Electromagnetic compatibility design method and device based on vehicle audio system

Abstract

The present invention provides an electromagnetic compatibility design method and device based on a vehicle audio system, including: determining a target level of electromagnetic compatibility performance; performing a risk assessment on devices in a drawing to obtain a risk assessment result; selecting a clock frequency of signal radiation from devices that meet the design requirements; performing simulation verification on the vehicle audio system to determine whether the vehicle audio system reaches the target level; if not, performing an optimization design; if yes, performing a near-field test on the entire machine; determining whether the near-field test reaches the target level; if not, performing an optimization design; if yes, performing a far-field test on the entire machine; determining whether the far-field test reaches the target level; if not, performing an optimization design; if yes, ending the process; through simulation optimization, ensuring that the electromagnetic compatibility of the entire machine design can reach the expected target level, thereby significantly improving the quality and reliability of the product; and also shortening the R&D cycle and reducing R&D costs.

Description

Technical Field

[0001] The present invention relates to the field of automobile control technology, and in particular to an electromagnetic compatibility design method and device based on an on-board audio system. Background Art

[0002] With the widespread adoption of audio systems in areas such as audio equipment, in-car audio systems, and smart voice devices, the electromagnetic compatibility (EMC) challenges they face are becoming increasingly severe. To achieve miniaturization, high efficiency, and low heat generation, high-frequency Class D amplifiers are often used. This EMC challenge is particularly prominent in audio systems. Failure to adhere to good design practices during the design and development phase can result in equipment exceeding standards and failing testing.

[0003] When measured to exceed the standard, custom cast aluminum thick metal casings are used for shielding to ensure EMC compliance. This approach has numerous drawbacks: the metal casing's shielding effectiveness is suboptimal at certain high frequencies; the production cost of custom metal casings is high; the mold-making cycle is long; and the product weight is increased. These shortcomings make existing audio systems difficult to meet the stringent EMC requirements for audio equipment in new energy vehicles. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide an electromagnetic compatibility design method and device based on an in-vehicle audio system. Through simulation optimization, it is ensured that the electromagnetic compatibility of the entire device design can reach the expected target level, thereby significantly improving the quality and reliability of the product; it can also shorten the R&D cycle and reduce R&D costs.

[0005] In a first aspect, an embodiment of the present invention provides an electromagnetic compatibility design method based on a vehicle audio system, the method comprising:

[0006] Determine the target level of electromagnetic compatibility performance;

[0007] Performing a risk assessment on the devices in the drawings to obtain a risk assessment result; wherein the risk assessment result includes devices that meet the design requirements and devices that do not meet the design requirements;

[0008] Selecting a clock frequency point of signal radiation from devices that meet the design requirements;

[0009] Performing simulation verification on the in-vehicle audio system to determine whether the in-vehicle audio system reaches the target level;

[0010] If the in-vehicle audio system does not meet the target level, reselect components that meet the design requirements, reselect the clock frequency, redesign the shielding, filtering, and grounding of the clock frequency, re-optimize the PCB, and reconfigure the registers until the in-vehicle audio system meets the design requirements;

[0011] If the in-vehicle audio system reaches the target level, performing a near-field test on the entire device;

[0012] determining whether the near-field test reaches the target level;

[0013] If the near-field test does not meet the target level, re-designing the shielding, filtering, and grounding of the clock frequency, re-optimizing the PCB, and re-configuring the registers until the near-field test meets the design requirements;

[0014] If the near-field test reaches the target level, performing a far-field test on the entire device;

[0015] Determining whether the far-field test reaches the target level;

[0016] If the far-field test does not meet the target level, re-design the shielding, filtering, and grounding of the clock frequency, re-optimize the PCB, and re-configure the registers until the far-field test meets the design requirements;

[0017] If the far-field test reaches the target level, the process ends.

[0018] Furthermore, a risk assessment is performed on the components in the drawings to obtain risk assessment results, including:

[0019] Get the out-of-standard frequency point of the current device;

[0020] If the frequency points that exceed the standard are the multiplication of the audio power amplifier and the audio bus clock, the current device does not meet the design requirements;

[0021] If the inductance performance, capacitance performance and filtering curve parameters of the audio power amplifier output in the current device meet the requirements, the current device meets the design requirements;

[0022] If the rising edge and the falling edge of the clock of the bus buffer in the current device meet the parameter requirements, then the current device meets the design requirements;

[0023] If the current device has not been evaluated, the risk certification of the current device fails, and the current device does not meet the design requirements.

[0024] Furthermore, the method further comprises:

[0025] When the clock frequency exceeds the standard, the radiation source is obtained by locating a frequency close to the clock frequency or a multiple of the clock frequency;

[0026] Shielding design, filtering design and grounding design are performed on the clock frequency according to the radiation source, so that the clock frequency is within a set range.

[0027] Furthermore, shielding design, filtering design, and grounding design are performed on the clock frequency according to the radiation source so that the clock frequency is within a set range, including:

[0028] Selecting a higher radiation frequency point or an interference device from the clock frequency points; wherein the interference device is a device whose radiation value is greater than a set value;

[0029] Based on the on-board design, the higher-frequency radiation point or the interference device is enclosed in a circle by a GND line to form a first cavity;

[0030] Based on the first cavity, the locations of the frequency points exceeding the standard in the board are checked in sequence, and the GND lines are used to close the second cavity;

[0031] After the first cavity and the second cavity are subjected to a window opening and copper exposure process, they form a Faraday cage with the outer shell;

[0032] The Faraday cage is used to suppress external interference of the radiation source.

[0033] Further, re-optimize the PCB, including:

[0034] Adjusting the layout of the vehicle audio system DSP to output audio signals;

[0035] Low-pass filtering the audio signal and adopting a one-line layout;

[0036] After adjusting the spacing between multiple resistors and capacitors in the inline layout and increasing the board edge distance so that the crystal oscillator is perpendicular to and away from the analog signal, an optimized PCB is obtained.

[0037] Furthermore, an input list of whole-machine design documents is obtained, which includes the internal standards / regulations and standard documents of the automobile manufacturer, the audio link system architecture diagram, the circuit schematic diagram, the device specification sheet, and the software and firmware files; wherein, the internal standards / regulations and standard documents of the automobile manufacturer include the electromagnetic radiation limits of vehicle components.

[0038] Further, determining whether the near-field test reaches the target level includes:

[0039] After the near-field probe scans the current device data, first spectrum data is obtained;

[0040] Testing the frequency points in the first spectrum data in sequence by using the near-field probe;

[0041] If the frequency points in the first spectrum data are within the electromagnetic radiation limit of the vehicle-mounted component, the near-field test reaches the target level;

[0042] If the frequency points in the first spectrum data are not within the electromagnetic radiation limit of the vehicle-mounted components, the near-field test fails to reach the target level.

[0043] Further, determining whether the far-field test reaches the target level includes:

[0044] acquiring second spectrum data by using laboratory equipment;

[0045] testing the frequency points in the second spectrum data in sequence by using the laboratory equipment;

[0046] If the frequency points in the second spectrum data are within the electromagnetic radiation limit of the vehicle-mounted component, the far-field test reaches the target level;

[0047] If the frequency points in the second spectrum data are not within the electromagnetic radiation limit of the vehicle-mounted components, the far-field test fails to reach the target level.

[0048] In a second aspect, an embodiment of the present invention provides an electromagnetic compatibility design device based on a vehicle audio system, the device comprising:

[0049] A determination module, used to determine the target level of electromagnetic compatibility performance;

[0050] An assessment module, configured to perform risk assessment on the devices in the drawings and obtain risk assessment results; wherein the risk assessment results include devices that meet the design requirements and devices that do not meet the design requirements;

[0051] A selection module, configured to select a clock frequency of signal radiation from devices that meet the design requirements;

[0052] a first judgment module, configured to perform simulation verification on the in-vehicle audio system to determine whether the in-vehicle audio system reaches the target level;

[0053] a first optimization module, configured to, if the in-vehicle audio system does not reach the target level, reselect components that meet the design requirements, reselect the clock frequency, re-design shielding, filtering, and grounding for the clock frequency, re-optimize the PCB, and re-configure registers until the in-vehicle audio system reaches the design requirements;

[0054] a near-field test module, configured to perform a near-field test on the entire vehicle audio system when the vehicle audio system reaches the target level;

[0055] A second judgment module is used to judge whether the near-field test reaches the target level;

[0056] A second optimization module is configured to, if the near-field test fails to reach the target level, re-perform shielding design, filtering design, and grounding design on the clock frequency, re-optimize the PCB, and re-configure the registers until the near-field test reaches the design requirement;

[0057] A far-field test module, configured to perform a far-field test on the entire device if the near-field test reaches the target level;

[0058] A third judgment module is used to judge whether the far-field test reaches the target level;

[0059] The third optimization module is used to, if the far-field test does not reach the target level, re-perform the shielding design, filtering design and grounding design of the clock frequency, re-optimize the PCB and reconfigure the register until the far-field test meets the design requirements; if the far-field test reaches the target level, the test ends.

[0060] In a third aspect, an embodiment of the present invention provides an electronic device, including a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and the processor implements the above-mentioned method when executing the computer program.

[0061] An embodiment of the present invention provides an electromagnetic compatibility design method and device based on an in-vehicle audio system, including: determining a target level of electromagnetic compatibility performance; performing a risk assessment on components in a drawing to obtain a risk assessment result; wherein the risk assessment result includes components that meet design requirements and components that do not meet design requirements; selecting a clock frequency of signal radiation from the components that meet design requirements; performing simulation verification on the in-vehicle audio system to determine whether the in-vehicle audio system meets the target level; if the in-vehicle audio system does not meet the target level, reselecting components that meet design requirements, reselecting clock frequencies, re-designing shielding, filtering, and grounding for the clock frequencies, re-optimizing the PCB, and re-configuring registers until the in-vehicle audio system meets design requirements; if the in-vehicle audio system meets the target level, performing a near-field test on the entire system; Determine whether the near-field test reaches the target level; if the near-field test does not reach the target level, re-design the shielding, filtering and grounding of the clock frequency, re-optimize the PCB and re-configure the registers until the near-field test meets the design requirements; if the near-field test reaches the target level, perform a far-field test on the entire machine; determine whether the far-field test reaches the target level; if the far-field test does not reach the target level, re-design the shielding, filtering and grounding of the clock frequency, re-optimize the PCB and re-configure the registers until the far-field test meets the design requirements; if the far-field test reaches the target level, end the test; through simulation optimization, ensure that the electromagnetic compatibility of the entire machine design can reach the expected target level, thereby significantly improving the quality and reliability of the product; it can also shorten the R&D cycle and reduce R&D costs.

[0062] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or understood by practicing the present invention. The objectives and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0063] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0065] Figure 1A flow chart of the electromagnetic compatibility design method based on the vehicle audio system provided in the first embodiment of the present invention;

[0066] Figure 2 This is a flowchart of step S102 in the electromagnetic compatibility design method for a vehicle audio system provided in the first embodiment of the present invention;

[0067] Figure 3 This is a schematic diagram of an electromagnetic compatibility design device based on a vehicle audio system provided in the second embodiment of the present invention. DETAILED DESCRIPTION

[0068] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0069] To facilitate understanding of this embodiment, the embodiment of the present invention is described in detail below.

[0070] Example 1:

[0071] Figure 1 This is a flow chart of the electromagnetic compatibility design method based on the vehicle audio system provided in Example 1 of the present invention.

[0072] Reference Figure 1 , the method comprises the following steps:

[0073] Step S101, determining a target level of electromagnetic compatibility performance;

[0074] Specifically, the target level of electromagnetic compatibility performance is one of the key indicators that must be met during design. EMI emissions from automotive components must pass Class 3, clearly quantifying electromagnetic compatibility indicators. For example: at 70.55 MHz, the quasi-peak radiation must not exceed 31 dBuV / m; at 196.6 MHz, the average value must not exceed 22 dBuV / m. These are the radiation value limits for Class 3 in the enterprise standard. See Table 1 for details:

[0075] Table 1

[0076]

[0077] Table 2

[0078]

[0079] When the test certification fails, the radiation data of the equipment tested in the certified product compliance laboratory will exceed the standard as follows: 70.55MHZ exceeds the standard by 3.9dB; 196.6MHZ exceeds the standard by 6.83dB. Please refer to Table 2 for details.

[0080] Step S102: performing a risk assessment on the components in the drawing to obtain a risk assessment result; wherein the risk assessment result includes components that meet the design requirements and components that do not meet the design requirements;

[0081] Here, we select the components shown in the drawings and assess their potential risks to ensure they meet the design requirements. Risk assessment primarily focuses on evaluating the performance, reliability, and compatibility of the components.

[0082] Step S103, selecting a clock frequency of signal radiation from devices that meet the design requirements;

[0083] Specifically, selecting the clock frequency of signal radiation from devices that meet design requirements ensures signal accuracy and stability. Determining the clock frequency requires consideration of factors such as the signal's frequency, phase, and amplitude. If the clock frequency is not compliant, fine-tune and optimize each step in the flowchart until it complies.

[0084] For example, the frequencies of 70.55 MHz and 196.6 MHz exceed the standard. When the clock frequency exceeds the standard, the radiation source is found by locating the frequency or frequency multiplication method. When the test or simulation exceeds the standard of 70.55 MHz, the table calculation shows that the 35-fold frequency of 2 MHz produces 70.55. When the test or simulation exceeds the standard of 196.6 MHz, the table calculation shows that the 16-fold frequency of 12.28 MHz produces 196.6 MHz. Please refer to Table 3 for details:

[0085] Table 3

[0086]

[0087] Step S104, performing simulation verification on the vehicle audio system to determine whether the vehicle audio system reaches the target level; if the vehicle audio system does not reach the target level, executing step S105; if the vehicle audio system reaches the target level, executing step S106;

[0088] Step S105: reselect components that meet the design requirements, reselect the clock frequency, redesign the shielding, filtering, and grounding of the clock frequency, reoptimize the PCB, and reconfigure the registers until the in-vehicle audio system meets the design requirements;

[0089] Step S106, performing a near-field test on the entire device;

[0090] Specifically, the system determines whether the in-vehicle audio system meets the target level; if it fails, the design must be revised. Software simulation uses configuration tools to test whether the radiation frequency exceeds the standard. If it fails, components that meet the design requirements will be reselected, the clock frequency will be reselected, shielding, filtering, and grounding designs will be redesigned, the PCB will be optimized, and registers will be reconfigured until the in-vehicle audio system meets the design requirements.

[0091] Shield the signal cavity GND, adjust the straight-line layout and crystal oscillator position, and configure the software. Optimize and fine-tune the performance of each component and signal until a balanced and compliant system is achieved. This is verified through pure software simulation and theoretical development and design verification. If the in-car audio system passes verification, conduct near-field testing of the entire device.

[0092] Step S107, determining whether the near field test reaches the target level; if the near field test does not reach the target level, executing step S108; if the near field test reaches the target level, executing step S109;

[0093] Step S108, re-designing the shielding, filtering, and grounding of the clock frequency, re-optimizing the PCB, and re-configuring the registers until the near-field test meets the design requirements;

[0094] Step S109, performing far-field testing on the entire device;

[0095] Step S110, determining whether the far field test reaches the target level; if the far field test does not reach the target level, executing step S111; if the far field test reaches the target level, executing step S112;

[0096] Step S111: re-design the shielding, filtering, and grounding of the clock frequency, re-optimize the PCB, and re-configure the registers until the far-field test meets the design requirements;

[0097] Step S112, end.

[0098] This application aims to solve the problems of insufficient targeting, poor results and high costs in existing designs, in order to meet the needs of high-quality audio systems. The method first conducts a detailed analysis of the overall design documents to clarify the target level of electromagnetic compatibility performance. Then, the components in the drawings are carefully selected and their potential risks are evaluated to ensure that the selected components can meet the design requirements. In addition, the method also involves listing the clock frequencies of signal radiation, as well as performing shielding design, filtering design and grounding design, which are key links in electromagnetic compatibility design and can effectively reduce electromagnetic interference. In order to further improve the performance and reliability of the circuit, the method also includes optimization of PCB layout and wiring. At the same time, the in-vehicle audio system is simulated and verified to ensure that its design meets the expected performance requirements.

[0099] On the software side, optimization is achieved through register-based EMI mode configuration and spread spectrum technology. During the verification phase, this approach includes near-field and far-field testing of the entire device to obtain spectrum data. This systematic design and verification process ensures that the electromagnetic compatibility performance of the entire device design meets the expected target level, significantly improving product quality and reliability.

[0100] Traditional design methods increase electromagnetic compatibility by adding a metal casing, which not only increases costs but also prolongs the mass production cycle. This application addresses electromagnetic compatibility issues at the source, achieving greater accuracy and effectiveness. Furthermore, through simulation optimization, this application can shorten R&D cycles and reduce R&D costs, providing a cost-effective, high-quality solution for audio system design.

[0101] Further, refer to Figure 2 , step S102 includes the following steps:

[0102] Step S201, obtaining the out-of-standard frequency point of the current device;

[0103] Here, the selection is based on the frequency points that exceed the standard, such as 70.55MHZ and 196.6MHZ. These two frequency points are respectively the audio power amplifier 2MHZ frequency multiplication exceeds the standard and the audio bus clock 12.28MHZ exceeds the standard.

[0104] Step S202: If the frequency points that exceed the standard are the multiplication of the audio power amplifier and the audio bus clock, the current device does not meet the design requirements;

[0105] Step S203: If the inductance performance, capacitance performance, and filter curve parameters of the audio power amplifier output in the current device meet the requirements, the current device meets the design requirements;

[0106] Step S204: If the rising edge and falling edge of the clock of the bus buffer in the current device meet the parameter requirements, the current device meets the design requirements;

[0107] Step S205: If the current device has not been evaluated, the risk certification of the current device fails, and the current device does not meet the design requirements.

[0108] Specifically, when non-compliance is detected, it is necessary to purchase samples to test the performance of different series. If the components are selected directly without evaluation, there is a risk of certification failure and excessive radiation exceeding the standard.

[0109] When non-compliance occurs, it is necessary to continue selecting other series of devices to suppress the required frequency points. This is a process of continuously optimizing and adjusting different series of devices to have a suppressive effect on the frequency points.

[0110] Furthermore, the method further comprises the following steps:

[0111] Step S301: When the clock frequency exceeds the standard, the radiation source is obtained by locating a frequency close to the clock frequency or a frequency multiplier.

[0112] Step S302 : performing shielding design, filtering design, and grounding design on the clock frequency according to the radiation source, so that the clock frequency is within a set range.

[0113] Furthermore, step S302 includes the following steps:

[0114] Step S401, selecting a higher radiation frequency point or an interference device from the clock frequency points; wherein the interference device is a device whose radiation value is greater than a set value;

[0115] Step S402: Based on the in-board design, the higher-frequency radiation point or the interference device is enclosed by a GND line to form a first cavity;

[0116] Step S403: Based on the first cavity, the locations of the frequency points exceeding the standard in the board are checked in sequence, and the second cavity is sealed by using the GND line.

[0117] Step S404, performing a window opening process on the first cavity and the second cavity to expose the copper, and then forming a Faraday cage with the outer shell;

[0118] Step S405: Suppressing external interference of the radiation source by using a Faraday cage.

[0119] Specifically, shielding design, filtering design, and grounding design are key aspects of electromagnetic compatibility design, effectively reducing electromagnetic interference. Shielding design includes the selection of shielding materials and the design of shielding structures; filtering design includes the selection of filters and the design of filtering circuits; and grounding design includes the selection of grounding methods and the control of grounding resistance.

[0120] Without increasing costs, based on the on-board design, the higher-frequency radiation points or interfering devices are enclosed in a circle by GND lines to form the first cavity, achieving cost-free but effective shielding. The frequency points exceeding the standard on the board are checked one by one, and the GND is enclosed to form the second cavity to optimize the external radiation of the signal on the board. The plate making process is required to open windows and expose copper in the first and second cavities. This is an optimization for 70.55MHZ, which is essentially an optimization for the 2MHZ power amplifier clock frequency, because the 35-fold harmonics of 2MHZ will cause the radiation to exceed the standard by 3.9dB. Refer to Table 4:

[0121] Table 4

[0122]

[0123] The enclosed cavity also requires innovative plate-making techniques. The first and second cavities are opened to expose the copper, which, when assembled with the outer shell, forms a Faraday cage. The Faraday cage effect effectively suppresses external interference from the radiation source.

[0124] For example, if the radiation exceeds the standard by 3.9dB, it can be reduced to 1.25dB by combining shielding design with window opening technology and assembling it properly. Refer to Table 5:

[0125] Table 5

[0126]

[0127] By adjusting the width and dimensions of the closed cavity (fine-tuning the width of the square closed cavity, increasing or decreasing the dimensions will have an effect), multiple adjustments are required. Finally, the width of the exposed copper wire is increased by 0.55mm, and the length of the cuboid is reduced by 1mm.

[0128] This frequency point is optimized. In Table 6, there is no negative number exceeding the standard for this frequency point 70.55MHZ. It is necessary to verify the effect through repeated adjustments. Refer to Table 6:

[0129] Table 6

[0130]

[0131] Through the innovative cooperation of plate making process, the closed cavity is opened to expose the copper. The exposed copper process forms a Faraday cage after assembly with the help of the outer shell, which completely suppresses the 2MHZ radiation.

[0132] In filtering design, the output of a Class D amplifier (switching amplifier) ​​is a PWM pulse wave, which needs to be converted back to analog audio through an LC low-pass filter to remove high-frequency switching noise (typical switching frequency is 200kHz to 1MHz). A parallel RC damping network (e.g., R = 10Ω, C = 0.1μF) is added after the LC filter to eliminate the resonant peaks of the inductor and capacitor and improve the frequency response flatness.

[0133] For digital-to-analog conversion, the IIS is first decoded into an analog signal by the DAC. An LPF (low-pass filter) is required at the DAC output to filter out sampling noise (for example, when sampling at 44.1kHz, signals > 22.05kHz need to be filtered out). A typical solution is a Sallen-Key second-order LPF with a cutoff frequency set to 25~30kHz.

[0134] In grounding design, the audio chain has both digital and analog grounds. If these two grounds share a common ground line, the high current fluctuations in the digital circuit will generate a voltage drop in the common ground impedance, which will be superimposed on the analog signal (such as high-frequency glitches in the DAC output). The high-frequency current in the digital ground generates a magnetic field, which couples into the analog signal chain through mutual inductance (for example, when the IIS trace is adjacent to the analog audio line).

[0135] Chip-level grounding design processing: DAC chips (such as ES9038PRO) usually have independent DGND and AGND pins. The corresponding ground planes need to be separated on the PCB to avoid direct connection.

[0136] Module-level grounding design divides digital circuits (such as MCU, IIS transceiver) and analog circuits (DAC, op amp) into independent ground planes, which are isolated by "ground trenches" (copper-free areas) in the middle to reduce capacitive coupling.

[0137] The digital ground and analog ground connection method is to connect DGND and AGND at the star ground point through a 0Ω resistor, ferrite bead, or inductor to avoid loops formed by multiple grounding points.

[0138] Layered grounding design, top layer: analog signal routing (away from digital circuits), bottom layer: digital signal routing (away from analog circuits), inner layer 1: analog ground plane (completely covering the analog circuit area), inner layer 2: digital ground plane (completely covering the digital circuit area).

[0139] Furthermore, in step S105, re-optimizing the PCB includes:

[0140] Step S501, adjusting the layout of the vehicle audio system DSP to output audio signals;

[0141] Step S502, low-pass filtering the audio signal and adopting a one-line layout;

[0142] Step S503 , adjusting the spacing between the plurality of resistors and capacitors in the inline layout and increasing the distance from the board edge so that the crystal oscillator is perpendicular to and away from the analog signal, thereby obtaining an optimized PCB.

[0143] Specifically, optimize the PCB (printed circuit board) layout and routing to improve circuit performance and reliability. Layout and routing optimization must consider factors such as signal integrity, power integrity, and thermal management. For example, when adjusting the layout of the audio DSP output low-pass filter, a single-line layout is required. Referring to Table 7, the over-frequency point is 196.6 MHz, with a margin of -6.83.

[0144] Table 7

[0145]

[0146] Traditionally, analog small-signal filter components are placed only according to the signal flow direction, which will cause the audio frequency of 196.6MHZ to exceed the standard by 6.83dB.

[0147] The innovative layout utilizes a straight-line filter arrangement to suppress interference, ensuring effective signal transmission and superior radiation performance. External GND grounding further suppresses radiation. This straight-line arrangement significantly reduces radiation by several dB. Referring to Table 8, the overshoot frequency is 196.6 MHz, with a margin of -4.49.

[0148] Table 8

[0149]

[0150] Then adjust the spacing between several resistors and capacitors in the line layout, increase the distance from the board edge, and keep the crystal oscillator perpendicular to and away from the analog signal, and optimize again by a few dB. Refer to Table 9:

[0151] Table 9

[0152]

[0153] Furthermore, the software optimizes the electromagnetic compatibility EMI spread spectrum register configuration. By configuring different spread spectrum effects through the chip register, the signal output waveform can be optimized. For details, refer to Table 10:

[0154] Table 10

[0155]

[0156] The effect was verified by configuring several registers in software, including SSC1, SCC2, SCC3, SCC4, and PWM Phase. After optimization, the 196.6 MHZ frequency point disappeared, and the test was conducted without exceeding the standard, with a margin increase of 2.52 dB. For details, see Table 11:

[0157] Table 11

[0158]

[0159] This application follows a specific, sequential, and logical process for electromagnetic compatibility (EMC) design, verification, testing, and rectification to ensure that the product meets the target EMC performance level. This application combines shielding, filtering, and grounding design with PCB layout optimization, and provides a comprehensive EMC design approach with software-configured EMI modes and spread spectrum functionality. By implementing multiple simulation verification and testing phases (including in-vehicle audio system simulation, near-field testing, and far-field testing), and continuously refining and optimizing based on the verification results, we ensure that the target EMC performance level is ultimately achieved.

[0160] Furthermore, obtain the input list of the whole machine design documents, which includes the internal standards / regulations and standard documents of the automobile company, the audio link system architecture diagram, the circuit schematic diagram, the device specification sheet, and the software and firmware files. Among them, the internal standards / regulations and standard documents of the automobile company include the electromagnetic radiation limits of vehicle components. The enterprise standard requirements are higher than the national standards. For details, please refer to the electromagnetic radiation index requirements of the enterprise standard.

[0161] Furthermore, step S107 includes the following steps:

[0162] Step S601, after the near-field probe scans the current device data, first spectrum data is obtained;

[0163] Step S602: testing the frequency points in the first spectrum data in sequence using a near-field probe;

[0164] Step S603: If the frequency points in the first spectrum data are within the electromagnetic radiation limit of the vehicle components, the near-field test reaches the target level;

[0165] Step S604: If the frequency point in the first spectrum data is not within the electromagnetic radiation limit of the vehicle-mounted components, the near-field test does not reach the target level.

[0166] Specifically, once the in-vehicle audio system passes verification, near-field testing of the entire system is performed to obtain spectrum data. Near-field testing primarily assesses the electromagnetic compatibility performance of the entire system at close range.

[0167] The first spectrum data is used as an indicator in the standard document to determine radiation parameters. A near-field probe is used to measure each frequency point sequentially, and the target level is re-verified. If it fails, the design must be revised. The instrument scans the radiation frequency points. The acquisition parameter indicators for both the 70.55 MHz and 196.6 MHz devices are displayed on the panel. The device can determine if there has been a decrease (in dB) compared to the previous data. This is used to determine if the above measures have improved the 70.55 MHz and 196.6 MHz frequencies. If not, the clock frequency shielding, filtering, and grounding designs will be redesigned, along with PCB optimization and register reconfiguration, until the near-field test meets the design requirements.

[0168] Furthermore, step S110 includes the following steps:

[0169] Step S701, obtaining second spectrum data through laboratory equipment;

[0170] Step S702, testing the frequency points in the second spectrum data in sequence using laboratory equipment;

[0171] Step S703: If the frequency points in the second spectrum data are within the electromagnetic radiation limit of the vehicle components, the far-field test reaches the target level;

[0172] Step S704: If the frequency points in the second spectrum data are not within the electromagnetic radiation limit of the vehicle-mounted components, the far-field test does not reach the target level.

[0173] Specifically, if the near-field test passes, the entire device undergoes far-field testing to obtain a second spectrum. Far-field testing primarily assesses the device's electromagnetic compatibility performance at long distances. Finally, a check is performed to see if the target level is met. If it passes, the design process concludes. If not, the design must be revised, including redesigning the shielding, filtering, and grounding design for the clock frequency, re-optimizing the PCB, and reconfiguring registers until the far-field test meets the design requirements.

[0174] The certification laboratory will use professional sites, instruments and equipment, and host computer software to collect data to determine whether it is qualified. If it is not qualified, a Fail frequency point will be displayed. Far-field testing can fully verify whether it has passed the laboratory certification. For details, please refer to Table 12:

[0175] Table 12

[0176]

[0177] This systematic design and verification process ensures that the electromagnetic compatibility performance of the entire device design meets the expected target level, thereby improving product quality and reliability. The technical solution of this application has the following advantages: it provides a systematic, operational, traceable, and optimizable method for the electromagnetic compatibility design of the entire device, which can effectively improve the electromagnetic compatibility performance of the entire device and meet the needs of different application scenarios.

[0178] Example 2:

[0179] Figure 3 This is a schematic diagram of an electromagnetic compatibility design device based on a vehicle audio system provided in the second embodiment of the present invention.

[0180] Reference Figure 3 , the device comprises:

[0181] A determination module, used to determine the target level of electromagnetic compatibility performance;

[0182] An assessment module, configured to perform risk assessment on the components in the drawings and obtain risk assessment results; wherein the risk assessment results include components that meet the design requirements and components that do not meet the design requirements;

[0183] A selection module is used to select the clock frequency of signal radiation from devices that meet the design requirements;

[0184] The first judgment module is used to perform simulation verification on the vehicle audio system to determine whether the vehicle audio system reaches the target level;

[0185] The first optimization module is used to reselect components that meet the design requirements, reselect the clock frequency, redesign the shielding, filtering, and grounding of the clock frequency, re-optimize the PCB, and reconfigure the registers until the in-vehicle audio system meets the design requirements if the in-vehicle audio system does not meet the target level.

[0186] Near-field test module, used to perform near-field testing on the entire vehicle when the in-vehicle audio system reaches the target level;

[0187] The second judgment module is used to judge whether the near-field test reaches the target level;

[0188] The second optimization module is used to redesign the shielding, filtering, and grounding of the clock frequency, re-optimize the PCB, and re-configure the registers if the near-field test fails to meet the target level, until the near-field test meets the design requirements.

[0189] Far-field test module, used to perform far-field testing on the entire device when the near-field test reaches the target level;

[0190] The third judgment module is used to judge whether the far-field test reaches the target level;

[0191] The third optimization module is used to re-design the shielding, filtering and grounding of the clock frequency, re-optimize the PCB and re-configure the registers if the far-field test does not reach the target level, until the far-field test meets the design requirements; if the far-field test reaches the target level, the process ends.

[0192] This application has the following advantages:

[0193] 1) Systematic process: A complete and orderly electromagnetic compatibility design process has been established, covering everything from design input to final testing. Each link is closely connected to fully control electromagnetic compatibility.

[0194] 2) Multi-dimensional design: Comprehensively utilize shielding, filtering, grounding design, and PCB layout optimization to reduce electromagnetic interference from different levels, rather than a single measure.

[0195] 3) Multiple Verification and Optimization: Set up multiple simulation verification and testing links (in-vehicle audio system simulation, near-field testing, far-field testing), and continuously improve and optimize based on the verification results to ensure that the target level of electromagnetic compatibility performance is ultimately achieved.

[0196] An embodiment of the present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the electromagnetic compatibility design method based on the vehicle audio system provided in the above embodiment are implemented.

[0197] An embodiment of the present invention further provides a computer-readable medium having a non-volatile program code executable by a processor. The computer-readable medium stores a computer program. When the computer program is executed by the processor, the steps of the electromagnetic compatibility design method based on the vehicle audio system of the above embodiment are executed.

[0198] The computer program product provided in the embodiments of the present invention includes a computer-readable storage medium storing program code. The instructions included in the program code can be used to execute the methods described in the previous method embodiments. For specific implementation, please refer to the method embodiments and will not be repeated here.

[0199] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described systems and devices can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0200] In addition, in the description of the embodiments of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0201] If the functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage media include various media capable of storing program code, such as USB flash drives, mobile hard drives, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical disks.

[0202] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0203] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the above-described embodiments, those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the above-described embodiments within the technical scope disclosed by the present invention, or replace some of the technical features therein with equivalents. Such modifications, changes, or replacements do not deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. An electromagnetic compatibility design method based on a vehicle audio system, characterized in that: The method comprises: Determine the target level of electromagnetic compatibility performance; Performing a risk assessment on the devices in the drawings to obtain a risk assessment result; wherein the risk assessment result includes devices that meet the design requirements and devices that do not meet the design requirements; Selecting a clock frequency point of signal radiation from devices that meet the design requirements; Performing simulation verification on the in-vehicle audio system to determine whether the in-vehicle audio system reaches the target level; If the in-vehicle audio system does not meet the target level, reselect components that meet the design requirements, reselect the clock frequency, redesign the shielding, filtering, and grounding of the clock frequency, re-optimize the PCB, and reconfigure the registers until the in-vehicle audio system meets the design requirements; If the in-vehicle audio system reaches the target level, performing a near-field test on the entire device; determining whether the near-field test reaches the target level; If the near-field test does not meet the target level, re-designing the shielding, filtering, and grounding of the clock frequency, re-optimizing the PCB, and re-configuring the registers until the near-field test meets the design requirements; If the near-field test reaches the target level, performing a far-field test on the entire device; Determining whether the far-field test reaches the target level; If the far-field test does not meet the target level, re-design the shielding, filtering, and grounding of the clock frequency, re-optimize the PCB, and re-configure the registers until the far-field test meets the design requirements; If the far-field test reaches the target level, the process ends.

2. The electromagnetic compatibility design method based on the vehicle audio system according to claim 1 is characterized in that: Perform risk assessment on the components in the drawings and obtain risk assessment results, including: Get the out-of-range frequency point of the current device; If the frequency points that exceed the standard are the multiplication of the audio power amplifier and the audio bus clock, the current device does not meet the design requirements; If the inductance performance, capacitance performance and filtering curve parameters of the audio power amplifier output in the current device meet the requirements, the current device meets the design requirements; If the rising edge and the falling edge of the clock of the bus buffer in the current device meet the parameter requirements, then the current device meets the design requirements; If the current device has not been evaluated, the risk certification of the current device fails, and the current device does not meet the design requirements.

3. The electromagnetic compatibility design method based on the vehicle audio system according to claim 1, characterized in that: The method further comprises: When the clock frequency exceeds the standard, the radiation source is obtained by locating a frequency close to the clock frequency or a multiple of the clock frequency; Shielding design, filtering design and grounding design are performed on the clock frequency according to the radiation source, so that the clock frequency is within a set range.

4. The electromagnetic compatibility design method based on the vehicle audio system according to claim 3 is characterized in that: Performing shielding, filtering, and grounding design on the clock frequency based on the radiation source to keep the clock frequency within a set range includes: Selecting a higher radiation frequency point or an interference device from the clock frequency points; wherein the interference device is a device whose radiation value is greater than a set value; Based on the on-board design, the higher-frequency radiation point or the interference device is enclosed in a circle by a GND line to form a first cavity; Based on the first cavity, the locations of the frequency points exceeding the standard in the board are checked in sequence, and the GND lines are used to close the second cavity; After the first cavity and the second cavity are subjected to a window opening and copper exposing process, they form a Faraday cage with the outer shell; The Faraday cage is used to suppress external interference of the radiation source.

5. The electromagnetic compatibility design method based on the vehicle audio system according to claim 1, characterized in that: Re-optimize the PCB, including: Adjusting the layout of the vehicle audio system DSP to output audio signals; Low-pass filtering the audio signal and adopting a one-line layout; After adjusting the spacing between multiple resistors and capacitors in the inline layout and increasing the board edge distance so that the crystal oscillator is perpendicular to and away from the analog signal, an optimized PCB is obtained.

6. The electromagnetic compatibility design method based on the vehicle audio system according to claim 1, characterized in that: Obtain a complete machine design document input list, which includes the vehicle manufacturer's internal standards / regulations and standard documents, audio link system architecture diagrams, circuit schematics, device specifications, and software and firmware files; wherein, the vehicle manufacturer's internal standards / regulations and standard documents include electromagnetic radiation limits for vehicle components.

7. The electromagnetic compatibility design method based on the vehicle audio system according to claim 6, characterized in that: Determining whether the near-field test reaches the target level includes: After the near-field probe scans the current device data, first spectrum data is obtained; Testing the frequency points in the first spectrum data in sequence by using the near-field probe; If the frequency points in the first spectrum data are within the electromagnetic radiation limit of the vehicle-mounted component, the near-field test reaches the target level; If the frequency points in the first spectrum data are not within the electromagnetic radiation limit of the vehicle-mounted components, the near-field test fails to reach the target level.

8. The electromagnetic compatibility design method based on the vehicle audio system according to claim 6, characterized in that: Determining whether the far-field test reaches the target level includes: acquiring second spectrum data by using laboratory equipment; testing the frequency points in the second spectrum data in sequence by using the laboratory equipment; If the frequency points in the second spectrum data are within the electromagnetic radiation limit of the vehicle-mounted component, the far-field test reaches the target level; If the frequency points in the second spectrum data are not within the electromagnetic radiation limit of the vehicle-mounted components, the far-field test fails to reach the target level.

9. An electromagnetic compatibility design device based on a vehicle audio system, characterized in that: The device comprises: A determination module, used to determine the target level of electromagnetic compatibility performance; An assessment module, configured to perform risk assessment on the devices in the drawings and obtain risk assessment results; wherein the risk assessment results include devices that meet the design requirements and devices that do not meet the design requirements; A selection module, configured to select a clock frequency of signal radiation from devices that meet the design requirements; a first judgment module, configured to perform simulation verification on the in-vehicle audio system to determine whether the in-vehicle audio system reaches the target level; a first optimization module, configured to, if the in-vehicle audio system does not reach the target level, reselect components that meet the design requirements, reselect the clock frequency, re-design shielding, filtering, and grounding for the clock frequency, re-optimize the PCB, and re-configure registers until the in-vehicle audio system reaches the design requirements; a near-field test module, configured to perform a near-field test on the entire vehicle audio system when the vehicle audio system reaches the target level; A second judgment module is used to judge whether the near-field test reaches the target level; A second optimization module is configured to, if the near-field test fails to reach the target level, re-perform shielding design, filtering design, and grounding design on the clock frequency, re-optimize the PCB, and re-configure the registers until the near-field test reaches the design requirement; A far-field test module, configured to perform a far-field test on the entire device if the near-field test reaches the target level; A third judgment module is used to judge whether the far-field test reaches the target level; The third optimization module is used to, if the far-field test does not reach the target level, re-perform the shielding design, filtering design and grounding design of the clock frequency, re-optimize the PCB and reconfigure the register until the far-field test meets the design requirements; if the far-field test reaches the target level, the test ends.

10. An electronic device comprising a memory and a processor, wherein the memory stores a computer program that can be run on the processor, wherein: When the processor executes the computer program, the method according to any one of claims 1 to 8 is implemented.

Images