Three-phase overvoltage and undervoltage protector circuit with split-phase fusing function

Abstract

The utility model discloses a three-phase overvoltage and undervoltage protector circuit with a split-phase fusing function, relates to the technical field of protector circuits, and solves the problem of limitation of protection under high-voltage impact. A split-phase fusing protection module is connected in series between the power supply access processing circuit and the three-phase input end and comprises a protective tube RA connected with an A phase, a protective tube RB connected with a B phase, a protective tube RC connected with a C phase and a protective tube RN connected with an N phase; the piezoresistor RV1, the piezoresistor RV2 and the piezoresistor RV3 are respectively bridged between the A phase and the B phase, between the A phase and the C phase and between the B phase and the C phase, and the piezoresistor RV4, the piezoresistor RV5 and the piezoresistor RV6 are respectively bridged between the A phase and the N phase, between the B phase and the N phase and between the C phase and the N phase. The protective tube and the piezoresistor work cooperatively, and when the piezoresistor loses efficacy due to overload, the protective tube is fused quickly to cut off a fault loop, so that the element is prevented from being overheated and fired, and an active power-off protection mechanism is formed.

Description

A three-phase over / under voltage protection circuit with phase-by-phase fuse function Technical Field

[0001] This utility model relates to the field of protector circuit technology, specifically to a three-phase over / under voltage protector circuit with phase-by-phase fuse function. Background Technology

[0002] Currently, three-phase four-wire self-resetting over / under voltage protector circuits are widely used in industrial and household electrical appliances. Their core function is to quickly disconnect the circuit when the mains voltage is abnormal (overvoltage, undervoltage, phase loss) and automatically reconnect it after the voltage recovers. In existing technology, such as the patent with authorization announcement number CN214590575U, a protector circuit is disclosed. Its power supply processing circuit uses a combination of varistors RU1-RU4 and winding resistors RX2-RX4 to achieve surge isolation and interference suppression. The winding resistors utilize resistive and inductive characteristics to limit transient current. However, this solution has the following drawbacks when dealing with extreme power grid impacts:

[0003] In its technical solution, although the varistor can clamp surge voltage through its nonlinear characteristics, when an external instantaneous high voltage far exceeds the design threshold, such as lightning strikes, pulses generated during the start-up and shutdown of industrial equipment, or power grid surges, the varistor may break down and short-circuit due to energy overload. In this case, relying solely on the passive current-limiting effect of the wire-wound resistor is insufficient to quickly disconnect the faulty circuit. The thermal accumulation effect of the wire-wound resistor may lead to component overheating, circuit board carbonization, and even a fire risk. Therefore, its passive protection under high-voltage surges has limitations. Summary of the Invention

[0004] The purpose of this utility model is to overcome the defects of the prior art by providing a three-phase over / under voltage protector circuit with phase-by-phase fuse function, thereby solving the problem of limited protection under high voltage surges.

[0005] The technical solution of this utility model includes a three-phase input terminal, a power supply processing circuit, and a working power supply circuit. The power supply processing circuit is connected to the three-phase input terminal, and the working power supply circuit is connected to the power supply processing circuit. The three-phase input terminal includes phase A, phase B, phase C, and phase N. A phase-by-phase fuse protection module is connected in series between the power supply processing circuit and the three-phase input terminal. The phase-by-phase fuse protection module includes a fuse RA connected to phase A, a fuse RB connected to phase B, a fuse RC connected to phase C, and a fuse RN connected to phase N. The power supply processing circuit includes varistors RV1, RV2, RV3, RV4, RV5, and RV6. Varistors RV1, RV2, and RV3 are respectively connected between phase A and phase B, phase A and phase C, and phase B and phase C. Varistors RV4, RV5, and RV6 are respectively connected between phase A and phase N, phase B and phase N, and phase C and phase N.

[0006] Using the above technical solution, each phase has an independent series fuse. When an overcurrent occurs in a phase, such as a high-voltage surge or overcurrent fault, the corresponding fuse blows quickly, actively cutting off the power supply to the faulty phase. This avoids the heat accumulation risk of passive current limiting by traditional wire-wound resistors, preventing the circuit board from overheating and catching fire. Furthermore, only the fuse of the corresponding faulty phase blows, while non-faulty phases remain powered, preventing a complete system power outage and significantly improving power supply continuity. In addition, interphase varistors (RV1-RV3) suppress inter-line surges such as motor start-stop and cross-phase pulses caused by lightning strikes, compensating for the deficiencies of the phase-zero circuit. Phase-zero varistors (RV4-RV6) enhance the interference isolation function, forming a dual surge protection network of interphase and phase-zero circuits, covering common-mode and differential-mode interference, effectively absorbing high-energy surges and suppressing voltage spikes. In this way, the fuses and varistors work together. When a varistor fails due to overload, the fuse blows quickly, cutting off the fault circuit and preventing the component from overheating and catching fire, forming an active power-off protection mechanism.

[0007] In one possible design, the power supply circuit includes a three-phase rectifier bridge composed of six diodes, and the three-phase rectifier bridge is connected to the output of the power input processing circuit.

[0008] Using the above design, the three-phase rectifier bridge converts three-phase AC power into DC power, providing a stable operating power supply for the subsequent circuits. At the same time, it utilizes the unidirectional conduction characteristics of diodes to block reverse current and reduce energy loss.

[0009] In one possible design, the power supply circuit also includes a wire-wound resistor R6, a varistor RV7, a surface-mount varistor RV7-1, and an electrolytic capacitor C2. The wire-wound resistor R6 is connected in series with the output terminal of the three-phase rectifier bridge, and the varistor RV7, the surface-mount varistor RV7-1, and the electrolytic capacitor C2 are connected in parallel and are respectively connected to the wire-wound resistor R6.

[0010] With the above design, the varistor RV7 and the surface mount varistor RV7-1 are connected in parallel to ground to clamp high-frequency common-mode interference (such as switching power supply noise), making up for the lack of protection in the high-frequency band and expanding the high-frequency interference suppression capability.

[0011] In one possible design, fuses RA, RB, RC, and RN are plug-in fuses.

[0012] With the above design, the plug-in fuse adopts a physical plug-in structure, which has the characteristics of high temperature resistance and high current impact resistance, and is suitable for industrial-grade environments; at the same time, the independent packaging design facilitates quick replacement after failure, reducing maintenance costs. Attached Figure Description

[0013] Figure 1 is a circuit block diagram of this utility model;

[0014] Figure 2 is a circuit diagram of this utility model;

[0015] Among them, 1. Three-phase input terminal; 2. Power supply processing circuit; 3. Working power supply circuit; 31. Three-phase rectifier bridge; 4. Phase-by-phase fuse protection module. Detailed Implementation

[0016] As shown in Figures 1 and 2, a three-phase over / under voltage protector circuit with phase-by-phase fuse function includes a three-phase input terminal 1, a power input processing circuit 2, and a working power supply circuit 3. The power input processing circuit 2 is connected to the three-phase input terminal 1, and the working power supply circuit 3 is connected to the power input processing circuit 2. The three-phase input terminal 1 includes phase A, phase B, phase C, and phase N (neutral). A phase-by-phase fuse protection module 4 is connected in series between the power input processing circuit 2 and the three-phase input terminal 1. The phase-by-phase fuse protection module 4 includes a fuse RA connected to phase A, a fuse RB connected to phase B, a fuse RC connected to phase C, and a fuse RN connected to phase N. Each fuse is a 1A plug-in fuse, adopts a physical plug-in structure, is transparently packaged, and has a fuse indication window. It has high temperature resistance (260℃) and fast fusing characteristics (fusing time <10ms at 5 times the rated current) to ensure rapid disconnection of the fault circuit under high voltage impact.

[0017] The power supply processing circuit 2 includes three phase-to-phase varistors (RV1, RV2, and RV3) and three phase-to-zero varistors (RV4, RV5, and RV6). RV1 is connected between phases A and B, RV2 between phases A and C, RV3 between phases B and C, RV4 between phases A and N, RV5 between phases B and N, and RV6 between phases C and N. All varistors RV1-RV6 are 10112 varistors with a nominal voltage of 420V ± 10% and a current capacity of 6kA. Compared to traditional models, this represents a 20% increase in withstand voltage and a 30% increase in current capacity, ensuring effective voltage clamping during lightning strikes or grid surges. This forms a dual surge protection network of phase-to-phase and phase-to-zero, covering both common-mode (phase-to-zero) and differential-mode (phase-to-phase) interference.

[0018] The power supply circuit 3 includes a three-phase rectifier bridge 31 composed of six diodes, which is connected to the output of the power input processing circuit 2. The rectifier bridge uses SM520A Schottky diodes (D3, D5, D7-D10) to form a three-phase full-bridge rectifier circuit, replacing the discrete diode combination in existing technologies. The non-repetitive peak forward surge current of the SM520A diodes has been increased from 25A to 30A, the reverse withstand voltage has been increased from 1600V to 2000V, and the package size has been optimized to 5.30mm × 3.0mm × 2.44mm (previously 2.9mm × 1.9mm × 1.08mm), increasing the heat dissipation area by 50% and reducing temperature rise by 15%. The full-bridge rectification efficiency is ≥95% and the ripple factor is <5%, providing a stable DC input for subsequent circuits. It also blocks reverse current through unidirectional conduction characteristics, reducing energy loss. Furthermore, the rectifier bridge is directly connected to the output of the power input processing circuit 2, reducing intermediate conversion links, improving power processing efficiency, and reducing the impact of electromagnetic interference on subsequent circuits.

[0019] The power supply circuit 3 also includes a wire-wound resistor R6, a varistor RV7, a surface-mount varistor RV7-1, and an electrolytic capacitor C2. The wire-wound resistor R6 is connected in series with the output terminal of the three-phase rectifier bridge 31. The varistor RV7, the surface-mount varistor RV7-1, and the electrolytic capacitor C2 are connected in parallel and are respectively connected to the wire-wound resistor R6. The wire-wound resistor R6 (10Ω±5%) is connected in series with the output terminal of the rectifier bridge to suppress transient current surges and prevent overcurrent damage to subsequent circuits. The varistor RV7 and the surface-mount varistor RV7-1 are connected in parallel to absorb high-frequency common-mode interference and provide a fast response to high-frequency interference above 10MHz. The surface-mount varistor RV7-1 has a fast response time (≤25ns) and can quickly absorb high-frequency transient interference (such as EFT, ESD) to protect sensitive electronic components. Electrolytic capacitor C2 has a capacitance of 470μF and provides low-frequency surge absorption and DC filtering functions, filtering out low-frequency ripple below 100Hz. Together with the varistor, it forms high and low frequency segmented filtering to improve power supply purity.

[0020] Thus, this application is equivalent to solving the problems of high voltage surge, incomplete surge protection, and insufficient power supply stability in the prior art through triple improvements of phase-by-phase fuse blowing, multi-layer varistor protection, and high-efficiency rectification and filtering. Especially in extreme scenarios such as lightning strikes and industrial power grid impacts, it can shorten the fault response time and reduce the risk of component overheating.

Claims

1. A three-phase over / under voltage protector circuit with phase-by-phase fuse function, comprising a three-phase input terminal (1), a power supply processing circuit (2), and a working power supply circuit (3), wherein the power supply processing circuit (2) is connected to the three-phase input terminal (1), and the working power supply circuit (3) is connected to the power supply processing circuit (2), wherein the three-phase input terminal (1) comprises phase A, phase B, phase C, and phase N; characterized in that: A phase-by-phase fuse protection module (4) is connected in series between the power supply processing circuit (2) and the three-phase input terminal (1). The phase-by-phase fuse protection module (4) includes a fuse RA connected to phase A, a fuse RB connected to phase B, a fuse RC connected to phase C, and a fuse RN connected to phase N. The power supply processing circuit (2) includes a varistor RV1, a varistor RV2, a varistor RV3, a varistor RV4, a varistor RV5, and a varistor RV6. The varistor RV1, varistor RV2, and varistor RV3 are connected across phase A-phase, phase A-phase, and phase B-phase, respectively. The varistor RV4, varistor RV5, and varistor RV6 are connected across phase A-phase, phase B-phase, and phase C-phase, respectively.

2. The three-phase over / under-voltage protector circuit having a phase-splitting fusing function according to claim 1, characterized by: The working power supply circuit (3) includes a three-phase rectifier bridge (31) composed of six diodes, and the three-phase rectifier bridge (31) is connected to the output terminal of the power supply access processing circuit (2).

3. The three-phase over / under voltage protection circuit with phase-by-phase fuse function according to claim 2, characterized in that: The working power supply circuit (3) also includes a wire-wound resistor R6, a varistor RV7, a chip varistor RV7-1, and an electrolytic capacitor C2. The wire-wound resistor R6 is connected in series to the output terminal of the three-phase rectifier bridge (31). The varistor RV7, the chip varistor RV7-1, and the electrolytic capacitor C2 are connected in parallel and respectively connected to the wire-wound resistor R6.

4. The three-phase over / under-voltage protector circuit having a phase-splitting fuse function according to claim 1 or 2, characterized by: The fuses RA, RB, RC, and RN are plug-in type fuses.

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