Communication interference optimization circuit for CAN communication

Abstract

The utility model provides a communication interference optimization circuit for CAN communication, which can obviously improve the anti-interference capability and the communication stability of the CAN communication, a power supply filtering module comprises a voltage stabilizer U8, the input end of the voltage stabilizer U8 is connected with a 5V power supply, the output end of the voltage stabilizer U8 is connected with a power supply filtering unit, and the power supply filtering unit is connected with the CAN communication module. The power supply filtering unit is used for filtering the output of the voltage stabilizer, and the power supply filtering unit outputs filtered 5V power supply; the CAN controller side of the isolation CAN transceiver U9 is powered by a 3.3 V power supply, the CAN bus side of the isolation CAN transceiver U9 is powered by a 5V power supply output by the power supply filtering module, the CAN bus side of the isolation CAN transceiver U9 is provided with a CAN port connected with a CAN bus, and a signal filtering unit and a protection unit are arranged between the CAN port of the isolation CAN transceiver U9 and the CAN bus.

Description

TECHNICAL FIELD

[0001] The utility model relates to CAN communication technical field, concretely relates to a communication interference optimization circuit for CAN communication. BACKGROUND

[0002] CAN communication as a common communication mode, in the application is influenced by complex electromagnetic environment, appears CAN and data transmission loss problem of dropping line, its interference problem can be caused by the following factors:

[0003] 1, electromagnetic interference: in the automobile or industrial environment, ignition system, motor, radio communication and other electromagnetic noise and interference source can disturb CAN bus, influence the stability and reliability of communication.

[0004] 2, line problem: the line on CAN bus can exist impedance mismatch, unreasonable filter structure, filter line is too long, line damage etc.

[0005] 3, power problem: the unstable power supply or existence noise interference can influence CAN controller's normal work, the common mode and differential mode noise of power supply causes the influence to the communication quality.

[0006] 4, CAN communication line common mode and differential mode interference filter bad leading to communication data error. INVENTION CONTENT

[0007] In view of the above problem, the utility model provides a communication interference optimization circuit for CAN communication, can improve CAN communication's anti -interference ability and communication stability significantly.

[0008] The technical scheme is as follows: a communication interference optimization circuit for CAN communication, comprising:

[0009] The power filter module and CAN communication module are connected, the power filter module is configured to power the CAN communication module, and the CAN communication module is used to support the signal receiving and conversion between CAN controller and CAN bus,

[0010] The power filter module includes a voltage stabilizer U8, the input end of the voltage stabilizer U8 is connected with a 5V power supply, the output end of the voltage stabilizer U8 is connected with a power filter unit, the power filter unit is used to filter the output of the voltage stabilizer, and the power filter unit outputs the filtered 5V power supply;

[0011] The CAN communication module includes a CAN transceiver, the CAN transceiver adopts an isolated CAN transceiver U9, the isolated CAN transceiver U9 includes an isolated CAN bus side and a CAN controller side, the CAN controller side of the isolated CAN transceiver U9 is powered by a 3.3V power supply, the CAN bus side of the isolated CAN transceiver U9 is powered by a 5V power supply output by the power supply filtering module, the CAN controller side of the isolated CAN transceiver U9 is provided with a port connected CAN controller, the CAN bus side of the isolated CAN transceiver U9 is provided with a CAN port for connecting CAN bus CAN_H and CAN_L, and a signal filtering unit and a protection unit are arranged between the CAN port of the isolated CAN transceiver U9 and the CAN bus, the signal filtering unit is used for filtering communication signals, and the protection unit is used for protecting communication signals.

[0012] Further, the power supply filtering unit includes a toroidal filter L5, 2 ports of the toroidal filter L5 are connected to an output end of a voltage stabilizer U8, the output end of the voltage stabilizer U8 is further connected to a 1 port of the toroidal filter L5 after being connected to a parallel capacitor R196 and a capacitor C143, the toroidal filter L5 is used for filtering common mode interference in the power supply, 1 and 2 ports of the toroidal filter L5 are further connected to a capacitor CY12 and a capacitor CY11 respectively and then connected to a reference point PE, for guiding interference signals into the reference point PE, a capacitor C141 is connected between 3 and 4 ports of the toroidal filter, the 3 port of the toroidal filter is connected to a filter inductor L4 and then outputs a 5V power supply, the 4 port of the toroidal filter is connected to a filter inductor L6 and then grounded, the filter inductor L4 and the filter inductor L6 are used for differential mode filtering, and the 3 port of the toroidal filter outputs the 5V power supply and is further connected to a filter capacitor C142 and then grounded, the filter capacitor C142 is used for low-frequency filtering.

[0013] Further, the voltage stabilizer U8 is of an LM7805 type, an input end of the voltage stabilizer U8 is connected to a 5V power supply, and the 5V power supply is connected to a capacitor C140 and then grounded.

[0014] Further, the 5V power supply input to the voltage stabilizer U8 is connected to a reference ground CANG, the 5V power supply output by the voltage stabilizer U8 and the filtering module is connected to a reference ground CANG1, and the reference ground CANG1 and the reference ground CANG are different ground ports and are used for isolating the output of the power supply filtering module and the output.

[0015] Further, the reference point PE is a metal shell.

[0016] Further, the signal filter unit comprises a capacitor C150 and a toroidal filter L10 and a capacitor C151 constituting a Π type filter structure, for filtering out the common mode signal in the communication process, the capacitor C151 further constitutes an RC filter structure with a resistor R199, for shaping the communication signal, the capacitor C150 is connected between the CAN_H and CAN_L ports of the isolation CAN transceiver U9, the 1 and 2 ports of the toroidal filter L10 are respectively connected to the CAN_H and CAN_L ports of the isolation CAN transceiver U9, the 3 and 4 ports of the toroidal filter L10 are connected to both ends of the capacitor C151, the signal filter unit further comprises a differential mode chip inductor L8 arranged between the 3 port of the toroidal filter L10 and the CAN_H of the CAN bus and a differential mode chip inductor L12 arranged between the 4 port of the toroidal filter L10 and the CAN_L of the CAN bus, the differential mode chip inductors L8 and L12 are used for differential mode filtering, the differential mode chip inductor L8 further constitutes a CLC filter structure with a capacitor C149, a capacitor C146 and a capacitor C145, the differential mode chip inductor L12 further constitutes a CLC filter structure with a capacitor C152, a capacitor C154 and a capacitor C155, the CAN_H of the CAN bus is further connected to a reference point PE after connecting the capacitor C145 and the capacitor C146, the CAN_L of the CAN bus is further connected to the reference point PE after connecting the capacitor C155 and the capacitor C156, and the capacitor C149 and the capacitor C152 are further connected to a reference ground CANG1.

[0017] Further, the model of the isolation CAN transceiver U9 is ISO1050, the power input end VDD2 of the CAN bus side of the isolation CAN transceiver U9 is further connected to the reference ground CANG1 after connecting a capacitor C148, the GND2 port of the CAN bus side of the isolation CAN transceiver U9 is connected to the reference ground CANG1, the power input end VDD1 of the CAN controller side of the isolation CAN transceiver U9 is connected to one end of an inductor L7 after connecting a capacitor C147 and a capacitor C144 in parallel, the other end of the inductor L7 is connected to a 3.3V DLC power supply, and the capacitor C147 and the capacitor C144 are respectively connected to a reference ground LCAG.

[0018] Further, the protection unit includes diode D61, diode D62, diode D63, diode D64 and TVS tube TVS1 connected to the CAN_H and CAN_L ports of the isolation CAN transceiver U9, the CAN_H port of the isolation CAN transceiver U9 is connected to the forward diode D61, the reverse TVS tube TVS1 and the reference ground CANG1, the CAN_H port of the isolation CAN transceiver U9 is connected to the reverse diode D63 and the reference ground CANG1, the CAN_L port of the isolation CAN transceiver U9 is connected to the forward diode D62, the reverse TVS tube TVS1 and the reference ground CANG1, and the CAN_L port of the isolation CAN transceiver U9 is connected to the reverse diode D64 and the reference ground CANG1.

[0019] The utility model discloses a communication interference optimization circuit for CAN communication, through setting the power filter module including voltage stabilizer and power filter unit, can effectively remove various interference in power supply, ensure for CAN communication module provides pure, stable power supply, in the utility model, CAN communication module uses isolation CAN transceiver U9 and realizes the signal transceiver and conversion between CAN controller and CAN bus, and the isolation design of isolation CAN transceiver U9 effectively prevents the chip damage caused by communication loop short circuit. Meanwhile, set up signal filter unit between the CAN_H and CAN_L port of isolation CAN transceiver and CAN bus, realized the effective filtering of communication signal, rationally utilized different types of grounding mode, optimized the transmission path of signal, reduced signal interference, still set up the protection unit that comprises diode and TVS tube in the CAN_H and CAN_L port of isolation CAN transceiver in the utility model, can respond quickly when encountering overvoltage pulse, and the circuit is not damaged. The utility model discloses a communication interference optimization circuit for CAN communication, can significantly improve the anti -interference ability of CAN communication, reduces the influence of electromagnetic interference, line problem and power problem to communication. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a module block diagram for the communication interference optimization circuit for CAN communication of the utility model;

[0021] Figure 2 It is the circuit diagram of power filter module in the embodiment;

[0022] Figure 3 It is the circuit diagram of CAN communication module in the embodiment. DETAILED DESCRIPTION

[0023] To make the technical problems solved by the utility model, the technical scheme adopted and the technical effects reached more clear, the technical scheme of the utility model embodiment is further described in detail below.In the description of the present specification, the description of reference terms such as "embodiment" means that the specific features, structures or characteristics described in conjunction with the embodiment are contained in at least one embodiment or example of the utility model.In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example.

[0024] See Figure 1 The utility model discloses a communication interference optimization circuit for CAN communication, comprising: the power filter module 100 and CAN communication module 200 of interconnection, the power filter module 100 is configured to power supply CAN communication module 200, CAN communication module 200 is used to support the signal transceiving and conversion between CAN controller and CAN bus, specifically, CAN communication module 200 can convert the data provided by CAN controller into the data that can be sent by CAN bus;CAN communication module 200 can receive the data of CAN bus, and the received data is converted back to the format that CAN controller can identify and is passed to CAN controller;

[0025] In the embodiment, the power filter module 100 includes voltage stabilizer U8, the input end of voltage stabilizer U8 is connected with 5V power supply, the output end of voltage stabilizer U8 is connected with power filter unit, the power filter unit is used to filter the output of voltage stabilizer, the power filter unit outputs the 5V power supply after filtering,

[0026] The CAN communication module includes CAN transceiver, and the CAN transceiver adopts isolation CAN transceiver U9, the isolation CAN transceiver U9 includes isolated CAN bus side and CAN controller side, the CAN controller side of isolation CAN transceiver U9 is powered by 3.3V power supply, the CAN bus side of isolation CAN transceiver U9 is powered by the 5V power supply output by power filter module, the CAN controller side of isolation CAN transceiver U9 is provided with port connection CAN controller, and in the embodiment, the port connection CAN controller is CAN1RXA and CAN1TXA, the CAN bus side of isolation CAN transceiver U9 is provided with CAN port, and in the embodiment, the CAN port is CAN_H and CAN_L, which are used to connect CAN_H and CAN_L of CAN bus, and the signal filter unit and protection unit are arranged between the CAN port of isolation CAN transceiver U9 and CAN bus, the signal filter unit is used to filter communication signal, and the protection unit is used to protect communication signal.

[0027] In the implementation, the problem of strong interference and lightning strike is solved by using an isolated power supply, the power supply is subjected to enhanced common mode and differential mode filtering, the influence of electromagnetic interference of power supply on communication is reduced, different power supplies are used for the CAN controller side and the CAN bus side of the isolated CAN transceiver U9, 3.3V is used for power supply of the CAN controller side, 5V from the power supply filtering module 100 is used for power supply of the CAN bus side, and the two power supplies are isolated from each other, the isolated power supply can avoid short circuit of the communication loop and burn the chip, can prevent high voltage or transient peak interference on the CAN bus side from being transmitted to the CAN controller side, and protect the control circuit, the isolated CAN transceiver can also effectively suppress common mode interference and differential mode interference. Since the CAN bus is usually exposed to an electromagnetic noise environment, by using the isolated CAN transceiver, the influence of the interference on the CAN controller can be reduced.

[0028] Specifically in one embodiment, the model of the voltage stabilizer U8 is LM7805, the input end of the voltage stabilizer U8 is connected with a 5V power supply, the 5V power supply is connected with the capacitor C140 and then grounded, the 5V power supply input into the voltage stabilizer U8 is connected to the reference ground CANG, the 5V power supply output from the voltage stabilizer U8 and the filtering module is connected to the reference ground CANG1, the reference ground CANG1 and the reference ground CANG are different ground ports, which are used for isolating the output of the power supply filtering module, and the voltage stabilizer U8 can stabilize the input 5V power supply;

[0029] The power supply filtering unit includes a toroidal filter L5, the 2 port of the toroidal filter L5 is connected with the output end of the voltage stabilizer U8, the output end of the voltage stabilizer U8 is further connected with the 1 port of the toroidal filter L5 after being connected with the capacitor C143 and the capacitor R196 in parallel, the capacitor C143 can filter, the toroidal filter L5 is used for filtering common mode interference in the power supply, the 1 port and the 2 port of the toroidal filter L5 are further connected with the capacitor CY12 and the capacitor CY11 respectively and then connected to the reference point PE, the two capacitors CY11 and CY12 form a filtering network to the ground, the two capacitors guide interference signals to the reference point PE, the reference point PE is a metal shell, connecting the reference point to the shell of the equipment can ensure that the current can safely flow to the ground through the shell in case of failure, thereby preventing the danger of electric shock, the capacitor C141 is connected between the 3 port and the 4 port of the toroidal filter, the 3 port of the toroidal filter is connected with the filtering inductor L4 and then outputs the 5V power supply, the 4 port of the toroidal filter is connected with the filtering inductor L6 and then grounded, the filtering inductor L4 and the filtering inductor L6 are used for differential mode filtering, the 5V power supply output from the 3 port of the toroidal filter is further grounded after being connected with the filtering capacitor C142, and the filtering capacitor C142 is used for low frequency filtering; in the embodiment, the output end of the voltage stabilizer U8 is connected with the power supply filtering unit, the common mode and differential mode filtering and low frequency filtering are performed through the power supply filtering unit, so that the power supply provided for the CAN communication module has low ripple and interference, thereby improving the working stability of the CAN controller.

[0030] In detail, in one embodiment, the model of the isolation CAN transceiver U9 is ISO1050, the signal filter unit includes a capacitor C150 and a toroidal filter L10 and a capacitor C151 which constitute a Π type filter structure, for filtering the common mode signal in the communication process, the capacitor C151 also constitutes an RC filter structure with a resistor R199, for shaping the communication signal, the capacitor C150 is connected between the CAN_H and CAN_L ports of the isolation CAN transceiver U9, the 1 and 2 ports of the toroidal filter L10 are respectively connected to the CAN_H and CAN_L ports of the isolation CAN transceiver U9, the 3 and 4 ports of the toroidal filter L10 are connected to both ends of the capacitor C151, the signal filter unit further includes a differential mode chip inductor L8 arranged between the 3 port of the toroidal filter L10 and the CAN_H of the CAN bus and a differential mode chip inductor L12 arranged between the 4 port of the toroidal filter L10 and the CAN_L of the CAN bus, the differential mode chip inductors L8 and L12 are used for differential mode filtering, the differential mode chip inductor L8 further constitutes a CLC filter structure with a capacitor C149, a capacitor C146 and a capacitor C145, the differential mode chip inductor L12 further constitutes a CLC filter structure with a capacitor C152, a capacitor C154 and a capacitor C155, the CAN_H of the CAN bus is further connected to a reference point PE after connecting the capacitor C145 and the capacitor C146, the CAN_L of the CAN bus is further connected to the reference point PE after connecting the capacitor C155 and the capacitor C156, and the capacitor C149 and the capacitor C152 are further connected to a reference ground CANG1.

[0031] The power input end VDD2 of the CAN bus side of the isolation CAN transceiver U9 is further connected to the reference ground CANG1 after connecting the capacitor C148, the GND2 port of the CAN bus side of the isolation CAN transceiver U9 is connected to the reference ground CANG1, and the power input end VDD1 of the CAN controller side of the isolation CAN transceiver U9 is connected to one end of an inductor L7 after connecting the capacitor C147 and the capacitor C144 in parallel, the other end of the inductor L7 is connected to a 3.3V DLC power supply, and the capacitor C147 and the capacitor C144 are further connected to a reference ground LCAG.

[0032] In the embodiment, the CAN communication module adopts the isolation CAN transceiver and the signal filter unit, which can effectively filter the common mode and differential mode interference in the communication signal, the toroidal filter L10 can well resist the external common mode interference, the differential mode chip inductors L8 and L9 can reduce the differential mode interference, various interferences in the communication line are filtered, and effective filtering of the communication signal is realized.

[0033] In the embodiment, the common mode rejection capacitor C149 and the capacitor C152 are selected according to actual conditions to connect the CANG1 ground of the isolation CAN transceiver U9, by introducing the common mode interference into the ground, the influence of the interference on the signal transmission can be reduced, the common mode rejection capacitor C149 and the C152 are directly connected to the CANG1 ground of the isolation CAN transceiver U9, which can ensure that the grounding path is short and direct, reduce the filter impedance caused by the long line, and optimize the grounding path to increase the filtering effect; in addition, the bus signal is connected to the reference point PE through the capacitor, the CAN bus signal is connected to the reference point PE through the capacitor C145, the capacitor C146, the capacitor C155 and the capacitor C156, which can effectively filter out high-frequency interference, and the capacitor and the differential mode inductors L8 and L12 form a complex filter network to perform differential mode filtering on CAN_H and CAN_L, reduce the interference of the differential mode signal of the communication line, and L8, C149, C145 and C146 form a CLC filter, L12, C152, C154 and C155 form a CLC filter to form a better filtering effect.

[0034] In one embodiment, the protection unit includes diodes D61, D62, D63, D64 and TVS tube TVS1 connected to the CAN_H and CAN_L ports of the isolation CAN transceiver U9, the CAN_H port of the isolation CAN transceiver U9 is connected to the forward diode D61, the reverse TVS tube TVS1 and the reference ground CANG1, the CAN_H port of the isolation CAN transceiver U9 is connected to the reverse diode D63 and the reference ground CANG1, the CAN_L port of the isolation CAN transceiver U9 is connected to the forward diode D62, the reverse TVS tube TVS1 and the reference ground CANG1, and the CAN_L port of the isolation CAN transceiver U9 is connected to the reverse diode D64 and the reference ground CANG1. In the embodiment, the diodes and TVS are added to the CAN_H and CAN_L ports of the isolation CAN transceiver U9 to limit the amplitude of the interference pulse and improve the anti-surge pulse capability, so as to protect the circuit from high-intensity interference, the diodes D61, D63, D62 and D64 and the TVS tube TVS1 are connected to the CANG1 to limit the voltage pulse and reduce the risk of chip damage caused by overvoltage on the communication line, and the insertion impedance of L10 can further reduce the surge current and reduce the risk of damaging U9.

[0035] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand.

[0036] The technical principles of the present application are described above in combination with specific embodiments. These descriptions are only for explaining the principles of the present application, and cannot be interpreted as limiting the protection scope of the present application in any way. Based on the explanations herein, other specific embodiments of the present application can be conceived by those skilled in the art without creative efforts, and these embodiments will all fall within the protection scope of the present application.

Claims

1. A communication interference optimization circuit for CAN communication, comprising: a power filtering module and a CAN communication module connected in series, the power filtering module being configured to power the CAN communication module, the CAN communication module being used to support signal transceiving and conversion between a CAN controller and a CAN bus, characterized in that: the power filtering module comprises a voltage stabilizer U8, an input end of the voltage stabilizer U8 being connected to a 5V power supply, an output end of the voltage stabilizer U8 being connected to a power filtering unit, the power filtering unit being used to filter the output of the voltage stabilizer, the power filtering unit outputting a filtered 5V power supply; the CAN communication module comprises a CAN transceiver, the CAN transceiver adopting an isolated CAN transceiver U9, the isolated CAN transceiver U9 comprising an isolated CAN bus side and a CAN controller side, the CAN controller side of the isolated CAN transceiver U9 being powered by a 3.3V power supply, the CAN bus side of the isolated CAN transceiver U9 being powered by the 5V power supply output by the power filtering module, the CAN controller side of the isolated CAN transceiver U9 being provided with a port connected to a CAN controller, the CAN bus side of the isolated CAN transceiver U9 being provided with a CAN port used to connect CAN_H and CAN_L of the CAN bus, a signal filtering unit and a protection unit being arranged between the CAN port of the isolated CAN transceiver U9 and the CAN bus, the signal filtering unit being used to filter communication signals, the protection unit being used to protect communication signals.

2. The communication interference optimization circuit for CAN communication according to claim 1, characterized in that: the power filtering unit comprises a toroidal filter L5, a 2 port of the toroidal filter L5 being connected to an output end of the voltage stabilizer U8, the output end of the voltage stabilizer U8 further being connected to a 1 port of the toroidal filter L5 after being connected to a parallel capacitor R196 and a capacitor C143, the toroidal filter L5 being used to filter common mode interference in the power supply, the 1 and 2 ports of the toroidal filter L5 further being connected to a capacitor CY12 and a capacitor CY11 respectively before being connected to a reference point PE, for leading interference signals to the reference point PE, a capacitor C141 being connected between the 3 and 4 ports of the toroidal filter, the 3 port of the toroidal filter being connected to a filter inductor L4 before outputting a 5V power supply, the 4 port of the toroidal filter being connected to a filter inductor L6 before being grounded, the filter inductor L4 and the filter inductor L6 being used for differential mode filtering, the 3 port of the toroidal filter outputting a 5V power supply further being connected to a filter capacitor C142 before being grounded, the filter capacitor C142 being used for low frequency filtering.

3. The communication interference optimization circuit for CAN communication according to claim 2, characterized in that: the voltage stabilizer U8 is of the model LM7805, an input end of the voltage stabilizer U8 being connected to a 5V power supply, the 5V power supply being connected to a capacitor C140 before being grounded.

4. The communication interference optimization circuit for CAN communication according to claim 3, characterized in that: the 5V power supply input to the voltage stabilizer U8 is connected to a reference ground CANG, the 5V power supply output by the voltage stabilizer U8 and the filtering module is connected to a reference ground CANG1, the reference ground CANG1 and the reference ground CANG being different ground ports, for isolating the output of the power filtering module and the output.

5. The communication interference optimization circuit for CAN communication according to claim 2, wherein: the reference point PE is a metal shell.

6. The communication interference optimization circuit for CAN communication according to claim 1, wherein: The signal filter unit comprises a capacitor C150 and a ring filter L10 constituting a Π type filter structure and a capacitor C151 for filtering common mode signals in the communication process, the capacitor C151 also constitutes an RC filter structure with a resistor R199 for shaping the communication signals, the capacitor C150 is connected between the CAN_H and CAN_L ports of the isolation CAN transceiver U9, the 1 and 2 ports of the ring filter L10 are connected to the CAN_H and CAN_L ports of the isolation CAN transceiver U9 respectively, and the 3 and 4 ports of the ring filter L10 are connected to both ends of the capacitor C151, the signal filter unit further comprises a differential mode chip inductor L8 arranged between the 3 port of the ring filter L10 and the CAN_H of the CAN bus and a differential mode chip inductor L12 arranged between the 4 port of the ring filter L10 and the CAN_L of the CAN bus, the differential mode chip inductors L8 and L12 are used for differential mode filtering, the differential mode chip inductor L8 further constitutes a CLC filter structure with a capacitor C149, a capacitor C146 and a capacitor C145, the differential mode chip inductor L12 further constitutes a CLC filter structure with a capacitor C152, a capacitor C154 and a capacitor C155, the CAN_H of the CAN bus is further connected to a reference point PE after connecting the capacitor C145 and the capacitor C146, the CAN_L of the CAN bus is further connected to the reference point PE after connecting the capacitor C155 and the capacitor C156, and the capacitor C149 and the capacitor C152 are further connected to a reference ground CANG1.

7. The communication interference optimization circuit for CAN communication according to claim 6, characterized in that: The model of the isolation CAN transceiver U9 is ISO1050, the power input end VDD2 of the CAN bus side of the isolation CAN transceiver U9 is further connected to the reference ground CANG1 after connecting a capacitor C148, the GND2 port of the CAN bus side of the isolation CAN transceiver U9 is connected to the reference ground CANG1, the power input end VDD1 of the CAN controller side of the isolation CAN transceiver U9 is connected to one end of an inductor L7 after connecting a capacitor C147 and a capacitor C144 in parallel, the other end of the inductor L7 is connected to a 3.3V DLC power supply, and the capacitor C147 and the capacitor C144 are further connected to a reference ground LCAG respectively.

8. The communication interference optimization circuit for CAN communication according to claim 1, wherein: The protection unit comprises diodes D61, D62, D63 and D64 and a TVS tube TVS1 connected between the CAN_H and CAN_L ports of the isolation CAN transceiver U9, the CAN_H port of the isolation CAN transceiver U9 is connected to the diode D61 in positive connection and the TVS tube TVS1 in reverse connection and then connected to the reference ground CANG1, the CAN_H port of the isolation CAN transceiver U9 is connected to the diode D63 in reverse connection and then connected to the reference ground CANG1, the CAN_L port of the isolation CAN transceiver U9 is connected to the diode D62 in positive connection and the TVS tube TVS1 in reverse connection and then connected to the reference ground CANG1, and the CAN_L port of the isolation CAN transceiver U9 is connected to the diode D64 in reverse connection and then connected to the reference ground CANG1.

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