CAN interface overvoltage detection and protection circuit based on plant protection unmanned aerial vehicle

Abstract

The invention discloses a CAN interface overvoltage detection and protection circuit based on a plant protection unmanned aerial vehicle, and the circuit comprises a CAN controller U1, and also comprises a comparator module which is used for detecting the port voltage of the CAN controller U1, and determining the use state of a CAN interface of the plant protection unmanned aerial vehicle according to the port voltage, and the use state comprises normal conduction and abnormal conduction, when the use state is specifically abnormal conduction, a cut-off signal is generated and transmitted to the solid-state relay module; the solid-state relay module is used for receiving the cut-off signal and cutting off information transmission of a corresponding port of the CAN controller U1 according to the cut-off signal; and the control unit is used for controlling the CAN controller U1 to perform information interaction with electronic equipment of the plant protection unmanned aerial vehicle. According to the CAN interface overvoltage detection and protection circuit based on the plant protection unmanned aerial vehicle, overvoltage protection of the CAN interface of the plant protection unmanned aerial vehicle is realized. The combination of the PTC thermistor and the TVS tube can limit voltage and current and protect the CAN controller from being damaged by instantaneous high voltage during the delay action of the comparator.

Description

Technical Field

[0001] The present invention relates to the technical field of CAN interface of a plant protection UAV, and in particular to a CAN interface overvoltage detection and protection circuit based on a plant protection UAV. Background Art

[0002] When the plant protection drone is spraying pesticides and fertilizers, various residues will remain on the fuselage frame, and the residual substances are generally difficult to clean. The residual substances on the fuselage frame will accumulate over time, causing the original insulation layer of the battery interface to be contaminated by the residual substances and become conductive. At this time, the voltage of the positive electrode of the battery will be applied to the CAN communication interface, thereby damaging the electronic equipment that uses the CAN interface for communication, causing the plant protection drone to be unable to work normally. According to statistical data, this failure mode occurs frequently, greatly affecting the user experience and increasing after-sales costs.

[0003] Currently, the more common protection for CAN controllers is to add TVS tubes for ESD protection. This protection has a good protection effect for transient high voltages at the ns or us level, but it cannot cope with persistent short circuits and cannot meet the needs of CAN protection in the field of plant protection drones. Summary of the invention

[0004] In order to solve the technical problems existing in the background technology, the present invention proposes a CAN interface overvoltage detection and protection circuit based on a plant protection UAV.

[0005] The present invention proposes a CAN interface overvoltage detection and protection circuit based on a plant protection UAV, including: a CAN controller U1, and also including: The comparator module is used to detect the port voltage of the CAN controller U1, and determine the use status of the CAN interface of the plant protection drone according to the port voltage. The use status includes normal conduction and abnormal conduction. When the use status is abnormal conduction, a cut-off signal is generated and transmitted to the solid-state relay module; The solid-state relay module is used to receive a cut-off signal and cut off information transmission of a corresponding port of the CAN controller U1 according to the cut-off signal; The control unit is used to control the CAN controller U1 to exchange information with the electronic equipment of the plant protection drone; Among them, the control unit and the CAN controller U1 are communicatively connected with each other; the CANH port of the CAN controller U1 and the CANL port of the CAN controller U1 are electrically connected to the output end of the solid-state relay module respectively; the output end of the comparator module is electrically connected to the input end of the solid-state relay module; the output end of the solid-state relay module is electrically connected to the input end of the comparator module.

[0006] Preferably, the solid-state relay module includes a first solid-state relay U3 and a second solid-state relay U4; the comparator module specifically includes a first comparing unit and a second comparing unit.

[0007] Preferably, the first comparison unit specifically includes: a comparator U5, a resistor R5, a resistor R7, a resistor R8, a resistor R11, a resistor R12, and a capacitor C3; a positive power supply terminal of the comparator U5 is connected to a +5V power supply, a positive power supply terminal of the comparator U5 is electrically connected to one end of the capacitor C3, the other end of the capacitor C3 is grounded, and a negative power supply terminal of the comparator U5 is grounded; a negative input terminal of the comparator U5 is electrically connected to one end of the resistor R8, the other end of the resistor R8 is connected to a +5V power supply, and one end of the resistor R8 is electrically connected to one end of the resistor R12. , the other end of the resistor R12 is grounded; the positive input end of the comparator U5 is electrically connected to one end of the resistor R7, one end of the resistor R7 is electrically connected to one end of the resistor R11, and the other end of the resistor R11 is grounded; the output end of the comparator U5 is electrically connected to the input end IN- of the first solid-state relay U3, the input end IN+ of the first solid-state relay U3 is electrically connected to one end of the resistor R5, and the other end of the resistor R5 is connected to the +5V power supply; the output end OUT+ of the first solid-state relay U3 is electrically connected to the CANH port of the CAN controller U1.

[0008] Preferably, the second comparison unit specifically includes: a comparator U6, a resistor R6, a resistor R9, a resistor R10, a resistor R13, a resistor R14, and a capacitor C4; the positive power supply terminal of the comparator U6 is connected to a +5V power supply, the positive power supply terminal of the comparator U6 is electrically connected to one end of the capacitor C4, the other end of the capacitor C4 is grounded, and the negative power supply terminal of the comparator U6 is grounded; the positive input terminal of the comparator U6 is electrically connected to one end of the resistor R10, the other end of the resistor R10 is connected to a +5V power supply, one end of the resistor R10 is electrically connected to one end of the resistor R14 The negative input terminal of the comparator U6 is electrically connected to one end of the resistor R9, one end of the resistor R9 is electrically connected to one end of the resistor R13, and the other end of the resistor R13 is grounded; the output terminal of the comparator U6 is electrically connected to the input terminal IN- of the second solid-state relay U4, the input terminal IN+ of the second solid-state relay U4 is electrically connected to one end of the resistor R6, and the other end of the resistor R6 is connected to the +5V power supply; the output terminal OUT+ of the second solid-state relay U4 is electrically connected to the CANL port of the CAN controller U1.

[0009] Preferably, two groups of PTC thermistors are further included, one group of PTC thermistors is arranged between the CANL port of the CAN controller U1 and the CANL port of the solid-state relay module; the other group of PTC thermistors is arranged between the CANH port of the CAN controller U1 and the CANH port of the solid-state relay module.

[0010] Preferably, two groups of TVS tubes are further included, one group of TVS tubes is electrically connected to the CANL port of the CAN controller U1; and the other group of TVS tubes is electrically connected to the CANH port of the CAN controller U1.

[0011] Preferably, the two groups of PTC thermistors are specifically thermistor PTC1 and thermistor PTC2; the two groups of TVS tubes are specifically TVS tube group U2; one end of thermistor PTC1 is electrically connected to one end of resistor R3, and the other end of resistor R3 is electrically connected to the other end of thermistor PTC2; the CANL port of the CAN controller U1 is electrically connected to one end of thermistor PTC2, and the CANH port of the CAN controller U1 is electrically connected to the other end of thermistor PTC1; the CANL port of the CAN controller U1 is electrically connected to the first end of the TVS tube group U2, the CANH port of the CAN controller U1 is electrically connected to the second end of the TVS tube group U2, and the third end of the TVS tube group U2 is grounded.

[0012] Preferably, the TVS tube group U2 is specifically two groups of TVS tubes with common ends being grounded.

[0013] In the present invention, the proposed CAN interface overvoltage detection and protection circuit based on the plant protection drone, when the system is working normally, the transmission on the CANH port and the CANL port is a normal CMOS level, the solid-state relay is normally turned on, and the CAN signal can be smoothly transmitted to the subsequent CAN controller and the control unit. When an abnormally high voltage appears, the comparator can respond quickly, and the comparator generates a cut-off signal to cut off the solid-state relay, blocking the high voltage from passing to the subsequent circuit, thereby realizing overvoltage protection of the CAN interface of the plant protection drone. The combination of the PTC thermistor and the TVS tube can limit the voltage and current for a short time during the delayed action of the comparator to protect the CAN controller from being damaged by instantaneous high voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the circuit architecture of a CAN interface overvoltage detection and protection circuit based on a plant protection UAV proposed by the present invention; Figure 2 The present invention is a schematic diagram of a circuit implementation structure of a CAN interface overvoltage detection and protection circuit based on a plant protection UAV. DETAILED DESCRIPTION

[0015] Reference Figure 1 and Figure 2 The present invention proposes a CAN interface overvoltage detection and protection circuit based on a plant protection UAV, comprising: a CAN controller U1, and also comprising: The comparator module is used to detect the port voltage of the CAN controller U1, and determine the use status of the CAN interface of the plant protection drone according to the port voltage. The use status includes normal conduction and abnormal conduction. When the use status is abnormal conduction, a cut-off signal is generated and transmitted to the solid-state relay module; The solid-state relay module is used to receive a cut-off signal and cut off information transmission of a corresponding port of the CAN controller U1 according to the cut-off signal; The control unit is used to control the CAN controller U1 to exchange information with the electronic equipment of the plant protection drone; Among them, the control unit and the CAN controller U1 are communicatively connected with each other; the CANH port of the CAN controller U1 and the CANL port of the CAN controller U1 are electrically connected to the output end of the solid-state relay module respectively; the output end of the comparator module is electrically connected to the input end of the solid-state relay module; the output end of the solid-state relay module is electrically connected to the input end of the comparator module.

[0016] In this embodiment, the control unit is specifically an MCU processor, and the MCU processor performs CAN communication with other devices through the CAN controller U1. When the system is working normally, the transmission on the CANH port and the CANL port is a normal CMOS level, and the signal output by the comparator drives the solid-state relay to turn on normally, and the CAN signal can be smoothly transmitted to the subsequent CAN controller and MCU. When an abnormally high voltage appears, the comparator can respond quickly, cut off the solid-state relay, and block the high voltage from passing to the subsequent circuit to achieve the protection function. The combination of PTC and TVS can limit the voltage and current for a short time during the delayed action of the comparator, protecting the CAN controller from being damaged by instantaneous high voltage. In this embodiment, the solid-state relay module includes a first solid-state relay U3 and a second solid-state relay U4; the comparator module specifically includes a first comparing unit and a second comparing unit.

[0017] In this embodiment, the first comparison unit specifically includes: a comparator U5, a resistor R5, a resistor R7, a resistor R8, a resistor R11, a resistor R12, and a capacitor C3; the positive power supply terminal of the comparator U5 is connected to a +5V power supply, the positive power supply terminal of the comparator U5 is electrically connected to one end of the capacitor C3, the other end of the capacitor C3 is grounded, and the negative power supply terminal of the comparator U5 is grounded; the negative input terminal of the comparator U5 is electrically connected to one end of the resistor R8, the other end of the resistor R8 is connected to the +5V power supply, one end of the resistor R8 is electrically connected to one end of the resistor R12 The positive input terminal of the comparator U5 is electrically connected to one end of the resistor R7, one end of the resistor R7 is electrically connected to one end of the resistor R11, and the other end of the resistor R11 is grounded; the output terminal of the comparator U5 is electrically connected to the input terminal IN- of the first solid-state relay U3, the input terminal IN+ of the first solid-state relay U3 is electrically connected to one end of the resistor R5, and the other end of the resistor R5 is connected to a +5V power supply; the output terminal OUT+ of the first solid-state relay U3 is electrically connected to the CANH port of the CAN controller U1.

[0018] In this embodiment, the second comparison unit specifically includes: a comparator U6, a resistor R6, a resistor R9, a resistor R10, a resistor R13, a resistor R14, and a capacitor C4; the positive power supply terminal of the comparator U6 is connected to a +5V power supply, the positive power supply terminal of the comparator U6 is electrically connected to one end of the capacitor C4, the other end of the capacitor C4 is grounded, and the negative power supply terminal of the comparator U6 is grounded; the positive input terminal of the comparator U6 is electrically connected to one end of the resistor R10, the other end of the resistor R10 is connected to the +5V power supply, one end of the resistor R10 is connected to one end of the resistor R14 The negative input terminal of the comparator U6 is electrically connected to one end of the resistor R9, one end of the resistor R9 is electrically connected to one end of the resistor R13, and the other end of the resistor R13 is grounded; the output terminal of the comparator U6 is electrically connected to the input terminal IN- of the second solid-state relay U4, the input terminal IN+ of the second solid-state relay U4 is electrically connected to one end of the resistor R6, and the other end of the resistor R6 is connected to the +5V power supply; the output terminal OUT+ of the second solid-state relay U4 is electrically connected to the CANL port of the CAN controller U1.

[0019] In this embodiment, two groups of PTC thermistors are also included. One group of PTC thermistors is arranged between the CANL port of the CAN controller U1 and the CANL port of the solid-state relay module; the other group of PTC thermistors is arranged between the CANH port of the CAN controller U1 and the CANH port of the solid-state relay module.

[0020] In this embodiment, two groups of TVS tubes are further included. One group of TVS tubes is electrically connected to the CANL port of the CAN controller U1 ; and the other group of TVS tubes is electrically connected to the CANH port of the CAN controller U1 .

[0021] In this embodiment, the two groups of PTC thermistors are specifically thermistor PTC1 and thermistor PTC2; the two groups of TVS tubes are specifically TVS tube group U2; one end of thermistor PTC1 is electrically connected to one end of resistor R3, and the other end of resistor R3 is electrically connected to the other end of thermistor PTC2; the CANL port of the CAN controller U1 is electrically connected to one end of thermistor PTC2, and the CANH port of the CAN controller U1 is electrically connected to the other end of thermistor PTC1; the CANL port of the CAN controller U1 is electrically connected to the first end of the TVS tube group U2, the CANH port of the CAN controller U1 is electrically connected to the second end of the TVS tube group U2, and the third end of the TVS tube group U2 is grounded.

[0022] In this embodiment, the TVS tube group U2 is specifically a common ground for the common ends of two groups of TVS tubes.

[0023] In this embodiment, R1 is a pull-down resistor, PTC1 and PTC2 cooperate with TVS tube to provide instantaneous voltage protection for CAN communication line. R3 is a CAN communication terminal resistor, R7, R8, R11, R12 constitute the voltage acquisition network of CANH port line, R9, R10, R13, R14 constitute the voltage acquisition network of CANL port line; R5 and R6 are used to control the current of solid-state relay input terminal.

[0024] In this embodiment, when the system is working normally, what is transmitted on CANH_IN and CANL_IN is a normal communication level, and the amplitude is below 5V. At this time, the voltage collected by the in-phase terminal 1PIN of the comparator U5 and U6 is less than the voltage collected by the inverting terminal 3PIN. According to the comparator characteristics, at this time, 4PIN outputs 0V, and the input terminals of the solid-state relays U3 and U4 have a driving current flowing through, and then the output terminals PIN3 and PIN4 are turned on, and the CAN signal can flow normally in both directions in the system. When the system has an abnormality caused by a short circuit, at this time, a high voltage of about 80V is introduced to CANH_IN or CANL_IN, and at this time, the voltage of the in-phase input terminal 1PIN of the comparator U5 and U6 is greater than the voltage of the inverting input terminal 3PIN. According to the characteristics of the comparator, at this time, 4PIN outputs 5V, and there is no driving current flowing through the input terminals of the solid-state relays U3 and U4, and then the output terminals PIN3 and PIN4 of U3 and U4 are disconnected, cutting off the CAN communication line to prevent the 80V voltage from damaging the CAN controller U1. The protection action is realized from the high voltage appearing on the line to the disconnection of the solid-state relay. There is a microsecond delay in between. During this delay time, PTC and TVS can be used to clamp the voltage on CANH or CANL to protect the 6PIN CANL or 7PIN CANH of the CAN controller from high voltage damage.

[0025] In this embodiment, the clamping voltage of the TVS should be lower than the maximum withstand voltage of the 6PIN and 7PIN of the CAN controller. The resistance value of the PTC at room temperature cannot be too high, otherwise the dominant differential voltage of CANH and CANL will be reduced, introducing the risk of bit errors. The resistance value cannot be too low, otherwise the surge current borne by the TVS will exceed the maximum flow rate, causing irreversible damage to the TVS.

[0026] In this embodiment, when the abnormal point is detected and the fault is eliminated, the normal TTL or CMOS level is restored on the CAN communication line. At this time, the entire system works normally and the CAN communication line will resume normal communication. By automatically detecting the abnormal high voltage of the CAN communication line, when high voltage appears, it can respond quickly, and then cooperate with PTC and TVS to apply reliable protection to the CAN controller. When the abnormality is eliminated, it can automatically resume normal operation, which is very suitable for scenes such as plant protection drones with harsh working environments and may be contaminated by water and chemicals at any time.

[0027] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A CAN interface overvoltage detection and protection circuit based on a plant protection drone, comprising: The CAN controller U1 is characterized by further comprising: The comparator module is used to detect the port voltage of the CAN controller U1, and determine the use status of the CAN interface of the plant protection drone according to the port voltage. The use status includes normal conduction and abnormal conduction. When the use status is abnormal conduction, a cut-off signal is generated and transmitted to the solid-state relay module; The solid-state relay module is used to receive a cut-off signal and cut off information transmission of a corresponding port of the CAN controller U1 according to the cut-off signal; The control unit is used to control the CAN controller U1 to exchange information with the electronic equipment of the plant protection drone; Among them, the control unit and the CAN controller U1 are communicatively connected with each other; the CANH port of the CAN controller U1 and the CANL port of the CAN controller U1 are electrically connected to the output end of the solid-state relay module respectively; the output end of the comparator module is electrically connected to the input end of the solid-state relay module; the output end of the solid-state relay module is electrically connected to the input end of the comparator module.

2. According to claim 1, the CAN interface overvoltage detection and protection circuit based on the plant protection drone is characterized in that: The solid-state relay module includes a first solid-state relay U3 and a second solid-state relay U4; the comparator module specifically includes a first comparing unit and a second comparing unit.

3. The CAN interface overvoltage detection and protection circuit based on the plant protection UAV according to claim 2 is characterized in that: The first comparison unit specifically includes: a comparator U5, a resistor R5, a resistor R7, a resistor R8, a resistor R11, a resistor R12, and a capacitor C3; a positive power supply terminal of the comparator U5 is connected to a +5V power supply, a positive power supply terminal of the comparator U5 is electrically connected to one end of the capacitor C3, the other end of the capacitor C3 is grounded, and a negative power supply terminal of the comparator U5 is grounded; a negative input terminal of the comparator U5 is electrically connected to one end of the resistor R8, the other end of the resistor R8 is connected to a +5V power supply, one end of the resistor R8 is electrically connected to one end of the resistor R12, and the negative input terminal of the comparator U5 is electrically connected to one end of the resistor R8. The other end of the resistor R12 is grounded; the positive input end of the comparator U5 is electrically connected to one end of the resistor R7, one end of the resistor R7 is electrically connected to one end of the resistor R11, and the other end of the resistor R11 is grounded; the output end of the comparator U5 is electrically connected to the input end IN- of the first solid-state relay U3, the input end IN+ of the first solid-state relay U3 is electrically connected to one end of the resistor R5, and the other end of the resistor R5 is connected to a +5V power supply; the output end OUT+ of the first solid-state relay U3 is electrically connected to the CANH port of the CAN controller U1.

4. The CAN interface overvoltage detection and protection circuit based on the plant protection UAV according to claim 2 is characterized in that: The second comparison unit specifically includes: a comparator U6, a resistor R6, a resistor R9, a resistor R10, a resistor R13, a resistor R14, and a capacitor C4; the positive power supply terminal of the comparator U6 is connected to a +5V power supply, the positive power supply terminal of the comparator U6 is electrically connected to one end of the capacitor C4, the other end of the capacitor C4 is grounded, and the negative power supply terminal of the comparator U6 is grounded; the positive input terminal of the comparator U6 is electrically connected to one end of the resistor R10, the other end of the resistor R10 is connected to a +5V power supply, and one end of the resistor R10 is electrically connected to one end of the resistor R14. , the other end of the resistor R14 is grounded; the negative input end of the comparator U6 is electrically connected to one end of the resistor R9, one end of the resistor R9 is electrically connected to one end of the resistor R13, and the other end of the resistor R13 is grounded; the output end of the comparator U6 is electrically connected to the input end IN- of the second solid-state relay U4, the input end IN+ of the second solid-state relay U4 is electrically connected to one end of the resistor R6, and the other end of the resistor R6 is connected to the +5V power supply; the output end OUT+ of the second solid-state relay U4 is electrically connected to the CANL port of the CAN controller U1.

5. The CAN interface overvoltage detection and protection circuit based on the plant protection UAV according to claim 1 is characterized in that: It also includes two groups of PTC thermistors, one group of PTC thermistors is arranged between the CANL port of the CAN controller U1 and the CANL port of the solid-state relay module; the other group of PTC thermistors is arranged between the CANH port of the CAN controller U1 and the CANH port of the solid-state relay module.

6. The CAN interface overvoltage detection and protection circuit based on the plant protection UAV according to claim 5 is characterized in that: It also includes two groups of TVS tubes, one group of TVS tubes is electrically connected to the CANL port of the CAN controller U1; the other group of TVS tubes is electrically connected to the CANH port of the CAN controller U1.

7. The CAN interface overvoltage detection and protection circuit based on the plant protection UAV according to claim 6 is characterized in that: The two groups of PTC thermistors are specifically thermistor PTC1 and thermistor PTC2; the two groups of TVS tubes are specifically TVS tube group U2; one end of thermistor PTC1 is electrically connected to one end of resistor R3, and the other end of resistor R3 is electrically connected to the other end of thermistor PTC2; the CANL port of the CAN controller U1 is electrically connected to one end of thermistor PTC2, and the CANH port of the CAN controller U1 is electrically connected to the other end of thermistor PTC1; the CANL port of the CAN controller U1 is electrically connected to the first end of the TVS tube group U2, the CANH port of the CAN controller U1 is electrically connected to the second end of the TVS tube group U2, and the third end of the TVS tube group U2 is grounded.

8. The CAN interface overvoltage detection and protection circuit based on the plant protection UAV according to claim 7 is characterized in that: The TVS tube group U2 is specifically a common ground for the common ends of the two groups of TVS tubes.

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