CAN communication filtering device

Abstract

The invention discloses a CAN communication filtering device which comprises a vehicle and a charging pile and further comprises a first CAN transceiver, an MCU, a second CAN transceiver, a filtering protection circuit, a CAN1 port and a CAN2 port, the first CAN transceiver is connected with the vehicle through the CAN1 port, the first CAN transceiver and the second CAN transceiver are connected with the MCU, the second CAN transceiver is connected with the filtering protection circuit, and the filtering protection circuit is connected with the MCU. The filtering protection circuit is connected with the charging pile through a CAN2 port. According to the scheme, the electromagnetic immunity level of CAN communication can be improved; the requirements of different Baud rates and protocols can be self-adapted; the typical application of the CAN communication filtering device is that the CAN communication filtering device is connected in series between a charging pile and a vehicle CAN port, and the CAN communication filtering device not only can filter various types of electromagnetic interference from a power grid, but also can protect a vehicle from being impacted under the extreme conditions of power grid abnormity or lightning stroke and the like, thereby greatly improving the availability and adaptability of charging equipment; the scheme can be expanded and applied according to requirements, for example, the scheme can be applied to other double-line differential communication systems.

Description

Technical Field

[0001] The invention belongs to the technical field of communications, and in particular relates to a CAN communication filtering device. Background Art

[0002] CAN communication, full name Controller Area Network, is a high-performance, high-reliability serial communication protocol bus. It is mainly used in real-time applications, such as communication between various components in a car. CAN communication is implemented through the CAN bus, using twisted pair to transmit signals, with the advantages of high performance, high reliability, and real-time performance. CAN communication is widely used in civil, industrial and vehicle systems. Especially in recent years, with the development of new energy vehicles and the improvement of charging facilities, the CAN on the vehicle side and the CAN on the charging pile side are interconnected. In modern cars, CAN communication is widely used for data exchange and communication between various control modules. For example, the engine control module, brake control module, body control module, etc. all need to transmit and communicate data through the CAN bus. Through CAN communication, these control modules can share key information in real time, such as vehicle speed, engine speed, brake status, etc., thereby realizing intelligent and automatic control of the vehicle.

[0003] Existing charging piles serve as a bridge between the power grid and vehicles, connecting the power grid on one side and the vehicle on the other. Due to the good electromagnetic environment on the vehicle side, the electromagnetic immunity items in the vehicle electrical appliance standard assessment are few and the requirements are low, while the electromagnetic environment on the power grid side is complex and full of various electromagnetic interferences. There are more and more charging failures or vehicle damages caused by electromagnetic interference in the market, which has seriously restricted the healthy development of the industry.

[0004] Therefore, the present invention proposes a CAN communication filtering device, which can eliminate electromagnetic interference. Summary of the invention

[0005] In response to the problems raised by the above background technology, the purpose of the present invention is to provide a CAN communication filtering device, which is connected in series between the charging pile and the vehicle CAN port. The device can not only filter out various types of electromagnetic interference from the power grid, but also protect the vehicle from impact under extreme conditions such as power grid abnormalities or lightning strikes, thereby greatly improving the availability and adaptability of the charging equipment.

[0006] In order to achieve the above technical objectives, the technical solution adopted by the present invention is as follows:

[0007] A CAN communication filtering device includes a vehicle and a charging pile, and also includes a first CAN transceiver, an MCU, a second CAN transceiver, a filtering protection circuit, a CAN1 port and a CAN2 port, wherein the first CAN transceiver is connected to the vehicle through the CAN1 port, the first CAN transceiver and the second CAN transceiver are respectively connected to the MCU, the second CAN transceiver is connected to the filtering protection circuit, and the filtering protection circuit is connected to the charging pile through the CAN2 port.

[0008] It is further defined that the filtering protection circuit includes D1, D2, C1, C2, C3, C4, L1, R1, R2, R3, R4 and G1, wherein D1 and D2 are transient voltage suppression diodes TVS, C1 and C2 are differential mode capacitors, L1 is a common mode inductor, C3 and C4 are common mode capacitors, R1, R2, R3 and R4 are resistors, and G1 is a gas discharge tube;

[0009] The D1, D2, differential mode capacitor C1 and differential mode capacitor C2 are connected in parallel;

[0010] The common mode capacitor C3, the common mode capacitor C4, the resistor R1 and the resistor R2 are connected in parallel;

[0011] The differential mode capacitor C2 is connected to one end of the common mode inductor L1, the common mode capacitor C3 is connected to the other end of the common mode inductor L1, and the common mode inductor L1 is also connected to the resistor R3 and the resistor R4;

[0012] The resistor R3 and the resistor R4 are connected in parallel, and the resistor R3 and the resistor R4 are connected to the gas discharge tube G1 respectively.

[0013] Further defined, the MCU selects a chip with at least two CAN interfaces. With such a structural design, the MCU selects a chip with two CAN interfaces, which can not only realize data transmission between CAN1 and CAN2, but also convert the baud rate and protocol of the two CANs, thereby adapting to the use requirements of different buses.

[0014] It is further defined that it also includes a first 485 transceiver and a second 485 transceiver, wherein the first 485 transceiver replaces the first CAN transceiver, and the second 485 transceiver replaces the second CAN transceiver.

[0015] It is further defined that it also includes a bridge circuit, which replaces the TVS diode parallel circuit of D1 and D2; the bridge circuit includes fast recovery diodes D1, D2, D3, D4 and TVS diode D5; the cathode of the diode D1 is connected to the cathode of the diode D4, the anode of the diode D3 is connected to the anode of the diode D2, one end of the TVS diode D5 is connected to the cathodes of the diodes D1 and D4, and the other end is connected to the anodes of the diodes D3 and D2.

[0016] It is further defined that it also includes magnetic beads L1 and magnetic beads L2 for replacing the common mode inductor L1; the magnetic beads L1 and magnetic beads L2 are connected in parallel.

[0017] Beneficial effects of the present invention:

[0018] 1. This solution provides a CAN communication filter device that can improve the electromagnetic interference immunity level of CAN communication;

[0019] 2. It can also adapt to the requirements of different baud rates and protocols.

[0020] 3. The typical application of the CAN communication filter device is to be connected in series between the charging pile and the vehicle CAN port. The device can not only filter out various types of electromagnetic interference from the power grid, but also protect the vehicle from impact under extreme conditions such as power grid abnormalities or lightning strikes, thereby greatly improving the availability and adaptability of the charging equipment. This solution can also be expanded and applied according to needs, such as in other two-wire differential communication systems, such as 485 communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention can be further illustrated by the non-limiting examples given in the accompanying drawings;

[0022] Figure 1 A device principle block diagram of an embodiment of a CAN communication filter device of the present invention;

[0023] Figure 2 A circuit schematic diagram of an embodiment of a CAN communication filter device of the present invention;

[0024] Figure 3 It is a principle block diagram of a 485 communication filter device of an embodiment of a CAN communication filter device of the present invention;

[0025] Figure 4 It is a schematic diagram of an extended filtering protection circuit of an embodiment of a CAN communication filtering device of the present invention;

[0026] Figure 5 The figure is a schematic diagram of an extended filtering protection circuit of an embodiment of a CAN communication filtering device of the present invention. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0028] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0029] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] It is important to understand that the working principle of the CAN bus is based on broadcasting, using identifiers to identify whether the data is sent to itself, and using differential signal transmission to ensure reliability and real-time performance. When a node sends data, the CPU of the node sends the data and identifier to the CAN chip of this node and puts it into a ready state. Once the CAN chip receives the bus assignment, it changes to the message sending state and sends the data in the specified message format. At this time, other nodes in the network are in the receiving state, and all nodes must first receive it and determine whether the message is sent to themselves through detection.

[0031] like Figure 1As shown, a CAN communication filtering device of the present invention includes a vehicle and a charging pile, and also includes a first CAN transceiver, an MCU, a second CAN transceiver, a filtering protection circuit, a CAN1 port and a CAN2 port. The first CAN transceiver is connected to the vehicle through the CAN1 port, the first CAN transceiver and the second CAN transceiver are respectively connected to the MCU, the second CAN transceiver is connected to the filtering protection circuit, and the filtering protection circuit is connected to the charging pile through the CAN2 port.

[0032] Specifically, the CAN1 port is connected to the vehicle-side CAN bus, which is characterized by short distance, high baud rate, many nodes, and low possibility of electromagnetic interference, but is sensitive to port hardware filtering and cannot accept large inductance or large capacitance filtering.

[0033] The CAN2 port is connected to the pile-end CAN bus, which is characterized by long distance, low baud rate, single node, and high possibility of electromagnetic interference, but is not sensitive to port hardware filtering and can accept large inductance or large capacitance filtering.

[0034] The electromagnetic immunity index of CAN2 port is shown in Table 1:

[0035] project grade Electrostatic discharge immunity Contact discharge: ±8kV, air discharge: ±15kV Radiated radio frequency electromagnetic field immunity 80MHz~6GHz:30V / m Electrical fast transient burst immunity ±4kV Surge immunity Common mode: ±6kV Immunity to conducted disturbances induced by radio frequency fields 150kHz~80MHz:10V Inrush current Common mode: ±5kA

[0036] Preferably, the filtering protection circuit includes D1, D2, C1, C2, C3, C4, L1, R1, R2, R3, R4 and G1, wherein D1 and D2 are transient voltage suppression diodes TVS, C1 and C2 are differential mode capacitors, L1 is a common mode inductor, C3 and C4 are common mode capacitors, R1, R2, R3 and R4 are resistors, and G1 is a gas discharge tube;

[0037] The D1, D2, differential mode capacitor C1 and differential mode capacitor C2 are connected in parallel;

[0038] The common mode capacitor C3, the common mode capacitor C4, the resistor R1 and the resistor R2 are connected in parallel;

[0039] The differential mode capacitor C2 is connected to one end of the common mode inductor L1, the common mode capacitor C3 is connected to the other end of the common mode inductor L1, and the common mode inductor L1 is also connected to the resistor R3 and the resistor R4;

[0040] The resistor R3 and the resistor R4 are connected in parallel, and the resistor R3 and the resistor R4 are connected to the gas discharge tube G1 respectively.

[0041] Preferably, the MCU uses a chip with at least two CAN interfaces. With such a structural design, the MCU uses a chip with two CAN interfaces, which can not only realize data transmission between CAN1 and CAN2, but also convert the baud rates and protocols of the two CANs, thereby adapting to the use requirements of different buses.

[0042] Embodiment 2: Embodiment 2 is an expansion on the basis of Embodiment 1; Figure 3 As shown, preferably, it also includes a first 485 transceiver and a second 485 transceiver, wherein the first 485 transceiver replaces the first CAN transceiver, and the second 485 transceiver replaces the second CAN transceiver. Therefore, the communication filter device can also be used in other two-wire differential communication systems, such as 485 communication.

[0043] Embodiment 3: Figure 4 As shown, preferably, it also includes a bridge circuit, which replaces the TVS diode parallel circuit of D1 and D2; the bridge circuit includes fast recovery diodes D1, D2, D3, D4 and TVS diode D5; the cathode of the diode D1 is connected to the cathode of the diode D4, the anode of the diode D3 is connected to the anode of the diode D2, one end of the TVS diode D5 is connected to the cathodes of the diodes D1 and D4, and the other end is connected to the anodes of the diodes D3 and D2.

[0044] The solution of the third embodiment adds a bridge circuit compared to the solution of the first embodiment, and has a lower junction capacitance than the TVS diode parallel protection circuit of D1 and D2 in the embodiment.

[0045] Embodiment 4: Figure 5 As shown, preferably, it also includes magnetic beads L1 and L2 for replacing the common mode inductor L1; the magnetic beads L1 and L2 are connected in parallel. This embodiment is improved on the basis of the third embodiment, Figure 5 Will Figure 4 The common-mode inductor L1 in the circuit is replaced with a magnetic bead, where L1 and L2 are magnetic beads. Figure 5 and Figure 4 It has lower cost and lower line differential impedance, and can be applied to ultra-high-speed differential communication circuits.

[0046] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A CAN communication filtering device, comprising a vehicle and a charging pile, characterized in that: It also includes a first CAN transceiver, an MCU, a second CAN transceiver, a filtering protection circuit, a CAN1 port and a CAN2 port. The first CAN transceiver is connected to the vehicle through the CAN1 port, the first CAN transceiver and the second CAN transceiver are connected to the MCU respectively, the second CAN transceiver is connected to the filtering protection circuit, and the filtering protection circuit is connected to the charging pile through the CAN2 port.

2. A CAN communication filtering device according to claim 1, characterized in that: The filtering protection circuit includes D1, D2, C1, C2, C3, C4, L1, R1, R2, R3, R4 and G1, wherein D1 and D2 are transient voltage suppression diodes TVS, C1 and C2 are differential mode capacitors, L1 is a common mode inductor, C3 and C4 are common mode capacitors, R1, R2, R3 and R4 are resistors, and G1 is a gas discharge tube; The D1, D2, differential mode capacitor C1 and differential mode capacitor C2 are connected in parallel; The common mode capacitor C3, the common mode capacitor C4, the resistor R1 and the resistor R2 are connected in parallel; The differential mode capacitor C2 is connected to one end of the common mode inductor L1, the common mode capacitor C3 is connected to the other end of the common mode inductor L1, and the common mode inductor L1 is also connected to the resistor R3 and the resistor R4; The resistor R3 and the resistor R4 are connected in parallel, and the resistor R3 and the resistor R4 are connected to the gas discharge tube G1 respectively.

3. A CAN communication filtering device according to claim 1, characterized in that: The MCU uses a chip with at least two CAN interfaces.

4. A CAN communication filtering device according to claim 1, characterized in that: It also includes a first 485 transceiver and a second 485 transceiver, wherein the first 485 transceiver replaces the first CAN transceiver, and the second 485 transceiver replaces the second CAN transceiver.

5. A CAN communication filtering device according to claim 2, characterized in that: It also includes a bridge circuit, which replaces the TVS diode parallel circuit of D1 and D2; the bridge circuit includes fast recovery diodes D1, D2, D3, D4 and TVS diode D5; the cathode of the diode D1 is connected to the cathode of the diode D4, the anode of the diode D3 is connected to the anode of the diode D2, one end of the TVS diode D5 is connected to the cathodes of the diodes D1 and D4, and the other end is connected to the anodes of the diodes D3 and D2.

6. A CAN communication filtering device according to claim 5, characterized in that: It also includes magnetic beads L1 and L2 for replacing the common mode inductor L1; the magnetic beads L1 and L2 are connected in parallel.

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