Anti-surge high-voltage switching power supply circuit

Abstract

The utility model provides an anti-surge high-voltage switching power supply circuit, which relates to the technical field of switching power supply circuits, and comprises an isolation transformer, a first-stage protection loop and a second-stage protection loop, the first-stage protection loop comprises an I-shaped inductor and a fuse which are arranged at a zero line input end and a live line input end, and an output end is connected with a piezoresistor in parallel; two ends of the piezoresistor are output ends of the first-stage protection loop; the second-stage protection loop is arranged between the first-stage protection loop and the primary winding of the isolation transformer T1 and comprises a rectifier bridge, the alternating current input end of the rectifier bridge is connected with a piezoresistor, and the direct current output end of the rectifier bridge is connected with a first CLC filter; and the battery is arranged on the rear side of the secondary winding of the isolation transformer and is used for standby power supply when alternating current input is abnormal. According to the utility model, enhanced protection of the high-voltage switching power supply circuit is realized through the two-stage protection loop, voltage surge and transient overvoltage are effectively resisted, and the stability and safety of a power supply system are ensured.

Description

Technical Field

[0001] This utility model relates to the field of switching power supply circuit technology, and in particular to a surge-proof high-voltage switching power supply circuit. Background Technology

[0002] With the rapid development of modern electronic technology, electrical and electronic equipment is increasingly widely used in various fields. The normal operation of these devices depends on a stable and secure power supply. However, voltage fluctuations, transient overvoltages, and external factors such as lightning strikes and electrostatic discharges in the power system can all damage electrical equipment, affect its performance, and even cause safety accidents. National standards typically stipulate that the withstand voltage rating of electrical equipment is 2kV to protect personal and equipment safety and ensure the reliability of the equipment under intended operating conditions.

[0003] While a 2kV withstand voltage rating is sufficient for many conventional applications, it may be inadequate for high-voltage transient overvoltage situations in specific environments and applications, such as areas with frequent lightning strikes, areas where the electrical equipment is highly sensitive electronic equipment, areas with medical power supply, and equipment operating in high-voltage or high-energy environments. These areas have a more urgent need for protection against voltage surges and transient overvoltages. Utility Model Content

[0004] To overcome the shortcomings of existing technologies, the technical problem to be solved by this utility model is to propose a surge-protected high-voltage switching power supply circuit, which adopts the following technical solution:

[0005] A surge-protected high-voltage switching power supply circuit includes an isolation transformer and a switching power supply chip, and also includes...

[0006] The first-level protection circuit is set at the AC input terminal of the above circuit, including a first I-shaped inductor set at the neutral input terminal or the live input terminal, a fuse connected in series at the live input terminal, and a varistor connected in parallel at the output terminal of the above-mentioned first-level protection circuit.

[0007] The second-level protection circuit is set between the first-level protection circuit and the primary winding of the isolation transformer. It includes a rectifier bridge, the AC input terminal of the rectifier bridge is connected to the varistor, the DC output terminal is connected to the first CLC filter, and a protection resistor is set between the varistor and the first CLC filter.

[0008] A battery, located on the rear side of the secondary winding of the aforementioned isolation transformer, is used as a backup power supply in case of AC input abnormalities.

[0009] As a further improvement, the inductance value of the first I-shaped inductor is 10uH; the fuse is a slow-blow explosion-proof fuse with a rated current of 3.15A; and the clamping voltage of the varistor is 775V, and the peak surge current is 4.5kA.

[0010] As a further improvement, the aforementioned live wire input terminal or neutral wire input terminal is provided with a second I-shaped inductor, the inductance value of which is 10uH.

[0011] As a further improvement, the aforementioned rectifier bridge includes four diodes, and the reverse voltage rating of the four diodes is V. R ≥775V.

[0012] As a further improvement, the first CLC filter includes a first electrolytic capacitor and a second electrolytic capacitor connected in parallel, and a third inductor is connected in parallel between the first electrolytic capacitor and the second electrolytic capacitor. The withstand voltage of the first electrolytic capacitor and the second electrolytic capacitor is greater than 450V.

[0013] As a further improvement, a second CLC filter is provided on the rear side of the secondary winding of the isolation transformer. The second CLC filter includes a fourth electrolytic capacitor and a fifth electrolytic capacitor connected in parallel with each other, and a fourth inductor is connected in parallel between the fourth electrolytic capacitor and the fifth electrolytic capacitor.

[0014] As a further improvement, the fourth electrolytic capacitor is connected in parallel with a fifth capacitor, and the fifth electrolytic capacitor is connected in parallel with a voltage divider resistor.

[0015] As a further improvement, the battery is located behind the second CLC filter, and both the output terminals of the second CLC filter and the battery are equipped with anti-reverse current diodes.

[0016] As a further improvement, the battery output terminal is provided with a voltage detection circuit, including a voltage detector and a switch. The second CLC filter and the output terminal of the battery are connected to the input terminal of the voltage detector. A current-limiting resistor is connected in series between the battery and the voltage detector. The output terminal of the voltage detector is connected to the switch via a voltage divider branch. The switch is used to control the conduction and disconnection of the battery power supply branch.

[0017] As a further improvement, the voltage detector is an HT70 series voltage detector, the switching device is a PMOS transistor, the gate of the PMOS transistor is connected to the output terminal of the voltage detector, the source is connected to the output terminal of the battery, and the drain is connected to the output terminal of the second CLC filter.

[0018] Compared with the prior art, the beneficial effects of this utility model are:

[0019] Firstly, this invention incorporates a first-stage protection circuit and a second-stage protection circuit on the primary side of the isolation transformer, significantly improving the circuit's surge protection capability. Specifically, by setting up a first-stage protection circuit at the AC input terminal of the circuit, including a combination of a first I-type inductor, a slow-blow explosion-proof fuse, and a varistor, it effectively suppresses high-frequency spikes and transient overvoltages that may occur at the mains input terminal. The varistor has a clamping voltage of 775V and a peak surge current withstand capability of 4.5kA, enabling it to quickly clamp and disperse surge energy. Furthermore, a second-stage protection circuit is set between the first-stage protection circuit and the primary winding of the isolation transformer, utilizing a rectifier bridge and a first CLC filter to further eliminate residual surge voltage and high-frequency noise. This structure effectively prevents surge damage to subsequent circuits, significantly improving the reliability and stability of the entire switching power supply circuit.

[0020] Secondly, this invention incorporates a first CLC filter and a second CLC filter, optimizing the power output quality. Specifically, the first and second CLC filters are respectively located on both sides of the primary and secondary windings of the isolation transformer, suppressing high-frequency ripple and noise in the circuit. The first CLC filter effectively filters out high-frequency components in the DC output, ensuring smooth current transmission on the primary side of the isolation transformer. The second CLC filter on the secondary side adopts a similar structure, further incorporating voltage-dividing resistors and a fifth inductor to further stabilize the output voltage. This structure significantly improves the output quality of the high-voltage switching power supply and reduces electromagnetic interference problems during equipment operation.

[0021] Thirdly, this invention includes a backup battery branch for providing backup power in case of AC input abnormalities. When the AC input is abnormal, the battery located after the second CLC filter automatically connects as a backup power source, and an anti-reverse current diode ensures unidirectional current flow between the battery and the filter circuit, preventing charging current backflow from damaging the battery. Furthermore, the voltage detection circuit, through the cooperation of a voltage detector and a PMOS transistor, achieves precise control over the on / off state of the battery branch. Specifically, when the voltage detector detects an abnormality such as a decrease or disconnection of the output voltage of the second CLC filter, it controls the PMOS transistor to turn on, switching to battery power. When the input voltage returns to normal, the voltage detector controls the PMOS transistor to turn off, cutting off the battery power supply branch, ensuring efficient and safe system operation. This effectively improves the power supply reliability of the power system, making it particularly suitable for scenarios with high requirements for power supply continuity, such as communication base stations or medical equipment power supply systems. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the frame structure of this utility model;

[0024] Figure 2 This is a schematic diagram of the circuit structure of this utility model;

[0025] Figure 3 This is a connection frame diagram of the voltage detection circuit of this utility model;

[0026] Figure 4 This is a schematic diagram of an embodiment of the voltage detection circuit of this utility model.

[0027] Figure label:

[0028] T1 - Isolation transformer; U1 - Switching power supply chip; BAT - Battery; L1 - First I-shaped inductor; L2 - Second I-shaped inductor; F1 - Fuse; MOV - Varistor; BD - Rectifier bridge; EC1 - First electrolytic capacitor; EC2 - Second electrolytic capacitor; EC4 - Fourth electrolytic capacitor; EC5 - Fifth electrolytic capacitor; L4 - Fourth inductor; C5 - Fifth capacitor; R12 - Voltage divider resistor; U2 - Voltage detector; Q1 - Switch; DZ - Zener diode; R14 - Protection resistor; R18 - Current limiting resistor;

[0029] 1-First-level protection circuit; 2-Second-level protection circuit; 4-Voltage detection circuit; 21-First CLC filter; 31-Second CLC filter. Detailed Implementation

[0030] To facilitate understanding by those skilled in the art, the structure of this utility model will now be described in further detail with reference to the accompanying drawings:

[0031] In the description of this utility model, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. The terms "part," "side," "end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on this utility model.

[0032] like Figures 1-2 As shown, this application provides a surge-protected high-voltage switching power supply circuit, including an isolation transformer T1 and a switching power supply chip U1, and also includes a first-stage protection circuit 1. The first-stage protection circuit 1 is set at the AC input terminal of the circuit, including a first I-shaped inductor L1 set at the neutral input terminal or the live input terminal, a fuse F1 connected in series at the live input terminal, and a varistor MOV connected in parallel at the output terminal of the first-stage protection circuit 1. The two ends of the varistor MOV are the output terminals of the first-stage protection circuit 1.

[0033] In one specific embodiment, a first I-shaped inductor L1 and a fuse F1 are connected in series on the live wire input terminal, and the aforementioned varistor is connected in parallel between the live wire input terminal and the neutral wire input terminal. The inductance of the first I-shaped inductor L1 is 10uH; the fuse F1 is a slow-blow explosion-proof fuse with a rated current of 3.15A. Its slow-blow characteristic means that it will not immediately melt when subjected to surge current, but will allow the surge current to pass through after a short delay, avoiding unnecessary interruption due to instantaneous current surge. The melting time is typically between a few milliseconds and tens of milliseconds. The clamping voltage of the varistor MOV is 775V, and the peak surge current is 4.5kA. When the differential-mode surge voltage between the live and neutral wires exceeds the clamping voltage of the varistor MOV, the varistor MOV will conduct, diverting the differential-mode surge energy through the path between the live and neutral wires, limiting the excessive voltage to 775V, thereby protecting the subsequent circuitry.

[0034] Preferably, a second I-shaped inductor L2 is provided at the neutral input terminal. The inductance value of the second I-shaped inductor L2 is 10uH, which further enhances the surge suppression at the input terminal, reduces electromagnetic interference, and improves circuit stability.

[0035] like Figures 1-2 As shown, it also includes a second-level protection circuit 2, which is set between the first-level protection circuit 1 and the primary winding of the isolation transformer T1. It includes a rectifier bridge BD, the AC input terminal of the rectifier bridge BD is connected to a varistor MOV, the DC output terminal is connected to a first CLC filter 21, and a protection resistor R15 is set between the varistor MOV and the first CLC filter 21.

[0036] In one specific embodiment, the rectifier bridge BD includes four diodes, and the reverse withstand voltage V of the four diodes is... R ≥775V, the first CLC filter 21 includes a first electrolytic capacitor EC1 and a second electrolytic capacitor EC2 connected in parallel, a third inductor L3 connected in parallel between the first electrolytic capacitor EC1 and the second electrolytic capacitor EC2, and the withstand voltage of the first electrolytic capacitor EC1 and the second electrolytic capacitor EC2 is greater than 450V.

[0037] In the above embodiment, by setting a first-stage protection circuit 1 at the AC input terminal of the circuit, including a combination of a first I-type inductor L1, a slow-blow fuse F1, and a varistor MOV, high-frequency spikes and transient overvoltages that may occur at the mains input terminal are effectively suppressed. The varistor MOV has a clamping voltage of 775V and a peak surge current withstand capability of 4.5kA, enabling it to quickly clamp and disperse surge energy. Furthermore, a second-stage protection circuit 2 is set between the first-stage protection circuit 1 and the primary winding of the isolation transformer T1, using a rectifier bridge BD and a first CLC filter 21 to further eliminate residual surge voltage and high-frequency noise. This structure effectively avoids damage to subsequent circuits from surges, ensuring high voltage levels while improving the reliability and stability of the entire switching power supply circuit.

[0038] like Figure 2 As shown, the aforementioned switching power supply chip U1 is a primary-side feedback switching power supply chip with a built-in MOSFET. Its peripheral circuit includes a spike absorption circuit composed of diode D1, resistors R1, R2, and capacitor C1; a current detection circuit composed of resistors R9 and R10; and a voltage feedback circuit composed of resistors R4, R6, R8, and capacitor C2. The primary-side signal is detected through the voltage feedback circuit and the current detection circuit, and the output voltage is regulated by the built-in MOSFET using pulse width modulation (PWM) technology. Those skilled in the art should be able to understand and implement this based on the conventional settings of switching power supply circuits, and will not be elaborated further here.

[0039] like Figure 2 As shown, a second CLC filter 31 is provided on the rear side of the secondary winding of the isolation transformer T1. Specifically, the second CLC filter 31 includes a fourth electrolytic capacitor EC4 and a fifth electrolytic capacitor EC5 connected in parallel, with a fourth inductor L4 connected in parallel between the fourth and fifth electrolytic capacitors EC4 and EC5. Further, a fifth capacitor C5 is connected in parallel with the fourth electrolytic capacitor EC4, and a voltage divider resistor R12 is connected in parallel with the fifth electrolytic capacitor EC5. The main function of the fifth capacitor C5 is to filter out high-frequency noise and suppress high-frequency interference from the secondary winding of the isolation transformer T1 and the pulse width modulation of the switching power supply chip U1. The main function of the voltage divider resistor R12 is to provide a discharge path for the capacitors and balance the voltage, ensuring the safety and stability of the circuit.

[0040] As a preferred option, such as Figure 2 As shown, a rectifier unit is also provided between the isolation transformer T1 and the second CLC filter 31, including diodes D4 and D7 connected in parallel and an RC branch. Furthermore, two common-mode capacitors CY1 and CY2 connected in series are connected in parallel between the ground terminal of the auxiliary winding on the primary side of the isolation transformer T1 and the second CLC filter 31 to suppress common-mode noise coupled from the primary side of the isolation transformer.

[0041] In the above embodiment, the first CLC filter 21 effectively filters out high-frequency components in the DC output, ensuring smooth current transmission on the primary side of the isolation transformer T1. The second CLC filter 31 on the secondary side adopts a similar structure to further stabilize the output voltage, improve the output quality of the high-voltage switching power supply, and reduce electromagnetic interference problems during equipment operation.

[0042] like Figures 2-4 As shown, a battery BAT is installed on the secondary winding of the isolation transformer T1 as a backup power source to provide backup power in case of AC input abnormalities. Specifically, the battery is located on the rear side of the second CLC filter 31, and both the second CLC filter 31 and the battery BAT have anti-reverse current diodes at their output terminals, such as... Figure 2 As shown, the anode of the first anti-reverse current diode D5 is connected to the side closer to the battery, and the cathode points to the output terminal of the circuit; the anode of the second anti-reverse current diode D6 is connected to the side closer to the second CLC filter 31, and the cathode points to the output terminal of the circuit.

[0043] As one embodiment, when AC power is supplied normally, it is supplied to the downstream circuit through the isolation transformer T1. When AC power supply is abnormal, such as when the voltage decreases or disappears, the voltage of the battery BAT branch is higher than the output voltage of the second CLC filter 31, and the output terminal is powered by the battery BAT. Furthermore, the fifth capacitor C5 decouples high-frequency noise, and the voltage divider resistor R12 balances the voltage and releases residual charge, which can also make the voltage more stable when the battery BAT switches, thus improving the stability of the circuit when switching power sources.

[0044] like Figures 2-4 As shown, the output terminal of the battery BAT is equipped with a voltage detection circuit 4, including a voltage detector U2 and a switch Q1. The second CLC filter 31 and the output terminal of the battery BAT are connected to the input terminal of the voltage detector U2. A current-limiting resistor R18 is connected in series between the battery BAT and the voltage detector U2. The output terminal of the voltage detector U2 is connected to the switch Q1 through a voltage divider branch. The switch Q1 is used to control the conduction and disconnection of the power supply branch of the battery BAT.

[0045] In a preferred embodiment, voltage detector U2 is an HT70 series voltage detector, and switching element Q1 is a PMOS transistor. The gate of this PMOS transistor is connected to the output terminal of voltage detector U2, the source is connected to the output terminal of battery BAT, and the drain is connected to the output terminal of the second CLC filter 31. Figure 2 and Figure 3As shown, the voltage divider branch includes voltage divider resistors R16 and R17. When the AC power supply is normal, the voltage detector U2 outputs a low level. At this time, the source of the PMOS transistor is connected to the battery power supply voltage, the gate is pulled low, and it is in the off state, thus the battery power supply branch is disconnected. When the AC power is abnormal, that is, when the output voltage of the second CLC filter 31 drops or disappears, the voltage detector U2 is powered by the battery BAT through the current limiting resistor R18, and the voltage detector U2 outputs a high level. At this time, the gate voltage of the PMOS transistor is close to the source voltage and is in the on state, thus the battery power supply branch is turned on, that is, it switches to battery power supply.

[0046] The above technical solution achieves precise control over the on / off state of the battery power supply branch through the cooperation of voltage detector U2 and PMOS transistor, effectively improving the power supply reliability of the power system. It is especially suitable for scenarios with high requirements for power supply continuity, such as communication base stations or medical equipment power supply systems.

[0047] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A surge-protected high-voltage switching power supply circuit, comprising an isolation transformer (T1) and a switching power supply chip (U1), characterized in that: Also includes The first-level protection circuit (1) is set at the AC input terminal of the circuit, including a first I-shaped inductor (L1) set at the neutral input terminal or the live input terminal, a fuse (F1) connected in series at the live input terminal, and a varistor (MOV) connected in parallel at the output terminal of the first-level protection circuit (1). The second-level protection circuit (2) is set between the first-level protection circuit (1) and the primary winding of the isolation transformer (T1), including a rectifier bridge (BD). The AC input terminal of the rectifier bridge (BD) is connected to the varistor (MOV), and the DC output terminal is connected to the first CLC filter (21). A protection resistor (R15) is set between the varistor (MOV) and the first CLC filter (21). A battery (BAT) is located on the rear side of the secondary winding of the isolation transformer (T1) for backup power supply in case of AC input abnormality.

2. The surge-protected high-voltage switching power supply circuit as described in claim 1, characterized in that: The inductance of the first I-shaped inductor (L1) is 10uH; the fuse (F1) is a slow-blow explosion-proof fuse with a rated current of 3.15A; the clamping voltage of the varistor (MOV) is 775V and the peak surge current is 4.5kA.

3. The surge-protected high-voltage switching power supply circuit as described in claim 2, characterized in that: The live wire input terminal or the neutral wire input terminal is provided with a second I-shaped inductor (L2), and the inductance value of the second I-shaped inductor (L2) is 10uh.

4. The surge-protected high-voltage switching power supply circuit as described in claim 1, characterized in that: The rectifier bridge (BD) includes four diodes, and the reverse breakdown voltage V of the four diodes is... R ≥775V.

5. The surge-protected high-voltage switching power supply circuit as described in claim 1, characterized in that: The first CLC filter (21) includes a first electrolytic capacitor (EC1) and a second electrolytic capacitor (EC2) connected in parallel. A third inductor (L3) is connected in parallel between the first electrolytic capacitor (EC1) and the second electrolytic capacitor (EC2). The withstand voltage of the first electrolytic capacitor (EC1) and the second electrolytic capacitor (EC2) is greater than 450V.

6. The surge-protected high-voltage switching power supply circuit as described in claim 1, characterized in that: A second CLC filter (31) is provided on the rear side of the secondary winding of the isolation transformer (T1). The second CLC filter (31) includes a fourth electrolytic capacitor (EC4) and a fifth electrolytic capacitor (EC5) connected in parallel with each other. A fourth inductor (L4) is connected in parallel between the fourth electrolytic capacitor (EC4) and the fifth electrolytic capacitor (EC5).

7. The surge-protected high-voltage switching power supply circuit as described in claim 6, characterized in that: The fourth electrolytic capacitor (EC4) is connected in parallel with a fifth capacitor (C5), and the fifth electrolytic capacitor (EC5) is connected in parallel with a voltage divider resistor (R12).

8. The surge-protected high-voltage switching power supply circuit as described in claim 7, characterized in that: The battery is located behind the second CLC filter (31), and both the output terminals of the second CLC filter (31) and the battery (BAT) are equipped with anti-reverse current diodes.

9. The surge-protected high-voltage switching power supply circuit as described in claim 8, characterized in that: The output terminal of the battery (BAT) is provided with a voltage detection circuit (4), including a voltage detector (U2) and a switch (Q1). The second CLC filter (31) and the output terminal of the battery (BAT) are connected to the input terminal of the voltage detector (U2). A current-limiting resistor (R18) is connected in series between the battery and the voltage detector (U2). The output terminal of the voltage detector (U2) is connected to the switch (Q1) through a voltage divider branch. The switch (Q1) is used to control the conduction and disconnection of the power supply branch of the battery (BAT).

10. The surge-protected high-voltage switching power supply circuit as described in claim 9, characterized in that: The voltage detector (U2) is an HT70 series voltage detector, and the switching device is a PMOS transistor. The gate of the PMOS transistor is connected to the output terminal of the voltage detector (U2), the source is connected to the output terminal of the battery (BAT), and the drain is connected to the output terminal of the second CLC filter (31).

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