Protection method for PoE power supply port of industrial switch

Abstract

The invention discloses a protection method for a PoE power supply port of an industrial switch, and the method comprises the steps: firstly, connecting a first-stage protection circuit in parallel at the PoE power supply port, and discharging lightning stroke type current surge energy through the first-stage protection circuit; 2, connecting a second-stage protection circuit at the tail end of the first-stage protection circuit in parallel, and adjusting the number of switched-on piezoresistors according to the detected voltage surge intensity through voltage sampling so as to adjust the discharge intensity; and 3, arranging a third-stage protection circuit at the tail end of the second-stage protection circuit, and further clamping the residual voltage to a safety level. Lightning stroke type current surge energy is discharged through the first-stage protection circuit firstly, then the surge intensity is judged in real time through the self-adaptive control module, the piezoresistor combination is dynamically adjusted, and finally the residual voltage is further clamped to the safety level by using the bidirectional TVS, so that the protection precision is improved, the service life of a device is prolonged, and the reliability of the device is improved. And the adaptability of the whole circuit to surges with different intensities is also enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of communication equipment protection, in particular to a protection method for a PoE power supply port of an industrial switch. BACKGROUND

[0002] Industrial switches are often deployed outdoors or in complex electromagnetic environments. Their PoE ports not only transmit data but also supply power to remote devices (IP cameras, wireless APs), so they are more vulnerable to lightning surge transient overvoltage. Traditional PoE port protection circuits mostly use simple TVS diodes or simple multi-stage protection structures. Such protection methods often have problems such as mismatched response speed, high residual voltage, and limited service life. In particular, the lack of energy coordination between multi-stage protection devices can easily lead to premature damage to some devices, reducing overall protection reliability. In addition, traditional circuits lack adaptive adjustment capabilities and cannot dynamically adjust the discharge path according to the surge intensity, which performs poorly when dealing with surges of different intensities. In view of this, the present application proposes a protection method for a PoE power supply port of an industrial switch to solve the above problems. SUMMARY

[0003] The present application aims to provide a protection method for a PoE power supply port of an industrial switch to solve the problems raised in the background.

[0004] To achieve the above-mentioned purpose, the present application provides the following technical solution: a protection method for a PoE power supply port of an industrial switch, comprising the following operation steps: First, a first-stage protection circuit is connected in parallel to the PoE power supply port to discharge lightning current surge energy through the first-stage protection circuit; Second, a second-stage protection circuit is connected in parallel to the end of the first-stage protection circuit, and the number of connected varistors is adjusted according to the detected voltage surge intensity through voltage sampling, thereby adjusting the discharge intensity; When the rising edge of the surge voltage is smooth and the amplitude does not exceed the device damage value, only a single varistor is turned on; When the surge voltage rises rapidly for a short time and the amplitude exceeds the device damage value, multiple varistors are turned on at the same time; Third, a third-stage protection circuit is set at the end of the second-stage protection circuit to further clamp the residual voltage to a safe level.

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

[0006] Preferably, the second-stage protection circuit is composed of an adjustable transient suppression unit and an adaptive control module. The adjustable transient suppression unit is composed of a combination of voltage-dependent resistors and a combination of controllable switches in series; The adaptive control module is used for detecting the amplitude and waveform of the surge voltage, and adjusting the number of voltage-dependent resistors in the combination of voltage-dependent resistors by controlling the conduction state of the controllable switches in the combination of controllable switches.

[0007] Preferably, the combination of voltage-dependent resistors includes voltage-dependent resistors MOV1 and MOV2, and the combination of controllable switches includes switches K1 and K2, the switch K1 is in series with the voltage-dependent resistor MOV1, and the switch K2 is in series with the voltage-dependent resistor MOV2.

[0008] Preferably, the adaptive control module is connected to the control end of the adjustable transient suppression unit, and dynamically adjusts the combination of voltage-dependent resistors according to the surge characteristics to perform multi-stage energy coordination and adaptive protection.

[0009] Preferably, the adaptive control module is composed of a voltage sampling circuit, a waveform identification circuit and a logic control unit; The voltage sampling circuit monitors the voltage change rate of the end port of the first protection circuit in real time, the waveform identification circuit judges the surge type according to the voltage rise time, and the logic control unit outputs a control signal to the combination of controllable switches according to the judgment result, and the combination of controllable switches adopts a solid-state relay.

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

[0011] Preferably, the TVS diode array adopts a bidirectional TVS to protect the PoE differential data line and the DC power line respectively.

[0012] Preferably, a delay inductance is connected in parallel between the conduction lines connected by the first protection circuit, the second protection circuit and the third protection circuit, for realizing inter-stage decoupling and delay cooperation of the first protection circuit, the second protection circuit and the third protection circuit.

[0013] Preferably, the delay inductance adopts a winding inductance.

[0014] Technical effects and advantages of the present application: When the present application is used for protecting the PoE power supply port of the switch for outdoor use, the lightning current surge energy is first discharged by the first protection circuit, then the surge intensity is judged in real time by the adaptive control module and the combination of voltage-dependent resistors is dynamically adjusted, and finally the residual voltage is clamped to a safe level by the bidirectional TVS, so that the protection is set, which not only improves the protection precision and the device life, but also enhances the adaptive ability of the overall circuit to different intensity surges. 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] Second, the end of the first protection circuit and parallel second protection circuit, through voltage sampling, according to the detected voltage surge strength to adjust the number of voltage-dependent resistor switch on, and then adjust the discharge strength; When the rising edge of the surge voltage is detected to be gentle and the amplitude does not exceed the device damage value, only a single voltage-dependent resistor is turned on; When the surge voltage is detected to rise rapidly for a short time and the amplitude exceeds the device damage value, multiple voltage-dependent resistors are turned on at the same time; It should be noted that the surge voltage, also known as transient overvoltage, surge or voltage spike, refers to a transient pulse in a circuit with a very short duration (from nanoseconds to milliseconds) but a magnitude far exceeding the normal operating voltage. The voltage value of the surge voltage is several times, several tens of times or even tens of thousands of times the normal operating voltage, and the duration is in the order of microseconds to milliseconds, and it carries a huge amount of energy.

[0022] Specifically, the second protection circuit is composed of an adjustable transient suppression unit and an adaptive control module. The adjustable transient suppression unit is composed of a voltage-dependent resistor combination and a controllable switch combination. The voltage-dependent resistor combination includes voltage-dependent resistors MOV1 and MOV2, and the controllable switch combination includes switches K1 and K2. Switch K1 is connected in series with voltage-dependent resistor MOV1, and switch K2 is connected in series with voltage-dependent resistor MOV2. The adaptive control module is used to detect the amplitude and waveform of the surge voltage and adjust the number of voltage-dependent resistors in the voltage-dependent resistor combination by controlling the conduction state of the controllable switches in the controllable switch combination. The adaptive control module is connected to the control end of the adjustable transient suppression unit, dynamically adjusts the voltage-dependent resistor combination according to the surge characteristics, and performs multi-stage energy coordination and adaptive protection.

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

[0024] Further, the adaptive control module is composed of a voltage sampling circuit, a waveform identification circuit and a logic control unit. The voltage sampling circuit monitors the voltage change rate of the end port of the first protection circuit in real time, the waveform identification circuit judges the surge type according to the voltage rise time, and the logic control unit outputs the control signal to the controllable switch combination according to the judgment result. The controllable switch combination adopts a solid-state relay, which can dynamically adjust the surge resistance combination by real-time judgment of the surge intensity through the adaptive control module, thereby improving the protection accuracy and device life, and enhancing the adaptability of the overall circuit to surges of different intensities.

[0025] The solid-state relay is a new type of non-contact switching device composed of solid-state electronic components (optoelectronic coupler, transistor, thyristor, power MOSFET). It uses the electromagnetic induction characteristics (optoelectronic, magneto-electric) of electronic components to realize the isolation and control between input and output. The solid-state relay has no moving parts, so it is not easy to wear and tear, has a longer service life, is more resistant to external impact and vibration, and has a switching speed of microseconds, which is much faster than the millisecond response time of electromagnetic relays. At the same time, the solid-state relay requires low power for control signal input, which is suitable for low-power circuits, and protects the control circuit through electrical isolation between input and output.

[0026] The voltage sampling circuit monitors the voltage of the end port of the first protection circuit (the key node after the GDT and before the voltage-dependent resistor) in real time. High voltage change rate (dV / dt) means that the voltage rises sharply in a very short time; low voltage change rate means that the voltage rises in a relatively long time (microseconds to milliseconds); the waveform identification circuit receives the voltage signal from the sampling circuit to analyze the rise time of the voltage waveform, and the internal preset judgment threshold; the logic control unit is used to receive the judgment result of the waveform identification circuit and control the opening and closing of the controllable switch combination according to the preset protection strategy.

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

[0028] It should be noted that the TVS diode array is a device that integrates multiple TVS diodes on a single chip, specially designed for protecting multiple data / signal lines. The bidirectional TVS diode is a special TVS that can provide protection for both positive and negative overvoltages. The most common implementation is to connect two unidirectional TVS diodes in a "back-to-back" manner; when a surge hits, one unidirectional TVS diode breaks down in reverse (avalanche mode), while the other unidirectional TVS diode turns on in forward direction. Regardless of the voltage direction, the entire device exhibits a breakdown characteristic, clamping the voltage below a safe voltage. Bidirectional TVS diodes have the same or very close clamping voltage for positive and negative pulses through symmetric protection, eliminating the need to distinguish between positive and negative when installing in a circuit, simplifying design and installation.

[0029] Specifically, a delay inductance is connected in parallel between the conduction circuits of the first, second, and third protection circuits, for realizing inter-stage decoupling and delay coordination of the first, second, and third protection circuits. The delay inductance is a wound inductance, which absorbs residual surge current, limits the port residual voltage within the range that can be tolerated by the internal circuit of the switch, delays the surge rise time, ensures that the previous stage circuit acts first, and realizes energy staged discharge.

[0030] It should be noted that wound inductance is the most basic and common type of inductance in electronic circuits, and its structure consists of a conductor and a magnetic core. The conductor is a copper enameled wire, and the thickness of the enameled wire determines the current it can withstand. The magnetic core is the core component that determines the performance and purpose of the inductance. Wound inductance is mainly divided into two categories according to different magnetic cores: Air-core inductance: The coil has no magnetic core or a non-magnetic support frame. Air-core inductance has a small inductance and no magnetic saturation problem, but the magnetic field will disperse. Magnetic core inductance: The coil is wound on a magnetic material (ferrite, magnetic powder core, iron-silicon-aluminum). Magnetic core inductance: improves inductance and concentrates magnetic flux. However, there is a magnetic saturation phenomenon - when the current is too large, the magnetic permeability of the magnetic core will decrease sharply, causing the inductance to decrease sharply.

[0031] The operation of wound inductance 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, and this changing magnetic field generates an induced electromotive force (reverse voltage) to resist the change in current.

[0032] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art will appreciate that the technical solutions described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalent features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A protection method for an industrial switch PoE power supply port, characterized in that, The protection method comprises the following operation steps: First, a first-stage protection circuit is connected in parallel to the PoE power supply port, and the first-stage protection circuit is used to discharge the surge energy of lightning current; Second, a second-stage protection circuit is connected in parallel to the end of the first-stage protection circuit, and the second-stage protection circuit is used to adjust the number of connected varistors according to the detected voltage surge strength, so as to adjust the discharge strength; When it is detected that the rising edge of the surge voltage is gentle and the amplitude does not exceed the damage value of the equipment, only one varistor is connected; When it is detected that the surge voltage rises rapidly in a short time and the amplitude exceeds the damage value of the equipment, multiple varistors are connected at the same time; Third, a third-stage protection circuit is arranged at the end of the second-stage protection circuit, and the third-stage protection circuit is used to further clamp the residual voltage to a safe level.

2. The protection method for the PoE power supply port of the industrial switch according to claim 1, characterized in that, The first-stage protection circuit is composed of a gas discharge tube (GDT) and is connected in parallel to the PoE power supply port.

3. The protection method for PoE power supply port of industrial switch according to claim 1, characterized in that, The second-stage protection circuit is composed of an adjustable transient suppression unit and an adaptive control module. The adjustable transient suppression unit is composed of a varistor combination and a controllable switch combination. The adaptive control module is used to detect the amplitude and waveform of the surge voltage, and adjust the number of connected varistors in the varistor combination by controlling the conduction state of the controllable switch in the controllable switch combination.

4. The protection method for the PoE power supply port of the industrial switch according to claim 3, characterized in that, The varistor combination comprises varistors MOV1 and MOV2, and the controllable switch combination comprises switches K1 and K2, wherein the switch K1 is connected in series with the varistor MOV1, and the switch K2 is connected in series with the varistor MOV2.

5. The protection method for PoE power supply port of industrial switch according to claim 3, characterized in that, The adaptive control module is connected to the control end of the adjustable transient suppression unit, and dynamically adjusts the varistor combination according to the surge characteristics, so as to perform multi-stage energy coordination and adaptive protection.

6. The protection method for PoE power supply port of industrial switch according to claim 5, characterized in that, The adaptive control module is composed of a voltage sampling circuit, a waveform identification circuit and a logic control unit. The voltage sampling circuit monitors the voltage change rate of the end port of the first-stage protection circuit in real time, the waveform identification circuit judges the surge type according to the voltage rise time, and the logic control unit outputs a control signal to the controllable switch combination according to the judgment result, and the controllable switch combination adopts a solid-state relay.

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

8. The protection method for the PoE power supply port of the industrial switch according to claim 7, characterized in that, The TVS diode array adopts a bidirectional TVS, and protects the PoE differential data line and the DC power supply line respectively.

9. The protection method for PoE power supply port of industrial switch according to claim 1, characterized in that, A delay inductance is connected in parallel between the conduction circuits connected by the first-stage protection circuit, the second-stage protection circuit and the third-stage protection circuit, so as to realize the inter-stage decoupling and delay cooperation of the first-stage protection circuit, the second-stage protection circuit and the third-stage protection circuit.

10. The protection method for PoE power supply port of industrial switch according to claim 9, characterized in that, The delay inductance adopts a winding inductance.

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