Power supply two-stage protection circuit applied to gas meter and power adapter

Abstract

The invention belongs to the technical field of power supply protection, and particularly relates to a power supply two-stage protection circuit applied to a gas meter and a power adapter, the power supply two-stage protection circuit applied to the gas meter comprises a switching power supply circuit and a cuttable explosion-proof protection circuit, the input end of the switching power supply circuit is connected with an external power supply, and the output end of the switching power supply circuit is connected with the explosion-proof protection circuit. The output end of the switching power supply circuit is connected with the input end of the cuttable explosion-proof protection circuit, and the cuttable explosion-proof protection circuit comprises a filtering protection circuit, a voltage-stabilizing two-stage protection circuit and a current-limiting protection circuit; wide-range adaptation of input voltage can be achieved, stable direct-current voltage can be output, filtering protection is achieved through devices such as resistance-capacitance fuses, voltage stabilization protection is achieved through silicon controlled rectifiers, current limiting protection is achieved through the power source over-current and overload protection technology, and the strict requirement of a gas meter for a power source can be met. The two-stage protection mechanism can effectively prevent electronic components in the gas meter from being damaged due to abnormal voltage.

Description

Technical Field

[0001] The invention belongs to the technical field of power supply protection, and specifically refers to a power supply double-stage protection circuit and a power adapter applied to a gas meter. Background Art

[0002] With the continuous development of intelligent gas meters, the electronic components and circuits inside them have increasingly higher requirements for the stability and safety of the power supply. Gas meters usually need to be connected to an external power supply to ensure their normal operation. However, in the actual use environment, the power supply voltage may fluctuate or be abnormal. On the one hand, the power supply network itself may produce voltage spikes, surges or voltage drops due to changes in grid load, power failure recovery process, etc. For example, during thunderstorms, lightning may impact the grid, causing the voltage to rise instantly; or during peak hours of electricity consumption, the voltage in some areas may drop; on the other hand, due to the wide installation location of gas meters, they may be interfered by surrounding electrical equipment, making their power input voltage unstable.

[0003] The current emergency or backup power supply circuit device of the gas meter is not perfect in design, and it is difficult to ensure stable operation under complex and changeable power supply environments. Some electronic components in the circuit (such as relays, fuses, etc.) are prone to aging, poor contact and other faults under long-term frequent switching operations and unstable power supply conditions, further reducing the reliability of the circuit and affecting the timely and effective supply of emergency backup power. Traditional power supply circuits and power adapters can often only protect a single voltage threshold, but this single threshold protection method cannot fully cope with complex and changeable voltage abnormalities, especially for some more special or extreme voltage changes, which may lead to untimely protection or false operation, thereby affecting the normal operation of the gas meter, and may even damage sensitive electronic components inside the gas meter, causing safety hazards. In addition, gas meters of different models and brands may have different requirements for power supply, and existing power control circuits and adapters often lack compatibility and are difficult to meet the needs of multiple gas meters. Summary of the invention

[0004] In order to solve the above-mentioned problems, the present invention provides a two-stage power protection circuit and a power adapter for gas meters, which can achieve wide range adaptation of input voltage, output stable DC voltage, realize filtering protection through devices such as resistors and capacitors, fuses, realize voltage stabilization protection through thyristors, and realize current limiting protection through power supply overcurrent and overload protection technology. It can meet the strict requirements of gas meters on power supply, and the two-stage protection mechanism can effectively prevent damage to the internal electronic components of the gas meter due to abnormal voltage.

[0005] In order to achieve the above functions, the technical solution adopted by the present invention is as follows: a two-stage power protection circuit applied to a gas meter, comprising a switching power supply circuit, a cut-off explosion-proof protection circuit and an external power supply, wherein the external power supply comprises a main power supply and an emergency backup power supply, the input end of the switching power supply circuit is connected to the external power supply, the output end of the switching power supply circuit is connected to the input end of the cut-off explosion-proof protection circuit, the switching power supply circuit comprises an electromagnetic filter circuit, an input rectifier filter circuit, a conversion circuit, a detection circuit, a control circuit and an output rectifier filter circuit, the input end of the electromagnetic filter circuit is connected to the external power supply, the output end of the electromagnetic filter circuit is connected to the output end of the input rectifier filter circuit The input end of the input rectifier and filter circuit is connected to the input end of the conversion circuit, the output end of the conversion circuit is connected to the input end of the output rectifier and filter circuit, the output end of the output rectifier and filter circuit outputs a stable DC signal, the control circuit is connected to the conversion circuit, one end of the detection circuit is connected to the output rectifier and filter circuit, and the other end of the detection circuit is connected to the control circuit; the cut-off explosion-proof protection circuit includes a filter protection circuit, a voltage stabilizing two-stage protection circuit and a current limiting protection circuit, the filter protection circuit, the voltage stabilizing two-stage protection circuit and the current limiting protection circuit are electrically connected in sequence, and the input end of the filter protection circuit is connected to the output end of the output rectifier and filter circuit; The electromagnetic filtering circuit includes a disposable fuse F1, a varistor R1, a capacitor C1 and an inductor L1. The disposable fuse F1 is connected to a main power supply, the varistor R1 is connected to an output end of the disposable fuse F1 and an emergency backup power supply, the capacitor C1 is connected to an output end of the disposable fuse F1 and an emergency backup power supply, one end of the inductor L1 is connected to an output end of the disposable fuse F1 and an emergency backup power supply, and the other end of the inductor L1 is connected to an input rectifier filtering circuit.

[0006] As a preferred technical solution of the present invention, the input rectification and filtering circuit includes a rectifier bridge and a capacitor C2, the rectifier bridge is composed of a diode D1, a diode D2, a diode D3 and a diode D4, and the rectifier bridge has four terminals, two of which are used to connect to AC input and the other two are used to connect to DC output. The two input terminals of the rectifier bridge are connected to the output end of the inductor L1, one output terminal of the rectifier bridge is connected to the anode of the capacitor C2, the other output terminal of the rectifier bridge is grounded, and the cathode of the capacitor C2 is grounded.

[0007] As a preferred technical solution of the present invention, the conversion circuit includes a capacitor C3, a resistor R3, a diode D5 and a transformer T1, the transformer T1 is composed of a primary coil and a secondary coil, one end of the primary coil is connected to the output terminal of the rectifier bridge, the other end of the primary coil is connected to the anode of the diode D5, the anode of the diode D5 is connected to the control circuit, one end of the capacitor C3 and the resistor R3 is connected to the output terminal of the rectifier bridge, the other end of the capacitor C3 and the resistor R3 is connected to the cathode of the diode D5, and the secondary coil is connected to the output rectifier filter circuit.

[0008] As a preferred technical solution of the present invention, the control circuit includes a power control chip U1, a photocoupler U2, a capacitor C4 and a capacitor C5, the first pin and the second pin of the power control chip U1 are grounded, the third pin of the power control chip U1 is connected to the third pin of the photocoupler U2, the fourth pin of the power control chip U1 is connected to the fourth pin of the photocoupler U2, the power control chip U1 is electrically connected to the anode of the diode D5 through the fifth pin, the sixth pin, the seventh pin and the eighth pin, the fourth pin of the photocoupler U2 is connected to the anode of the capacitor C4, the third pin of the photocoupler U2 is connected to one end of the capacitor C5, and the cathode of the capacitor C4 and the other end of the capacitor C5 are both grounded.

[0009] As a preferred technical solution of the present invention, the output rectification and filtering circuit includes a diode D6, a capacitor C6 and a resistor R5, one end of the secondary coil is connected to the anode of the diode D6, the other end of the secondary coil is grounded, the anode of the capacitor C6 is connected to the cathode of the diode D6, the cathode of the capacitor C6 is grounded, one end of the resistor R5 is connected to the cathode of the diode D6, and the other end of the resistor R5 is grounded.

[0010] As a preferred technical solution of the present invention, the detection circuit includes a resistor R4 and a zener diode D7, one end of the resistor R4 is connected to the cathode of the diode D6, the other end of the resistor R4 is connected to the first pin of the photocoupler U2, the cathode of the zener diode D7 is connected to the second pin of the photocoupler U2, and the anode of the zener diode D7 is connected to the resistor R5.

[0011] As a preferred technical solution of the present invention, the filtering protection circuit includes a RC fuse F2, a capacitor C12 and a capacitor C13, one end of the capacitor C12 is connected to the output end of the output rectifier and filter circuit, the other end of the capacitor C12 is grounded, the anode of the capacitor C13 is connected to the output end of the output rectifier and filter circuit, the cathode of the capacitor C13 is grounded, one end of the RC fuse F2 is connected to the output end of the output rectifier and filter circuit, and the other end of the RC fuse F2 is connected to the voltage stabilizing dual-stage protection circuit.

[0012] As a preferred technical solution of the present invention, the voltage-stabilized two-stage protection circuit includes a voltage-stabilizing diode D8, a voltage-stabilizing diode D9, a bidirectional thyristor Q2, a bidirectional thyristor Q4, a resistor R8, a resistor R10, a resistor R11, a resistor R13, a capacitor C14 and a capacitor C15. The voltage-stabilizing diode D8 and the voltage-stabilizing diode D9 are connected to the output end of the resistance-capacitance fuse F2, one end of the resistor R8 is connected to the anode of the voltage-stabilizing diode D8, and the other end of the resistor R8 is grounded. One end of the capacitor C14 is connected to the anode of the voltage-stabilizing diode D8, and the other end of the capacitor C14 is grounded. The resistor R10 is connected to the anode of the voltage-stabilizing diode D8. One end of the bidirectional thyristor Q2 is connected to the output end of the RC fuse F2, the other end of the bidirectional thyristor Q2 is grounded, and the G pole of the bidirectional thyristor Q2 is connected to the resistor R10; one end of the resistor R11 is connected to the anode of the zener diode D9, the other end of the resistor R11 is grounded, one end of the capacitor C15 is connected to the anode of the zener diode D9, the other end of the capacitor C15 is grounded, the resistor R13 is connected to the anode of the zener diode D9, one end of the bidirectional thyristor Q4 is connected to the output end of the RC fuse F2, the other end of the bidirectional thyristor Q4 is grounded, and the G pole of the bidirectional thyristor Q4 is connected to the resistor R13.

[0013] As a preferred technical solution of the present invention, the current limiting protection circuit includes a control chip U4, a control chip U3, a resistor R23, a resistor R25, a resistor R26, a resistor R18, a resistor R19 and a resistor R20, the 6th pin of the control chip U4 is connected to the output circuit of the voltage stabilizing dual-stage protection circuit, the 1st pin of the control chip U4 is connected to the 6th pin of the control chip U3, the 2nd pin of the control chip U4 is connected to one end of the resistor R26, and the other end of the resistor R26 is grounded, the 3rd pin of the control chip U4 is connected to one end of the resistor R23, and the other end of the resistor R23 is connected to the 1st pin of the control chip U4, and the control chip U The 4th pin of the control chip U4 is connected to one end of the resistor R25, the other end of the resistor R25 is connected to the 6th pin of the control chip U4, the 5th pin of the control chip U4 is grounded, the 1st pin of the control chip U3 is connected to the delivery port, the 3rd pin of the control chip U3 is connected to the resistor R20, the other end of the resistor R20 is connected to the 1st pin of the control chip U3, the 2nd pin of the control chip U3 is connected to one end of the resistor R19, the other end of the resistor R19 is grounded, the 4th pin of the control chip U3 is connected to one end of the resistor R18, the other end of the resistor R18 is connected to the 6th pin of the control chip U3, and the 5th pin of the control chip U3 is grounded.

[0014] The present invention also provides an adapter, which includes a shell and the above-mentioned two-stage power protection circuit applied to the gas meter, the two-stage power protection circuit applied to the gas meter is arranged in the shell, and the power adapter also includes an output interface connected to the two-stage power protection circuit applied to the gas meter, and the output interface is used to connect to a load.

[0015] Compared with the prior art, the present invention adopts the above structure to achieve the following beneficial effects: 1. The power control circuit and power adapter can provide graded protection for different voltage abnormalities. The first-level protection threshold is set for the more common voltage fluctuation range. When the voltage exceeds this range but has not reached the extremely dangerous value, the circuit can adjust the output voltage in time so that the gas meter can still work under relatively stable power supply conditions, avoiding equipment restart or abnormal operation due to slight voltage fluctuations. When the voltage further deteriorates and reaches the second-level protection threshold, the circuit will take more decisive protection measures, thereby effectively protecting the gas meter from damage by extreme voltage, ensuring that it can operate stably in various complex voltage environments, and improving the adaptability of the gas meter to different power supply conditions; 2. The power control circuit and power adapter design with dual-stage protection function can be better compatible with different types of gas meters and surrounding electrical systems. It can adapt to the power requirements and voltage characteristics of different gas meters, work stably in a variety of electrical environments, and reduce compatibility problems caused by power mismatch. At the same time, when voltage abnormalities occur, its hierarchical protection characteristics make fault troubleshooting and positioning easier. Maintenance personnel can quickly determine the severity of the problem and possible fault sources based on the protection level, which improves the maintainability of the equipment and reduces maintenance costs and maintenance time; 3. It can accurately trigger the corresponding protection action according to the degree to which the voltage exceeds the threshold, quickly cut off the excessive voltage or take voltage stabilization measures when undervoltage occurs, prevent the sensitive electronic components inside the gas meter from being damaged, ensure its stable operation, and greatly reduce the probability of failure caused by voltage problems. By integrating rectification and filtering, voltage stabilization protection, current limiting protection and filtering protection, each part works together to provide comprehensive circuit protection. This multiple protection mechanism effectively prevents damage to the circuit caused by various unexpected situations in practical applications, prolongs the service life of the equipment, and reduces maintenance costs. The highly integrated design concept integrates multiple functional modules into one system. This design not only saves space, but also simplifies the circuit layout and improves the stability and reliability of the system. 4. Through the design of the conversion circuit, efficient energy conversion is achieved. By using transformer T1 and rectifier filter components, different forms of input power can be converted into stable DC output. This efficient energy conversion will bring lower energy loss and higher system efficiency, thereby saving energy and reducing operating costs; 5. By testing the circuit, problems in the circuit can be discovered in time, and clear fault information can be provided to maintenance personnel, which helps to quickly locate and solve problems, reduce equipment downtime, and improve system reliability and availability; 6. Through the design of the voltage-stabilizing dual-stage protection circuit, a high-precision 5V, 2.5A stable output can be achieved, which is essential for electronic devices that require precise power supply and can ensure the normal operation and stable performance of the equipment; 7. The main power supply and the emergency backup power supply are automatically switched. The emergency backup power supply can provide power to the load in a timely and reliable manner, ensuring the normal operation of the equipment and improving the economy and sustainability of the gas meter power supply system. When the emergency backup power supply is connected, the diode guides the current steadily, and cooperates with the inductor, capacitor and other filtering elements in the circuit to buffer the voltage spikes caused by power switching, ensuring that the voltage and current input to the load are always in a stable range that the equipment can withstand. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A circuit diagram of a switch power supply circuit part in a power supply double-stage protection circuit applied to a gas meter proposed by the present invention; Figure 2 A circuit diagram of a cut-off explosion-proof protection circuit portion in a two-stage power protection circuit for a gas meter proposed by the present invention; Figure 3 A circuit diagram of an electromagnetic filter circuit part in a two-stage power protection circuit for a gas meter proposed by the present invention; Figure 4 A circuit diagram of an input rectifier and filter circuit part in a two-stage power protection circuit for a gas meter proposed by the present invention; Figure 5 A circuit diagram of a conversion circuit part in a two-stage power protection circuit for a gas meter proposed by the present invention; Figure 6 A circuit diagram of a control circuit part in a two-stage power protection circuit for a gas meter proposed by the present invention; Figure 7 A circuit diagram of an output rectifier and filter circuit part in a two-stage power protection circuit for a gas meter proposed by the present invention; Figure 8 A circuit diagram of a detection circuit part in a two-stage power protection circuit for a gas meter proposed by the present invention; Fig. 9 A circuit diagram of a filter protection circuit part in a two-stage power protection circuit for a gas meter proposed by the present invention; Fig.10A circuit diagram of a voltage stabilizing double-stage protection circuit part in a power double-stage protection circuit for a gas meter proposed by the present invention; Fig.11 A circuit diagram of a current limiting protection circuit part in a two-stage power protection circuit for a gas meter proposed by the present invention; Fig.12 The present invention provides a circuit diagram of an automatic switching circuit between a main power supply and an emergency backup power supply in a two-stage power supply protection circuit for a gas meter.

[0017] Among them, 1. switching power supply circuit, 11. electromagnetic filtering circuit, 12. input rectification and filtering circuit, 13. conversion circuit, 14. control circuit, 15. output rectification and filtering circuit, 16. detection circuit, 2. cut-off explosion-proof protection circuit, 21. filtering protection circuit, 22. voltage stabilization double-stage protection circuit, 23. current limiting protection circuit. DETAILED DESCRIPTION

[0018] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] like Figure 1-Figure 12As shown, the present invention provides a power supply double-stage protection circuit and a power adapter for a gas meter, comprising a switching power supply circuit 1, a cut-off explosion-proof protection circuit 2 and an external power supply, wherein the external power supply comprises a main power supply and an emergency backup power supply, the input end of the switching power supply circuit 1 is connected to the external power supply, the output end of the switching power supply circuit 1 is connected to the input end of the cut-off explosion-proof protection circuit 2, the switching power supply circuit 1 comprises an electromagnetic filter circuit 11, an input rectifier filter circuit 12, a conversion circuit 13, a detection circuit 16, a control circuit 14 and an output rectifier filter circuit 15, the input end of the electromagnetic filter circuit 11 is connected to the external power supply, the output end of the electromagnetic filter circuit 11 is connected to the input end of the input rectifier filter circuit 12, the output end of the input rectifier filter circuit 12 is connected to the input end of the conversion circuit 13, and the output end of the conversion circuit 13 is connected to the input end of the conversion circuit 13. The output end is connected to the input end of the output rectifier and filter circuit 15, and the output end of the output rectifier and filter circuit 15 outputs a stable DC signal. The control circuit 14 is connected to the conversion circuit 13, and one end of the detection circuit 16 is connected to the output rectifier and filter circuit 15, and the other end of the detection circuit 16 is connected to the control circuit 14. The detection circuit 16 transforms the conversion circuit 13 and feeds back the rectified and filtered voltage to the control circuit 14. The control circuit 14 mediates and controls the power supply two-stage protection circuit 14 applied to the gas meter; the cut-off explosion-proof protection circuit 2 includes a filtering protection circuit 21, a voltage stabilizing two-stage protection circuit 22 and a current limiting protection circuit 23. The filtering protection circuit 21, the voltage stabilizing two-stage protection circuit 22 and the current limiting protection circuit 23 are electrically connected in sequence, and the input end of the filtering protection circuit 21 is connected to the output end of the output rectifier and filter circuit 15.

[0020] like Figure 1 and Figure 3 As shown, the electromagnetic filter circuit 11 includes a disposable fuse F1, a varistor R1, a capacitor C1 and an inductor L1. The disposable fuse F1 is connected to the main power supply, the varistor R1 is connected to the output end of the disposable fuse F1 and the emergency backup power supply, the capacitor C1 is connected to the output end of the disposable fuse F1 and the emergency backup power supply, one end of the inductor L1 is connected to the output end of the disposable fuse F1 and the emergency backup power supply, and the other end of the inductor L1 is connected to the input rectifier filter circuit. The disposable fuse F1 provides effective overcurrent protection, the varistor R1 is used to limit the voltage input, the capacitor C1 is used for filtering, and the inductor L1 is used as a coupling inductor. Fig.12As shown, two IN4007 diodes are used to implement the switching circuit of the main and standby power supplies. When the main power supply is normally supplied, the current flows to the disposable fuse F1 through the diode connected to the main power supply. The varistor R1, capacitor C1 and inductor L1 perform overcurrent, overvoltage protection and filtering on the main power supply to ensure that the main power supply supplies power to the circuit in a stable and safe state. When the disposable fuse F1 is blown or the main power supply fails, the emergency standby power supply starts to supply power through the two parallel diodes connected to it to ensure continuous power supply. The inductor L1 can reduce the current impact that may be generated at the moment of power switching and protect the subsequent circuits. At the same time, the varistor R1 and capacitor C1 also help to stabilize the voltage when the emergency standby power supply is connected to avoid the voltage fluctuation caused by power switching. The circuit has an adverse effect on the circuit.

[0021] like Figure 1 and Figure 4 As shown, the input rectification and filtering circuit 12 includes a rectifier bridge and a capacitor C2. The rectifier bridge is composed of a diode D1, a diode D2, a diode D3 and a diode D4, and the rectifier bridge has four terminals, two of which are used to connect to the AC input, and the other two are used to connect to the DC output. When the input voltage is in the positive half cycle, the diodes D1 and D3 are forward-conducted, and D2 and D4 are reverse-cut off. When the input voltage is in the negative half cycle, the diodes D2 and D4 are forward-conducted, and D1 and D3 are reverse-cut off. The two input terminals of the rectifier bridge are connected to the output end of the inductor L1, and one of the output terminals of the rectifier bridge is connected to the anode of the capacitor C2, and another output terminal of the rectifier bridge is grounded. The cathode of the capacitor C2 is grounded, and the rectifier bridge is used for rectification, and then a capacitor C2 is connected in parallel for filtering.

[0022] like Figure 1 and Figure 5 As shown, the conversion circuit 13 includes a capacitor C3, a resistor R3, a diode D5 and a transformer T1. The transformer T1 is composed of a primary coil and a secondary coil. One end of the primary coil is connected to the output terminal of the rectifier bridge, and the other end of the primary coil is connected to the anode of the diode D5. The anode of the diode D5 is connected to the control circuit 14. One end of the capacitor C3 and the resistor R3 are connected to the output terminal of the rectifier bridge, and the other end of the capacitor C3 and the resistor R3 are connected to the cathode of the diode D5. The secondary coil is connected to the output rectifier filter circuit 15. The capacitor C3 is used to filter out high-frequency clutter in the circuit to make the voltage more stable. The resistor R3 is used to limit the current flowing through the capacitor C3 to prevent the capacitor C3 from generating excessive current during charging or discharging. The diode D5 is used to rectify the AC voltage output by the transformer T1 to make it a unidirectional pulsating DC voltage. The transformer T1 changes the input and output voltages according to the turns ratio of its windings to convert the voltage into a target value.

[0023] like Figure 1 and Figure 6 As shown, the control circuit 14 includes a power control chip U1, a photocoupler U2, a capacitor C4 and a capacitor C5. The first pin and the second pin of the power control chip U1 are grounded, the third pin of the power control chip U1 is connected to the third pin of the photocoupler U2, the fourth pin of the power control chip U1 is connected to the fourth pin of the photocoupler U2, the power control chip U1 is electrically connected to the anode of the diode D5 through the fifth pin, the sixth pin, the seventh pin and the eighth pin, the fourth pin of the photocoupler U2 is connected to the anode of the capacitor C4, the third pin of the photocoupler U2 is connected to one end of the capacitor C5, the cathode of the capacitor C4 and the other end of the capacitor C5 are grounded, and the photocoupler U2 adopts a photocoupler of model PC817A, which can realize input and The electrical isolation of the output end makes it possible to have no direct electrical connection between the control circuit 14 and the controlled part, thereby effectively reducing interference and improving the stability and reliability of the circuit. PC817A is a linear optocoupler, and its current transfer characteristic curve is close to a straight line. It has better performance when the signal is small, and can be isolated and controlled with linear characteristics, which helps to control the output of the power supply more accurately. The power control chip U1 adopts the control chip model DK112. The power control chip U1 is used in conjunction with the optocoupler U2. Since the signal is transmitted through light, direct coupling of electrical signals can be avoided, and the influence of external electromagnetic interference on the two-stage protection circuit 14 of the power supply used for the gas meter can be reduced. The two can form an optocoupler feedback circuit, and the duty cycle can be changed by adjusting the control current, so as to achieve the purpose of precise voltage regulation and make the output more stable.

[0024] like Figure 1 and Figure 7 As shown, the output rectification and filtering circuit 15 includes a diode D6, a capacitor C6 and a resistor R5. One end of the secondary coil is connected to the anode of the diode D6, and the other end of the secondary coil is grounded. The anode of the capacitor C6 is connected to the cathode of the diode D6, and the cathode of the capacitor C6 is grounded. One end of the resistor R5 is connected to the cathode of the diode D6, and the other end of the resistor R5 is grounded. The diode D6 protects the current direction, and then a capacitor C6 is connected in parallel for filtering. A 510-ohm resistor R5 is added as the final load resistor. The capacitor C6 filters the pulsating direct current, and through the charging and discharging process, the AC component is filtered out, so that the output voltage is smoother and more stable, close to the DC voltage. The resistor R5 plays the role of current limiting and voltage dividing in the circuit, limiting the current in the circuit to prevent excessive current from damaging other components, and also sharing the voltage in the circuit to a certain extent. Finally, the circuit outputs a stable 5V / 2.5A direct current to power subsequent circuits or equipment.

[0025] like Figure 1 and Figure 8 As shown, the detection circuit 16 includes a resistor R4 and a Zener diode D7, one end of the resistor R4 is connected to the cathode of the diode D6, the other end of the resistor R4 is connected to the first pin of the photocoupler U2, the cathode of the Zener diode D7 is connected to the second pin of the photocoupler U2, and the anode of the Zener diode D7 is connected to the resistor R5. The detection circuit 16 feeds back the voltage transformed by the transformer T1 to the control circuit 14. When the output voltage of the transformer T1 changes, the changed voltage will act on the Zener diode D7 through the branch where the resistor R4 and the Zener diode D7 are located. If the output voltage of the transformer T1 increases, the voltage across the Zener diode D7 exceeds its regulated value, and the Zener diode D7 starts to conduct. At this time, the current flows to the feedback node through the Zener diode D7 and the resistor R4. The feedback node transmits the signal related to the output voltage of the transformer T1 to the control circuit 14. The control circuit 14 adjusts the working state according to the feedback signal to maintain the stability of the output voltage.

[0026] like Figure 2 and Fig. 9 As shown, the filtering protection circuit 21 includes a RC fuse F2, a capacitor C12 and a capacitor C13, one end of the capacitor C12 is connected to the output end of the output rectification and filtering circuit 15, the other end of the capacitor C12 is grounded, the anode of the capacitor C13 is connected to the output end of the output rectification and filtering circuit 15, the cathode of the capacitor C13 is grounded, one end of the RC fuse F2 is connected to the output end of the output rectification and filtering circuit 15, and the other end of the RC fuse F2 is connected to the voltage stabilizing dual-stage protection circuit 22. The filtering protection is realized by the RC fuse F2, the voltage converted by the switching power supply circuit 1 is filtered, and the primary current and voltage are protected.

[0027] like Figure 2 and Fig.10As shown, the voltage-stabilizing dual-stage protection circuit 22 includes a voltage-stabilizing diode D8, a voltage-stabilizing diode D9, a bidirectional thyristor Q2, a bidirectional thyristor Q4, a resistor R8, a resistor R10, a resistor R11, a resistor R13, a capacitor C14 and a capacitor C15, the voltage-stabilizing diode D8 and the voltage-stabilizing diode D9 are connected to the output end of the RC fuse F2, one end of the resistor R8 is connected to the anode of the voltage-stabilizing diode D8, the other end of the resistor R8 is grounded, one end of the capacitor C14 is connected to the anode of the voltage-stabilizing diode D8, the other end of the capacitor C14 is grounded, the resistor R10 is connected to the anode of the voltage-stabilizing diode D8, one end of the bidirectional thyristor Q2 is connected to the output end of the RC fuse F2, the other end of the bidirectional thyristor Q2 is grounded, and the G pole of the bidirectional thyristor Q2 is connected to the resistor R10; One end of the resistor R11 is connected to the anode of the Zener diode D9, and the other end of the resistor R11 is grounded. One end of the capacitor C15 is connected to the anode of the Zener diode D9, and the other end of the capacitor C15 is grounded. The resistor R13 is connected to the anode of the Zener diode D9. One end of the bidirectional thyristor Q4 is connected to the output end of the RC fuse F2, and the other end of the bidirectional thyristor Q4 is grounded. The G pole of the bidirectional thyristor Q4 is connected to the resistor R13. When the voltage is higher than five volts, the Zener diode D8 and the Zener diode D9 are reversely broken down, causing the bidirectional thyristor Q2 and the bidirectional thyristor Q4 to be turned on. Then the large current will blow the RC fuse F2, causing the entire power supply to be disconnected to achieve the purpose of voltage stabilization protection. R8 and R11 are 470K and 10K respectively, which can correspond to different voltages to achieve double-stage protection.

[0028] like Figure 2 and Fig.11As shown, the current limiting protection circuit 23 includes a control chip U4, a control chip U3, a resistor R23, a resistor R25, a resistor R26, a resistor R18, a resistor R19 and a resistor R20. The 6th pin of the control chip U4 is connected to the output circuit of the voltage stabilizing dual-stage protection circuit 22. The 1st pin of the control chip U4 is connected to the 6th pin of the control chip U3. The 2nd pin of the control chip U4 is connected to one end of the resistor R26, and the other end of the resistor R26 is grounded. The 3rd pin of the control chip U4 is connected to one end of the resistor R23, and the other end of the resistor R23 is connected to the 1st pin of the control chip U4. The 4th pin of the control chip U4 is connected to one end of the resistor R25, and the other end of the resistor R25 is connected to the 6th pin of the control chip U4. The 5th pin of the control chip U4 is connected to the 6th pin of the control chip U4. The pin is grounded, the 1st pin of the control chip U3 is connected to the delivery port, the 3rd pin of the control chip U3 is connected to the resistor R20, the other end of the resistor R20 is connected to the 1st pin of the control chip U3, the 2nd pin of the control chip U3 is connected to one end of the resistor R19, the other end of the resistor R19 is grounded, the 4th pin of the control chip U3 is connected to one end of the resistor R18, the other end of the resistor R18 is connected to the 6th pin of the control chip U3, the 5th pin of the control chip U3 is grounded, the control chip U4 and the control chip U3 use the TPS25200 chip of TI to realize current limiting protection. The TPS25200 chip is a 5V electronic fuse with high-precision current limit and overvoltage clamping, which can provide reliable protection for the load and power supply during overvoltage and overcurrent events.

[0029] The power adapter includes a shell and the above-mentioned two-stage power protection circuit applied to the gas meter, the two-stage power protection circuit applied to the gas meter is arranged in the shell, and the power adapter also includes an output interface connected to the two-stage power protection circuit applied to the gas meter, and the output interface is used to connect to the load.

[0030] The present invention and its embodiments are described above, and such description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if ordinary technicians in the field are inspired by it, without departing from the purpose of the invention, they can design a structure and embodiment similar to the technical solution without creativity, which should belong to the protection scope of the present invention.

Claims

1. A two-stage power protection circuit for a gas meter, comprising an external power supply, wherein the external power supply comprises a main power supply and an emergency backup power supply, characterized in that: The power supply dual-stage protection circuit further comprises a switching power supply circuit (1) and a cut-off explosion-proof protection circuit (2); the input end of the switching power supply circuit (1) is connected to an external power supply, the output end of the switching power supply circuit (1) is connected to the input end of the cut-off explosion-proof protection circuit (2); the switching power supply circuit (1) comprises an electromagnetic filter circuit (11), an input rectifier filter circuit (12), a conversion circuit (13), a detection circuit (16), a control circuit (14) and an output rectifier filter circuit (15); the input end of the electromagnetic filter circuit (11) is connected to an external power supply, the output end of the electromagnetic filter circuit (11) is connected to the input end of the input rectifier filter circuit (12), the output end of the input rectifier filter circuit (12) is connected to the conversion circuit (13), the detection circuit (16), the control circuit (14) and the output rectifier filter circuit (15); The control circuit (14) is connected to the conversion circuit (13), the output end of the conversion circuit (13) is connected to the input end of the output rectifier filter circuit (15), the control circuit (14) is connected to the conversion circuit (13), one end of the detection circuit (16) is connected to the output rectifier filter circuit (15), and the other end of the detection circuit (16) is connected to the control circuit (14); the cut-off explosion-proof protection circuit (2) comprises a filter protection circuit (21), a voltage stabilizing two-stage protection circuit (22) and a current limiting protection circuit (23); the filter protection circuit (21), the voltage stabilizing two-stage protection circuit (22) and the current limiting protection circuit (23) are electrically connected in sequence, and the input end of the filter protection circuit (21) is connected to the output end of the output rectifier filter circuit (15).

2. According to claim 1, a two-stage protection circuit for a power supply used in a gas meter is characterized in that: The filter protection circuit (21) comprises a resistor-capacitor fuse F2, a capacitor C12 and a capacitor C13; one end of the capacitor C12 is connected to the output end of the output rectification filter circuit (15); the other end of the capacitor C12 is grounded; the anode of the capacitor C13 is connected to the output end of the output rectification filter circuit (15); the cathode of the capacitor C13 is grounded; one end of the resistor-capacitor fuse F2 is connected to the output end of the output rectification filter circuit (15); and the other end of the resistor-capacitor fuse F2 is connected to the voltage stabilizing dual-stage protection circuit (22).

3. A two-stage power protection circuit for a gas meter according to claim 2, characterized in that: The voltage-stabilizing two-stage protection circuit (22) comprises a voltage-stabilizing diode D8, a voltage-stabilizing diode D9, a bidirectional thyristor Q2, a bidirectional thyristor Q4, a resistor R8, a resistor R10, a resistor R11, a resistor R13, a capacitor C14 and a capacitor C15, wherein the voltage-stabilizing diode D8 and the voltage-stabilizing diode D9 are connected to the output end of the resistance-capacitance fuse F2, one end of the resistor R8 is connected to the anode of the voltage-stabilizing diode D8, and the other end of the resistor R8 is grounded, one end of the capacitor C14 is connected to the anode of the voltage-stabilizing diode D8, and the other end of the capacitor C14 is grounded, the resistor R10 is connected to the anode of the voltage-stabilizing diode D8, and the bidirectional thyristor Q2 is connected to the anode of the voltage-stabilizing diode D4. One end of the silicon Q2 is connected to the output end of the RC fuse F2, the other end of the bidirectional thyristor Q2 is grounded, and the G pole of the bidirectional thyristor Q2 is connected to the resistor R10; one end of the resistor R11 is connected to the anode of the voltage-stabilizing diode D9, the other end of the resistor R11 is grounded, one end of the capacitor C15 is connected to the anode of the voltage-stabilizing diode D9, the other end of the capacitor C15 is grounded, the resistor R13 is connected to the anode of the voltage-stabilizing diode D9, one end of the bidirectional thyristor Q4 is connected to the output end of the RC fuse F2, the other end of the bidirectional thyristor Q4 is grounded, and the G pole of the bidirectional thyristor Q4 is connected to the resistor R13.

4. A two-stage power protection circuit for a gas meter according to claim 3, characterized in that: The current limiting protection circuit (23) comprises a control chip U4, a control chip U3, a resistor R23, a resistor R25, a resistor R26, a resistor R18, a resistor R19 and a resistor R20, the sixth pin of the control chip U4 being connected to the output circuit of the voltage stabilizing dual-stage protection circuit (22), the first pin of the control chip U4 being connected to the sixth pin of the control chip U3, the second pin of the control chip U4 being connected to one end of the resistor R26, the other end of the resistor R26 being grounded, the third pin of the control chip U4 being connected to one end of the resistor R23, the other end of the resistor R23 being connected to the first pin of the control chip U4, and the fourth pin of the control chip U4 being connected to the ground. The pin is connected to one end of the resistor R25, the other end of the resistor R25 is connected to the 6th pin of the control chip U4, the 5th pin of the control chip U4 is grounded, the 1st pin of the control chip U3 is connected to the delivery port, the 3rd pin of the control chip U3 is connected to the resistor R20, the other end of the resistor R20 is connected to the 1st pin of the control chip U3, the 2nd pin of the control chip U3 is connected to one end of the resistor R19, the other end of the resistor R19 is grounded, the 4th pin of the control chip U3 is connected to one end of the resistor R18, the other end of the resistor R18 is connected to the 6th pin of the control chip U3, and the 5th pin of the control chip U3 is grounded.

5. The double-stage protection circuit for power supply used in gas meter according to claim 1 is characterized in that: The control circuit (14) comprises a power control chip U1 and a photoelectric coupler U2, the power control chip U1 and the photoelectric coupler U2 are connected, the power control chip U1 is connected to a conversion circuit (13), and the photoelectric coupler U2 is connected to a detection circuit (16).

6. A two-stage protection circuit for a power supply used in a gas meter according to claim 5, characterized in that: The detection circuit (16) comprises a resistor R4 and a voltage regulator diode D7, one end of the resistor R4 is connected to the output rectification and filtering circuit (15), the other end of the resistor R4 is connected to the photoelectric coupler U2, the cathode of the voltage regulator diode D7 is connected to the photoelectric coupler U2, and the anode of the voltage regulator diode D7 is connected to the output rectification and filtering circuit (15).

7. A power adapter, characterized in that: It comprises the two-stage power protection circuit applied to the gas meter as described in any one of claims 1 to 6, and the power adapter also comprises an output interface connected to the two-stage power protection circuit applied to the gas meter, and the output interface is used to connect to the load.

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