Discrete output interface short circuit and open circuit detection circuit and detection method

Abstract

The application provides a discrete output interface short circuit and open circuit detection circuit and a detection method, and belongs to the technical field of circuit detection. The detection circuit comprises a first voltage, a second voltage, a MOS tube, a filter capacitor, a sampling resistor, a current-limiting resistor, a first diode and a second diode, wherein the first voltage is connected to the sampling resistor and to the drain electrode of the MOS tube, the voltage control signal of the discrete output interface is connected to the gate electrode of the MOS tube, the source electrode of the MOS tube is connected to the filter capacitor and then grounded, the second voltage is sequentially connected to the first diode, the current-limiting resistor and then to the source electrode of the MOS tube, the second diode is arranged between the source electrode of the MOS tube and a load, and the other end of the load is grounded, wherein the output voltage is formed between the sampling resistor, and a voltage back sampling point is arranged between the load and the second diode. Compared with the existing discrete output interface detection circuit, the circuit of the application is simple, the number of components is small, a position monitoring device or a sensor does not need to be added at the load end, and the reliability is high.

Description

Technical Field

[0001] This invention belongs to the field of circuit testing technology, and specifically relates to a short-circuit and open-circuit detection circuit and method for discrete output interfaces. Background Technology

[0002] In the design of aircraft avionics system interfaces, 28V / open discrete output interface control circuits are frequently used. These are employed by electromechanical management computers for controlling and managing systems such as hydraulics, fuel, environmental control, and landing gear. For example, they drive solenoid valves to open and close, achieving energy scheduling and functional actions. When the interface circuit outputs 28V, it drives the load; when the output is open, the load does not operate. Due to the harsh operating environment of aircraft and prolonged mission flights, component reliability decreases, leading to issues such as wiring harness wear, solenoid valve coil disconnection, and interface failures. If a control circuit failure, wire disconnection, or open circuit occurs in the controlled object, the circuit will be broken, and the control function will fail. However, due to the lack of detection circuitry, the health status of the circuit cannot be monitored in real time. Functional failures are only detected during dynamic monitoring, leading to inefficient troubleshooting and fault location, which negatively impacts mission execution and flight safety.

[0003] Therefore, the common method for detecting the interface output path in existing technologies involves adding angle or position monitoring at the load end, with the interface control circuit controlling the load to reach the desired position and detecting whether the position feedback is normal in real time. This method requires adding a position monitoring device at the load end and a position monitoring interface circuit to the host computer, resulting in high resource consumption and cost. Furthermore, it cannot statically detect the health status of the control path in real time; it can only determine whether the position information meets expectations after the action is completed, and thus whether the system function is normal. Summary of the Invention

[0004] The purpose of this invention is to provide a short-circuit and open-circuit detection circuit and method for discrete output interfaces, so as to solve or alleviate at least one of the problems in the prior art.

[0005] On one hand, the technical solution of the present invention is: a discrete output interface short circuit and open circuit detection circuit, including a first voltage, a second voltage, a MOSFET, a filter capacitor, a sampling resistor, a current limiting resistor, a first diode, and a second diode. The first voltage is connected to the sampling resistor and then to the drain of the MOSFET. The voltage control signal of the discrete output interface is connected to the gate of the MOSFET. The source of the MOSFET is connected to the filter capacitor and then grounded. The second voltage is sequentially connected to the first diode and the current limiting resistor and then to the source of the MOSFET. The second diode is disposed between the source of the MOSFET and the load. The other end of the load is grounded. The sampling resistor forms an output voltage, and a voltage feedback point is provided between the load and the second diode.

[0006] In a preferred embodiment of the present invention, the voltage values ​​of the first voltage and the second voltage are different.

[0007] In a preferred embodiment of the present invention, the MOS transistor is an N-channel MOS transistor.

[0008] In a preferred embodiment of the present invention, the resistance value of the sampling resistor is not less than 100 times the load resistance value.

[0009] Secondly, the present invention provides a detection method using any of the discrete output interface short circuit and open circuit detection circuits described above, the detection content including open circuit detection when not outputting a first voltage, open circuit detection when outputting a first voltage, and short circuit detection.

[0010] The open-circuit detection process when the first voltage is not output is as follows:

[0011] When the control signal is transmitted to the MOSFET, the first voltage signal is not output. At this time, the MOSFET is turned off and the output path current is 0.

[0012] When the discrete output interface is normal, the second voltage of the discrete output interface passes through the first diode, and is divided by the current limiting resistor and the load resistor. After the voltage is divided, the output voltage is close to zero.

[0013] When an open circuit occurs in the path, the voltage sampled through the voltage sampling point is the second voltage. By setting an open circuit voltage judgment threshold, when the sampled voltage is higher than the open circuit voltage judgment threshold, the path is judged to be in an open circuit state.

[0014] In a preferred embodiment of the present invention, the open-circuit detection process when outputting the first voltage is as follows:

[0015] When the control signal transmits the first output voltage signal to the MOSFET, the MOSFET is turned on, and there is current in the output path. The output voltage on both sides of the sampling resistor is collected, and the current is calculated as a criterion for detecting whether the load output path is normal. When there is a sampling current, the path is determined to be in an open circuit state.

[0016] In a preferred embodiment of the present invention, the short-circuit detection process is as follows:

[0017] By monitoring the voltage at the interface output terminal voltage sampling point and the sampling resistor in the interface circuit, the output voltage is calculated in real time. When the output current is greater than the current threshold, a short circuit is determined to have occurred.

[0018] The discrete output interface short-circuit and open-circuit detection circuit and method provided by this invention are simpler than existing discrete output interface detection circuits, use fewer components, do not require additional position monitoring devices or sensors at the load end, have higher reliability, and stronger functionality, ultimately achieving the goal of cost reduction and efficiency improvement. When a short-circuit or open-circuit fault occurs in the path, it can be detected in real time and the fault information can be reported in a timely manner, improving the fault detection rate of the system. Attached Figure Description

[0019] To more clearly illustrate the technical solution provided by the present invention, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention.

[0020] Figure 1 This is a schematic diagram of the discrete output interface short-circuit and open-circuit detection circuit of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be described in more detail below with reference to the accompanying drawings.

[0022] To address the problems of traditional interface output circuits, this invention provides a discrete output interface short-circuit and open-circuit detection circuit and method, which can achieve the goal of real-time detection of the health status of the control path at minimal cost.

[0023] To this end, the present invention first provides a discrete output interface short circuit and open circuit detection circuit, which includes a MOS transistor D1, a filter capacitor C1, a sampling resistor R1, a current limiting resistor R2, a first diode V1, a second diode V2, a first voltage of 28V and a second voltage of 15V.

[0024] like Figure 1 As shown, the first voltage is connected to the sampling resistor R1 and then to the drain (D) of the MOSFET D1. The voltage control signal of the discrete output interface is connected to the gate (G) of the MOSFET D1. The source (S) of the MOSFET D1 is connected to the filter capacitor C1 and then grounded. The second voltage is connected in sequence to the first diode V1, the current-limiting resistor R2, and then to the source (S) of the MOSFET D1. The first diode V1 ensures that the current of the second voltage can only conduct unidirectionally towards the MOSFET D1. The second diode V2 is placed between the source (S) of the MOSFET D1 and the load, ensuring that the current can only conduct unidirectionally towards the load. The other end of the load is grounded. The sampling resistor R1 forms the output voltage Vc, and a voltage feedback point is provided between the load and the second diode V2.

[0025] In this invention, the MOS transistor is an N-channel MOS transistor.

[0026] Based on the above detection circuit, this invention also provides a method for detecting short circuits and open circuits of discrete output interfaces, including: open circuit detection when not outputting 28V, open circuit detection when outputting 28V, and short circuit detection, wherein:

[0027] 1) Open circuit detection when no 28V first voltage is output

[0028] The control signal is transmitted to MOSFET D1 without outputting the first 28V voltage signal. At this time, MOSFET D1 is turned off, so the output current is 0. Whether the load is online is determined by sampling the output voltage.

[0029] Under normal circumstances, the 15V second voltage of the discrete output interface circuit passes through the first diode V1, and is divided by the current limiting resistor R2 and the load resistor. Generally, the load (such as the solenoid valve coil) resistance is no more than 100Ω. By setting the resistance of the sampling resistor R1 to about 100 times the load resistance, for example, in this embodiment, the resistance of the sampling resistor R1 can be set to 10KΩ, so the output voltage is close to zero after voltage division.

[0030] When an open circuit occurs, the second voltage sampled is 15V. An open circuit voltage threshold is set; if the sampled voltage exceeds this threshold, the circuit is considered open. This threshold can be determined based on the current-limiting resistor R2 and the load resistance. For example, if the load resistance is 100Ω and the current-limiting resistor R2 is also 100Ω, the open circuit voltage threshold can be set to a voltage greater than 15V * [100Ω / (100Ω + 100Ω)] = 7.5V, such as 10V.

[0031] 2) Open circuit detection when outputting the first 28V voltage

[0032] When the control signal transmits the 28V first voltage signal to the MOSFET, because MOSFET D1 is turned on, there is a certain current in the output path. Considering the busbar voltage adjustment, when the 28V first voltage is the lowest voltage of 18V, the load resistance is calculated as 100Ω, and the current sampling is 0.18A. When the 28V first voltage is the highest voltage of 32V, the load resistance is calculated as 100Ω, and the current sampling is 0.32A. When the 28V first voltage is output, since the first diode V1 is not conducting when the product outputs the 28V first voltage, it is impossible to determine whether the load is open-circuited through voltage sampling. However, if the load is open-circuited, the current is 0 because there is no current path. Therefore, in this state, current sampling is used to determine whether the open circuit is detected. The sampling resistor R1 outputs the sampling voltage, and the current is calculated as a criterion for detecting whether the load output path is normal. When there is sampling current, the path can be considered to be open-circuited.

[0033] 3) Short circuit detection

[0034] The output voltage can be monitored in real time and the output current can be calculated by sampling the voltage at the interface output terminal and the sampling resistor terminal set in the interface circuit. When the output current exceeds the current threshold, a short circuit is considered to have occurred.

[0035] The discrete output interface short-circuit and open-circuit detection circuit and method provided by this invention are simpler than existing discrete output interface detection circuits, use fewer components, do not require additional position monitoring devices or sensors at the load end, have higher reliability, and stronger functionality, ultimately achieving the goal of cost reduction and efficiency improvement. When a short-circuit or open-circuit fault occurs in the path, it can be detected in real time and the fault information can be reported in a timely manner, improving the fault detection rate of the system.

[0036] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A discrete output interface short-circuit and open-circuit detection circuit, characterized in that, include: The system comprises a first voltage, a second voltage, a MOSFET, a filter capacitor, a sampling resistor, a current-limiting resistor, a first diode, and a second diode. The first voltage is connected to the sampling resistor and then to the drain of the MOSFET. The voltage control signal of the discrete output interface is connected to the gate of the MOSFET. The source of the MOSFET is connected to the filter capacitor and then grounded. The second voltage is connected to the first diode and the current-limiting resistor in sequence and then to the source of the MOSFET. The second diode is positioned between the source of the MOSFET and the load. The other end of the load is grounded. The sampling resistor forms the output voltage, and a voltage feedback point is provided between the load and the second diode.

2. The discrete output interface short-circuit and open-circuit detection circuit as described in claim 1, characterized in that, The first voltage and the second voltage have different voltage values.

3. The discrete output interface short-circuit and open-circuit detection circuit as described in claim 1, characterized in that, The MOS transistor is an N-channel MOS transistor.

4. The discrete output interface short-circuit and open-circuit detection circuit as described in claim 1, characterized in that, The resistance value of the sampling resistor is not less than 100 times the load resistance value.

5. A detection method employing the discrete output interface short-circuit and open-circuit detection circuit as described in any one of claims 1 to 4, characterized in that, The testing includes open-circuit testing when no first voltage is output, open-circuit testing when the first voltage is output, and short-circuit testing. The open-circuit detection process when the first voltage is not output is as follows: When the control signal is transmitted to the MOSFET, the first voltage signal is not output. At this time, the MOSFET is turned off and the output path current is 0. When the discrete output interface is normal, the second voltage of the discrete output interface passes through the first diode, and is divided by the current limiting resistor and the load resistor. After the voltage is divided, the output voltage is close to zero. When an open circuit occurs in the path, the voltage sampled through the voltage sampling point is the second voltage. By setting an open circuit voltage judgment threshold, when the sampled voltage is higher than the open circuit voltage judgment threshold, the path is judged to be in an open circuit state.

6. The detection method as described in claim 5, characterized in that, The open-circuit detection process when outputting the first voltage is as follows: When the control signal transmits the first output voltage signal to the MOSFET, the MOSFET is turned on, and there is current in the output path. The output voltage on both sides of the sampling resistor is collected, and the current is calculated as a criterion for detecting whether the load output path is normal. When there is a sampling current, the path is determined to be in an open circuit state.

7. The detection method as described in claim 5, characterized in that, The short circuit detection process is as follows: By monitoring the voltage at the interface output terminal voltage sampling point and the sampling resistor in the interface circuit, the output voltage is calculated in real time. When the output current is greater than the current threshold, a short circuit is determined to have occurred.

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