Overvoltage and overcurrent protection circuit

Abstract

The utility model discloses an overvoltage and overcurrent protection circuit, which is applied to an AI module channel and an AO module channel of a nuclear power station, and comprises an overvoltage and overcurrent protection module and a cut-off module, one end of the overvoltage and overcurrent protection module is connected with the circuit input end, and the other end of the overvoltage and overcurrent protection module is connected with the cut-off module; the other end of the cut-off module is connected with the circuit output end; when the overvoltage and overcurrent protection module detects that the current input by the input end of the circuit is larger than the maximum current threshold value, the circuit is adjusted to be constant current, and when the cut-off module detects that the voltage connected to the output end of the circuit is the maximum voltage threshold value, the voltage connected to the output end of the circuit is cut off. Therefore, two independent over-current and over-voltage protection circuits, namely the over-voltage and over-current protection module, are integrated into one circuit, so that the problems that the circuit is too complicated and the cost is relatively high are solved, and meanwhile, the safe and stable operation of nuclear power station equipment is also ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of industrial control, in particular to an overvoltage and overcurrent protection circuit. Background Art

[0002] In a nuclear power plant, AI (analog input) and AO (analog output) module channels usually refer to the input and output channels of analog signals, which are used to monitor, control and adjust the nuclear power plant, thereby ensuring the safe and efficient operation of the nuclear power plant system. Therefore, it is necessary to implement overvoltage and overcurrent protection circuits on AI and AO module channels so that they are not damaged or disturbed during normal operation, and to quickly stop the current flow in abnormal situations to prevent damage. A series of methods and equipment.

[0003] Therefore, in the existing technology, the overvoltage and overcurrent protection circuits of the AI ​​and AO module channels are usually implemented by two independent protection circuits. Among them, the current protection circuit generally uses a fuse to blow or controls the switch tube by detecting the current to ensure the stability of the current. The overvoltage protection circuit usually controls the switch tube by detecting the voltage with a voltage-stabilizing diode or a voltage-dividing resistor to achieve voltage stability.

[0004] Since the overvoltage and overcurrent protection circuits of the AI ​​and AO module channels are implemented by two independent protection circuits, the circuits are too complicated and the cost is high. Utility Model Content

[0005] Based on the above-mentioned deficiencies of the prior art, the utility model provides an overvoltage and overcurrent protection circuit to solve the problem of high cost brought about by the prior art.

[0006] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0007] The utility model provides an overvoltage and overcurrent protection circuit in a first aspect, which is applied to AI and AO module channels of a nuclear power plant, wherein the protection circuit comprises: an overvoltage and overcurrent protection module and a cutoff module;

[0008] One end of the overvoltage and overcurrent protection module is connected to the circuit input end, and the other end of the overvoltage and overcurrent protection module is connected to the cutoff module;

[0009] The other end of the cut-off module is connected to the circuit output end;

[0010] Among them, when the overvoltage and overcurrent protection module detects that the current input to the input end of the circuit is greater than the maximum current threshold, the circuit is adjusted to a constant current, and when the cut-off module detects that the voltage connected to the output end of the circuit is the maximum voltage threshold, the voltage connected to the output end of the circuit is cut off.

[0011] Optionally, in the above-mentioned overvoltage and overcurrent protection circuit, the overvoltage and overcurrent protection module includes: a first resistor, a first transistor, a second transistor and a second resistor;

[0012] The base of the first transistor is respectively connected to one end of the first resistor and the collector of the second transistor, the collector of the first transistor is respectively connected to the other end of the first resistor and the circuit input end, and the emitter of the first transistor is respectively connected to the base of the second transistor and one end of the second resistor;

[0013] The emitter of the second transistor is connected to the other end of the second resistor and one end of the cut-off module respectively.

[0014] Optionally, in the above-mentioned overvoltage and overcurrent protection circuit, the cutoff module includes: a diode;

[0015] The anode of the diode is connected to one end of the overvoltage and overcurrent protection module, and the cathode of the diode is connected to the circuit output end.

[0016] Optionally, in the above-mentioned overvoltage and overcurrent protection circuit, the model of the diode is MMSD4148T1G.

[0017] Optionally, in the above-mentioned overvoltage and overcurrent protection circuit, the second transistor is a surface-mounted NPN transistor.

[0018] Optionally, in the above-mentioned overvoltage and overcurrent protection circuit, the first transistor is an NPN transistor.

[0019] Optionally, in the above-mentioned overvoltage and overcurrent protection circuit, the model of the second transistor is MMBT5551LT1G.

[0020] Optionally, in the above-mentioned overvoltage and overcurrent protection circuit, the model of the first transistor is FJT44.

[0021] Optionally, in the above-mentioned overvoltage and overcurrent protection circuit, the second resistor is a current limiting resistor.

[0022] Optionally, in the above-mentioned overvoltage and overcurrent protection circuit, the reverse withstand voltage threshold of the diode is 100V.

[0023] The utility model provides an overvoltage and overcurrent protection circuit, which is applied to the AI ​​and AO module channels of a nuclear power plant. The protection circuit includes: an overvoltage and overcurrent protection module and a cutoff module. One end of the overvoltage and overcurrent protection module is connected to the circuit input end, and the other end of the overvoltage and overcurrent protection module is connected to the cutoff module. The other end of the cutoff module is connected to the circuit output end. When the overvoltage and overcurrent protection module detects that the current input to the circuit input end is greater than the maximum current threshold, the circuit is adjusted to a constant current, and when the cutoff module detects that the voltage connected to the circuit output end is the maximum voltage threshold, the voltage connected to the circuit output end is cut off. Thus, by integrating two independent overcurrent and overvoltage protection circuits into one circuit, namely the overvoltage and overcurrent protection module, the problem of overly complex circuits and high costs is solved, and the safe and stable operation of nuclear power plant equipment is also ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0025] Figure 1 A first structural block diagram of an overvoltage and overcurrent protection circuit provided by an embodiment of the utility model;

[0026] Figure 2 A second structural block diagram of an overvoltage and overcurrent protection circuit provided by an embodiment of the utility model;

[0027] Figure 3 A third structural block diagram of an overvoltage and overcurrent protection circuit provided by an embodiment of the utility model;

[0028] Figure 4 A flow chart of an overvoltage and overcurrent protection method provided in an embodiment of the utility model. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0030] In the present invention, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0031] As can be seen from the background technology, currently, the overvoltage and overcurrent protection circuits for the AI ​​and AO module channels of a nuclear power plant are usually implemented by two independent protection circuits, which leads to the problem that the circuits for implementing overvoltage and overcurrent are too complicated and costly.

[0032] Therefore, the embodiment of the utility model provides an overvoltage and overcurrent protection circuit, which is applied to the AI ​​and AO module channels of a nuclear power plant. The protection circuit includes: an overvoltage and overcurrent protection module and a cutoff module. Thus, the overvoltage and overcurrent protection module can realize both the overvoltage protection function of the AI ​​and AO module channels and the overcurrent function of the AI ​​and AO module channels, thereby effectively solving the problem of high cost and not causing disturbance to the equipment of the nuclear power plant.

[0033] See also Figure 1 , shows a first structural diagram of an overvoltage and overcurrent protection circuit provided by an embodiment of the utility model, the protection circuit includes: an overvoltage and overcurrent protection module 101 and a cut-off module 102.

[0034] One end of the overvoltage and overcurrent protection module 101 is connected to the circuit input end, and the other end of the overvoltage and overcurrent protection module 101 is connected to the cutoff module 102 .

[0035] It should be noted that the overvoltage and overcurrent protection module 101 is used to protect the circuit from damage caused by overvoltage and overcurrent. Specifically, when the voltage or current in the circuit exceeds a set threshold, the module will be triggered to limit the current to protect other components in the circuit from damage.

[0036] The other end of the cut-off module 102 is connected to the circuit output end.

[0037] It should also be noted that the cut-off module 102 is used to apply a reverse cut-off voltage under specific conditions, thereby preventing the circuit from being damaged.

[0038] When the overvoltage and overcurrent protection module 101 detects that the current input to the circuit input end is greater than the maximum current threshold, the circuit is adjusted to a constant current, and when the cutoff module 102 detects that the voltage connected to the circuit output end is the maximum voltage threshold, the voltage connected to the circuit output end is cut off.

[0039] In the embodiment of the utility model, the AI ​​and AO module channels of the nuclear power plant can be effectively protected from overvoltage and overcurrent through the overvoltage and overcurrent protection module 101 and the cut-off module 102, so that they are not damaged or disturbed during normal operation, thereby ensuring the safe and stable operation of the equipment in the nuclear power plant.

[0040] In some embodiments, in combination Figure 1 , see Figure 2 A second structural block diagram of an overvoltage and overcurrent protection circuit is shown, where the overvoltage and overcurrent protection module 101 includes: a first resistor (R1), a first transistor (Q1), a second transistor (Q2) and a second resistor (R2).

[0041] The base of the first transistor (pin B of Q1) is respectively connected to one end of the first resistor (R1) and the collector of the second transistor (pin C of Q2), the collector of the first transistor (pin C of Q1) is respectively connected to the other end of the first resistor (R1) and the circuit input end, and the emitter of the first transistor (pin E of Q1) is respectively connected to the base of the second transistor (pin B of Q2) and one end of the second resistor (R2).

[0042] In some embodiments, the first resistor (R1) is typically 10KΩ. When an external overvoltage occurs, both ends of the first resistor (R1) can withstand most of the overvoltage values, so that the first resistor (R1) is not easily damaged, avoiding frequent replacement of components and effectively reducing costs.

[0043] The emitter of the second transistor (the E pin of Q2 ) is connected to the other end of the second resistor ( R2 ) and one end of the cut-off module 102 , respectively.

[0044] It should be noted that the conduction voltage U between the base (B pin of Q2) and the emitter (E pin of Q2) of the second transistor needs to be determined first. BE , calculate the maximum current value that can pass through the circuit with AI and AO module channels, so as to know the maximum current value that the circuit can withstand. Therefore, when it is detected that the current in the circuit with AI and AO module channels exceeds the maximum current value, the voltage between the base (B pin of Q2) and the emitter (E pin of Q2) of the second transistor will exceed the conduction voltage U BE, the voltage between the base (B pin of Q1) and the emitter (E pin of Q1) of the first transistor will be less than the conduction voltage UBE, then the second transistor (Q2) will be turned on, and the first transistor (Q1) will not be turned on. Therefore, the circuit path in the circuit of the AI ​​and AO module channels is the first resistor (R1) → the second transistor (Q2) → the cutoff module 102 → the circuit output end, thereby achieving the circuit of the AI ​​and AO module channels to maintain a constant current output to the outside, thereby achieving the overcurrent protection function of the AI / AO channel. The maximum current value is

[0045]

[0046] It should also be noted that when the circuit output terminal is connected to the maximum negative voltage value (such as -40V), the maximum voltage between the second transistor (B pin of Q2) and the emitter (E pin of Q2) is U BEMAX , at this time the current at the output of the circuit will be limited to U BEMAX / R2, such as U BEMAX =0.85V, R2=22Ω, then the current at the output end of the circuit is I=0.85V / 22Ω=about 38mA, at this time the power consumption of the first transistor (Q1) is (40V-0.85V-0.5V)*0.038A=1.469W, at this time the power consumption of the first transistor (Q1) should be greater than the calculated 1.469W, so as not to cause damage to the circuit, thereby playing a role of overvoltage protection of the reverse maximum voltage value. Therefore, in some embodiments, the model of the first transistor (Q1) is FJT44, of course, the embodiment of the utility model is not limited to this model, as long as the power consumption of the model of the first transistor (Q1) is greater than the power consumption of the first transistor (Q1) when it is at the negative maximum voltage value.

[0047] In some embodiments, the first transistor (Q1) is of NPN transistor type, and the second transistor (Q2) is of surface-mount NPN transistor type. Because NPN transistors have the advantages of easy control, high reliability and low cost, they can significantly reduce the later operation and maintenance costs of nuclear power plants while ensuring safe and reliable operation of nuclear power plants, and have strong economic benefits.

[0048] In some embodiments, the model of the second transistor (Q2) is MMBT5551LT1G. Of course, the embodiments of the present invention are not limited to this model, and the specific model can be set according to the needs.

[0049] In some embodiments, the second resistor (R2) is a current limiting resistor, and different overcurrent protection thresholds in the circuit can be achieved by changing the resistance value of the second resistor (R2).

[0050] In the embodiment of the utility model, through the first resistor (R1), the second resistor (R2) and two back-to-back transistors, the circuit structure is relatively simple, the cost is relatively simple, and different overcurrent protection thresholds in the circuit can be achieved by changing the resistance value of the second resistor (R2), thereby meeting the safety, reliability and economy requirements of the nuclear power plant.

[0051] In some embodiments, in combination Figure 1 as well as Figure 2 , see Figure 3 In the third structural block diagram of an overvoltage and overcurrent protection circuit shown, the cutoff module 102 includes: a diode (D1).

[0052] The anode of the diode (D1) is connected to one end of the overvoltage and overcurrent protection module 101, and the cathode of the diode is connected to the circuit output end.

[0053] In some embodiments, the model of the diode (D1) is MMSD4148T1G, and the reverse withstand voltage threshold of the diode (D1) is 100 V. It should be noted that the model of the diode (D1) with a larger reverse withstand voltage threshold is applicable to the embodiments of the present utility model.

[0054] It should be noted that when the circuit output terminal is connected to the maximum forward voltage value (such as +40V), the diode (D1) will play a reverse cutoff role, so as not to cause circuit damage to the circuits connected to the AI ​​and AO module channels, thereby providing overvoltage protection for the maximum forward voltage value.

[0055] The above embodiments are related to an overvoltage and overcurrent protection circuit. Figure 4 The embodiment of the utility model also provides a flow chart of an overvoltage and overcurrent protection method, which is applied to the AI ​​and AO module channels of a nuclear power plant, and specifically includes the following steps:

[0056] S401 , using an overvoltage and overcurrent protection module to detect whether the current current in the circuit exceeds a maximum current threshold.

[0057] Specifically, in order to avoid overcurrent and overvoltage in the circuits passing through the AI ​​and AO module channels of the nuclear power plant, thereby affecting the operation of the nuclear power plant, in an embodiment of the utility model, an overvoltage and overcurrent protection module is used to detect whether the current current in the circuit exceeds the maximum current threshold. If it is detected that the current current in the circuit exceeds the maximum current threshold, it means that the current flowing at this time will cause damage to the circuit, so step S402 is executed at this time.

[0058] Optionally, if the current current in the circuit does not exceed the maximum current threshold, no processing is performed and the flow direction of the current current is maintained.

[0059] S402 , conducting the second transistor in the overvoltage and overcurrent protection module, and not conducting the first transistor in the overvoltage and overcurrent protection module.

[0060] It can be understood that if the current current in the circuit exceeds the maximum current threshold, the second transistor in the overvoltage and overcurrent protection module needs to be conducted, and the first transistor in the overvoltage and overcurrent protection module needs to be blocked, so that the circuit maintains a constant current output to the outside.

[0061] S403: Using the cutoff module, determine whether the voltage connected to the output end of the circuit is a forward voltage.

[0062] Specifically, after the current detection is completed, the connected voltage needs to be detected to avoid circuit overvoltage. Since the new embodiment of this embodiment handles the positive voltage and the negative voltage exceeding the threshold differently, the cutoff module will be used in advance to determine whether the voltage connected to the output end of the circuit is a positive voltage. If the voltage connected to the output end of the circuit is a positive voltage, further detection will be performed, so step S404 is executed.

[0063] Optionally, if the voltage connected to the output end of the circuit is a negative voltage, the overvoltage and overcurrent protection module is used to detect whether the negative voltage exceeds the maximum negative voltage threshold. If the negative voltage exceeds the maximum negative voltage threshold, the first transistor in the overvoltage and overcurrent protection module will positively cut off the negative voltage, thereby preventing damage to the circuit.

[0064] S404: Detect whether the forward voltage is a maximum forward voltage threshold.

[0065] Specifically, when the voltage connected to the circuit output terminal is a forward voltage, it is necessary to continue to detect whether the forward voltage is the maximum forward voltage threshold to avoid excessive voltage values ​​from damaging the nuclear power plant. Therefore, if the forward voltage is greater than the maximum forward voltage threshold, step S405 is executed.

[0066] S405: the voltage connected to the output end of the reverse cutoff circuit.

[0067] Specifically, when the forward voltage is greater than the maximum forward voltage threshold, the cutoff module is used to reverse the voltage connected to the output end of the cutoff circuit, thereby protecting the forward voltage value.

[0068] It should be noted that the execution principle of step S401 to step S405 can be found in the above-mentioned description of the overvoltage and overcurrent protection circuit, which will not be repeated here.

[0069] The utility model provides an overvoltage and overcurrent protection circuit, which is applied to the AI ​​and AO module channels of a nuclear power plant. The protection circuit includes: an overvoltage and overcurrent protection module and a cutoff module. One end of the overvoltage and overcurrent protection module is connected to the circuit input end, and the other end of the overvoltage and overcurrent protection module is connected to the cutoff module. The other end of the cutoff module is connected to the circuit output end. When the overvoltage and overcurrent protection module detects that the current input to the circuit input end is greater than the maximum current threshold, the circuit is adjusted to a constant current, and when the cutoff module detects that the voltage connected to the circuit output end is the maximum voltage threshold, the voltage connected to the circuit output end is cut off. Thus, by integrating two independent overcurrent and overvoltage protection circuits into one circuit, namely the overvoltage and overcurrent protection module, the problem of overly complex circuits and high costs is solved, and the safe and stable operation of nuclear power plant equipment is also ensured.

[0070] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present utility model.

[0071] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An overvoltage and overcurrent protection circuit, characterized in that: Applied to the AI ​​and AO module channels of nuclear power plants, the protection circuit includes: an overvoltage and overcurrent protection module and a cutoff module; One end of the overvoltage and overcurrent protection module is connected to the circuit input end, and the other end of the overvoltage and overcurrent protection module is connected to the cutoff module; The other end of the cut-off module is connected to the circuit output end; Among them, when the overvoltage and overcurrent protection module detects that the current input to the input end of the circuit is greater than the maximum current threshold, the circuit is adjusted to a constant current, and when the cut-off module detects that the voltage connected to the output end of the circuit is the maximum voltage threshold, the voltage connected to the output end of the circuit is cut off.

2. The protection circuit according to claim 1, characterized in that: The overvoltage and overcurrent protection module includes: a first resistor, a first transistor, a second transistor and a second resistor; The base of the first transistor is respectively connected to one end of the first resistor and the collector of the second transistor, the collector of the first transistor is respectively connected to the other end of the first resistor and the circuit input end, and the emitter of the first transistor is respectively connected to the base of the second transistor and one end of the second resistor; The emitter of the second transistor is connected to the other end of the second resistor and one end of the cut-off module respectively.

3. The protection circuit according to claim 1, characterized in that: The cut-off module includes: a diode; The anode of the diode is connected to one end of the overvoltage and overcurrent protection module, and the cathode of the diode is connected to the circuit output end.

4. The protection circuit according to claim 3, characterized in that: The model of the diode is MMSD4148T1G.

5. The protection circuit according to claim 2, characterized in that: The second transistor is a surface mounted NPN transistor.

6. The protection circuit according to claim 2, characterized in that: The first transistor is an NPN transistor.

7. The protection circuit according to claim 5, characterized in that: The model of the second transistor is MMBT5551LT1G.

8. The protection circuit according to claim 6, characterized in that: The model of the first transistor is FJT44.

9. The protection circuit according to claim 2, characterized in that: The second resistor is a current limiting resistor.

10. The protection circuit according to claim 3, characterized in that: The reverse withstand voltage threshold of the diode is 100V.

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