A protection method for industrial switch PoE power supply port

Abstract

The application discloses a protection method for an industrial switch PoE power supply port, which comprises the following steps: firstly, a first-stage protection circuit is connected in parallel to the PoE power supply port to discharge lightning current surge energy; secondly, a second-stage protection circuit is connected in parallel to the end of the first-stage protection circuit, voltage sampling is performed, the number of connected voltage-dependent resistors is adjusted according to the detected voltage surge intensity, and then the discharge intensity is adjusted; and thirdly, a third-stage protection circuit is arranged at the end of the second-stage protection circuit to further clamp the residual voltage to a safe level. The application firstly discharges lightning current surge energy through the first-stage protection circuit, then uses a self-adaptive control module to determine the surge intensity in real time and dynamically adjusts the combination of voltage-dependent resistors, and finally uses a bidirectional TVS to further clamp the residual voltage to a safe level, so that the protection precision and the service life of the device are improved, and the adaptability of the overall circuit to surges with different intensities is enhanced.

Description

Technical Field

[0001] This invention relates to the field of communication equipment protection technology, and in particular to a protection method for the PoE power supply port of an industrial switch. Background Technology

[0002] Industrial switches are often deployed outdoors or in complex electromagnetic environments. Their PoE ports, while transmitting data, also need to power remote devices (IP cameras, wireless APs), making them more susceptible to transient overvoltages such as lightning surges. Traditional PoE port protection circuits often employ simple TVS diodes or simple multi-stage protection structures. These methods often suffer from mismatched response speeds, high residual voltage, and limited lifespan. In particular, insufficient energy coordination and distribution among multi-stage protection devices can easily lead to premature failure of certain stages, reducing overall protection reliability. Furthermore, traditional circuits lack adaptive adjustment capabilities and cannot dynamically adjust the discharge path according to surge intensity, resulting in poor performance when dealing with surges of varying strengths. Therefore, this solution proposes a protection method for the PoE power supply ports of industrial switches to address these issues. Summary of the Invention

[0003] The purpose of this invention is to provide a protection method for the PoE power supply port of an industrial switch, so as to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a protection method for the PoE power supply port of an industrial switch, the protection method comprising the following steps: The first step is to connect a first-level protection circuit in parallel at the PoE power supply port to discharge the surge energy of lightning current. The second step is to connect a second-level protection circuit in parallel at the end of the first-level protection circuit. By sampling the voltage, the number of varistor connections is adjusted according to the detected voltage surge intensity, thereby adjusting the discharge intensity. When a surge voltage rise edge is detected to be flat and the amplitude does not exceed the equipment damage value, only a single varistor is connected; When a surge voltage is detected to rise rapidly in a short period of time and the amplitude exceeds the damage value of the equipment, multiple varistors are connected at the same time. The third step is to install a third-level protection circuit at the end of the second-level protection circuit to further clamp the residual voltage to a safe level.

[0005] Preferably, the first-stage protection circuit is constructed from a gas discharge tube (GDT) and is connected to the PoE power supply port in parallel.

[0006] Preferably, the second-level protection circuit consists of an adjustable transient suppression unit and an adaptive control module; The adjustable transient suppression unit consists of a combination of varistor and a series-connected controllable switch; The adaptive control module is used to detect the amplitude and waveform of the surge voltage, and to adjust the number of varistor connected in the varistor combination by controlling the conduction state of the controllable switches in the controllable switch combination.

[0007] Preferably, the varistor assembly includes varistor MOV1 and varistor MOV2, and the controllable switch assembly includes switch K1 and switch K2, wherein switch K1 is connected in series with varistor MOV1, and switch K2 is connected in series with varistor MOV2.

[0008] Preferably, the adaptive control module is connected to the control terminal of the adjustable transient suppression unit, and dynamically adjusts the varistor combination according to the surge characteristics to perform multi-level energy coordination and adaptive protection.

[0009] Preferably, the adaptive control module consists of a voltage sampling circuit, a waveform recognition circuit, and a logic control unit; The voltage sampling circuit monitors the voltage change rate at the end port of the first-level protection circuit in real time. The waveform recognition circuit determines the surge type based on the voltage rise time. The logic control unit outputs a control signal to the controllable switch combination based on the judgment result. The controllable switch combination uses solid-state relays.

[0010] Preferably, the third-level protection circuit is composed of a TVS diode array, which is connected in parallel to the end of the second-level protection circuit.

[0011] Preferably, the TVS diode array is a bidirectional TVS, which protects the PoE differential data line and the DC power line respectively.

[0012] Preferably, a time-delay inductor is connected in parallel between the conducting lines connecting the first-level protection circuit, the second-level protection circuit, and the third-level protection circuit, in order to achieve inter-level decoupling and time-delay coordination among the first-level protection circuit, the second-level protection circuit, and the third-level protection circuit.

[0013] Preferably, the delay inductor is a wire-wound inductor.

[0014] The technical effects and advantages of this invention are as follows: When protecting the PoE power supply port of a switch for outdoor use, this invention first discharges the surge energy of lightning current through a first-level protection circuit. Then, the adaptive control module judges the surge intensity in real time and dynamically adjusts the combination of varistor resistors. Finally, a bidirectional TVS is used to further clamp the residual voltage to a safe level. This protection setup not only improves the protection accuracy and device lifespan, but also enhances the overall circuit's adaptability to surges of different intensities. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating the implementation of the operation method of the present invention.

[0016] Figure 2 This is a block diagram of the circuit structure of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0018] This invention provides, for example Figure 1 The method for protecting the PoE power supply port of an industrial switch, as shown, includes the following steps: The first step is to connect a first-level protection circuit in parallel to the PoE power supply port. The first-level protection circuit is constructed by gas discharge tubes (GDTs) and is connected to the PoE power supply port in parallel. It should be noted that the PoE power supply port of an industrial switch can transmit data and power simultaneously via Ethernet cable. A gas discharge tube (GDT) is an overvoltage protection device that operates based on the principle of gas discharge. In this solution, it is used in parallel with the PoE power supply port. The GDT can quickly discharge most of the energy to ground in the face of extremely high-energy lightning surges, thus forming the first level of circuit protection. The gas discharge tube (GDT) includes the following states: Normal state (insulation state): Under normal operating voltage, the inert gas inside the GDT does not ionize, exhibiting extremely high impedance (typically in the GΩ range), equivalent to an open circuit. At this time, only microampere-level leakage current flows, having no effect on the protected circuit.

[0019] Breakdown discharge state (protection state): When a transient overvoltage occurs on the line and the voltage exceeds the breakdown voltage of the GDT, the strong electric field will cause the gas between the electrodes to undergo avalanche ionization, forming plasma. This allows the GDT to change from high impedance to extremely low impedance (below 1Ω) in an extremely short time (nanosecond to microsecond), instantly discharging the huge surge current to ground.

[0020] Recovery State (Extinguished Arc State): After the overvoltage disappears, the line voltage returns to normal. When the voltage drops below the arc sustaining voltage of the GDT, the gas discharge stops, and the GDT returns from a conductive state to a high-impedance insulating state, waiting for the next operation.

[0021] The second step is to connect a second-level protection circuit in parallel at the end of the first-level protection circuit. By sampling the voltage, the number of varistor connections is adjusted according to the detected voltage surge intensity, thereby adjusting the discharge intensity. When a surge voltage rise edge is detected to be flat and the amplitude does not exceed the equipment damage value, only a single varistor is connected; When a surge voltage is detected to rise rapidly in a short period of time and the amplitude exceeds the damage value of the equipment, multiple varistors are connected at the same time. It should be noted that surge voltage, also known as transient overvoltage, surge, or voltage spike, refers to an instantaneous pulse in a circuit that has an extremely short duration (from nanoseconds to milliseconds) but an amplitude far exceeding the normal operating voltage. The voltage value of surge voltage is several times, tens of times, or even tens of thousands of times that of normal operating voltage, the duration is in the range of microseconds to milliseconds, and it carries enormous energy.

[0022] Specifically, the second-level protection circuit consists of an adjustable transient suppression unit and an adaptive control module; The adjustable transient suppression unit consists of a combination of varistors and a series-connected controllable switch combination. The varistor combination includes varistor MOV1 and varistor MOV2, and the controllable switch combination includes switch K1 and switch K2. Switch K1 is connected in series with varistor MOV1, and switch K2 is connected in series with varistor MOV2. The adaptive control module is used to detect the amplitude and waveform of surge voltage, and adjusts the number of varistor connected in the varistor combination by controlling the conduction state of the controllable switches in the controllable switch combination. The adaptive control module is connected to the control terminal of the adjustable transient suppression unit and dynamically adjusts the varistor combination according to the surge characteristics to perform multi-level energy coordination and adaptive protection.

[0023] It should be noted that a varistor is a voltage-limiting overvoltage protection device, composed of a polycrystalline ceramic body made up of many tiny zinc oxide grains. Each grain and its grain boundary layer are equivalent to a Zener diode. Countless such micro-diodes are connected in series and parallel to form a macroscopic varistor. The operation of a varistor is based on the Zener breakdown effect of the grain boundary layer, including the following states: Normal state (low voltage): When the voltage applied across the two ends is lower than its threshold voltage, the grain boundary layer is in a high impedance state, and only microampere-level leakage current passes through, which is equivalent to an insulator. Operating state (high voltage): When the applied voltage exceeds its threshold (varistor voltage), the strong electric field causes Zener breakdown of the grain boundary layer, the micro diode quickly conducts, and the impedance of the varistor drops sharply (nanosecond level), forming a low-resistance path to discharge the instantaneous large current to ground, thereby limiting the port voltage to a relatively fixed level. Recovery state: When the surge voltage disappears and the line voltage returns to normal, the varistor will automatically recover from the breakdown state to the high resistance state.

[0024] Furthermore, the adaptive control module consists of a voltage sampling circuit, a waveform recognition circuit, and a logic control unit; The voltage sampling circuit monitors the voltage change rate at the end port of the first-level protection circuit in real time. The waveform recognition circuit determines the surge type based on the voltage rise time. The logic control unit outputs a control signal to the controllable switch combination based on the judgment result. The controllable switch combination uses solid-state relays. The adaptive control module judges the surge intensity in real time and dynamically adjusts the varistor combination, which not only improves the protection accuracy and device life, but also enhances the overall circuit's adaptability to surges of different intensities.

[0025] Solid-state relays are a new type of contactless switching device composed entirely of solid-state electronic components (optocouplers, transistors, thyristors, power MOSFETs). They utilize the electromagnetic induction characteristics (photoelectric and magnetoelectric) of electronic components to achieve isolation and control between input and output. Solid-state relays have no moving parts, so they are less prone to wear, have a longer service life, and are more resistant to external shocks and vibrations. Their switching speed is typically in the microsecond range, much faster than the millisecond response time of electromagnetic relays. At the same time, solid-state relays require less power when inputting control signals, making them suitable for low-power circuits. They also protect control circuits through electrical isolation between input and output.

[0026] The voltage sampling circuit monitors the port voltage at the end of the first-stage protection circuit (a critical node after the GDT and before the varistor) in real time. A high voltage change rate (dV / dt) means the voltage spikes in a very short time; a low voltage change rate means the voltage rises over a relatively long time (microseconds to milliseconds). The waveform recognition circuit receives the voltage signal from the sampling circuit and analyzes the rise time of the voltage waveform, with an internally preset judgment threshold. The logic control unit receives the judgment result from the waveform recognition circuit and performs controllable switch combination on / off control according to the preset protection strategy.

[0027] The third step is to set up a third-level protection circuit at the end of the second-level protection circuit to further clamp the residual voltage to a safe level and limit the residual voltage of the PoE power supply port to the range that the internal circuit of the switch can withstand. The third-level protection circuit is composed of a TVS diode array, which is connected in parallel at the end of the second-level protection circuit. The TVS diode array adopts bidirectional TVS to protect the PoE differential data line and the DC power line respectively.

[0028] It's important to note that a TVS diode array is a device that integrates multiple TVS diodes onto a single chip, specifically designed to protect multiple data / signal lines. A bidirectional TVS diode is a special type of TVS that provides protection against overvoltages in both positive and negative directions. The most common implementation involves connecting two unidirectional TVS diodes in series back-to-back; when a surge occurs, one unidirectional TVS diode breaks down in reverse (avalanche mode), while the other conducts in the forward direction. Regardless of the voltage direction, the entire device exhibits a breakdown characteristic, clamping the voltage below a safe level. Bidirectional TVS diodes provide symmetrical protection with equal or very close clamping voltages to both positive and negative pulses, eliminating the need to distinguish between positive and negative terminals during circuit installation, thus simplifying design and installation.

[0029] Specifically, delay inductors are connected in parallel between the conductive lines connecting the first-level protection circuit, the second-level protection circuit, and the third-level protection circuit. These inductors are used to achieve inter-level decoupling and delay coordination among the first-level protection circuit, the second-level protection circuit, and the third-level protection circuit. The delay inductors are wire-wound inductors that absorb residual surge current, limit the residual voltage at the port to the range that the internal circuitry of the switch can withstand, delay the surge rise time, ensure that the preceding circuitry operates first, and achieve graded energy discharge.

[0030] It should be noted that wire-wound inductors are the most basic and common type of inductor in electronic circuits. Their structure consists of a conductor and a magnetic core. The conductor is made of copper enameled wire, and the thickness of the enameled wire determines the current it can handle. The magnetic core is the core component that determines the inductor's performance and application. Wire-wound inductors are mainly divided into two categories based on the type of magnetic core: Air-core inductor: The coil has no magnetic core, or is a non-magnetic support frame. Air-core inductors have low inductance and no magnetic saturation problem, but the magnetic field will diverge. Magnetic-core inductor: The coil is wound on a magnetic material (ferrite, magnetic powder core, iron-silicon-aluminum). Magnetic-core inductors increase inductance and concentrate the magnetic flux. However, they are susceptible to magnetic saturation—when the current is too high, the permeability of the magnetic core drops sharply, causing a sudden decrease in inductance.

[0031] The operation of a wire-wound inductor is based on the law of electromagnetic induction. When current flows through the coil, a magnetic field is generated. When the current changes, the magnetic field also changes. This changing magnetic field generates an induced electromotive force (reverse voltage) to oppose the change in current.

[0032] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A protection method for the PoE power supply port of an industrial switch, characterized in that, The protection method includes the following steps: The first step is to connect a first-level protection circuit in parallel at the PoE power supply port to discharge the surge energy of lightning current. The second step is to connect a second-level protection circuit in parallel at the end of the first-level protection circuit. By sampling the voltage, the number of varistor connections is adjusted according to the detected voltage surge intensity, thereby adjusting the discharge intensity. When a surge voltage rise edge is detected to be flat and the amplitude does not exceed the equipment damage value, only a single varistor is connected; When a surge voltage is detected to rise rapidly in a short period of time and the amplitude exceeds the damage value of the equipment, multiple varistors are connected at the same time. The second-level protection circuit consists of an adjustable transient suppression unit and an adaptive control module; The adjustable transient suppression unit consists of a combination of varistors and a series-connected controllable switch combination. The varistor combination includes varistor MOV1 and varistor MOV2, and the controllable switch combination includes switch K1 and switch K2. Switch K1 is connected in series with varistor MOV1, and switch K2 is connected in series with varistor MOV2. The adaptive control module is used to detect the amplitude and waveform of the surge voltage, and adjusts the number of varistor connected in the varistor combination by controlling the conduction state of the controllable switches in the controllable switch combination. The adaptive control module is connected to the control terminal of the adjustable transient suppression unit and dynamically adjusts the varistor combination according to the surge characteristics to perform multi-level energy coordination and adaptive protection. The adaptive control module consists of a voltage sampling circuit, a waveform recognition circuit, and a logic control unit. The voltage sampling circuit monitors the voltage change rate at the end port of the first-level protection circuit in real time. The waveform recognition circuit determines the surge type based on the voltage rise time. The logic control unit outputs a control signal to the controllable switch combination based on the judgment result. The controllable switch combination uses solid-state relays. The third step is to install a third-level protection circuit at the end of the second-level protection circuit to further clamp the residual voltage to a safe level.

2. The protection method for the PoE power supply port of an industrial switch according to claim 1, characterized in that, The first-stage protection circuit is constructed from gas discharge tubes (GDTs) and is connected to the PoE power supply port in parallel.

3. The protection method for the PoE power supply port of an industrial switch according to claim 1, characterized in that, The third-level protection circuit is composed of a TVS diode array, which is connected in parallel to the end of the second-level protection circuit.

4. A protection method for a PoE power supply port of an industrial switch according to claim 3, characterized in that, The TVS diode array uses bidirectional TVS to protect the PoE differential data line and the DC power line respectively.

5. A protection method for a PoE power supply port of an industrial switch according to claim 1, characterized in that, A time-delay inductor is connected in parallel between the conducting lines of the first-level protection circuit, the second-level protection circuit, and the third-level protection circuit to achieve inter-level decoupling and time-delay coordination.

6. A protection method for a PoE power supply port of an industrial switch according to claim 5, characterized in that, The delay inductor is a wire-wound inductor.

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