signal strength caused by the supply voltage. With phase change and based on the change in the received signal strength indication. With phase change The current value of the measured conductor is obtained by inversion. : ; in, =-0.52.

[0014] One of the above technical solutions has the following beneficial effects: (1) Seamless switching between energy adaptive dual modes to completely eliminate measurement blind zone: The system automatically switches between active ADC sampling and passive RFID backscatter sensing according to the energy of the conductor current, covering the full dynamic range from large current to extremely small current, fundamentally solving the dead zone problem in the low current range of traditional passive current sensors, and realizing continuous monitoring of the entire range.

[0015] (2) Completely battery-free and truly maintenance-free long-term operation: All the working energy of the system comes from the current transformer sensing the current of the conductor. It does not use any batteries, does not rely on external power supply, does not need to be charged, and does not need to replace components. It can work stably for a long time in unattended scenarios such as smart grids, industrial Internet of Things, and field equipment.

[0016] (3) High accuracy and stable and reliable operation in active mode: The active sampling unit adopts a triple protection mechanism of multi-level energy storage, undervoltage lockout and output voltage monitoring to ensure that the MCU and ADC work under stable and safe voltage conditions, avoid problems such as undervoltage failure and logic disorder, and realize high-precision digital sampling under high current conditions.

[0017] (4) Passive mode has extremely low power consumption and strong anti-interference capability: The passive mode adopts Schmitt oscillation periodic power supply and RFID backscatter modulation, reducing the power consumption to the microwatt level; at the same time, combined with differential processing algorithm, it effectively removes environmental noise such as temperature drift, electromagnetic interference, and distance change, greatly improving the accuracy and robustness of weak signal measurement.

[0018] (5) Innovative use of RFID chip as a sensing element: Breaking through the traditional use of RFID only as a communication tag, the EM4320 is directly used as a sensing element in a low-energy state. The strong correlation between its scattering parameters and the power supply voltage is used to realize current signal modulation, and effective signal sensing and wireless transmission are completed without MCU startup.

[0019] (6) Unified current calculation unit, high system integration and good data consistency: An independent current calculation unit is set up to process and standardize the active sampling data and passive sensing data in a unified manner. The data output format is consistent, which is convenient for the host computer to read, store and analyze, and improves the overall integration and practicality of the system.

[0020] (7) The working threshold is configurable and has a wide range of compatibility: the mode switching threshold Vs, the active unit start threshold Vstart, and the shutdown threshold Vstop can all be configured and adjusted through the peripheral circuit of the power management chip. It is compatible with different power chips, different current ranges and different application scenarios, and the system has strong scalability and adaptability. Attached Figure Description

[0021] Figure 1 This is an overall schematic diagram of a battery-free adaptive dual-mode wire current sensor system; Figure 2 This is a schematic diagram of a battery-free adaptive dual-mode wire current sensor system. Figure 3 This is a signal timing diagram of the acquisition switching unit in an adaptive dual-mode wire current sensor system that does not require batteries; Figure 4 This is a signal timing diagram of the active sampling unit in a battery-free adaptive dual-mode wire current sensor system. Figure 5 This is a signal timing diagram of a passive sampling unit in a battery-free adaptive dual-mode wire current sensor system. Figure 6 This is a schematic diagram of the RFID principle of the current calculation unit in an adaptive dual-mode wire current sensor system that does not require batteries. Figure 7 This is a diagram of the RFID backscatter signal detection architecture of the current calculation unit in a battery-free adaptive dual-mode wire current sensor system. Figure 8 This is a graph showing the RSSI of the current calculation unit in a battery-free adaptive dual-mode wire current sensor system as a function of the chip's power supply voltage. Figure 9 This is a curve showing the phase of the current calculation unit in a battery-free adaptive dual-mode wire current sensor system as a function of the chip's power supply voltage. Figure 10 This is a graph showing the RSSI and phase variation with sampling time of the current calculation unit in a battery-free adaptive dual-mode wire current sensor system. Detailed Implementation

[0022] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0023] An adaptive dual-mode conductor current sensor system that does not require batteries includes a current acquisition unit 1, an acquisition switching unit 2, an active sampling unit 3, a passive sampling unit 4, and a current calculation unit 5. The input terminal of the current acquisition unit 1 is connected to the conductor under test, the output terminal of the current acquisition unit 1 is connected to the input terminal of the acquisition switching unit 2, the first output terminal of the acquisition switching unit 2 is connected to the active sampling unit 3, and the second output terminal of the acquisition switching unit 2 is connected to the passive sampling unit 4. The acquisition switching unit 2 is used to select and activate either the active sampling unit 3 or the passive sampling unit 4 according to the amplitude of the energy signal output by the current acquisition unit 1. The output terminals of both the active sampling unit 3 and the passive sampling unit 4 are connected to the current calculation unit 5, which is used to calculate the current value of the conductor under test based on the sampling data.

[0024] This technical solution introduces an energy-adaptive intelligent switching mechanism, enabling the system to perform high-precision active ADC sampling when energy is sufficient, and switch to a passive sensing mode based on RFID backscatter modulation when energy is scarce, thereby achieving seamless and accurate measurement of currents with a wide dynamic range, especially weak currents.

[0025] like Figure 1As shown, this technical solution mainly consists of five parts: a current acquisition unit 1, an acquisition switching unit 2, an active sampling unit 3, a passive sampling unit 4, and a current calculation unit 5. The current acquisition unit 1 is responsible for converting the alternating current in the conductor under test into an electrical signal and working energy usable by the system. The acquisition switching unit 2 automatically selects and activates either the active sampling unit 3 or the passive sampling unit 4 based on the amplitude of the energy signal output by the current acquisition unit 1, ensuring that only one mode operates at a time, avoiding energy waste and mode conflicts. The active sampling unit 3 is used for high-precision current sampling under sufficient energy conditions; the passive sampling unit 4 is used for low-power passive current sensing under insufficient energy conditions. The current calculation unit 5 uniformly receives the sampling data output by the active sampling unit 3 and the passive sampling unit 4, calculates the current value of the conductor under test according to the corresponding mode's calculation rules, forming a complete, continuous, and blind-zone-free current detection path covering large currents to micro currents.

[0026] In summary, this system requires no battery at all; all operating energy is obtained from the current sensing of the wires. The acquisition switching unit 2 enables automatic mutual exclusion switching between active and passive sampling. Together with the unified current calculation unit 5, it completes dual-mode data processing and current calculation, fundamentally solving the problems of low current blind zone, low energy utilization, and susceptibility to interference of weak signals in traditional passive sensors.

[0027] To further explain, the current acquisition unit 1 includes a current transformer (CT) and an AC-DC module 11; The sensing end of the current transformer (CT) surrounds the conductor being measured, and the output end of the current transformer (CT) is connected to the input end of the AC-DC module 11. The AC-DC module 11 is used to convert the AC signal output by the current transformer (CT) into a DC voltage signal and output it to the acquisition and switching unit 2.

[0028] like Figure 2 As shown, the current acquisition unit 1 consists of a current transformer (CT) and an AC-DC module 11. The current transformer (CT) adopts a through-hole structure, with its sensing end surrounding the conductor being measured. The alternating current flowing through the conductor generates an alternating magnetic field. Under the action of electromagnetic induction, the current transformer (CT) outputs an AC voltage signal Vct proportional to the measured current. The AC voltage signal is input to the AC-DC module 11, which mainly consists of a rectifier bridge DB1, a capacitor C2, and a resistor R1. The AC-DC module 11 rectifies, filters, and converts the fluctuating AC signal Vct into a stable DC voltage signal. This DC voltage signal serves as both a sensing signal reflecting the magnitude of the measured current and an energy source for the entire system circuitry. It is synchronously output to the acquisition switching unit 2, providing the basic signal and energy for subsequent mode judgment, sampling, and calculation.

[0029] To further explain, the acquisition switching unit 2 includes an input voltage comparison module 21, a switch S1, and a switch S2; The input terminal of the input voltage comparison module 21 is connected to the output terminal of the AC-DC module 11. The first output terminal of the input voltage comparison module 21 is connected to the active sampling unit 3 through the switch S1. The second output terminal of the input voltage comparison module 21 is connected to the passive sampling unit 4 through the switch S2. The output terminal of switch S1 serves as the first output terminal of the acquisition switching unit 2, and the output terminal of switch S2 serves as the second output terminal of the acquisition switching unit 2. The input voltage comparison module 21 is set with a threshold voltage Vs. The input voltage comparison module 21 is used to receive the DC voltage output by the AC-DC module 11 and compare it with the threshold voltage Vs. When the DC voltage signal is greater than the threshold voltage Vs, a first control signal is output to control the switch S1 to close and the switch S2 to open. When the DC voltage signal is less than the threshold voltage Vs, a second control signal is output to control the switch S2 to close and the switch S1 to open.

[0030] like Figure 2 As shown, the acquisition switching unit 2 consists of an input voltage comparison module 21, switch S1, and switch S2. The input voltage comparison module 21 mainly consists of a voltage comparator. Its input terminal directly receives the DC voltage signal output from the AC-DC module 11. The input voltage comparison module 21 has a preset mode switching threshold voltage Vs. The input voltage comparison module 21 continuously compares the real-time input DC voltage signal with the threshold voltage Vs: when the DC voltage signal amplitude is greater than the threshold voltage Vs, it determines that the current conductor current is large and the induced energy is sufficient, outputting a first control signal to close switch S1 and open switch S2, enabling the active sampling unit 3; when the DC voltage signal amplitude is less than Vs, it determines that the current conductor current is small and the induced energy is insufficient, outputting a second control signal to close switch S2 and open switch S1, enabling the passive sampling unit 4, thereby achieving automatic, seamless, and mutually exclusive switching between the two working modes. Figure 3 As shown.

[0031] To further explain, the active sampling unit 3 includes an active sampling module 31, an undervoltage lockout module 32, a Buck conversion module 33, an output voltage comparison module 34, an input storage capacitor C0, an output storage capacitor C1, and a switch S3; The two ends of the active sampling module 31 are respectively connected to the first output terminal of the acquisition switching unit 2 and the ADC sampling terminal of the MCU. The active sampling module 31 is used to output the sensing signal to the MCU. The two ends of the input storage capacitor C0 are respectively connected to the first output terminal of the acquisition switching unit 2 and the input terminal of the switch S3. The output terminal of the switch S3 is connected to the input terminal of the Buck conversion module 33. The output terminal of the Buck conversion module 33 is connected to the power supply terminal of the MCU through the output storage capacitor C1. The output storage capacitor C1 is used to supply power to the MCU. The detection terminal of the output voltage comparison module 34 is connected to the output storage capacitor C1, and the output terminal of the output voltage comparison module 34 is connected to the input terminal of the undervoltage lockout module 32 and the operating terminal of the MCU respectively. The detection terminal of the undervoltage lockout module 32 is connected to the input storage capacitor C0, and the output terminal of the undervoltage lockout module 32 is connected to the control terminal of the switch S3. The undervoltage lockout module 32 is configured with a start-up threshold voltage Vstart and a stop-down threshold voltage Vstop. The undervoltage lockout module 32 is used to receive the capacitor voltage VC0 of the input storage capacitor C0 and compare it with the start-up threshold voltage Vstart and the stop-down threshold voltage Vstop, respectively. When the capacitor voltage VCO is greater than the start-up threshold voltage Vstart, the output control signal drives the switch S3 to close, and the Buck conversion module 33 is powered on and put into operation. When the capacitor voltage VCO is less than the turn-off threshold voltage Vstop, the output control signal drives the switch S3 to open, and the Buck conversion module 33 stops working; The output voltage comparison module 34 is set with the turn-off threshold voltage Vstop. The output voltage comparison module 34 is used to receive the capacitor voltage VC1 of the output storage capacitor C1 and compare it with the turn-off threshold voltage Vstop respectively. When the capacitor voltage VC1 is lower than the shutdown threshold voltage Vstop, the output voltage comparison module 34 shuts down the operation of the MCU and outputs a prompt signal to the undervoltage lockout module 32 to open the switch S3.

[0032] like Figure 2As shown, the active sampling unit 3 includes an active sampling module 31, an undervoltage lockout module 32, a Buck conversion module 33, an output voltage comparison module 34, an input storage capacitor C0, an output storage capacitor C1, and a switch S3. The active sampling module 31 includes a series resistor R0 and a filter RC1. The active sampling module 31 sends the sensing signal output from the acquisition switching unit 2 to the ADC sampling terminal of the MCU for digital sampling. The input storage capacitor C0 continuously collects the induced energy output from the AC-DC module 11, and the voltage VC0 across it gradually increases during the charging process. The undervoltage lockout module 32 monitors the VC0 voltage in real time and uses preset thresholds Vstart and Vstop as judgment thresholds: when VC0 is greater than Vstart, the output control signal closes the switch S3, the Buck conversion module 33 is powered on and starts, converting the energy on the input storage capacitor C0 into a stable low voltage and delivering it to the output storage capacitor C1; when VC0 is less than Vstop, the output control signal opens the switch S3, and the Buck conversion module 33 immediately stops working. Figure 3 As shown. The output storage capacitor C1 serves as the system's energy storage element, providing a stable power supply to the MCU. The output voltage comparison module 34 monitors the voltage VC1 of the output storage capacitor C1 in real time, using Vstop as the minimum operating threshold: when VC1 falls below Vstop, the MCU's operation is immediately shut down, and a warning signal is output to the undervoltage lockout module 32, causing the undervoltage lockout module 32 to open the control switch S3, and the system returns to a low-power standby state. This mechanism prevents the system from erroneously starting, malfunctioning, or experiencing a sharp drop in efficiency when there is insufficient energy or low voltage, ensuring that the active sampling unit 3 always operates stably within a safe voltage range.

[0033] To further explain, the passive sampling unit 4 includes a voltage doubler rectifier module 41, a Schmitt oscillator switch module 42, and a switch S4; The input terminals of the voltage doubler rectifier module 41 are all connected to the second output terminal of the acquisition switching unit 2. The first output terminal of the voltage doubler rectifier module 41 is connected to the input terminal of the switch S4. The second output terminal of the voltage doubler rectifier module 41 is connected to the input terminal of the Schmitt oscillation switch module 42. The output terminal of the Schmitt oscillation switch module 42 is connected to the control terminal of the switch S4. The output terminal of the switch S4 is connected to the sampling terminal of the RFID chip to output a sensing signal. The Schmitt oscillator switch module 42 is used to drive the switch S4 to switch on and off at a fixed period and duty cycle, periodically applying a DC voltage signal to the RFID chip.

[0034] like Figure 2As shown, the passive sampling unit 4 includes a voltage doubler rectifier module 41, a Schmitt trigger oscillator switch module 42, and a switch S4. The voltage doubler rectifier module 41 is composed of capacitors C3 and C4, diodes D1 and D2. The voltage doubler rectifier module 41 further rectifies and doubles the weak DC voltage input from the acquisition switching unit 2 to provide a usable weak power supply for subsequent circuits; the voltage doubler rectifier module 41 supplies power to both switch S4 and the Schmitt trigger oscillator switch module 42. The Schmitt trigger oscillation switch module 42 consists of a Schmitt trigger Schch, a resistor R2, and a charging / discharging capacitor C4. Stable oscillation is achieved through capacitor charging / discharging and trigger threshold switching, outputting a control signal with a fixed period and fixed duty cycle, such as a square wave signal VSch with a 5-second period and a 50% duty cycle. This signal directly drives switch S4 to perform periodic on / off actions, applying a weak DC voltage intermittently to the sampling terminal of the RFID chip. This allows the RFID chip to be periodically activated under low-energy conditions, achieving backscatter signal modulation and preventing continuous energy consumption that would render it inoperable. Figure 5 As shown.

[0035] To further explain, the current calculation unit 5 includes a current calculation module, the MCU, and the RFID; The MCU writes the sampled current data into the storage area of ​​the RFID chip via the SPI interface.

[0036] like Figure 2 As shown, the current calculation unit 5 consists of a current calculation module, an MCU, and an RFID chip, and is the core of the system's unified dual-mode data processing. In active sampling mode, after the MCU completes the ADC sampling of the current signal, it writes the digitized current data into the built-in storage area of ​​the RFID chip through the SPI serial communication interface, enabling the current data to be wirelessly read by the RFID reader. In passive sampling mode, the RFID chip outputs the backscatter signal characteristic parameters to the current calculation module, which performs weak signal decoding and current inversion, realizing unified processing and output of dual-mode data.

[0037] To further clarify, the MCU model is MSP430FR2433.

[0038] In a preferred embodiment, the low-power microcontroller MSP430FR2433 is selected. This device features extremely low static power consumption, wide power supply range, stable data storage, and support for SPI communication. It can stably complete ADC sampling, data processing, and storage writing operations with limited sensing energy, making it suitable for low-power system applications that do not require batteries.

[0039] To further clarify, the RFID chip is model EM4320.

[0040] In a preferred embodiment, the passive RFID chip EM4320 is selected. This chip does not require a built-in battery, can operate at extremely low supply voltage and microwatt-level power consumption, and its backscattered signal has a stable voltage correlation, making it suitable as a sensing and communication element in passive mode to realize wireless sensing and transmission of weak current signals, such as... Figure 6-7 As shown.

[0041] To further explain, the backscatter signal of the RFID chip includes a received signal strength indication and a phase, wherein the received signal strength indication changes positively with the supply voltage, and the phase changes negatively with the supply voltage.

[0042] Specifically, the backscatter signal of the EM4320 chip includes two key parameters: received signal strength indication and phase. Within the effective power supply range of 0.1V to 0.8V, the amplitude of the received signal strength indication increases with the increase of the supply voltage across the chip, showing a positive correlation; the phase value decreases with the increase of the supply voltage across the chip, showing an inverse correlation. Figure 8-9 As shown. This fixed physical characteristic allows changes in the supply voltage to be converted into regular changes in the characteristics of the wireless radio frequency signal, providing a basis for inverting the current through the wireless signal in passive mode.

[0043] To further explain, the RFID chip performs differential processing on the backscattered signals in both the on and off states of the sensing signal to extract the change in received signal strength caused by the supply voltage. With phase change and based on the change in the received signal strength indication. With phase change The current value of the measured conductor is obtained by inversion. : ; in, =-0.52.

[0044] To eliminate common-mode interference caused by ambient temperature, tag-reader distance, multipath reflection, and electromagnetic interference, the system performs differential processing on the backscattered signals in both the closed and open states of the sensor signal input switch S4 and the open sensor signal output switch S4. After removing interference components, only the RSSI change caused by the power supply voltage variation is retained. RSSI and phase change PHASE, such as Figure 10 As shown; the current calculation unit 5 calculates the above changes according to the fusion formula, and directly obtains the current value A_Ac of the conductor being measured. The formula is: ; in, =-0.52.

[0045] The above methods can significantly improve the anti-interference capability and calculation accuracy of weak current measurement, and realize reliable detection under low energy and low current conditions.

[0046] Furthermore, the functional units in the various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0047] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A battery-free adaptive dual-mode wire current sensor system, characterized in that, It includes a current acquisition unit (1), an acquisition switching unit (2), an active sampling unit (3), a passive sampling unit (4), and a current calculation unit (5); The input terminal of the current acquisition unit (1) is connected to the conductor under test, the output terminal of the current acquisition unit (1) is connected to the input terminal of the acquisition switching unit (2), the first output terminal of the acquisition switching unit (2) is connected to the active sampling unit (3), and the second output terminal of the acquisition switching unit (2) is connected to the passive sampling unit (4). The acquisition switching unit (2) is used to select and activate either the active sampling unit (3) or the passive sampling unit (4) according to the amplitude of the energy signal output by the current acquisition unit (1). The output terminals of the active sampling unit (3) and the passive sampling unit (4) are both connected to the current calculation unit (5), which is used to calculate the current value of the conductor under test based on the sampling data.

2. The battery-free adaptive dual-mode wire current sensor system according to claim 1, characterized in that, The current acquisition unit (1) includes a current transformer (CT) and an AC-DC module (11). The sensing end of the current transformer CT surrounds the conductor being measured, and the output end of the current transformer CT is connected to the input end of the AC-DC module (11). The AC-DC module (11) is used to convert the AC signal output by the current transformer CT into a DC voltage signal and output it to the acquisition switching unit (2).

3. The battery-free adaptive dual-mode wire current sensor system according to claim 2, characterized in that, The acquisition switching unit (2) includes an input voltage comparison module (21), switch S1 and switch S2; The input terminal of the input voltage comparison module (21) is connected to the output terminal of the AC-DC module (11). The first output terminal of the input voltage comparison module (21) is connected to the active sampling unit (3) through the switch S1. The second output terminal of the input voltage comparison module (21) is connected to the passive sampling unit (4) through the switch S2. The output terminal of switch S1 serves as the first output terminal of the acquisition switching unit (2), and the output terminal of switch S2 serves as the second output terminal of the acquisition switching unit (2). The input voltage comparison module (21) is set with a threshold voltage Vs. The input voltage comparison module (21) is used to receive the DC voltage output by the AC-DC module (11) and compare it with the threshold voltage Vs. When the DC voltage signal is greater than the threshold voltage Vs, a first control signal is output to control the switch S1 to close and the switch S2 to open. When the DC voltage signal is less than the threshold voltage Vs, a second control signal is output to control the switch S2 to close and the switch S1 to open.

4. The battery-free adaptive dual-mode wire current sensor system according to claim 3, characterized in that, The active sampling unit (3) includes an active sampling module (31), an undervoltage lockout module (32), a Buck conversion module (33), an output voltage comparison module (34), an input storage capacitor C0, an output storage capacitor C1, and a switch S3; The two ends of the active sampling module (31) are respectively connected to the first output end of the acquisition switching unit (2) and the ADC sampling end of the MCU. The active sampling module (31) is used to output the sensing signal to the MCU. The two ends of the input storage capacitor C0 are respectively connected to the first output terminal of the acquisition switching unit (2) and the input terminal of the switch S3. The output terminal of the switch S3 is connected to the input terminal of the Buck conversion module (33). The output terminal of the Buck conversion module (33) is connected to the power supply terminal of the MCU through the output storage capacitor C1. The output storage capacitor C1 is used to power the MCU. The detection terminal of the output voltage comparison module (34) is connected to the output storage capacitor C1, and the output terminal of the output voltage comparison module (34) is connected to the input terminal of the undervoltage lockout module (32) and the operating terminal of the MCU respectively. The detection terminal of the undervoltage lockout module (32) is connected to the input storage capacitor C0, and the output terminal of the undervoltage lockout module (32) is connected to the control terminal of the switch S3. The undervoltage lockout module (32) is configured with a start-up threshold voltage Vstart and a stop-down threshold voltage Vstop. The undervoltage lockout module (32) is used to receive the capacitor voltage VC0 of the input storage capacitor C0 and compare it with the start-up threshold voltage Vstart and the stop-down threshold voltage Vstop respectively. When the capacitor voltage VCO is greater than the start-up threshold voltage Vstart, the output control signal drives the switch S3 to close, and the Buck conversion module (33) is powered on and put into operation. When the capacitor voltage VCO is less than the turn-off threshold voltage Vstop, the output control signal drives the switch S3 to open, and the Buck conversion module (33) stops working; The output voltage comparison module (34) is set with the turn-off threshold voltage Vstop. The output voltage comparison module (34) is used to receive the capacitor voltage VC1 of the output storage capacitor C1 and compare it with the turn-off threshold voltage Vstop respectively. When the capacitor voltage VC1 is lower than the shutdown threshold voltage Vstop, the output voltage comparison module (34) shuts down the operation of the MCU and outputs a prompt signal to the undervoltage lockout module (32) to open the switch S3.

5. The battery-free adaptive dual-mode wire current sensor system according to claim 4, characterized in that, The passive sampling unit (4) includes a voltage doubler rectifier module (41), a Schmitt oscillator switch module (42), and a switch S4; The input terminals of the voltage doubler rectifier module (41) are all connected to the second output terminal of the acquisition switching unit (2). The first output terminal of the voltage doubler rectifier module (41) is connected to the input terminal of the switch S4. The second output terminal of the voltage doubler rectifier module (41) is connected to the input terminal of the Schmitt oscillator switch module (42). The output terminal of the Schmitt oscillator switch module (42) is connected to the control terminal of the switch S4. The output terminal of the switch S4 is connected to the sampling terminal of the RFID chip to output the sensing signal. The Schmitt oscillator switch module (42) is used to drive the switch S4 to switch on and off at a fixed period and duty cycle, and to periodically apply the DC voltage signal to the RFID chip.

6. The battery-free adaptive dual-mode wire current sensor system according to claim 5, characterized in that, The current calculation unit (5) includes a current calculation module, the MCU, and the RFID; The MCU writes the sampled current data into the storage area of ​​the RFID chip via the SPI interface.

7. The battery-free adaptive dual-mode wire current sensor system according to claim 6, characterized in that, The MCU model is MSP430FR2433.

8. A battery-free adaptive dual-mode wire current sensor system according to claim 6, characterized in that, The RFID chip is model EM4320.

9. A battery-free adaptive dual-mode wire current sensor system according to claim 8, characterized in that, The backscatter signal of the RFID chip includes a received signal strength indication and a phase, wherein the received signal strength indication changes positively with the supply voltage, and the phase changes negatively with the supply voltage.

10. A battery-free adaptive dual-mode wire current sensor system according to claim 9, characterized in that, The RFID chip performs differential processing on the backscattered signals under both connected and disconnected sensor states to extract the change in received signal strength caused by the power supply voltage. With phase change and based on the change in the received signal strength indication. With phase change The current value of the measured conductor is obtained by inversion. : ； in, =-0.52.

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