A small current induction power taking circuit and implementation method

Abstract

The application discloses a kind of small current induction power taking circuit and implementation method, including the following steps;Energy capture step, rectification protection step, standby power management and power supply step, voltage monitoring and charge-discharge protection step, low-power load control step, main standby power seamless switching step and industrial grade adaptation step.The application optimizes induction power taking module to improve weak magnetic field energy capture efficiency, breaks through the threshold of traditional CT power taking requiring large current, realizes stable power taking in wide current range (a few an to kilo-an level) full working condition;By adopting composite energy storage unit composed of super capacitor and auxiliary capacitor, the long-term standby power problem under small current condition is solved;By designing standby automatic switching module based on diode or gate logic and LDO voltage stabilizing, seamless switching of main and standby power supply is realized, and power supply continuity is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of online monitoring technology for power cables, specifically to a circuit and implementation method for small current induction power extraction. Background Technology

[0002] The large-scale development of the power Internet of Things (IoT) has created a demand for passive, maintenance-free, and stable power supply for edge monitoring devices under all operating conditions. In scenarios where mains power is not widely available, such as cable wells and cable tunnels, obtaining energy from the power cables themselves through sensing becomes the optimal solution.

[0003] Currently, the mainstream power extraction technology in the industry is based on conventional current transformers (CTs). However, this technology has inherent limitations: it has poor adaptability to operating conditions, can only work normally under high current conditions, has extremely weak ability to capture weak magnetic field energy in low current and light load scenarios, and has a high starting current threshold.

[0004] Furthermore, in existing power supply schemes, some devices rely solely on a main power supply. A power outage will cause core modules to cease operation, resulting in data loss and communication interruptions. Meanwhile, using ordinary capacitors for energy storage suffers from insufficient capacity, while battery backup faces drawbacks such as slow charging speed, short cycle life, and severe performance degradation at low temperatures. Existing main / backup switching circuits often suffer from large voltage drops, low efficiency, or lack of intelligent charge / discharge protection specific to supercapacitor characteristics. Moreover, the systems have high power consumption, weak anti-interference capabilities, and lack standardized industrial communication interfaces, making stable operation in complex industrial electromagnetic environments difficult. Summary of the Invention

[0005] To address these issues, the present invention provides a circuit and implementation method for low-current induction power extraction, thereby solving the problems of high system power consumption, weak anti-interference capability, lack of standardized industrial communication interface, and difficulty in stable operation in complex industrial electromagnetic environments in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A circuit and implementation method for small current induction power extraction, comprising the following steps;

[0008] Energy capture steps: Weak magnetic field energy is captured from the power cable through the inductive power extraction module and output induced alternating electrical energy;

[0009] Rectification and protection steps: The induced AC power is converted into DC power by the rectifier circuit of the rectifier protection module, and the DC power is triple protected by the limiting circuit, reverse connection protection circuit and surge protection circuit built into the rectifier protection module.

[0010] Backup power management and power supply steps: DC power processed by triple protection is transmitted to the first input terminal of the first DC-DC conversion module and the backup power automatic switching module respectively. The first DC-DC conversion module charges the supercapacitor energy storage module, and the backup power automatic switching module supplies power to the downstream load through its output terminal.

[0011] Voltage monitoring and charge / discharge protection steps: The voltage monitoring and protection module samples the voltage of the supercapacitor energy storage module in real time. When the sampled voltage reaches the preset overcharge threshold, its charging circuit is cut off; when the sampled voltage drops to the preset over-discharge threshold, its discharge circuit is cut off.

[0012] Low-power load management steps: The low-power main control module monitors the power supply status and backup power status in real time, and dynamically adjusts the working mode of the downstream loads according to the monitoring results, and shuts down unnecessary load modules to reduce the overall power consumption.

[0013] Seamless switching steps between primary and backup power supplies: When the backup power automatic switching module detects that the voltage at its first input terminal is lower than the voltage at its second input terminal, it automatically switches to power supply from the supercapacitor energy storage module via the second input terminal, and the switching process is uninterrupted.

[0014] Preferably, the inductive power harvesting module is made of a high-performance nanocrystalline material as the magnetic core to harvest power CT, which is used to capture small current and weak magnetic field energy.

[0015] Preferably, the rectifier protection module includes a diode full-bridge rectifier circuit, a varistor limiting circuit connected to the output terminal of the full-bridge rectifier circuit, a reverse connection protection diode connected in series with the downstream end of the limiting circuit, and a TVS transient suppression diode connected in parallel with the power supply path.

[0016] Preferably, the supercapacitor energy storage module includes a composite capacitor group consisting of two 25F supercapacitors and two 470uF auxiliary capacitors. An AONS32304 NMOS switch is connected in series in the charging and discharging path of the composite capacitor group, and the control terminal of the NMOS switch is connected to the output terminal of the voltage monitoring and protection module.

[0017] Preferably, the automatic backup power switching module includes a diode OR gate logic circuit and an LDO regulator. The first input terminal of the diode OR gate logic circuit is connected to the output of the rectifier protection module, the second input terminal is connected to the output of the supercapacitor energy storage module, and the common output terminal of the diode OR gate logic circuit is connected to the input terminal of the LDO regulator.

[0018] Preferably, the voltage monitoring and protection module includes a voltage divider sampling circuit and a hysteresis comparison circuit; the voltage divider sampling circuit consists of a first resistor R1, a second resistor R2 and a sampling capacitor C, wherein one end of the first resistor R1 is connected to the positive voltage node V_CAP of the supercapacitor energy storage module, the other end of the first resistor R1 is connected to one end of the second resistor R2 and one end of the sampling capacitor C, and the other end of the second resistor R2 and the other end of the sampling capacitor C are grounded;

[0019] The output voltage V_SAMPLE of the voltage divider sampling circuit is calculated by the formula V_SAMPLE = V_CAP × R2 / (R1+R2);

[0020] The hysteresis comparator circuit receives V_SAMPLE and compares it with a preset reference voltage V_REF. When V_SAMPLE exceeds V_REF, it determines that the overcharge threshold has been reached. When V_SAMPLE is lower than another V_REF, it determines that the over-discharge threshold has been reached, and outputs a charge / discharge control signal accordingly.

[0021] Preferably, the low-power main control module is an industrial-grade low-power MCU, which is configured with a sleep-wake-up working mode and dynamically adjusts the working mode of the downstream load according to the power consumption and backup power status.

[0022] Preferably, it also includes an industrial-grade adaptation step: integrating TVS transient suppression diodes and ESD electrostatic protection devices at the power input terminal and communication interface of the circuit for anti-interference protection, and realizing long-distance communication with external devices through a standard RS485 communication interface.

[0023] Preferably, the first DC-DC conversion module is used to charge the supercapacitor energy storage module, and also includes a second DC-DC conversion module. The input terminal of the second DC-DC conversion module is connected to the output terminal of the backup power automatic switching module, and is used to provide a stable operating voltage for the downstream load.

[0024] Preferably, the voltage monitoring and protection module performs real-time sampling and filtering of the positive terminal junction voltage of the composite capacitor bank through the 100KΩ sampling resistor and the sampling capacitor, and transmits the stable sampling voltage to the hysteresis comparison circuit. The hysteresis comparison algorithm accurately determines the overcharge and over-discharge states. When the voltage reaches a preset threshold, the NMOS switch is triggered to turn off the corresponding charging and discharging circuit to achieve overcharge and over-discharge protection. At the same time, it works with the Schottky diode connected in parallel on the power supply path to achieve secondary reverse connection protection.

[0025] The present invention has the following advantages: By optimizing the inductive power extraction module to improve the energy capture efficiency of weak magnetic fields, the present invention breaks through the threshold of traditional CT power extraction requiring large currents and achieves stable power extraction under all operating conditions in a wide current range (from a few amps to thousands of amps); by adopting a composite energy storage unit composed of supercapacitors and auxiliary capacitors, the problem of long-term backup power under low current conditions is solved.

[0026] By designing an automatic power switching module based on diode OR gate logic and LDO voltage regulation, seamless switching between primary and backup power supplies is achieved, ensuring power supply continuity.

[0027] An integrated voltage monitoring and protection module based on a hysteresis comparison algorithm is used to achieve precise overcharge and over-discharge protection for the energy storage unit.

[0028] By adopting a low-power main control module combined with an intelligent load management strategy, the power consumption of the whole machine is effectively reduced. It also integrates TVS, ESD protection devices and a standard RS485 communication interface, which greatly improves the adaptability and communication capability of the circuit in complex industrial environments. Attached Figure Description

[0029] To more intuitively illustrate the prior art and this application, exemplary drawings are provided below. It should be understood that the specific shapes and structures shown in the drawings should not generally be regarded as limiting conditions for implementing this application; for example, based on the technical concept disclosed in this application and the exemplary drawings, those skilled in the art are able to easily make conventional adjustments or further optimizations to the addition / reduction / classification, specific shapes, positional relationships, connection methods, size ratios, etc. of certain units (components).

[0030] Figure 1 This is a flowchart of a circuit and implementation method for small current induction power extraction according to the present invention;

[0031] Figure 2 This is a schematic diagram of the overall architecture of a circuit and implementation method for low-current induction power extraction according to the present invention.

[0032] Figure 3 This is a circuit diagram of the rectifier protection module in a circuit and implementation method for low-current induction power extraction according to the present invention.

[0033] Figure 4 This is a circuit diagram of the voltage monitoring and protection module in a low-current induction power extraction circuit and implementation method of the present invention.

[0034] Figure 5 This is a circuit diagram of the low-power main control module in the circuit and implementation method of a small current induction power extraction according to the present invention.

[0035] Figure 6This is a circuit diagram of the dual-channel DC-DC conversion module in a circuit and implementation method for low-current induction power extraction according to the present invention.

[0036] Figure 7 This is a circuit diagram of another part of the dual-channel DC-DC conversion module in the circuit and implementation method of a small current induction power extraction according to the present invention.

[0037] Figure 8 This is a circuit diagram of the industrial-grade adapter module in the circuit and implementation method of a small current induction power extraction according to the present invention. Detailed Implementation

[0038] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. It should be understood that these embodiments are merely for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Technical engineers in the field can make some non-essential improvements and adjustments to the present invention based on the above-described content. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Please see Figures 1-8 A circuit and implementation method for small current induction power extraction, comprising the following steps;

[0040] Energy capture steps: Weak magnetic field energy is captured from the power cable through the inductive power extraction module and output induced alternating electrical energy;

[0041] Rectification and protection steps: The induced AC power is converted into DC power by the rectifier circuit of the rectifier protection module, and the DC power is triple protected by the limiting circuit, reverse connection protection circuit and surge protection circuit built into the rectifier protection module.

[0042] Backup power management and power supply steps: DC power processed by triple protection is transmitted to the first input terminal of the first DC-DC conversion module and the backup power automatic switching module respectively. The first DC-DC conversion module charges the supercapacitor energy storage module, and the backup power automatic switching module supplies power to the downstream load through its output terminal.

[0043] Voltage monitoring and charge / discharge protection steps: The voltage monitoring and protection module samples the voltage of the supercapacitor energy storage module in real time. When the sampled voltage reaches the preset overcharge threshold, its charging circuit is cut off; when the sampled voltage drops to the preset over-discharge threshold, its discharge circuit is cut off.

[0044] Low-power load management steps: The low-power main control module monitors the power supply status and backup power status in real time, and dynamically adjusts the working mode of the downstream loads according to the monitoring results, and shuts down unnecessary load modules to reduce the overall power consumption.

[0045] Seamless switching steps between primary and backup power supplies: When the backup power automatic switching module detects that the voltage at its first input terminal is lower than the voltage at its second input terminal, it automatically switches to power supply from the supercapacitor energy storage module via the second input terminal, and the switching process is uninterrupted.

[0046] This embodiment provides a low-current inductive power supply circuit for powering an online temperature monitoring device inside a power cable well. The circuit mainly includes an inductive power supply module, a rectification and protection module, a supercapacitor energy storage module, a backup power automatic switching module, a voltage monitoring and protection module, a low-power main control module, a dual-channel DC-DC converter module, and an industrial-grade adapter module.

[0047] 1. Circuit structure and connection relationships

[0048] Please refer to the attached diagram. The output terminal of the inductive power supply module is connected to the input terminal of the rectifier protection module. The output terminal of the rectifier protection module is connected to the first input terminal of the automatic backup power switching module and the input terminal of the first DC-DC conversion circuit in the dual-channel DC-DC conversion module. The output terminal of the first DC-DC conversion circuit is connected to the charging input terminal of the supercapacitor energy storage module. The voltage sampling terminal of the supercapacitor energy storage module is connected to the input terminal of the voltage monitoring and protection module, and its discharge output terminal is connected to the second input terminal of the automatic backup power switching module. The output terminal of the automatic backup power switching module supplies power to the downstream monitoring equipment through the second DC-DC conversion circuit. The control signal output terminal of the voltage monitoring and protection module is connected to the charging and discharging control terminal of the supercapacitor energy storage module. The low-power main control module has bidirectional communication connections with the control terminals of the voltage monitoring and protection module, the dual-channel DC-DC conversion module, and the downstream load. The RS485 communication interface in the industrial-grade adapter module is connected to the communication terminal of the low-power main control module, and the TVS and ESD protection devices are connected in parallel to the power input terminal and the communication interface of the circuit.

[0049] 2. Detailed Structure and Working Process of Core Modules

[0050] (1) Inductive power supply module and rectifier protection module

[0051] In this embodiment, the inductive power-harvesting module uses a high-performance nanocrystalline magnetic core, and the power-harvesting CT is manufactured through optimized coil winding technology. Referring to the attached diagram, when a 5A current flows through the power cable, the power-harvesting CT outputs alternating current. This power first enters the rectifier protection module, where diodes D1-D4 form a full-bridge rectifier circuit to convert AC to DC. Simultaneously, a limiting circuit composed of varistor RV1, a reverse connection protection circuit composed of diode D5, and a surge protection circuit composed of TVS diode TVS1 work together to provide triple protection for the subsequent circuits, effectively suppressing surge impacts at the moment of power-on.

[0052] (2) Supercapacitor energy storage module and voltage monitoring and protection module

[0053] The rectified DC power is stepped down to 5.4V through the first DC-DC converter circuit (model: LTC3622) to charge the supercapacitor energy storage module. In this embodiment, the energy storage module consists of two 25F / 2.7V supercapacitors (C1, C2) connected in series and two 470uF auxiliary capacitors (C3, C4) connected in parallel, with the positive terminal connected to the voltage node V_CAP.

[0054] Please refer to the attached diagram. The voltage monitoring and protection module includes a voltage divider sampling circuit and a hysteresis comparison circuit. The voltage divider sampling circuit consists of a first resistor R1, a second resistor R2, and a sampling capacitor C. Specifically, one end of the first resistor R1 is connected to the positive voltage node V_CAP of the supercapacitor energy storage module; the other end of the first resistor R1 is connected to one end of the second resistor R2 and one end of the sampling capacitor C; the other ends of the second resistor R2 and the sampling capacitor C are grounded together. In this embodiment, R1 is 100KΩ, R2 is 10KΩ, and the sampling capacitor C is 0.1uF. The output voltage V_SAMPLE of the voltage divider sampling circuit is calculated using the formula V_SAMPLE = V_CAP × R2 / (R1+R2). When V_CAP is 5.4V, V_SAMPLE = 5.4 × 10 / (100+10) = 0.49V.

[0055] The voltage V_SAMPLE, a voltage divider sampled from the supercapacitor, is fed into a hysteresis comparator circuit consisting of comparator U1 (model: LM393). The hysteresis comparator circuit has a preset reference voltage V_REF. In this embodiment, the preset overcharge reference voltage V_REF_CH is 0.49V, and the preset over-discharge reference voltage V_REF_DIS is 0.245V. When V_SAMPLE exceeds 0.49V, the hysteresis comparator output flips, turning off the AONS32304 NMOS switch Q1 connected in series with the supercapacitor, stopping charging and achieving overcharge protection. During discharge, when V_SAMPLE drops below 0.245V, the hysteresis comparator activates again, shutting off the discharge circuit and achieving over-discharge protection. Schottky diode D14 is used for secondary reverse connection protection.

[0056] (3) Automatic power switching module and low-power main control module

[0057] The core of the automatic power switching module is a diode or gate circuit. The main power supply path (from the rectifier module) is connected in series with Schottky diode D6, and the supercapacitor backup power supply path (from V_CAP) is connected in series with Schottky diode D7. The two paths are combined and connected to the input of an LDO regulator (model: TPS7A4901). Under normal operation, the main power supply voltage (5.4V) is higher than the backup power voltage, D6 conducts, and the main power supply powers the subsequent stages while simultaneously charging the supercapacitor. When the main power supply is insufficient due to a sudden drop in line current below 3A, its voltage drops. When it falls below the backup power voltage (e.g., 4.5V), D7 automatically conducts, seamlessly switching to the supercapacitor to power the subsequent stages without interruption. The LDO regulator outputs a stable 3.3V voltage. The low-power main control module uses an STM32L0 series MCU. After detecting a main power failure, it enters a sleep-wake-up mode, wakes up once every 1 second, collects and stores temperature data, and shuts down unnecessary communication modules at other times, keeping the average power consumption of the whole machine at the microamp level, which greatly extends the backup power time.

[0058] (4) Industrial-grade adapter module

[0059] To adapt to the complex electromagnetic environment inside cable wells, this circuit incorporates a TVS diode (model: SMBJ6.0CA) and an ESD protection diode (model: ESD5V0L1B) in parallel on the power input side, effectively suppressing ±8KV electrostatic discharge and transient surges. Simultaneously, the low-power main control module provides a communication interface via a standard RS485 transceiver (model: MAX485), enabling stable and reliable data communication with the master station system located hundreds of meters away.

[0060] In summary, the low-current sensing power supply circuit of the present invention, through the collaborative work of multiple modules and refined design, successfully achieves stable power supply, efficient energy storage, seamless backup power switching and intelligent power consumption management under low current conditions of a few amperes, providing a highly reliable and maintenance-free power supply solution for edge devices of the power Internet of Things.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A circuit and implementation method for small current induction power extraction, characterized in that, Includes the following steps; Energy capture steps: Weak magnetic field energy is captured from the power cable through the inductive power extraction module and output induced alternating electrical energy; Rectification and protection steps: The induced AC power is converted into DC power by the rectifier circuit of the rectifier protection module, and the DC power is triple protected by the limiting circuit, reverse connection protection circuit and surge protection circuit built into the rectifier protection module. Backup power management and power supply steps: DC power processed by triple protection is transmitted to the first input terminal of the first DC-DC conversion module and the backup power automatic switching module respectively. The first DC-DC conversion module charges the supercapacitor energy storage module, and the backup power automatic switching module supplies power to the downstream load through its output terminal. Voltage monitoring and charge / discharge protection steps: The voltage monitoring and protection module samples the voltage of the supercapacitor energy storage module in real time. When the sampled voltage reaches the preset overcharge threshold, its charging circuit is cut off; when the sampled voltage drops to the preset over-discharge threshold, its discharge circuit is cut off. Low-power load management steps: The low-power main control module monitors the power supply status and backup power status in real time, and dynamically adjusts the working mode of the downstream loads according to the monitoring results, and shuts down unnecessary load modules to reduce the overall power consumption. Seamless switching steps between primary and backup power supplies: When the backup power automatic switching module detects that the voltage at its first input terminal is lower than the voltage at its second input terminal, it automatically switches to power supply from the supercapacitor energy storage module via the second input terminal, and the switching process is uninterrupted.

2. The circuit and implementation method for small current induction power extraction according to claim 1, characterized in that, The inductive power harvesting module uses a high-performance nanocrystalline material as the magnetic core to make a power harvesting CT, which is used to capture small current and weak magnetic field energy.

3. The circuit and implementation method for small current induction power extraction according to claim 2, characterized in that, The rectifier protection module includes a diode full-bridge rectifier circuit, a varistor limiting circuit connected to the output terminal of the full-bridge rectifier circuit, a reverse connection protection diode connected in series with the back end of the limiting circuit, and a TVS transient suppression diode connected in parallel with the power supply path.

4. The circuit and implementation method for small current induction power extraction according to claim 3, characterized in that, The supercapacitor energy storage module includes a composite capacitor group consisting of two 25F supercapacitors and two 470uF auxiliary capacitors. An AONS32304 NMOS switch is connected in series in the charging and discharging path of the composite capacitor group. The control terminal of the NMOS switch is connected to the output terminal of the voltage monitoring and protection module.

5. The circuit and implementation method for small current induction power extraction according to claim 4, characterized in that, The automatic backup power switching module includes a diode OR gate logic circuit and an LDO regulator. The first input terminal of the diode OR gate logic circuit is connected to the output of the rectifier protection module, the second input terminal is connected to the output of the supercapacitor energy storage module, and the common output terminal of the diode OR gate logic circuit is connected to the input terminal of the LDO regulator.

6. The circuit and implementation method for small current induction power extraction according to claim 5, characterized in that, The voltage monitoring and protection module includes a voltage divider sampling circuit and a hysteresis comparison circuit; the voltage divider sampling circuit consists of a first resistor R1, a second resistor R2 and a sampling capacitor C, wherein one end of the first resistor R1 is connected to the positive voltage node V_CAP of the supercapacitor energy storage module, the other end of the first resistor R1 is connected to one end of the second resistor R2 and one end of the sampling capacitor C, and the other end of the second resistor R2 and the other end of the sampling capacitor C are grounded. The output voltage V_SAMPLE of the voltage divider sampling circuit is calculated by the formula V_SAMPLE= V_CAP×R2 / (R1+R2); The hysteresis comparator circuit receives V_SAMPLE and compares it with a preset reference voltage V_REF. When V_SAMPLE exceeds V_REF, it determines that the overcharge threshold has been reached. When V_SAMPLE is lower than another V_REF, it determines that the over-discharge threshold has been reached, and outputs a charge / discharge control signal accordingly.

7. The circuit and implementation method for small current induction power extraction according to claim 6, characterized in that, The low-power main control module uses an industrial-grade low-power MCU. The MCU is configured with a sleep-wake-up working mode and dynamically adjusts the working mode of the downstream load according to the power consumption and backup power status.

8. The circuit and implementation method for small current induction power extraction according to claim 7, characterized in that, It also includes industrial-grade adaptation steps: TVS transient suppression diodes and ESD electrostatic protection devices are integrated at the power input and communication interface of the circuit for anti-interference protection, and long-distance communication with external devices is achieved through a standard RS485 communication interface.

9. The circuit and implementation method for small current induction power extraction according to claim 1, characterized in that, The first DC-DC conversion module is used to charge the supercapacitor energy storage module, and also includes a second DC-DC conversion module. The input terminal of the second DC-DC conversion module is connected to the output terminal of the backup power automatic switching module, and is used to provide a stable operating voltage for the downstream load.

10. The circuit and implementation method for small current induction power extraction according to claim 4, characterized in that, The voltage monitoring and protection module performs real-time sampling and filtering of the positive terminal junction voltage of the composite capacitor bank through the 100KΩ sampling resistor and the sampling capacitor. The stable sampling voltage is transmitted to the hysteresis comparison circuit, which accurately determines the overcharge and over-discharge states through the hysteresis comparison algorithm. When the voltage reaches the preset threshold, the NMOS switch is triggered to turn off the corresponding charging and discharging circuit to achieve overcharge and over-discharge protection. At the same time, it works with the Schottky diode connected in parallel to the power supply path to achieve secondary reverse connection protection.

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