Direct current system protection circuit capable of preventing reverse connection and overvoltage open circuit

Abstract

The utility model discloses a DC system protection circuit capable of preventing reverse connection and overvoltage circuit break. The DC system protection circuit comprises a reverse connection prevention circuit, an overvoltage circuit break circuit, an isolation circuit, a voltage stabilizing circuit, a filtering current-limiting network circuit, a reverse connection prevention driving circuit, an overvoltage protection driving circuit and an overvoltage protection control circuit. The corresponding end of the anti-reverse-connection driving circuit is electrically connected with the corresponding ends of the anti-reverse-connection circuit, the isolation circuit, the voltage stabilizing circuit and the overvoltage protection driving circuit. The corresponding end of the overvoltage protection control circuit is electrically connected with the corresponding ends of an overvoltage protection driving circuit, a filtering current-limiting network circuit and an overvoltage circuit break circuit respectively; and the corresponding end of the filtering current-limiting network circuit is also electrically connected with the corresponding ends of the voltage stabilizing circuit and the anti-reverse connection circuit. According to the utility model, the connection and disconnection of an input DC voltage are carried out by controlling the connection and disconnection of the anti-reverse connection NMOS tube and the overvoltage open circuit NMOS tube, so that a post-stage load is protected.

Description

TECHNICAL FIELD

[0001] The utility model relates to direct current power supply technical field especially relates to a direct current system protection circuit containing anti-reverse connection and overvoltage circuit breaking. BACKGROUND

[0002] With the rapid development of electronic technology, direct current power supply system has been widely used in various electronic devices and systems, such as communication equipment, computers, new energy vehicles, etc. These systems have very high requirements for the stability and safety of power supply. However, in practical application, direct current power supply system often encounters the problem of reverse polarity connection or input voltage being too high, which may cause system damage or performance degradation. Therefore, it is particularly important to design a protection circuit that can effectively prevent reverse polarity connection and overvoltage.

[0003] The existing protection circuit usually only has a single protection function, such as only anti-reverse connection or overvoltage protection, which cannot meet the two protection requirements at the same time. In addition, some circuits with comprehensive protection function have complex structure and high cost, which is not conducive to wide application. Therefore, there is an urgent need for a direct current system protection circuit with simple structure, low cost and simultaneous anti-reverse connection and overvoltage protection. SUMMARY

[0004] In view of the problems existing in the prior art, the utility model provides a direct current system protection circuit containing anti-reverse connection and overvoltage circuit breaking.

[0005] In order to achieve the above purpose, the technical scheme of the utility model is as follows:

[0006] The utility model provides a direct current system protection circuit containing anti-reverse connection and overvoltage circuit breaking, which comprises an anti-reverse connection circuit, an overvoltage circuit breaking circuit, an isolation circuit, a voltage stabilizing circuit, a filter current limiting network circuit, an anti-reverse connection driving circuit, an overvoltage protection driving circuit and an overvoltage protection control circuit.

[0007] The anti-reverse connection driving circuit is electrically connected to the corresponding end of the anti-reverse connection circuit, the isolation circuit, the voltage stabilizing circuit and the overvoltage protection driving circuit.

[0008] The overvoltage protection control circuit is also electrically connected to the corresponding end of the overvoltage protection driving circuit, the filter current limiting network circuit and the overvoltage circuit breaking circuit.

[0009] The filter current limiting network circuit is also electrically connected to the corresponding end of the voltage stabilizing circuit and the anti-reverse connection circuit. The isolation circuit is also electrically connected to the corresponding end of the overvoltage circuit breaking circuit.

[0010] Preferably, the reverse connection prevention circuit comprises a reverse connection prevention NMOS (Q1), a pull-down resistor (R1) and a diode (D2A); the gate of the reverse connection prevention NMOS (Q1) is electrically connected with the first end of the pull-down resistor (R1) and the diode (D2A) and the corresponding end of the reverse connection prevention driving circuit respectively, the source of the reverse connection prevention NMOS (Q1) is electrically connected with the second end of the pull-down resistor (R1) and the diode (D2A) and the corresponding end of the filter current limiting network circuit respectively, and the drain of the reverse connection prevention NMOS (Q1) is electrically connected with the GND end.

[0011] Preferably, the reverse connection prevention driving circuit comprises a triode (Q4), a driving current limiting resistor (R4) and a driving resistor (R2); the collector of the triode (Q4) is electrically connected with the gate of the reverse connection prevention NMOS (Q1) through the driving resistor (R2), and the base of the triode (Q4) is electrically connected with the emitter of the triode (Q4), the isolation circuit, the voltage stabilizing circuit and the corresponding end of the overvoltage protection driving circuit through the driving current limiting resistor (R4) respectively.

[0012] Preferably, the isolation circuit comprises a diode (D1); the first end of the diode (D1) is electrically connected with the base of the triode (Q4), and the second end of the diode (D1) is electrically connected with the VCC end and the corresponding end of the overvoltage protection circuit respectively.

[0013] Preferably, the voltage stabilizing circuit comprises a voltage stabilizing diode (D3A) and a voltage stabilizing diode (D4A); the first end of the voltage stabilizing diode (D3A) is electrically connected with the base of the triode (Q4), and the second end of the voltage stabilizing diode (D3A) is electrically connected with the corresponding end of the filter current limiting network circuit through the voltage stabilizing diode (D4A).

[0014] Preferably, the overvoltage protection driving circuit comprises a triode (Q3), a triode (Q5), a current limiting resistor (R8), a current limiting resistor (R9), a current limiting resistor (R10) and a diode (D5A); the base of the triode (Q3) is electrically connected with the emitter of the triode (Q4), one end of the resistor (R4), the collector of the triode (Q3) and the collector of the triode (Q5) through the current limiting resistor (R8) respectively, and the base of the triode (Q3) is also electrically connected with the first end of the diode (D5A) and the corresponding end of the overvoltage protection control circuit respectively;

[0015] the emitter of the triode (Q3) is electrically connected with the base of the triode (Q5), the emitter of the triode (Q5) is electrically connected with the corresponding end of the overvoltage protection control circuit, the corresponding end of the overvoltage protection circuit and the first end of the current limiting resistor (R9) through the current limiting resistor (R10) respectively, and the second end of the current limiting resistor (R9) is electrically connected with the second end of the diode (D5A), the corresponding end of the filter current limiting network circuit, the corresponding end of the overvoltage protection control circuit and the corresponding end of the overvoltage protection circuit respectively.

[0016] Preferably, the overvoltage protection control circuit comprises a transistor (Q8) and a transistor (Q7); the base of the transistor (Q8) is electrically connected with the corresponding end of the filter current limiting network circuit,

[0017] The emitter of the transistor (Q8) is electrically connected with the second end of a diode (D5A), the second end of a current limiting resistor (R9) and the corresponding end of the overvoltage circuit breaker respectively, the collector of the transistor (Q8) is electrically connected with the collector of a transistor (Q7), the base of the transistor (Q7) is electrically connected with the emitter of a transistor (Q5) and the corresponding end of the overvoltage circuit breaker respectively, and the emitter of the transistor (Q7) is electrically connected with the base of a transistor (Q3) correspondingly.

[0018] Preferably, the overvoltage circuit breaker comprises an overvoltage circuit breaker NMOS (Q2); the gate of the overvoltage circuit breaker NMOS (Q2) is electrically connected with the base of the transistor (Q7), the source of the overvoltage circuit breaker NMOS (Q2) is electrically connected with the emitter of the transistor (Q8), and the drain of the overvoltage circuit breaker NMOS (Q2) is electrically connected with the second end of a diode (D2).

[0019] Preferably, the filter current limiting network circuit comprises a resistor (R5), a resistor (R6), a resistor (R7), a capacitor (C1) and a capacitor (C2); the first end of the resistor (R5) is electrically connected with a stabilizing diode (D4A), the second end of the resistor (R5) is electrically connected with the first end of the capacitor (C1) and the first end of the resistor (R6) respectively, the second end of the resistor (R6) is electrically connected with the first end of the resistor (R7), the first end of the capacitor (C2), the base of the transistor (Q8) respectively, the second end of the capacitor (C2) is electrically connected with the second end of the resistor (R7), the second end of the capacitor (C1), the source of the anti-reverse connection NMOS (Q1), the second end of the current limiting resistor (R9), the second end of the diode (D5A), the emitter of the transistor (Q8) and the source of the overvoltage circuit breaker NMOS (Q2) respectively.

[0020] The technical scheme of the utility model has the following beneficial effects:

[0021] The utility model discloses a control anti-reverse connection NMOS (Q1) and overvoltage circuit breaker NMOS (Q2) conduction and cut-off to disconnect and communicate to the circuit to the input DC voltage and protect the load of back stage, has the advantage that the circuit is simple, and the cost is low, and the reliability is high, and is convenient for application in various DC systems.

[0022] The design of the anti-reverse connection circuit is as follows:

[0023] Prevent reverse current flow: Anti-reverse NMOS (Q1) ensures that current only flows to the load in the correct polarity, preventing circuit damage caused by reverse connection of the power supply.

[0024] Design of overvoltage protection circuit:

[0025] Overvoltage protection: Overvoltage protection NMOS (Q2) cuts off the current when the voltage exceeds the safe threshold, protecting the subsequent circuit from overvoltage damage; the overvoltage protection circuit design can quickly respond to voltage changes and disconnect the circuit in time, reducing potential damage.

[0026] Design of isolation circuit:

[0027] Electrical isolation: Diode (D1) provides circuit isolation to prevent mutual interference between different circuit parts and improve system stability. Prevent reverse current: Isolation circuit prevents reverse current from flowing, protecting the circuit from reverse voltage.

[0028] Design of voltage stabilization circuit:

[0029] Stable voltage supply: Voltage stabilization diodes (D3A and D4A) provide a stable reference voltage to ensure that the circuit works stably under different conditions. Protect subsequent circuits: The voltage stabilization circuit prevents voltage fluctuations from damaging subsequent circuits and improves the reliability of the entire system.

[0030] Design of filter current limiting network circuit:

[0031] Filter noise: The filter network composed of resistors (R5, R6, R7) and capacitors (C1, C2) reduces power supply noise and improves power supply quality.

[0032] Limit current: The filter current limiting network circuit limits the size of the current to prevent overcurrent damage to the circuit.

[0033] Design of anti-reverse connection drive circuit:

[0034] Accurate control: Triode (Q4) and its related resistors (R2, R4) accurately control the conduction and cutoff of anti-reverse NMOS (Q1).

[0035] Enhanced drive capability: The anti-reverse connection drive circuit enhances the drive capability of Q1, ensuring reliable operation under various conditions.

[0036] Design of overvoltage protection drive circuit:

[0037] Enhanced Overvoltage Protection: The transistors (Q3, Q5) and their associated resistors (R8, R9, R10) and diode (D5A) enhance the driving capability of the overvoltage protection NMOS (Q2), improving the reliability of overvoltage protection. The overvoltage protection drive circuit precisely controls Q2 through logic control, ensuring timely disconnection of the circuit under overvoltage conditions.

[0038] Design of Overvoltage Protection Control Circuit:

[0039] Accurate Overvoltage Detection: The transistors (Q8, Q7) and their associated resistors and diode (D5A) accurately detect overvoltage and control the conduction and cutoff of Q2. Improve System Safety: The overvoltage protection control circuit improves the safety of the entire system, preventing overvoltage damage to the circuit.

[0040] In summary, the DC system protection circuit designed in this application achieves comprehensive protection of the DC power supply system through the coordinated work of various circuit structures, with multiple beneficial effects such as improving safety, reducing cost, simplifying design, enhancing stability and adaptability, etc.

[0041] Prolong Equipment Life: The utility model prolongs the service life of electronic equipment and system by effectively protecting against overvoltage and reverse connection, reducing damage to electronic components caused by power supply problems.

[0042] Reduce Maintenance Costs: Due to the high reliability and stability of the circuit, maintenance and replacement requirements caused by power supply problems can be reduced, thereby reducing long-term maintenance costs. BRIEF DESCRIPTION OF DRAWINGS

[0043] Fig. 1 Circuit schematic diagram of the utility model;

[0044] Fig. 2 Circuit logic diagram of the utility model. DETAILED DESCRIPTION

[0045] The embodiments of the utility model are described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar reference numbers represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary and are intended to explain the utility model, and cannot be understood as limiting the utility model.

[0046] In the description of the utility model, it is necessary to understand that the orientation or positional relation indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like is the orientation or positional relation based on the orientation or positional relation shown in the drawings, which is only for the convenience of describing the utility model and simplifying the description, and therefore cannot be understood as a limitation on the utility model.

[0047] In addition, the terms "first" and "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the utility model, the meaning of "multiple" is two or more than two, unless otherwise specifically limited.

[0048] In the utility model, unless otherwise specifically defined and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication between two elements. For ordinary skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific situation.

[0049] In the utility model, unless otherwise specifically defined and limited, the "upper" or "lower" of the first feature in the second feature can include the direct contact of the first and second features, or it can include the contact of the first and second features without direct contact through another feature between them. Moreover, the "upper", "upper" and "upper" of the first feature in the second feature include the vertical direction of the first feature above and oblique above the second feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The "below", "below" and "below" of the first feature in the second feature include the vertical direction of the first feature below and oblique below the second feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0050] Reference Figs. 1-2 The utility model provides a kind of DC system protection circuit containing anti-reverse connection and overvoltage circuit breaker, including anti-reverse connection circuit 100, overvoltage circuit breaker circuit 500, isolation circuit 700, voltage stabilizing circuit 800, filter current-limiting network circuit 600, anti-reverse connection drive circuit 200, overvoltage protection drive circuit 300, overvoltage protection control circuit 400;

[0051] The anti-reverse connection driving circuit 200 is electrically connected with the anti-reverse connection circuit 100, the isolation circuit 700, the voltage stabilizing circuit 800 and the overvoltage protection driving circuit 300 respectively;

[0052] The overvoltage protection control circuit 400 is further electrically connected with the overvoltage protection driving circuit 300, the filter current limiting network circuit 600 and the overvoltage circuit breaker 500 respectively;

[0053] The filter current limiting network circuit 600 is further electrically connected with the voltage stabilizing circuit 800 and the anti-reverse connection circuit 100, and the isolation circuit 700 is further electrically connected with the overvoltage circuit breaker 500;

[0054] The anti-reverse connection circuit 100 is used for preventing the reverse flow of current when the power polarity is reversed, the overvoltage circuit breaker 500 is used for cutting off the power supply when the input voltage exceeds the set threshold value to protect the subsequent circuit, the isolation circuit 700 is used for isolating the protection circuit and the load end circuit, the voltage stabilizing circuit 800 is used for providing a stable reference voltage, the filter current limiting network circuit 600 is used for filtering the pulse interference in the input voltage and limiting the current, the anti-reverse connection driving circuit 200 is used for driving the switching element in the anti-reverse connection circuit 100, the overvoltage protection driving circuit 300 is used for driving the switching element in the overvoltage circuit breaker 500, and the overvoltage protection control circuit 400 is used for controlling the conduction and cutoff of the overvoltage protection driving circuit 300.

[0055] Further, the reverse connection prevention circuit comprises a reverse connection prevention NMOS (Q1), a pull-down resistor (R1) and a diode (D2A); the gate of the reverse connection prevention NMOS (Q1) is electrically connected with the first end of the pull-down resistor (R1) and the diode (D2A) and the corresponding end of the reverse connection prevention driving circuit 200 respectively, the source of the reverse connection prevention NMOS (Q1) is electrically connected with the second end of the pull-down resistor (R1) and the diode (D2A) and the corresponding end of the filter current limiting network circuit respectively, and the drain of the reverse connection prevention NMOS (Q1) is electrically connected with the GND end. In the embodiment, the reverse connection prevention NMOS (Q1) is the core element of the reverse connection prevention circuit, and its main function is to control the current direction according to the polarity of the input voltage. When the power polarity is correct, Q1 is turned on to allow the current to flow from the source to the drain; when the power polarity is incorrect, Q1 is turned off to prevent the current from flowing, thereby protecting the subsequent circuit from damage. The diode (D2A) is connected between the gate and the source of the reverse connection prevention NMOS (Q1), which is used to protect the gate of Q1 from being damaged by excessive voltage, especially when the power polarity is reversed, D2A can quickly conduct to clamp the gate voltage to a safe level, preventing Q1 from being damaged by excessive voltage. The pull-down resistor (R1) is connected between the gate of the reverse connection prevention NMOS (Q1) and the ground, which is used to pull down the gate voltage of Q1 when there is no driving signal, ensuring that Q1 remains in the off state when there is no input signal, thereby avoiding misoperation; by accurately controlling the current direction, the reverse connection prevention circuit significantly improves the reliability of the DC system and prevents circuit damage caused by reverse connection of the power supply polarity.

[0056] Further, the reverse connection prevention driving circuit 200 comprises a transistor (Q4), a driving current limiting resistor (R4) and a driving resistor (R2); the collector of the transistor (Q4) is electrically connected with the gate of the reverse connection prevention NMOS (Q1) through the driving resistor (R2), the base of the transistor (Q4) is electrically connected with the emitter of the transistor (Q4), the isolation circuit 700, the voltage stabilizing circuit 800 and the over-voltage protection driving circuit 300 through the driving current limiting resistor (R4) respectively; in the embodiment, the transistor (Q4) functions as a switch in the circuit, controlling the gate voltage of the reverse connection prevention NMOS (Q1) and thereby controlling the conduction and cutoff of Q1 to realize the reverse connection prevention function. The driving current limiting resistor (R4) is used to limit the current flowing into the base of the transistor (Q4) to protect the transistor (Q4) from being damaged by excessive base current. The driving resistor (R2) is used to provide a stable voltage for the gate of the reverse connection prevention NMOS (Q1) when the transistor (Q4) is turned on, ensuring that Q1 can be reliably turned on. Through the amplification of the transistor (Q4), a small current control signal can be converted into a large enough current to drive the reverse connection prevention NMOS (Q1), improving the driving capability of the circuit.

[0057] Further, the isolation circuit 700 comprises a diode (D1); the first end of the diode (D1) is electrically connected with the base of the triode (Q4), and the second end of the diode (D1) is electrically connected with the VCC end and the corresponding end of the overvoltage protection circuit 500 respectively; the diode (D1) acts as an isolation element in this circuit, and its function is to electrically isolate the anti-reverse connection driving circuit 200 from the overvoltage protection circuit 500, so as to prevent misoperation or damage caused by mutual influence between circuits. Through the isolation circuit 700, the safety of the entire protection circuit can be improved, and the circuit damage caused by reverse polarity of the power supply or overvoltage event can be prevented.

[0058] Further, the voltage stabilizing circuit 800 comprises a voltage stabilizing diode (D3A) and a voltage stabilizing diode (D4A); the first end of the voltage stabilizing diode (D3A) is electrically connected with the base of the triode (Q4), and the second end of the voltage stabilizing diode (D3A) is electrically connected with the corresponding end of the filter current limiting network circuit 600 through the voltage stabilizing diode (D4A); the main function of the voltage stabilizing diodes (D3A and D4A) is to clamp voltage, so as to ensure that the base voltage of the triode (Q4) and the input voltage of the filter current limiting network circuit 600 are kept within a safe and stable range; the use of the voltage stabilizing diodes enhances the protection capability of the circuit and reduces the risk of circuit damage caused by voltage fluctuation or transient overvoltage.

[0059] Further, the overvoltage protection drive circuit 300 comprises a transistor (Q3), a transistor (Q5), a current-limiting resistor (R8), a current-limiting resistor (R9), a current-limiting resistor (R10), and a diode (D5A); the base of the transistor (Q3) is electrically connected with the emitter of the transistor (Q4), one end of the resistor (R4), the collector of the transistor (Q3), and the collector of the transistor (Q5) through the current-limiting resistor (R8), and is also electrically connected with the first end of the diode (D5A) and the corresponding end of the overvoltage protection control circuit 400; the emitter of the transistor (Q3) is electrically connected with the base of the transistor (Q5), and the emitter of the transistor (Q5) is electrically connected with the corresponding end of the overvoltage protection control circuit, the corresponding end of the overvoltage protection circuit, and the first end of the current-limiting resistor (R9) through the current-limiting resistor (R10); the second end of the current-limiting resistor (R9) is electrically connected with the second end of the diode (D5A), the corresponding end of the filter current-limiting network circuit 600, the corresponding end of the overvoltage protection control circuit 400, and the corresponding end of the overvoltage protection circuit 500; in this embodiment, the Darlington pair composed of the transistors (Q3) and (Q5) can provide sufficient current to drive the overvoltage protection NMOS (Q2), ensuring that the power supply is quickly cut off under overvoltage conditions. The current-limiting resistors (R8), (R9), and (R10) are used to limit the current flowing through the base and collector of the transistor, preventing the transistor from being damaged due to overcurrent, thereby protecting the circuit; the diode (D5A) is used to clamp the voltage at the base of the transistor (Q3), preventing the voltage from being too high to damage the transistor, and also protecting the overvoltage protection control circuit; by enhancing the driving capability and limiting the current, the overvoltage protection drive circuit 300 improves the reliability of the entire overvoltage protection system; the circuit can accurately control the conduction and cutoff of the overvoltage protection NMOS (Q2), ensuring that the power supply is cut off in time when the input voltage exceeds the set threshold, thereby protecting the subsequent circuit. The voltage clamping function of the diode (D5A) protects the transistor (Q3) and the overvoltage protection control circuit, preventing them from being damaged due to excessive voltage. In summary, the overvoltage protection drive circuit 300 uses the Darlington pair composed of the transistors (Q3) and (Q5), current-limiting resistors, and the diode (D5A) to achieve the functions of enhancing the driving capability, limiting the current, clamping the voltage, and logical control, thereby improving the reliability, accurate control capability, and adaptability of the entire DC system protection circuit, while simplifying the circuit design and protecting the circuit components.

[0060] Further, the overvoltage protection control circuit 400 comprises a transistor (Q8) and a transistor (Q7); the base of the transistor (Q8) is electrically connected with the corresponding end of the filter current-limiting network circuit,

[0061] The emitter of the triode (Q8) is electrically connected with the second end of the diode (D5A), the second end of the current-limiting resistor (R9) and the corresponding end of the overvoltage protection circuit, respectively; the collector of the triode (Q8) is electrically connected with the collector of the triode (Q7); the base of the triode (Q7) is electrically connected with the emitter of the triode (Q5) and the corresponding end of the overvoltage protection circuit, respectively; and the emitter of the triode (Q7) is electrically connected with the base of the triode (Q3). In the embodiment, the triodes (Q8) and (Q7) jointly control the gate voltage of the overvoltage protection NMOS (Q2), so as to control the conduction and cutoff of the Q2, and realize overvoltage protection; through the cascade amplification of the triodes (Q8) and (Q7), a small current control signal can be converted into a large enough current to drive the overvoltage protection NMOS (Q2). The circuit can accurately control the conduction and cutoff of the overvoltage protection NMOS (Q2), and ensure that the power supply is cut off in time when the input voltage exceeds the set threshold, so as to protect the subsequent circuit.

[0062] Further, the overvoltage protection circuit 500 comprises an overvoltage protection NMOS (Q2); the gate of the overvoltage protection NMOS (Q2) is electrically connected with the base of the triode (Q7), the source of the overvoltage protection NMOS (Q2) is electrically connected with the emitter of the triode (Q8), and the drain of the overvoltage protection NMOS (Q2) is electrically connected with the second end of the diode (D2); when the overvoltage protection NMOS (Q2) detects that the input voltage exceeds the preset threshold, it will change from the conduction state to the cutoff state, so as to cut off the current flowing to the load, and realize overvoltage protection.

[0063] Further, the filter current limiting network circuit 600 comprises resistance (R5), resistance (R6), resistance (R7), capacitor (C1), capacitor (C2); the first end of the resistance (R5) is electrically connected with the stabilizing diode (D4A), the second end of the resistance (R5) is electrically connected with the first end of the capacitor (C1) and the first end of the resistance (R6) respectively, the second end of the resistance (R6) is electrically connected with the first end of the resistance (R7), the first end of the capacitor (C2) and the base of the triode (Q8) respectively, the second end of the capacitor (C2) is electrically connected with the second end of the resistance (R7), the second end of the capacitor (C1), the source of the reverse connection preventing NMOS (Q1), the second end of the current limiting resistance (R9), the second end of the diode (D5A), the emitter of the triode (Q8) and the source of the overvoltage protection triode (Q2) respectively. In the design of the filter current limiting network circuit 600 in the embodiment, the overvoltage protection triode is prevented from being triggered and the power supply is prevented from being disconnected when the front end has pulse interference; the capacitors (C1) and (C2) are used for filtering high frequency noise and pulse interference in the input voltage, so that the voltage received by the circuit is more smooth and stable; the resistances (R5), (R6) and (R7) are used for limiting the current flowing through the circuit, so that the circuit elements are prevented from being damaged by excessive current. By filtering high frequency noise and pulse interference, the filter current limiting network circuit 600 improves the stability and reliability of the entire direct current system protection circuit.

[0064] The utility model works principle:

[0065] In the 24~36V direct current system, the overvoltage threshold value 40V is set, and the maximum withstand maximum forward overvoltage 80V is required, and the reverse withstand voltage is 80V. Q1, Q2 select NMOS such as IRF840, D1 select ordinary diode such as 1N4007, 1N4148 etc., R1, R5, R6, R7, R10 select 1K resistance value, R2 select 6.8K resistance value, R4 select 10K resistance value, R8, R9 select 220K resistance value, C1 select 0.47uF, C2 select 100nF capacitance value, Q3, Q5, Q8 select NPN triode such as MMBT5551LT1, Q4, Q7 select PNP triode such as MMBT5401LT1, D3A, D4A select 18V stabilizing tube, D2A, D5A select 18V, TVS tube.

[0066] Fig. 2Is the logic diagram of input voltage, when input 80V reverse voltage, Q1 is off, Q1 is selected IRF840 withstand voltage 500V, meet the withstand voltage requirements circuit protection, when input 40V voltage, D3A, D4A conduction clamp 36V, Q8 base level and the emission voltage difference Vbe=(40V-36-VFD1)*R7 / (R5+R6+R7), VFD1 is the conduction voltage drop of diode D1 is 0.4V, all parameters are brought in Vbe=1.2V, Q8, Q7 conduction, Q3, Q5 off, Q2 off when input 80V forward voltage, Q2 withstand voltage 500V, meet the withstand voltage requirements, circuit protection.

[0067] The above only describes the preferred embodiments of the present application, and does not limit the patent range of the present application, and any equivalent structural transformation made by using the present application specification and drawings, or directly / indirectly applied in other related technical fields under the utility model concept of the present application are included in the patent protection range of the present application.

Claims

1. A direct current system protection circuit comprising reverse connection and overvoltage protection, characterized in that, The anti-reverse connection circuit, the overvoltage protection circuit, the isolation circuit, the voltage stabilizing circuit, the filter current limiting network circuit, the anti-reverse connection driving circuit, the overvoltage protection driving circuit and the overvoltage protection control circuit are connected in series. The anti-reverse connection driving circuit is electrically connected with the anti-reverse connection circuit, the isolation circuit, the voltage stabilizing circuit and the overvoltage protection driving circuit. The overvoltage protection control circuit is further electrically connected with the overvoltage protection driving circuit, the filter current limiting network circuit and the overvoltage protection circuit. The filter current limiting network circuit is further electrically connected with the voltage stabilizing circuit and the anti-reverse connection circuit.

2. A DC system protection circuit containing reverse connection and overvoltage protection according to claim 1, characterized in that, The anti-reverse connection circuit comprises an anti-reverse connection NMOS (Q1), a pull-down resistor (R1) and a diode (D2A).

3. A DC system protection circuit comprising reverse connection and overvoltage protection according to claim 2, characterized in that, The anti-reverse connection driving circuit comprises a triode (Q4), a driving current limiting resistor (R4) and a driving resistor (R2).

4. A DC system protection circuit comprising reverse connection and overvoltage protection according to claim 3, characterized in that, The isolation circuit comprises a diode (D1).

5. A DC system protection circuit containing reverse connection and overvoltage protection according to claim 4, characterized in that, The voltage stabilizing circuit comprises a voltage stabilizing diode (D3A) and a voltage stabilizing diode (D4A).

6. A DC system protection circuit containing reverse connection and overvoltage protection according to claim 5, characterized in that, The overvoltage protection driving circuit comprises a triode (Q3), a triode (Q5), a current limiting resistor (R8), a current limiting resistor (R9), a current limiting resistor (R10) and a diode (D5A). The emitter of the triode (Q3) is electrically connected with the base of the triode (Q5), the emitter of the triode (Q5) is electrically connected with the corresponding end of the overvoltage protection control circuit, the corresponding end of the overvoltage circuit breaker, the first end of the current limiting resistor (R10) and the first end of the current limiting resistor (R9) respectively, the second end of the current limiting resistor (R9) is electrically connected with the second end of the diode (D5A), the corresponding end of the filter current limiting network circuit, the corresponding end of the overvoltage protection control circuit, the corresponding end of the overvoltage circuit breaker respectively.

7. The DC system protection circuit containing reverse connection and overvoltage protection according to claim 1, characterized in that, The overvoltage protection control circuit comprises a triode (Q8) and a triode (Q7), the base of the triode (Q8) is electrically connected with the corresponding end of the filter current limiting network circuit, The emitter of the triode (Q8) is electrically connected with the second end of the diode (D5A), the second end of the current limiting resistor (R9), the corresponding end of the overvoltage circuit breaker respectively, the collector of the triode (Q8) is electrically connected with the collector of the triode (Q7), the base of the triode (Q7) is electrically connected with the emitter of the triode (Q5) and the corresponding end of the overvoltage circuit breaker respectively, the emitter of the triode (Q7) is electrically connected with the base of the triode (Q3) correspondingly.

8. The DC system protection circuit containing reverse connection and overvoltage protection according to claim 1, characterized in that, The overvoltage circuit breaker comprises an overvoltage circuit breaker NMOS (Q2), the gate of the overvoltage circuit breaker NMOS (Q2) is electrically connected with the base of the triode (Q7), the source of the overvoltage circuit breaker NMOS (Q2) is electrically connected with the emitter of the triode (Q8), and the drain of the overvoltage circuit breaker NMOS (Q2) is electrically connected with the second end of the diode (D2).

9. The DC system protection circuit containing reverse connection and overvoltage protection according to claim 1, characterized in that, The filter current limiting network circuit comprises a resistor (R5), a resistor (R6), a resistor (R7), a capacitor (C1) and a capacitor (C2), the first end of the resistor (R5) is electrically connected with the stabilizing diode (D4A), the second end of the resistor (R5) is electrically connected with the first end of the capacitor (C1) and the first end of the resistor (R6) respectively, the second end of the resistor (R6) is electrically connected with the first end of the resistor (R7), the first end of the capacitor (C2), the base of the triode (Q8) respectively, the second end of the capacitor (C2) is electrically connected with the second end of the resistor (R7), the second end of the capacitor (C1), the source of the anti-reverse NMOS (Q1), the second end of the current limiting resistor (R9), the second end of the diode (D5A), the emitter of the triode (Q8) and the source of the overvoltage circuit breaker NMOS (Q2) respectively.

Images