CAN transceiver circuit electromagnetic coupling simulation model establishment method

Abstract

The invention discloses a CAN transceiver circuit electromagnetic coupling simulation model building method, and belongs to the field of CAN bus electric control system electromagnetic protection. According to the built CAN transceiver circuit electromagnetic coupling simulation model, electromagnetic coupling simulation analysis can be carried out on the CAN transceiver circuit electromagnetic coupling simulation model, a model basis is provided for CAN bus strong electromagnetic pulse resistance reinforcement, and the CAN transceiver circuit electromagnetic coupling simulation model can be applied to the field of CAN bus electric control system electromagnetic protection. For example, a required protection circuit is designed according to the coupling voltage condition of each monitoring point on the model. According to the method, a new research method is provided for electromagnetic coupling effect analysis of the CAN transceiver circuit through a numerical simulation modeling method, and a reference basis is provided for electromagnetic pulse protection design of a CAN bus electronic control system.

Description

Technical Field

[0001] The invention relates to the field of electromagnetic protection of a CAN bus, and in particular to a method for establishing an electromagnetic coupling simulation model of a CAN transceiver circuit. Background Art

[0002] With the continuous development of automobile network communication technology, people have put forward higher and higher requirements for all aspects of automobile network information transmission. Most modern automobiles have internal functional modules that exchange information data through the CAN (Controller Area Network) bus. At present, the miniaturization and intelligentization technology of various functional chips are constantly improving. While the corresponding circuit integration degree is increasing, its ability to resist external electromagnetic pulse interference is constantly decreasing. When the CAN node module is exposed to a complex electromagnetic pulse environment, the radio frequency pulse current generated by the electromagnetic pulse source is coupled into the module, causing serious damage to its internal components, thereby threatening the normal operation of the entire CAN bus electronic control system. At present, the research on the electromagnetic compatibility of the CAN bus electronic control system mainly focuses on the stability of the bus digital signal transmission, ignoring the influence of the electromagnetic coupling characteristics of each functional circuit in the CAN node module on the electromagnetic compatibility of the CAN bus electronic control system.

[0003] CAN transceiver circuit is an important medium for signal conversion and transmission in CAN node module, and it is also the part most susceptible to electromagnetic interference. Moreover, the digital signal transmitted by CAN transceiver follows strict level standards, and it is likely to directly affect the quality of the transmitted signal after being subjected to electromagnetic interference. Therefore, it is very important to establish an effective method for establishing electromagnetic coupling simulation model for CAN transceiver circuit. Summary of the invention

[0004] The present invention provides a method for establishing an electromagnetic coupling simulation model of a CAN transceiver circuit. The method uses a numerical simulation modeling method to establish an electromagnetic coupling simulation model of a CAN transceiver circuit, thereby providing a reference for the electromagnetic pulse protection design of a CAN bus electric control system.

[0005] An embodiment of the present invention provides a method for establishing an electromagnetic coupling simulation model of a CAN transceiver circuit, comprising the following steps:

[0006] Step 1: Use CST software to establish a full-wave 3D model of the CAN node module PCB for electromagnetic simulation calculation;

[0007] Step 2: In the CST-MWS interface, add the lumped parameter models of the capacitors and resistors in the CAN transceiver circuit to the corresponding positions on the PCB, and connect the connector pins to the corresponding mounting holes on the PCB through the lumped parameter models;

[0008] Step 3: In the CST-MWS interface, add discrete ports at each monitoring point of the CAN transceiver circuit module and at the connector pins of the PCB;

[0009] Step 4: In the CST-DS interface, add the IBIS models of the CAN H, CAN L, and RCAN ports of the CAN transceiver, set the input control signal and enable signal of each IBIS model, and connect their outputs to the corresponding ports of the PCB 3D model;

[0010] Step 5: In the CST-DS interface, set the bias voltage to 2.5V and connect it to the output of the IBIS model of the CAN H and CAN L ports through a 50Ω resistor.

[0011] Optionally, in one embodiment of the present invention, the CAN node module PCB full-wave three-dimensional model established in step 1 includes a CAN transceiver circuit module, and the CAN H and CAN L pins of the CAN transceiver chip are connected to the corresponding mounting holes of the connector through PCB traces, and the two inner electrical layers of the PCB are respectively provided with a +5V power layer and a ground layer.

[0012] Optionally, in one embodiment of the present invention, in step 2, according to the designed CAN transceiver chip peripheral circuit, the linear electronic components in the circuit are added to the corresponding positions on the PCB in the form of a lumped parameter model, and in order to simulate the process of the pulse excitation signal coupling into the PCB through the connector, the connector pins are connected to the corresponding mounting holes on the PCB through the lumped parameter model.

[0013] Optionally, in one embodiment of the present invention, the positions of the discrete ports corresponding to the monitoring points on the PCB in step 3 are at the corresponding pads of CAN H, CAN L, RCAN, +5V and the connector mounting holes in the CAN transceiver circuit module, the port type is set to a surface port, the port impedance is set to 50Ω, and the ends of each port are connected to a perfect conductive plane in the CST-MWS interface.

[0014] Optionally, in one embodiment of the present invention, in step 3, the discrete port at the connector pin is used as the voltage pulse excitation signal input port, the position is set at the corresponding pins of +5V, CAN H, and CAN L, the port type is set to an edge port, the port impedance is set to 50Ω, and the ends of each port are connected to a perfect conductive plane through a perfect conductive line in the CST-MWS interface.

[0015] Optionally, in one embodiment of the present invention, in step 4, the established IBIS model of the CAN H and CAN L ports of the CAN transceiver is added in the CST-DS interface, and the model input control signal is set to a TTL level signal of a set frequency, and the two levels are opposite.

[0016] Optionally, in one embodiment of the present invention, in step 4, the enable end of each IBIS model is connected to the +5V port of the CAN transceiver circuit module, and a monitoring probe is provided at the output end of each IBIS model.

[0017] Optionally, in one embodiment of the present invention, in step 4, two input terminals of the IBIS model of the RCAN port are connected to output terminals of the IBIS model of the CAN H and CAN L ports respectively.

[0018] Optionally, in one embodiment of the present invention, in step 5, in the CST-DS interface, a +5V power supply is set, the power supply is connected to the +5V power supply port of the PCB full-wave three-dimensional model, and an external port is added at each monitoring port and excitation signal input port, and the port impedance is set to 50Ω.

[0019] Optionally, in one embodiment of the present invention, in step 5, in order to simulate the actual CAN transceiver peripheral circuit situation, in the CST-DS interface, a 2.5V bias voltage is set and connected to the output end of the IBIS model of the CAN H and CAN L ports through a 50Ω resistor.

[0020] The electromagnetic coupling simulation model of the CAN transceiver circuit established by the method for establishing the electromagnetic coupling simulation model of the CAN transceiver circuit in the embodiment of the present invention can be used to perform electromagnetic coupling simulation analysis, and provide a model basis for the reinforcement of the CAN bus against strong electromagnetic pulses, such as designing the required protection circuit according to the coupling voltage conditions of each monitoring point on the model. The present invention provides a new research method for the analysis of the electromagnetic coupling effect of the CAN transceiver circuit through the method of numerical simulation modeling, and provides a reference basis for the electromagnetic pulse protection design of the CAN bus electronic control system.

[0021] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0023] Figure 1 A flowchart of a method for establishing an electromagnetic coupling simulation model of a CAN transceiver circuit provided according to an embodiment of the present invention;

[0024] Figure 2 A schematic diagram of the process of establishing an electromagnetic coupling simulation model of a CAN transceiver circuit according to an embodiment of the present invention;

[0025] Figure 3 A full-wave three-dimensional model diagram of a CAN node module according to an embodiment of the present invention;

[0026] Figure 4 This is a simulation circuit model diagram of a CAN transceiver according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0028] Figure 1 The present invention provides a flowchart of a method for establishing an electromagnetic coupling simulation model of a CAN transceiver circuit according to an embodiment of the present invention.

[0029] like Figure 1 As shown, the method for establishing the electromagnetic coupling simulation model of the CAN transceiver circuit includes the following steps:

[0030] Step 1: Use CST software to establish a full-wave 3D model of the CAN node module PCB for electromagnetic simulation calculation.

[0031] Step 2: In the CST-MWS interface, add the lumped parameter models of the capacitors and resistors in the CAN transceiver circuit to the corresponding positions on the PCB, and connect the connector pins to the corresponding mounting holes on the PCB through the lumped parameter models.

[0032] Step 3: In the CST-MWS interface, add discrete ports at each monitoring point on the CAN transceiver circuit module and at the connector pins on the PCB.

[0033] Step 4: In the CST-DS interface, add the IBIS models of the CAN transceiver corresponding to the CAN H, CAN L, and RCAN ports, set the input control signal and enable signal of each IBIS model, and connect their output ends to the corresponding ports of the PCB 3D model.

[0034] Step 5: In the CST-DS interface, set the bias voltage to 2.5V and connect it to the output of the IBIS model of the CAN H and CAN L ports through a 50Ω resistor.

[0035] In an embodiment of the present invention, the CAN node module PCB full-wave three-dimensional model established in step 1 includes a CAN transceiver circuit module, and the CAN H and CAN L pins of the CAN transceiver chip are connected to the corresponding mounting holes of the connector through PCB traces, and the two inner electrical layers of the PCB are respectively provided with a +5V power layer and a ground layer.

[0036] In an embodiment of the present invention, in the CST-MWS interface of step 2, in order to build a complete CAN transceiver peripheral circuit model, according to the designed CAN transceiver chip peripheral circuit, the lumped parameter models (Lumped Elements) of the capacitors and resistors in the CAN transceiver circuit are added to the corresponding positions on the PCB to simulate the process of the pulse excitation signal coupling into the PCB through the connector, and the connector pins are connected to the corresponding mounting holes on the PCB through the lumped parameter model.

[0037] In an embodiment of the present invention, in step 3, the positions of the discrete ports corresponding to the monitoring points on the PCB are mainly at the corresponding pads of CAN H, CAN L, RCAN, +5V and the connector mounting holes in the CAN transceiver circuit module, the port type is set to a face port, the port impedance is set to 50Ω, and the ends of each port are connected to a perfect conductive plane (PEC Face) in the CST-MWS interface.

[0038] In an embodiment of the present invention, in step 3, the discrete port at the connector pin is used as the voltage pulse excitation signal input port, the port position is set at the pins corresponding to +5V, CAN H, and CAN L, the type is set to the edge port (Edgeport), the port impedance is set to 50Ω, and each port is connected to the perfect conductive plane (PEC Face) through a perfect conductive wire (PEC wire) in the CST-MWS interface.

[0039] In an embodiment of the present invention, in step 4, the established IBIS model of the CANH and CAN L ports of the CAN transceiver is added in the CST-DS interface, and the model input terminal (Ctrl) control signal is set to a TTL level signal of a certain frequency, and the two levels are opposite.

[0040] In an embodiment of the present invention, in step 4, the enable end (En) of each IBIS model is connected to the +5V port of the CAN transceiver circuit module, and a monitoring probe (Prob) is set at the output end (Out) of each IBIS model.

[0041] In the embodiment of the present invention, in step 4, two input terminals (Supply, Ctrl) of the IBIS model (Receiver) of the RCAN port are connected to the output terminals of the IBIS model of the CAN H and CAN L ports respectively.

[0042] In an embodiment of the present invention, in step 5, in the CST-DS interface, a +5V power supply is set and connected to the +5V power supply port of the PCB full-wave three-dimensional model, and an external port is added at each monitoring port and excitation signal input port, and the port impedance is set to 50Ω.

[0043] In the embodiment of the present invention, in step 5, in order to simulate the actual CAN transceiver peripheral circuit situation, a 2.5V bias voltage is set in the CST-DS interface and connected to the output end (Out) of the IBIS model of the CAN H and CAN L ports through a 50Ω resistor.

[0044] The method for establishing the electromagnetic coupling simulation model of the CAN transceiver circuit of the present invention is described in detail below through specific embodiments.

[0045] like Figure 2 As shown, the present invention adopts a numerical simulation modeling method, and the specific working principle is as follows:

[0046] Step 1: Aiming at the problem of establishing the electromagnetic coupling simulation model of the CAN transceiver circuit, the CAN node module PCB board is selected as the research object, and the CAN node PCB model is established in Altium Designer (AD). The CAN node module PCB contains the CAN transceiver circuit module, whose main function is to receive the TTL level signal sent by the CAN controller, convert it into a CAN differential signal and send it to the CAN bus, and reflect the bus differential voltage value and convert it into a TTL level signal and send it to the CAN controller. The CAN H and CAN L pin pads of the CAN transceiver chip are connected to the corresponding mounting holes of the connector through PCB traces, and the two inner electrical layers of the PCB are respectively set with a +5V power layer and a ground layer. The CAN node PCB model established in Altium Designer is imported into the CST software, and the three-dimensional model of the connector and the packaging box is established at the same time.

[0047] Step 2: If Figure 3As shown, in CST-MWS, the lumped parameter models (Lumped Elements) of the capacitors and resistors in the CAN transceiver circuit are added to the corresponding positions on the PCB of the CAN node module. To simulate the process of the pulse excitation signal coupling into the PCB through the connector, the connector pins (corresponding to CAN H, CAN L, +5V) are connected to the corresponding mounting holes of the PCB through the lumped parameter model.

[0048] Step 3: In the CST-MWS interface, discrete surface ports with a port impedance of 50Ω are uniformly set at the corresponding pads of CAN H, CAN L, RCAN, and +5V on the CAN node module PCB and the connector mounting holes as a medium to establish an electrical connection with the simulation circuit model in the CST-DS interface. At the same time, the coupling signal of each port can be monitored in the CST-MWS interface. In addition, the length of each monitoring port is set to 0.2mm, and the end of each port is connected to the perfect conductive plane (PEC Face). A discrete edge port with an impedance of 50Ω is set at the connector pin as the voltage pulse excitation signal input port. The port position is set at the corresponding pins of +5V, CAN H, and CAN L. The port length is set to 1mm, and each port is connected to the perfect conductive plane (PEC Face) through a perfect conductive wire (PEC wire) in the CST-MWS interface. The discrete port distribution in the CST-MWS interface is as follows: Figure 3 shown.

[0049] Step 4: Since general circuit simulation software ignores the influence of electromagnetic pulse fields, and the CAN transceiver chip is a nonlinear electronic component, its equivalent circuit needs to be built in the CST-DS interface. In the CST-DS interface, the full-wave 3D model of the CAN node module PCB will be converted into a 3D block, which establishes electrical connections with the equivalent circuit model through each port pin. The specific construction method of the equivalent circuit of the CAN transceiver is as follows Figure 4As shown. First, in the CST-DS interface, import the established IBIS models corresponding to the CAN H, CAN L, and RCAN ports of the CAN transceiver, and set the input terminal (Ctrl) control signal of the IBIS model of the CAN H and CAN L ports to a TTL level signal of a certain frequency, and the two levels are opposite. Then, connect the enable terminal (En) of each IBIS model to the +5V port of the CAN transceiver circuit module (this port corresponds to the VCC pin of the CAN transceiver chip), connect the output terminal (Out) to the CAN H, CAN L, and RCAN ports of the 3D block, and set a monitoring probe (Prob) at the output terminal (Out) of each IBIS model. In order to enable the CAN transceiver to reflect the differential voltage of the CAN H and CAN L ports, connect the two input terminals (Supply, Ctrl) of the IBIS model of the RCAN port to the output terminals of the IBIS model of the CAN H and CAN L ports respectively. In addition, a +5V DC power supply is set and connected to the +5V port of the PCB full-wave 3D model (this port corresponds to the +5V mounting hole of the connector), and an external port with a port impedance of 50Ω is added to each monitoring port and excitation signal input port of the 3D block.

[0050] Step 5: Figure 4 As shown in the figure, since the bias voltage of the CAN H and CAN L differential signals is 2.5V, in order to simulate the actual CAN transceiver peripheral circuit, a 2.5V bias voltage is set in the CST-DS interface and connected to the output end (Out) of the IBIS model of the CAN H and CAN L ports through a 50Ω resistor.

[0051] According to the method for establishing the electromagnetic coupling simulation model of the CAN transceiver circuit proposed in the embodiment of the present invention, the CAN node module PCB model is established using Altium Designer, the full-wave three-dimensional electromagnetic simulation model of the CAN node module is built in CST-MWS using CST software, and the CAN transceiver equivalent circuit simulation model is built in the CST-DS interface. In the modeling process, relevant discrete ports are added to the full-wave three-dimensional model of the CAN node module, and an electrical connection with the equivalent circuit model in the CST-DS interface is established. At the same time, the coupling signals of each port of each CAN transceiver circuit are monitored in the subsequent simulation analysis, and the CAN transceiver equivalent circuit model built in the CST-DS interface well simulates the operation of the CAN transceiver chip, and takes into account the influence of the electromagnetic pulse field on the circuit. The model can be used to analyze the coupling signal conditions of each monitoring point, and provide a model basis for the design of the electromagnetic protection circuit of the CAN bus electric control system. The present invention provides a new research method for the analysis of the electromagnetic coupling effect of the CAN transceiver circuit through the method of numerical simulation modeling, and provides a reference basis for the electromagnetic pulse protection design of the CAN bus electric control system.

[0052] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0053] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying 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 the description of the present invention, the meaning of "N" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0054] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present invention belong.

Claims

1. A method for establishing an electromagnetic coupling simulation model of a CAN transceiver circuit, characterized in that: The following steps are involved: Step 1: Use CST software to establish a full-wave 3D model of the CAN node module PCB for electromagnetic simulation calculation; Step 2: In the CST-MWS interface, add the lumped parameter models of the capacitors and resistors in the CAN transceiver circuit to the corresponding positions on the PCB, and connect the connector pins to the corresponding mounting holes on the PCB through the lumped parameter models; Step 3: In the CST-MWS interface, add discrete ports at each monitoring point of the CAN transceiver circuit module and at the connector pins of the PCB; Step 4: In the CST-DS interface, add the IBIS models of the CAN H, CAN L, and RCAN ports of the CAN transceiver, set the input control signal and enable signal of each IBIS model, and connect their outputs to the corresponding ports of the PCB 3D model; Step 5: In the CST-DS interface, set the bias voltage to 2.5V and connect it to the output of the IBIS model of the CAN H and CAN L ports through a 50Ω resistor.

2. The method according to claim 1, characterized in that: The CAN node module PCB full-wave three-dimensional model established in step 1 includes a CAN transceiver circuit module, and the CAN H and CAN L pins of the CAN transceiver chip are connected to the corresponding mounting holes of the connector through PCB traces, and the two inner electrical layers of the PCB are respectively provided with a +5V power layer and a ground layer.

3. The method according to claim 1, characterized in that In step 2, according to the designed CAN transceiver chip peripheral circuit, the linear electronic components in the circuit are added to the corresponding positions on the PCB in the form of a lumped parameter model. In order to simulate the process of the pulse excitation signal coupling into the PCB through the connector, the connector pins are connected to the corresponding mounting holes on the PCB through the lumped parameter model.

4. The method according to claim 1, characterized in that: The positions of the discrete ports corresponding to the monitoring points on the PCB in step 3 are at the corresponding pads of CAN H, CAN L, RCAN, +5V and the connector mounting holes in the CAN transceiver circuit module. The port type is set to surface port, the port impedance is set to 50Ω, and the ends of each port are connected to the perfect conductive plane in the CST-MWS interface.

5. The method according to claim 1, characterized in that In step 3, the discrete port at the connector pin is used as the voltage pulse excitation signal input port, the position is set at the corresponding pins of +5V, CAN H, and CAN L, the port type is set to edge port, the port impedance is set to 50Ω, and the end of each port is connected to the perfect conductive plane through a perfect conductive line in the CST-MWS interface.

6. The method according to claim 1, characterized in that In step 4, add the established IBIS model of the CAN H and CAN L ports of the CAN transceiver in the CST-DS interface, and set the model input control signal to a TTL level signal of the set frequency, with the two levels being opposite.

7. The method according to claim 1, characterized in that In step 4, the enable end of each IBIS model is connected to the +5V port of the CAN transceiver circuit module, and a monitoring probe is set at the output end of each IBIS model.

8. The method according to claim 1, characterized in that: In step 4, the two input terminals of the IBIS model of the RCAN port are connected to the output terminals of the IBIS model of the CAN H and CAN L ports respectively.

9. The method according to claim 1, characterized in that: In step 5, in the CST-DS interface, set the +5V power supply, connect the power supply to the +5V power supply port of the PCB full-wave 3D model, add external ports at each monitoring port and excitation signal input port, and set the port impedance to 50Ω.

10. The method according to claim 1, characterized in that In step 5, to simulate the actual CAN transceiver peripheral circuit, set a 2.5V bias voltage in the CST-DS interface and connect it to the output of the IBIS model of the CAN H and CAN L ports through a 50Ω resistor.

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