Power input surge protection and isolation device and system

Abstract

The utility model discloses a power supply input surge protection and isolation device, which comprises a piezoresistor, a surge decoupling power resistor and a TVS (Transient Voltage Suppressor) tube which are sequentially connected in series, and a self-adaptive surge control circuit which is connected with the surge decoupling power resistor in parallel, when surge overvoltage occurs, the TVS tube is firstly broken down, and transient large current flows through the adaptive surge control circuit; the surge decoupling power resistor is used for enabling the passing surge current to generate relatively large voltage drop after the TVS tube is broken down; the self-adaptive surge control circuit comprises a first MOS tube which is used for conducting transient large current passing through a TVS (Transient Voltage Suppressor) tube; when the voltage drop on the MOS tube is greater than the breakdown voltage of the voltage-regulator tube, the voltage-regulator tube is broken down to trigger the conduction of the triode; when the voltage-regulator tube is broken down, the triode is conducted, so that the GS voltage drop of the first MOS tube is reduced, and the first MOS tube is turned off; when the sum of the clamping voltage of the TVS tube end and the voltage drop of the surge decoupling power resistor exceeds the minimum action voltage of the piezoresistor, the piezoresistor acts, so that high-energy transient interference flows through the piezoresistor, and surge protection is realized. According to the utility model, the surge protection and isolation protection functions of the input end of the power supply can be effectively realized, and the safety and stability of the use of the power supply are ensured.

Description

Technical Field

[0001] This application relates to the field of power protection technology, and in particular to a power input surge protection and isolation device and system. Background Technology

[0002] Existing surge protection measures primarily target surge protection at the power input terminal, neglecting to account for surge current during power-on startup. Without surge current suppression, the reliability of the power supply operation may be affected: when the voltage across the capacitor is zero, a large surge current will occur at power-on, potentially causing malfunctions in power input fuses, circuit breakers, etc., leading to power-on failure; the transient high current may damage input reverse connection protection diodes, MOSFETs, or AC power supply rectifier bridges. Furthermore, the transient high current surge may damage input capacitors, affecting their lifespan, for example, causing tantalum capacitors to smoke or catch fire. Utility Model Content

[0003] This application provides a power input surge protection and isolation device and system that overcomes the shortcomings of the prior art. When a surge voltage occurs, the surge adaptive control circuit reduces the surge current through the TVS tube by limiting the current through the power resistor, thereby indirectly improving the surge absorption power of the subsequent stage and better protecting the subsequent stage circuit.

[0004] This application provides a power input surge protection and isolation device, including a varistor, a surge decoupling power resistor and a TVS diode connected in series, and an adaptive surge control circuit connected in parallel with the surge decoupling power resistor.

[0005] The TVS diode is connected to the input terminal of the adaptive surge control circuit. When a surge overvoltage occurs, the TVS diode is broken down first, and a transient large current flows through the adaptive surge control circuit.

[0006] The surge decoupling power resistor is connected to the input terminal of the TVS diode and is used to generate a large voltage drop in the surge current after the TVS diode is broken down.

[0007] The adaptive surge control circuit includes a first MOSFET, a Zener diode, and a transistor. The first MOSFET is connected to the input terminal of the TVS diode to conduct transient large currents through the TVS diode. The Zener diode is connected in parallel with the first MOSFET. When the voltage drop across the MOSFET exceeds the breakdown voltage of the Zener diode, the Zener diode breaks down, triggering the transistor to conduct. The transistor is connected to the Zener diode. When the Zener diode breaks down, the transistor conducts, causing the gate-source voltage drop of the first MOSFET to decrease, thereby turning off the first MOSFET.

[0008] When the sum of the clamping voltage at the TVS terminal and the voltage drop across the surge decoupling power resistor exceeds the minimum operating voltage of the varistor, the varistor activates, allowing high-energy transient interference to flow through it, thus achieving surge protection.

[0009] According to the power input surge protection and isolation device, the first MOSFET is connected in parallel with the surge decoupling power resistor. The first MOSFET is in the off state when powered on, and its on-resistance is large. The gate of the first MOSFET is connected to at least one charging capacitor through at least one charging resistor. By charging the charging capacitor, the gate-source voltage Vgs of the first MOSFET is gradually increased, so that the on-resistance of the first MOSFET gradually decreases from infinity to 0.

[0010] The power input surge protection and isolation device further includes a DC / DC isolation module. The input terminal of the DC / DC isolation module is connected to the output terminal of the TVS diode. The DC / DC isolation module includes an isolation branch, which includes a high-frequency isolation transformer and a feedback optocoupler connected in series. The electrical insulation index of the isolation branch is AC3000V - 4000V.

[0011] According to the power input surge protection and isolation device, the electrical insulation index of the power output to the chassis ground PE in the DC / DC isolation module is AC1500V - 3000V.

[0012] The power input surge protection and isolation device also includes a fuse connected to the output side of the adaptive surge control circuit to cut off the circuit and protect circuit components when the circuit is overloaded.

[0013] According to the power input surge protection and isolation device, the first MOSFET is connected to at least one overcurrent detection setting resistor for detecting overcurrent conditions.

[0014] The power input surge protection and isolation device also includes a reverse connection protection circuit. The output terminal of the reverse connection protection circuit is connected to the input terminal of the varistor to ensure that the current can only flow in from one direction, so as to prevent damage caused by incorrect connection of the positive / negative terminals of the power supply.

[0015] This application also provides a power input surge protection and isolation system, including the power input surge protection and isolation device described in any of the above claims.

[0016] The power input surge protection and isolation device and system provided by this utility model has the following advantages compared with the prior art:

[0017] (1) By utilizing the fast response and low clamping voltage of the TVS diode, the downstream circuit is better protected. When a surge voltage occurs, the surge current through the TVS diode is reduced by the current limiting power resistor, which indirectly improves the surge absorption power of the downstream circuit. By utilizing the slow-start impedance characteristics of the MOS transistor in the adaptive surge control circuit, the power-on inrush current of the power input is reduced, avoiding damage to the components at the power input terminal by transient overcurrent, or causing the short-circuit protection measures of the equipment to malfunction and affect the power-on of the system. Furthermore, by utilizing the varistor in the front stage, high-voltage and high-energy surges and overvoltages are resisted, reducing the number of varistor operations and improving its service life. This utility model can enhance the surge protection effect of isolated switching power supplies, extend the service life of surge protection circuits, avoid the need to disassemble / install protection devices during power withstand voltage testing, and reduce maintenance costs. At the same time, it strengthens the suppression of differential-mode surge overvoltage and power-on inrush current, better protecting the switching power supply. This power input surge protection and isolation device can effectively realize the surge protection and isolation protection functions of the power input terminal, ensuring the safety and stability of the power supply.

[0018] (2) By increasing the insulation strength of the isolating switching power supply, the transient overvoltage discharge path is effectively cut off, avoiding common-mode interference to sensitive circuits. Simultaneously, the breakdown voltage of the common-mode protection devices is increased, avoiding the problem of frequent disassembly and reassembly of protection devices due to power supply withstand voltage testing. This invention utilizes the insulation withstand voltage characteristics of the isolating switching power supply to achieve common-mode surge overvoltage protection, reducing the number of common-mode protection components, as frequent operation of common-mode protection components can affect system reliability. Attached Figure Description

[0019] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0020] Figure 1 This is one of the structural schematic diagrams of an optional power input surge protection and isolation device provided in an embodiment of this application.

[0021] Figure 2 This is a schematic diagram of an optional power surge overvoltage isolation protection structure provided in an embodiment of this application.

[0022] Figure 3 This is a second schematic diagram of an optional power input surge protection and isolation device provided in an embodiment of this application.

[0023] Figure 4 This is a schematic diagram of a power input surge protection and isolation system provided in an embodiment of this application. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] With the rapid development of power electronics, communications, and industrial control industries, the power requirements in various industries are becoming increasingly stringent. To ensure system stability and anti-interference capabilities, isolated switching power supplies have emerged. The block diagram of an isolated switching power supply is shown below. The isolated switching power supply mainly consists of a high-frequency isolation transformer L1, a PWM controller, a MOSFET P1, an output rectifier diode, an input filter circuit, an output filter circuit, and a feedback optocoupler.

[0026] Surge overvoltage is one of the main factors affecting the stable operation or lifespan of a power supply. The main causes of power input surges are induced lightning strikes and transient overvoltages during operation.

[0027] Operational transient overvoltages: These are related to equipment start-up and shutdown within the power supply system and faults in the power network. Within the power system, changes in internal state, such as circuit breaker operation, load connection and disconnection, or system faults, cause changes in system parameters, resulting in electromagnetic energy conversion or transmission electromagnetic interference. Surges within the system primarily originate from the impact of internal electrical loads, accounting for approximately 80%. The causes of internal overvoltages in the power system can be broadly categorized as follows:

[0028] 1) The connection and disconnection of large power loads;

[0029] 2) The application and removal of emotional load;

[0030] 3) The connection and disconnection of power factor compensation capacitors;

[0031] 4) Short circuit fault.

[0032] Surges can adversely affect electrical equipment, especially microelectronic devices such as computers, communication equipment, and monitoring equipment connected to the power grid, causing potentially fatal damage. Even if no permanent equipment damage occurs, the abnormal operation and shutdown of the system can have serious consequences.

[0033] This application provides a power input surge protection and isolation device. Figure 1 This is one of the structural schematic diagrams of a power input surge protection and isolation device provided in an embodiment of this application, such as... Figure 1As shown, the device includes a varistor, a surge decoupling power resistor, and a TVS diode connected in series, and an adaptive surge control circuit connected in parallel with the surge decoupling power resistor; the adaptive surge control circuit includes a first MOSFET, a Zener diode, and a transistor.

[0034] The TVS diode is connected to the input terminal of the adaptive surge control circuit. When a surge overvoltage occurs, the TVS diode is broken down first, and a transient large current flows through the adaptive surge control circuit.

[0035] The surge decoupling power resistor is connected to the input terminal of the TVS diode and is used to generate a large voltage drop of the surge current after the TVS diode is broken down.

[0036] The first MOSFET is connected to the input terminal of the TVS transistor to conduct transient large currents through the TVS transistor;

[0037] The Zener diode is connected in parallel with the first MOSFET. When the voltage drop across the MOSFET exceeds the breakdown voltage of the Zener diode, the Zener diode breaks down, triggering the transistor to conduct.

[0038] When the transistor is connected to the Zener diode, the transistor turns on when the Zener diode breaks down, causing the gate-gate voltage drop of the first MOSFET to decrease, thereby turning off the first MOSFET.

[0039] A varistor activates when the sum of the clamping voltage at the TVS diode terminal and the voltage drop across the surge decoupling power resistor exceeds the varistor's minimum operating voltage, allowing high-energy transient interference to flow through it.

[0040] Specifically, when a surge overvoltage occurs, the TVS diode, with its extremely fast response speed, is the first to break down. At this time, a large transient current will flow through the adaptive surge control circuit. The surge decoupling power resistor is connected to the input terminal of the TVS diode. When the TVS diode breaks down, the surge current passing through it will inevitably flow through the surge decoupling power resistor. Due to the characteristics of the resistor, a significant voltage drop will occur when the surge current passes through the surge decoupling power resistor. The first MOSFET is connected to the input terminal of the TVS diode, and its main function is to conduct the large transient current passing through the TVS diode.

[0041] The Zener diode and the transistor work together, with the Zener diode connected in parallel with the first MOSFET. When the voltage drop across the first MOSFET exceeds the breakdown voltage of the Zener diode, the Zener diode breaks down. The transistor is then connected to the Zener diode. When the Zener diode breaks down, the transistor turns on. Due to the transistor's conduction, the gate-source voltage drop across the first MOSFET decreases, causing the first MOSFET to turn off and limiting further current increases.

[0042] The operation of a varistor provides further protection in a circuit. When the sum of the clamping voltage at the TVS diode terminal and the voltage drop across the surge decoupling power resistor exceeds the minimum operating voltage of the varistor, the varistor activates, allowing high-energy transient interference to flow through it, thus protecting other components in the circuit from damage caused by surge overvoltage.

[0043] Based on the above embodiments, as an optional embodiment, in the power input surge protection and isolation device provided by this utility model, the first MOSFET is connected in parallel with the surge decoupling power resistor. The first MOSFET is in the off state when powered on, and its on-resistance is large. The gate of the first MOSFET is connected to at least one charging capacitor through at least one charging resistor. By charging the charging capacitor, the gate-source voltage Vgs of the first MOSFET is gradually increased, so that the on-resistance of the first MOSFET gradually decreases from infinity to 0.

[0044] The MOSFET soft-start function specifically includes a first MOSFET connected in parallel with a surge decoupling power resistor. During power-up, the first MOSFET is in the off state, with a high on-resistance. The gate of the first MOSFET is connected to at least one charging capacitor through at least one charging resistor. During power-up, the gate-source voltage Vgs of the first MOSFET gradually increases by charging the charging capacitor. As the Vgs voltage rises, the on-resistance of the first MOSFET gradually decreases from infinity to 0, achieving the soft-start function and avoiding the large current surge at power-up.

[0045] Based on the above embodiments, as an optional embodiment, the power input surge protection and isolation device provided by this utility model further includes a DC / DC isolation module connected to the output terminal of the TVS diode. The DC / DC isolation module includes an isolation branch, which comprises a high-frequency isolation transformer and a feedback optocoupler connected in series.

[0046] The electrical insulation index of this isolated branch is AC3000V - 4000V, which can effectively prevent low-frequency electromagnetic interference at the power input terminal from coupling to the output terminal when the insulation value is lower than this.

[0047] Furthermore, Figure 2 This is a schematic diagram of a power surge overvoltage isolation and protection structure provided in an embodiment of this application, as shown below. Figure 2 As shown, the electrical insulation index of the power output to the chassis ground PE in the DC / DC isolation module is AC1500V-3000V, which can prevent low-frequency electromagnetic interference below this withstand voltage value from being converted into electromagnetic interference.

[0048] By employing, for example, high-frequency isolation transformers, optocouplers, creepage distances, electrical clearances, and insulating materials, the insulation withstand voltage between the input and output of the switching power supply, and between the power input and the chassis ground (PE), can be strengthened. This insulation withstand voltage can be made higher than the residual voltage after the protection device operates, effectively controlling the transient overvoltage discharge path and avoiding interference to sensitive circuits. Alternatively, the insulation withstand voltage can be made higher than transient overvoltages that are insufficient to activate the surge protection circuit, cutting off the electromagnetic coupling path and preventing transient overvoltages from causing interference.

[0049] Increasing the breakdown voltage of the protective device means applying the insulation withstand voltage required for equipment testing between the power input terminal and the PE of the chassis. This prevents the protective device from failing the withstand voltage test due to excessive operating voltage (such as breakdown, spark discharge, etc.) and avoids the need to remove / install the protective device due to power withstand voltage testing.

[0050] Transient overvoltages caused by frequent field operations can easily lead to frequent activation of surge protection devices. Increasing the breakdown voltage of these devices can prevent damage from high-energy, low-voltage surges. Conversely, reducing the number of activations of surge protection devices helps extend the lifespan of surge protection circuits.

[0051] By increasing the insulation strength of the isolated switching power supply, the coupling path of such transient overvoltage electromagnetic interference to the switching power supply is cut off, preventing it from turning into interference and damaging the switching power supply module and its downstream load circuits. Therefore, the improved lightning surge protection scheme of this utility model, which combines "insulation strength + protective devices," not only provides effective surge protection for the isolated power supply but also extends the service life of the surge protection circuit. In addition, it avoids the need to remove / install protective devices during power supply withstand voltage testing.

[0052] Based on the above embodiments, as an optional embodiment, the power input surge protection and isolation device provided by this utility model also includes a fuse, which is connected to the output side of the adaptive surge control circuit and is used to cut off the circuit when the circuit is overloaded, thereby protecting the circuit components. When the circuit is overloaded, the fuse can cut off the circuit in time, thereby protecting the various components in the circuit from damage by excessive current.

[0053] Based on the above embodiments, as an optional embodiment, in the power input surge protection and isolation device provided by this utility model, the first MOSFET is connected to at least one overcurrent detection setting resistor for detecting overcurrent conditions.

[0054] Specifically, the first MOSFET is connected to at least one overcurrent detection setting resistor to detect overcurrent conditions in the circuit. When an overcurrent occurs in the circuit, the overcurrent detection setting resistor can detect this situation and provide a basis for subsequent protection measures.

[0055] Based on the above embodiments, as an optional embodiment, the power input surge protection and isolation device provided by this utility model is further equipped with a reverse connection protection circuit, the output of which is connected to the input of the varistor. The reverse connection protection circuit ensures that current can only flow in from one direction, preventing circuit damage caused by incorrect positive / negative connection of the power supply, and ensuring the safety of the circuit when connected to power.

[0056] Through the coordinated operation of the above components, this power input surge protection and isolation device can effectively achieve surge protection, isolation protection and other related protection functions at the power input terminal, ensuring the safety and stability of power supply use.

[0057] Figure 3 This is a second schematic diagram of a power input surge protection and isolation device provided in an embodiment of this application, as shown below. Figure 3 As shown, the working principle of the above-mentioned power input surge protection and isolation device is as follows:

[0058] The principle of the MOSFET soft-start circuit mainly relies on the characteristics of the MOSFET and the design of external circuit components to achieve a slow power-on, avoiding instantaneous large current surges or voltage jumps. As shown in the diagram above: When powered on, MOSFET Q15 is turned off (high on-resistance). The input voltage can only charge the downstream capacitor through the surge decoupling power resistor, suppressing the surge current during power-on. Simultaneously, it slowly charges capacitor R854 through resistor R852. The Vgs (gate voltage) of MOSFET Q15 gradually rises to its turn-on voltage, and the impedance of MOSFET Q15 gradually decreases from infinity to 0. Zener diode D33 is connected to the relevant circuit of the first MOSFET. When the voltage drop across the first MOSFET exceeds the breakdown voltage of Zener diode D33, Zener diode D33 breaks down.

[0059] At the same time, an overcurrent detection setting resistor FR9 is set to detect overcurrent conditions.

[0060] When a surge overvoltage occurs, the TVS diode, which reacts fastest, breaks down. A transient large current flows through the power MOSFET Q15 (including the current sensing setting resistor FR9). When the voltage drop exceeds the breakdown voltage of the Zener diode, transistor Q1 turns on, and the gate-gate voltage drop of MOSFET Q15 decreases, thus turning it off. The surge current through the TVS diode can only pass through the surge decoupling power resistor R855, generating a large voltage drop. The clamping voltage at the TVS terminal plus the voltage drop across the power resistor eventually exceeds the operating threshold (minimum operating voltage) of the varistor RV4, causing varistor RV4 to activate. A large-energy transient interference flows through varistor RV4. When the surge overvoltage is low, the TVS diode can also act as a Zener diode, forming a voltage regulator circuit with the power resistor to power the downstream load.

[0061] Furthermore, this application also provides another power input surge protection and isolation system, such as... Figure 4 As shown, Figure 4 This is a schematic diagram of a power input surge protection and isolation system provided in an embodiment of this application. The power input surge protection and isolation system includes a varistor, a surge decoupling power resistor, a TVS diode, a filter circuit, and a DC / DC isolation module connected in series, and an adaptive surge control circuit connected in parallel with the surge decoupling power resistor.

[0062] In summary, this invention provides a more effective and stable power input surge protection and isolation device and system, which enhances the surge protection effect of isolated switching power supplies, extends the service life of surge protection circuits, avoids the need to disassemble / install protection devices during power supply withstand voltage testing, and reduces maintenance costs. It also strengthens the suppression of differential mode surge overvoltage and power-on inrush current, providing better protection for the switching power supply.

[0063] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0064] Furthermore, the terms "first," "second," etc., used in the embodiments of this utility model are for descriptive purposes only and should not be construed as indicating or implying relative importance, or implicitly specifying the number of technical features indicated in this embodiment. Therefore, features defined with terms such as "first" and "second" in the embodiments of this utility model can explicitly or implicitly indicate that the embodiment includes at least one of those features. In the description of this utility model, the word "multiple" means at least two or more, such as two, three, four, etc., unless otherwise explicitly specified in the embodiments.

[0065] In this utility model, unless otherwise explicitly specified or limited in the embodiments, the terms "installation," "connection," "joining," and "fixing" appearing in the embodiments should be interpreted broadly. For example, a connection can be a fixed connection, a detachable connection, or an integral part; it can also be a mechanical connection, an electrical connection, etc. Of course, it can also be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two components, or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific implementation.

[0066] 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 power input surge protection and isolation device, characterized in that, It includes a varistor, a surge decoupling power resistor and a TVS diode connected in series, and an adaptive surge control circuit connected in parallel with the surge decoupling power resistor. The TVS diode is connected to the input terminal of the adaptive surge control circuit. When a surge overvoltage occurs, the TVS diode is broken down first, and a transient large current flows through the adaptive surge control circuit. The surge decoupling power resistor is connected to the input terminal of the TVS diode and is used to generate a large voltage drop in the surge current after the TVS diode is broken down. The adaptive surge control circuit includes a first MOSFET, a Zener diode, and a transistor. The first MOSFET is connected to the input terminal of the TVS diode to conduct transient large currents through the TVS diode. The Zener diode is connected in parallel with the first MOSFET. When the voltage drop across the MOSFET exceeds the breakdown voltage of the Zener diode, the Zener diode breaks down, triggering the transistor to conduct. The transistor is connected to the Zener diode. When the Zener diode breaks down, the transistor conducts, causing the gate-source voltage drop of the first MOSFET to decrease, thereby turning off the first MOSFET. When the sum of the clamping voltage at the TVS terminal and the voltage drop across the surge decoupling power resistor exceeds the minimum operating voltage of the varistor, the varistor activates, allowing high-energy transient interference to flow through it, thus achieving surge protection.

2. The power input surge protection and isolation device according to claim 1, characterized in that, The first MOSFET is connected in parallel with the surge decoupling power resistor. The first MOSFET is in the off state when powered on, and its on-resistance is large. The gate of the first MOSFET is connected to at least one charging capacitor through at least one charging resistor. By charging the charging capacitor, the gate-source voltage Vgs of the first MOSFET is gradually increased, so that the on-resistance of the first MOSFET gradually decreases from infinity to 0.

3. The power input surge protection and isolation device according to claim 1, characterized in that, It also includes a DC / DC isolation module, the input terminal of which is connected to the output terminal of the TVS diode. The DC / DC isolation module includes an isolation branch, which includes a high-frequency isolation transformer and a feedback optocoupler connected in series. The electrical insulation index of the isolation branch is AC3000V - 4000V.

4. The power input surge protection and isolation device according to claim 3, characterized in that, The electrical insulation rating of the power output to the chassis ground PE in the DC / DC isolation module is AC1500V - 3000V.

5. The power input surge protection and isolation device according to claim 1, characterized in that, It also includes a fuse connected to the output side of the adaptive surge control circuit to cut off the circuit and protect circuit components when the circuit is overloaded.

6. The power input surge protection and isolation device according to claim 1, characterized in that, The first MOSFET is connected to at least one overcurrent detection setting resistor for detecting overcurrent conditions.

7. The power input surge protection and isolation device according to claim 1, characterized in that, It also includes a reverse connection protection circuit, the output of which is connected to the input of the varistor to ensure that current can only flow in from one direction, in order to prevent damage caused by incorrect connection of the positive / negative terminals of the power supply.

8. A power input surge protection and isolation system, characterized in that, Includes the power input surge protection and isolation device as described in any one of claims 1-7.

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