Ground fault detection circuit, circuit board and ground fault detection equipment

Abstract

The embodiment of the invention discloses a ground fault detection circuit, a circuit board and ground fault detection equipment. Whether a grounding fault exists or not is detected through the voltage division circuit, then the sampling control circuit of the corresponding loop line is controlled to carry out voltage detection judgment on the single loop line, and then the specific loop with the grounding fault is confirmed. According to the method, the line with the grounding fault in the loop system can be quickly and accurately positioned under the condition that the grounding fault of the line is confirmed.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of circuit technology, and in particular to a ground fault detection circuit, a circuit board, and a ground fault detection device. Background Art

[0002] In bus-based application scenarios such as fire protection, monitoring the line status is an important guarantee for maintaining the normal operation of the entire system.

[0003] The inventors studied the existing line status monitoring solutions and found that they can only confirm whether there is a possibility of line failure based on the operating status of the entire system, but cannot accurately locate the line fault. Summary of the invention

[0004] The present invention provides a ground fault detection circuit, a circuit board and a ground fault detection device to solve the technical problem that the existing system can only confirm whether a line state has a possible fault based on the operating state of the entire system, but cannot accurately locate the line fault.

[0005] In a first aspect, an embodiment of the present invention provides a ground fault detection circuit, the ground fault detection circuit comprising a voltage divider circuit, a plurality of sampling control circuits, a drive circuit and a single chip microcomputer;

[0006] The sampling end of the voltage divider circuit is connected to the detection target, the output end of the voltage divider circuit is connected to the input end of the single chip microcomputer, the first output end of the single chip microcomputer is connected to the controlled end of the drive circuit, and the second output end of the single chip microcomputer is connected to the state control end of the sampling control circuit; the drive circuit is connected to the circuit to be tested in the detection target through the sampling control circuit, and each sampling control circuit corresponds to a circuit to be tested;

[0007] The single chip microcomputer is used to send a control signal to the sampling control circuit when confirming the presence of a ground fault through the sampling voltage input at the input end, so that the sampling resistor in the sampling control circuit is in an effective state in the circuit to be tested, and confirm whether the corresponding circuit to be tested has a fault based on the voltage difference between the two ends of the sampling resistor.

[0008] Wherein, the voltage divider circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a bidirectional TVS transient suppression diode, a first diode and a second diode;

[0009] The first end of the first resistor is used to connect to the first working voltage, and the second end of the first resistor, the first end of the second resistor and the first end of the bidirectional TVS transient suppression diode are all grounded;

[0010] The second end of the second resistor is connected to the first end of the third resistor, the second end of the bidirectional TVS transient suppression diode, and the first end of the fourth resistor;

[0011] The second end of the fourth resistor is connected to the first end of the fifth resistor and the first end of the sixth resistor; the second end of the third resistor, the second end of the sixth resistor and the positive electrode of the second diode are all grounded;

[0012] The second end of the fifth resistor is connected to the anode of the first diode and the cathode of the second diode as the output end of the voltage divider circuit, and the cathode of the first diode is used to access the second working voltage.

[0013] The model of the bidirectional TVS transient suppression diode is SMBJ6.5CA.

[0014] The models of the first diode and the second diode are both 1N4148W.

[0015] The parameters of the first resistor are 910K / 1% / 0603.

[0016] Wherein, each circuit to be tested is a bus circuit, and each of the sampling control circuits is connected to the corresponding bus circuit via a connection terminal of the bus circuit.

[0017] Each of the sampling control circuits includes two resistors and two switches, each resistor is connected in series between a pin of a corresponding terminal and the drive circuit, and each switch is connected in parallel with a resistor; when the switch is disconnected, the corresponding circuit is in an effective state in the circuit to be tested.

[0018] Wherein, the switch is a MOS tube.

[0019] In a second aspect, an embodiment of the present application provides a circuit board, which includes the ground fault detection circuit of any one of the first aspect.

[0020] In a third aspect, an embodiment of the present application provides a ground fault detection device, the circuit board comprising the circuit board of the second aspect.

[0021] In the above-mentioned ground fault detection circuit, circuit board and ground fault detection device, a voltage divider circuit is used to detect whether there is a ground fault, and then the sampling control circuit of the corresponding loop line is controlled to perform voltage detection and judgment on a single loop line, thereby confirming the specific loop where the ground fault occurs. When it is confirmed that the line has a ground fault, the line that has a ground fault in the loop system can be quickly and accurately located. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1A circuit schematic diagram of a voltage divider circuit in a ground fault detection circuit provided by an embodiment of the present invention;

[0023] Figure 2 A circuit schematic diagram of a sampling control circuit in a ground fault detection circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only the parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0025] It should be noted that due to space limitations, this application description does not list all optional implementation methods. After reading this application description, those skilled in the art should be able to understand that as long as the technical features do not contradict each other, any combination of technical features can constitute an optional implementation method.

[0026] Each embodiment is described in detail below.

[0027] Please refer to Figure 1 and Figure 2 , which are respectively a circuit schematic diagram of a voltage divider circuit and a circuit schematic diagram of a sampling control circuit in a ground fault detection circuit provided in an embodiment of the present invention. The ground fault detection circuit in the embodiment of the present application includes a voltage divider circuit, a plurality of sampling control circuits, a drive circuit and a single chip microcomputer; the sampling end of the voltage divider circuit is connected to the detection target, the output end of the voltage divider circuit is connected to the input end of the single chip microcomputer, the first output end of the single chip microcomputer is connected to the controlled end of the drive circuit, and the second output end of the single chip microcomputer is connected to the state control end of the sampling control circuit; the drive circuit is connected to the circuit to be tested in the detection target through the sampling control circuit, and each sampling control circuit corresponds to a circuit to be tested; the single chip microcomputer is used to send a control signal to the sampling control circuit when confirming the presence of a ground fault through the sampling voltage input at the input end, so that the sampling resistor in the sampling control circuit is in an effective state in the circuit to be tested, and confirm whether the corresponding circuit to be tested has a fault according to the voltage difference between the two ends of the sampling resistor.

[0028] In the embodiment of the present application, the voltage divider circuit is responsible for normalized detection, the sampling control circuit is responsible for accurately detecting the loop when a ground fault is detected during the normalized detection process, the drive circuit is responsible for driving the control circuit for detection, and the single-chip microcomputer is responsible for judging the result of the normalized detection signal and controlling the accurate detection process. The voltage divider circuit is used to detect whether there is a ground fault, and then the sampling control circuit of the corresponding loop line is controlled to perform voltage detection and judgment on a single loop line, thereby confirming the specific loop where the ground fault occurs. It can quickly and accurately locate the line in the loop system that has a ground fault based on the confirmation that the line has a ground fault.

[0029] In a specific implementation, Figure 1 As shown, the voltage divider circuit includes a first resistor R184, a second resistor R185, a third resistor R186, a fourth resistor R187, a fifth resistor R188, a sixth resistor R189, a bidirectional TVS transient suppression diode D55, a first diode D51 and a second diode D52;

[0030] The first end of the first resistor R184 is used to connect to the first working voltage, and the second end of the first resistor R184, the first end of the second resistor R185 and the first end of the bidirectional TVS transient suppression diode D55 are all grounded;

[0031] The second end of the second resistor R185 is connected to the first end of the third resistor R186, the second end of the bidirectional TVS transient suppression diode D55, and the first end of the fourth resistor R187;

[0032] The second end of the fourth resistor R187 is connected to the first end of the fifth resistor R188 and the first end of the sixth resistor R189; the second end of the third resistor R186, the second end of the sixth resistor R189 and the positive electrode of the second diode D52 are all grounded;

[0033] The second end of the fifth resistor R188 is connected to the anode of the first diode D51 and the cathode of the second diode D52 as the output end of the voltage divider circuit, and the cathode of the first diode D51 is used to access the second working voltage.

[0034] exist Figure 1 In the voltage divider circuit shown, when the positive line of the loop is grounded, the voltage detected at the ADC will increase, and when the negative line of the loop is grounded, the voltage detected at the ADC will decrease. The microcontroller obtains the voltage detected by the ADC, and can confirm the existence of a ground fault, and further control the specific circuit with the ground fault to accurately confirm it.

[0035] In the specific implementation, such as Figure 1As shown, the bidirectional TVS transient suppression diode D55 may be of SMBJ6.5CA. The first diode D51 and the second diode D52 may both be of 1N4148W. The parameters of the first resistor R184 may be 910K / 1% / 0603.

[0036] In another specific implementation, Figure 2 As shown, each circuit to be tested is a bus circuit, and each of the sampling control circuits is connected to the corresponding bus circuit through the wiring terminals of the bus circuit.

[0037] Considering that in a bus-based system, communication is accomplished through two sub-wires, Figure 2 Each of the sampling control circuits may further include two resistors and two switches, each resistor is connected in series between a pin of a corresponding terminal and the driving circuit, and each switch is connected in parallel with a resistor; when the switch is disconnected, the corresponding circuit is in an effective state in the circuit to be tested. The switch may be a MOS tube.

[0038] exist Figure 2 In the figure, only the connection mode of the resistor and the switch is described as an example. It should be understood that the conduction state of the switch is controlled by the single chip microcomputer, and the driving of the driving circuit is also controlled by the single chip microcomputer.

[0039] In the bus-based fire protection application scenario, the terminal block is used to connect to the bus. Various peripherals will be hung on the bus and distributed in various places in the building. If a wire of the bus is grounded, a fault will be reported. Generally, the field bus is laid in a wire tube. If the wire sheath is broken and touches the wire tube, a grounding fault will occur.

[0040] The voltage change of ADC can only confirm the existence of a ground fault. The single-chip microcomputer in the embodiment of the present application, when confirming the existence of a ground fault, controls the switch corresponding to the resistor R1 and the resistor R2 to disconnect according to the change of ADC, and then detects TP1-TP4 to complete the judgment of the loop where the ground fault is located. That is, a sampling resistor (i.e., resistor R1 and resistor R2) is connected in series on each positive and negative line of each loop line, and the two sampling resistors are usually short-circuited using a switch to make the loop work normally. When the existence of a ground fault is detected by ADC, the switch is temporarily disconnected. At this time, the resistor R1 and the resistor R2 are connected in series on the loop, that is, the resistor R1 and the resistor R2 are in an effective state. The single-chip microcomputer measures the voltages of TP1~TP4 at both ends of the resistor R1 and the resistor R2, and calculates the current on the positive and negative lines of the loop respectively. When the difference between the two voltages is greater than the threshold, it is judged that a ground fault has occurred in the loop.

[0041] The embodiment of the present application further provides a circuit board, which includes the ground fault detection circuit in any of the above embodiments.

[0042] The embodiment of the present application also provides a ground fault detection device, the circuit board includes the circuit board described above. The ground fault detection device in the embodiment of the present application can be the fire fighting device itself, that is, through the data processing capability of the single chip microcomputer inside the fire fighting device, ADC judgment and specific detection control can be performed, which can effectively control the hardware cost.

[0043] Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the functions in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing device to work in a specific way, so that the instructions stored in the computer-readable memory produce a product including an instruction device, which implements the functions specified in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide for implementing the process in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0044] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory. The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0045] Computer readable media include permanent and non-permanent, removable and non-removable media that can be used to store information by any method or technology. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0046] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity 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, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0047] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A ground fault detection circuit, characterized in that: It includes a voltage divider circuit, multiple sampling control circuits, a driving circuit and a single chip microcomputer; The sampling end of the voltage divider circuit is connected to the detection target, the output end of the voltage divider circuit is connected to the input end of the single chip microcomputer, the first output end of the single chip microcomputer is connected to the controlled end of the drive circuit, and the second output end of the single chip microcomputer is connected to the state control end of the sampling control circuit; the drive circuit is connected to the circuit to be tested in the detection target through the sampling control circuit, and each sampling control circuit corresponds to a circuit to be tested; The single chip microcomputer is used to send a control signal to the sampling control circuit when confirming the presence of a ground fault through the sampling voltage input at the input end, so that the sampling resistor in the sampling control circuit is in an effective state in the circuit to be tested, and confirm whether the corresponding circuit to be tested has a fault based on the voltage difference between the two ends of the sampling resistor.

2. The ground fault detection circuit according to claim 1, characterized in that: The voltage divider circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a bidirectional TVS transient suppression diode, a first diode and a second diode; The first end of the first resistor is used to connect to the first working voltage, and the second end of the first resistor, the first end of the second resistor and the first end of the bidirectional TVS transient suppression diode are all grounded; The second end of the second resistor is connected to the first end of the third resistor, the second end of the bidirectional TVS transient suppression diode, and the first end of the fourth resistor; The second end of the fourth resistor is connected to the first end of the fifth resistor and the first end of the sixth resistor; the second end of the third resistor, the second end of the sixth resistor and the positive electrode of the second diode are all grounded; The second end of the fifth resistor is connected to the anode of the first diode and the cathode of the second diode as the output end of the voltage divider circuit, and the cathode of the first diode is used to access the second working voltage.

3. The ground fault detection circuit according to claim 2, characterized in that: The model of the bidirectional TVS transient suppression diode is SMBJ6.5CA.

4. The ground fault detection circuit according to claim 2, characterized in that: The models of the first diode and the second diode are both 1N4148W.

5. The ground fault detection circuit according to claim 2, characterized in that: The parameters of the first resistor are 910K / 1% / 0603.

6. The ground fault detection circuit according to claim 1, characterized in that: Each circuit to be tested is a bus circuit, and each of the sampling control circuits is connected to the corresponding bus circuit via a connection terminal of the bus circuit.

7. The ground fault detection circuit according to claim 6, characterized in that: Each of the sampling control circuits includes two resistors and two switches, each resistor is connected in series between a pin of a corresponding terminal and the drive circuit, and each switch is connected in parallel with a resistor; when the switch is disconnected, the corresponding circuit is in an effective state in the circuit to be tested.

8. The ground fault detection circuit according to any one of claims 1 to 7, characterized in that: The switch is a MOS tube.

9. A circuit board, characterized in that The invention comprises the ground fault detection circuit as claimed in any one of claims 1 to 8.

10. A ground fault detection device, characterized in that: Includes the circuit board as claimed in claim 9.

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