RS485 interface surge prevention and EFT electric fast transient pulse train design optimization method

Abstract

The invention relates to the technical field of interfaces, and provides an RS485 interface surge prevention and EFT electric fast transient pulse train design optimization method, which comprises the following steps: determining an industrial environment of RS485 interface operation to be designed and interference characteristics corresponding to the industrial environment; according to the industrial environment, initial protection characteristics and an initial protection structure corresponding to the initial protection characteristics are determined; determining a protection interval reference according to the interference characteristics, and optimizing the initial protection structure into a target protection structure conforming to the protection interval reference; enabling the RS485 interface conforming to the target protection structure to pass through a surge test and an EFT electrical fast transient burst test in the industrial environment, and judging whether the RS485 interface has an output abnormality or not; wherein when the output is abnormal, an abnormal item and a protection characteristic corresponding to the abnormal item are determined, the target protection structure is optimized, and the previous step is repeated; and when the output abnormity does not exist, taking the target protection structure as a final structure of the to-be-designed RS485 interface.

Description

Technical Field

[0001] This invention relates to the field of interface protection technology, and in particular to a design optimization method for surge protection and EFT (Electronic Fast Transient / Bulk) protection of RS485 interfaces. Background Technology

[0002] The RS485 communication protocol supports multi-node communication, enabling fast and reliable data transmission between multiple devices. This protocol exhibits excellent anti-interference capabilities in harsh operating environments and supports long-distance communication. Its applications are increasingly widespread in today's industrial sectors, including energy storage power supply industrial water-cooled air conditioning control systems, factory access control systems, sensor networks, wireless control of industrial oil pipelines, remote monitoring, data acquisition, human-machine interfaces, and even industrial big data exchange liquid cooling systems. Compared to everyday home environments, electromagnetic interference, such as static electricity and surges, is far more severe in industrial control environments. In industrial settings, the start-up, shutdown, or malfunction of high-power load equipment can easily generate interference such as EFT / B and surges. Furthermore, the power supply also generates inrush current when monitoring equipment starts up. This interference can be conducted through communication cables to the RS485 interface and then into the PCB, easily causing malfunctions in the RS485 chip's control circuitry, or even irreversible damage, ultimately leading to abnormal monitoring displays and affecting the normal operation of the equipment.

[0003] In RS485 communication, surge immunity is a critical consideration. Surge interference can easily cause communication interruptions and even damage equipment. Current RS485 surge protection designs primarily assess and design for surge interference injection at the power input side of the device, without considering directly injecting low-voltage surges into the RS485 port to assess its protection capabilities. This leads to the following situation: while RS485 devices may show no abnormal behavior during surge testing at the power supply side (e.g., power adapter), in actual use under harsh conditions, they may still experience display abnormalities, malfunctions, or device damage due to surges and EFT (Electronic Fast Transient) burst interference. Summary of the Invention

[0004] This application proposes a design optimization method for surge protection and EFT (Electronic Fast Transient / Bulk) protection of RS485 interfaces. By quantifying the interference spectrum, common-mode / differential-mode component ratio, and coupling path in the industrial environment, the protection structure parameters are precisely matched with the interference characteristics. Based on the interference conduction coupling order, protection modules are divided, and the module parameters are dynamically adjusted through a test-feedback-iteration mechanism to achieve coordinated optimization of interference type, protection measures, and signal transmission. Furthermore, surge / EFT testing in the industrial environment is combined with anomaly tracing to form a closed loop from problem localization to structural optimization, avoiding blind debugging.

[0005] To achieve the above objectives, this application provides the following technical solution: Firstly, this application proposes a design optimization method for surge protection and EFT (Electronic Fast Transient / Bulk) protection of RS485 interfaces, including: Step 1: Determine the industrial environment in which the RS485 interface to be designed will be used, and the corresponding interference characteristics of the industrial environment; Step 2: Determine the initial protection characteristics and the corresponding initial protection structure based on the industrial environment; Step 3: Based on the interference characteristics, determine the protection zone reference and optimize the initial protection structure into a target protection structure that conforms to the protection zone reference; Step 4: Pass the RS485 interface conforming to the target protection structure through surge testing and EFT (Electronic Fast Transient / Burst) testing under the aforementioned industrial environment to determine whether the RS485 interface has any output abnormalities; wherein, Step 5: When an output anomaly exists, identify the anomaly item and the corresponding protection characteristic, optimize the target protection structure, and repeat step 4. Step 6: When there is no output anomaly, use the target protection structure as the final structure of the RS485 interface to be designed.

[0006] In conjunction with the first aspect, step 1 includes: Identify the high electromagnetic interference and conventional electromagnetic interference in the industrial environment, as well as the interference spectrum data of the industrial environment; Based on the interference spectrum data, determine the interference injection path, the common-mode conducted coupling path between the RS485 interface and the protective ground, and the differential-mode conducted coupling path between the signal lines, and distinguish the interference ratio of common-mode interference components and differential-mode interference components. Based on high electromagnetic interference and conventional electromagnetic interference, an association model based on differential-mode conducted coupling path is constructed; The interference ratio is introduced into the correlation model to determine the interference characteristics corresponding to the industrial environment.

[0007] In conjunction with the first aspect, the initial protection structure includes: a TVS clamping structure, a resistor current limiting structure, a ferrite bead filtering structure, and a capacitor decoupling structure; wherein, based on the initial protection characteristics, the protection sequence of the protection structure is determined by the order of interference received by the RS485 interface in the industrial environment.

[0008] In conjunction with the first aspect, step 2 includes: Based on the industrial environment, identify typical abnormal data of the RS485 interface to be designed in the industrial field; Based on typical anomaly data, determine the types of anomalies faced by the RS485 interface to be designed, as well as the initial protection characteristics of different anomalies; Based on the initial protection characteristics, the conduction coupling order of different anomalies is determined; whereby the conduction coupling order characterizes the order in which different anomalies appear in association. The initial protection structure is determined based on the anomaly type and the order of conductive coupling; wherein, the order of conductive coupling is used to characterize the modular structural sequence of the target protection structure.

[0009] In conjunction with the first aspect, determining the protection zone benchmark in step 3 includes: Based on the interference ratio of common-mode interference components and differential-mode interference components in the interference characteristics, the common-mode protection zone and the differential-mode protection zone are dynamically divided. Determine the coupling coefficient between the common-mode protection zone and the differential-mode protection zone, and set a zone overlap threshold so that the target protection structure gradually transitions between the common-mode protection and differential-mode protection frequency bands.

[0010] In conjunction with the first aspect, the optimization of the initial protective structure into the target protective structure in step 3 includes: A multi-objective genetic algorithm is used to optimize the parameters of TVS clamping voltage, resistor current limit value, ferrite bead impedance characteristics and capacitor value. With protection response time and signal transmission loss as dual objective functions, a Pareto optimal solution set is generated and the optimal parameter combination is dynamically selected based on real-time interference spectrum data of the industrial environment.

[0011] In conjunction with the first aspect, the surge test and EFT electrical fast transient / burst test in step 4 are performed as follows: Segmented EFT electrical fast transient burst testing based on interference spectrum data, gradually increasing the pulse intensity to the interface critical failure threshold in each frequency band; When the failure threshold is reached, a surge test is performed, and the injection polarity and waveform parameters of the surge test are dynamically adjusted according to the abnormal frequency band characteristics that appear in the segmented EFT electrical fast transient burst test.

[0012] In conjunction with the first aspect, the abnormal items identified in step 5 include: Based on the anomalies, an anomaly tracing model based on Bayesian networks is constructed, and the output anomalies are used as observation nodes. Based on the observation nodes, the parameter drift range of each component in the target protection structure is used as a latent variable. The failure probability ranking of each component is calculated by Markov chain Monte Carlo sampling, and the protection characteristic parameters with the highest failure probability are optimized first.

[0013] In conjunction with the first aspect, the optimization of the target protection structure in step 5 includes: When the proportion of common-mode interference corresponding to the abnormal item exceeds the target preset value, a common-mode choke is inserted between the ferrite bead filter structure and the capacitor decoupling structure. The number of turns of the choke and the permeability of the core material are dynamically adjusted according to the center frequency of the abnormal frequency band, so that the common-mode impedance is increased in the abnormal frequency band until the abnormal frequency band disappears.

[0014] In conjunction with the first aspect, after determining the final protective structure in step 6, the following steps are also included: A virtual model of the RS485 interface is constructed based on digital twin technology. The long-term electromagnetic aging effect in the industrial environment is simulated in the virtual environment to predict the life decay curve of the protective components. Based on the life decay curve, replaceable modular protection units are added to the final protection structure; wherein the replacement cycle of the modular protection units is set based on the life prediction results.

[0015] The beneficial effects of this application are as follows: This application achieves a precise match between the protection structure parameters and interference characteristics by quantifying the interference spectrum, common-mode / differential-mode component ratio, and coupling path in the industrial environment. It divides protection modules based on the interference conduction coupling order and dynamically adjusts module parameters through a test-feedback-iteration mechanism to achieve coordinated optimization of interference type, protection measures, and signal transmission. Furthermore, it combines surge / EFT electrical fast transient burst testing in the industrial environment with anomaly tracing to form a closed loop from problem localization to structural optimization, avoiding blind debugging.

[0016] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0019] In the attached diagram: Figure 1 This is a flowchart illustrating a design optimization method for surge protection and EFT (Electronic Fast Transient Burst) of an RS485 interface according to an embodiment of the present invention. Figure 2 This is a schematic diagram illustrating a design choice for surge protection and EFT (Electronic Fast Transient / Bulk) of the RS485 interface in an embodiment of the present invention. Figure 3 This is a diagram illustrating the design and architecture selection for surge protection and EFT (Electrical Fast Transient / Bulk) of the RS485 interface in this embodiment of the invention. Detailed Implementation

[0020] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0021] In existing technologies, the RS485 interface is widely and commonly used. Therefore, the RS485 interface is already considered a standard interface with high integration, high reliability, and wide adaptability.

[0022] However, in industrial environments with multi-node communication, the complex interference environment varies, and surge protection and EFT (Electrical Fast Transient / Bulk Transmission) still require dedicated optimized protection structures for RS485 interfaces in the corresponding industrial environments.

[0023] In this application, to address the mismatch between industrial environment-specific interference and general protection structures, the interference spectrum, common-mode / differential-mode component ratio, and coupling path in the industrial environment are quantified to achieve a precise match between protection structure parameters and interference characteristics. Protection modules are divided based on the interference conduction coupling order, and module parameters are dynamically adjusted through a test-feedback-iteration mechanism to achieve coordinated optimization of interference type, protection measures, and signal transmission. Furthermore, surge / EFT electrical fast transient burst testing in industrial environments is combined with anomaly tracing to form a closed loop from problem localization to structural optimization, avoiding blind debugging.

[0024] In response to the complex and unique industrial environment, this application provides the following specific solutions: Example 1: See Figure 1 and Figure 3 This application proposes a design optimization method for surge protection and EFT (Electrical Fast Transient / Bulk) protection of RS485 interfaces, including: Step 1: Determine the industrial environment in which the RS485 interface to be designed will be used, and the corresponding interference characteristics of the industrial environment; Step 2: Determine the initial protection characteristics and the corresponding initial protection structure based on the industrial environment; Step 3: Based on the interference characteristics, determine the protection zone reference and optimize the initial protection structure into a target protection structure that conforms to the protection zone reference; Step 4: Pass the RS485 interface conforming to the target protection structure through surge testing and EFT (Electronic Fast Transient / Burst) testing under the aforementioned industrial environment to determine whether the RS485 interface has any output abnormalities; wherein, Step 5: When an output anomaly exists, identify the anomaly item and the corresponding protection characteristic, optimize the target protection structure, and repeat step 4. Step 6: When there is no output anomaly, use the target protection structure as the final structure of the RS485 interface to be designed.

[0025] In one embodiment of this application, step 1 involves electromagnetic environment testing using a spectrum analyzer and coupling path simulation to identify interference sources in the industrial environment. These sources include, but are not limited to, motor sparks and inverter radiation. The interference characteristics are determined through interference spectrum distribution, common-mode / differential-mode interference ratio, and main coupling paths to construct an interference characteristic database. The interference spectrum distribution includes low-frequency surges and high-frequency EFTs. ​​Through the industrial environment, interference characteristics are determined, along with the specific interference characteristics of the interference sources corresponding to these characteristics. The interference characteristics are determined by the spectral characteristics of the interference spectrum distribution. Based on the interference conditions in the industrial environment, the required protection structure for the designed RS485 interface is determined. In this application, the interference characteristic database is an industry-level interference knowledge base containing various types of interference such as EFT bursts, surges, and electromagnetic radiation. It can also be networked for real-time updates.

[0026] In one embodiment of this application, step 2 classifies anomaly types based on typical abnormal data from the industrial environment and matches corresponding initial protection characteristics. Then, according to the interference conduction coupling sequence, the modular order of the protection structure is determined so that the performance of protection components is not canceled out due to random stacking. The initial protection characteristics are designed for the industrial environment, specifically for interference from different industrial equipment, temperature interference, gas humidity, and other environmental data. For example, ferrite bead filtering: L=100μH (based on interference frequency 1-100MHz); capacitor decoupling: C=100nF (based on differential mode interference amplitude 1-5V); common mode choke: N=20 turns (initial number of turns). These initial protection characteristics can be automatically matched according to the interference characteristic database. Then, according to the interference conduction coupling sequence, i.e., interference generated during the generation process due to state coupling between different devices or between devices and the environment, or superimposed interference, phenomena such as interference source superposition and system dynamic coupling occur. For example, when motors, frequency converters, switching power supplies, PLCs, etc., are running, they will generate electromagnetic interference through spatial electromagnetic field or power line / signal line coupling. When operating independently, the interference intensity of a single device is usually within the system's anti-interference margin. However, when started simultaneously or sequentially, the interference sources superimpose in time or space, causing the intensity to exceed the threshold and triggering communication structure interference. Consequently, when setting up the protection structure based on the order of interference conduction coupling, there is a modular sequence, which results in a cumulative effect on protection performance, meaning it is not designed specifically for a single type of interference.

[0027] In one possible implementation of this application, typical anomaly data classification includes dividing common-mode interference, differential-mode interference, and harmonic interference based on four dimensions: interference frequency, amplitude, duration, and coupling mode. In this process, the K-means clustering algorithm can be combined with a weighting factor based on the type of interference source to automatically classify the collected anomaly data.

[0028] In one embodiment of this application, step 3 divides the protection interval reference based on the spectral distribution in the interference characteristics; the protection interval reference includes a surge protection interval and an EFT protection interval, the surge protection interval corresponds to slow rise time interference, and the EFT protection interval corresponds to fast rise time interference; the RS485 interface adjusts the component parameters in the initial protection structure; for example, the component parameters include: TVS diode response time and ferrite bead impedance frequency characteristics, so that the protection capability of the target protection structure in each interval matches the interference intensity; for example, the ferrite bead impedance is increased in the high-frequency band to suppress EFT, and the clamping voltage is reduced in the low-frequency band to absorb surge energy.

[0029] In one embodiment of this application, step 4 simulates interference generation methods in an industrial environment to perform surge testing and EFT (Electronic Fast Transient / Burst) testing. The purpose of the tests is to identify deficiencies in the target protection structure. Exemplary interference generation methods include: contact / air discharge, line-to-ground / line-to-line coupling, followed by surge testing; exemplary methods include simulating lightning-induced overvoltage and performing EFT testing; and exemplary methods include simulating fast transient / burst testing. Finally, the output signal of the RS485 interface is monitored in real time. The output signal includes data frame integrity, level fluctuation range, and chip status; exemplary chip status includes whether a reset is triggered and whether the I / O port is damaged. This is used to determine whether the protection structure exhibits abnormal phenomena such as signal distortion or equipment failure.

[0030] In one embodiment of this application, step 5 involves locating the anomaly using the interference spectrum reverse deduction method when an anomaly occurs during testing, and associating it with the corresponding protection characteristics. This is achieved by increasing the number of common-mode inductor turns or optimizing the topology, and by connecting a π-type filter in series in the differential-mode path to specifically enhance the protection capability corresponding to the anomaly. For example, interference spectrum reverse deduction includes deducing the protection interval corresponding to the frequency components of the abnormal signal; anomalies include signal jitter caused by insufficient common-mode interference suppression. Protection characteristics include factors such as insufficient common-mode inductor impedance. Interference spectrum reverse deduction deduces the spectral characteristics of the interference source from the interface anomaly phenomenon. For example, based on the interface anomaly waveform, it is determined whether the signal is distorted. The frequency of the distorted signal is analyzed using FFT. The spectrum of the interference source is deduced using inverse filtering technology.

[0031] In one embodiment of this application, after multiple rounds of testing and optimization in step 6, when the RS485 interface shows no abnormalities during industrial environment simulation testing, the target protection structure at this point is solidified as the final design, including component parameters, module topology, and installation process. Component parameters include: TVS diode model and resistor value; module topology includes component arrangement order and grounding method; installation process includes distance control between the protection circuit and the interface chip.

[0032] In one specific embodiment, based on the characteristics of surge interference and EFT (Electronic Fast Transient) bursts—transient pulse-type interference signals—interference testing is performed by directly injecting the signal into the RS485 port via CDN; such as... Figure 2At the port, both the AB signal traces have transient suppression diodes D1-D3 connected to ground. These devices can be used to bypass transient interference and clamp the voltage on the signal lines to a lower level. Ferrite beads FB1 and FB2, together with capacitors C1-C4, form a π-type filter to suppress EFT (Electronic Fast Transient) interference. At the same time, the common-mode inductor filter L1 can further suppress residual common-mode interference. Through the above scheme, the surge protection capability of the RS485 port is improved to 60V, i.e., low-voltage surge direct injection is adopted. The surge test withstand voltage level of the corresponding power supply port can also reach 2kV, and the EFT interference can reach 3kV.

[0033] The beneficial effects of the above technical solution are as follows: In practical implementation, this application allows for dedicated optimization of the RS485 interface for specific industrial environments. During the design optimization process, the interference characteristics of the industrial environment are used to determine the coupled and superimposed interference conditions, thus constructing a protective structure with superimposed protective performance rather than a single interference source. Furthermore, it can continuously optimize the design even when defects exist in the protective structure, thereby improving the overall product design. In terms of optimization sequence, it integrates dynamic analysis of interference characteristics, baseline division of protection zones, and multi-round test optimization, enabling automatic adjustment of the optimization scheme based on the perception of the industrial environment.

[0034] Example 2: Step 1 includes: Identify the high electromagnetic interference and conventional electromagnetic interference in the industrial environment, as well as the interference spectrum data of the industrial environment; Based on the interference spectrum data, determine the interference injection path, the common-mode conducted coupling path between the RS485 interface and the protective ground, and the differential-mode conducted coupling path between the signal lines, and distinguish the interference ratio of common-mode interference components and differential-mode interference components. Based on high electromagnetic interference and conventional electromagnetic interference, an association model based on differential-mode conducted coupling path is constructed; The interference ratio is introduced into the correlation model to determine the interference characteristics corresponding to the industrial environment.

[0035] In one embodiment of this application, interference spectrum data acquisition is achieved by deploying a spectrum analyzer and interference source location equipment on-site to monitor the electromagnetic environment, identify typical interference sources in the industrial environment such as high-power motors, frequency converters, and electrostatic discharge, distinguish between high electromagnetic interference such as instantaneous strong pulses and conventional electromagnetic interference such as continuous electromagnetic noise, and collect the spectrum distribution of interference signals to form an interference spectrum database, thereby enabling the division of interference spectrum data in the industrial environment.

[0036] In one embodiment of this application, based on interference spectrum data, conducted path simulation is achieved through cable coupling testing and grounding impedance analysis to locate the main paths of interference injection into the interface. These main paths include conducted coupling through the RS485 signal line and common-mode coupling through the shielding layer. The interference proportions of these two paths are quantified using a common-mode / differential-mode separation network. The common-mode / differential-mode separation network includes transformer coupling and balanced-to-unbalanced switching to determine the interference proportions between different devices in the interference superposition effect. A common-mode conducted coupling path indicates that the RS485 interface and protective ground share noise, and their potentials rise or fall simultaneously relative to the reference ground. A differential-mode conducted coupling path indicates that the noise voltage is differential, generated by the potential difference between the two devices.

[0037] In one embodiment of this application, by analyzing the coupling relationship between high electromagnetic interference and conventional electromagnetic interference in the differential mode conduction path, a correlation model between interference type and differential mode path response is constructed through time-series coupling simulation. This model characterizes the differential mode resonance that different interference surge pulses may induce in cables, thereby amplifying the synergistic effect of high-frequency EFT interference in the differential mode path and enabling the prediction of multi-source coupling effects. For example, the coupling relationship includes time-series coupling.

[0038] In one embodiment of this application, the proportion of common-mode / differential-mode interference is introduced as a weighting factor into the correlation model to correct the contribution of different interference types in the coupling process. The final output includes comprehensive interference characteristics that include interference type, propagation path, component proportion, and coupling law. For example, when the common-mode proportion is high, the model focuses on the common-mode to differential-mode conversion effect; when the differential-mode proportion is high, the model focuses on the differential-mode signal distortion law.

[0039] The beneficial effects of the above technical solution are as follows: This application constructs a dynamic correction mechanism by using a path model and the proportion of interference components, thereby improving the accuracy of interference characteristic identification when determining interference characteristics.

[0040] Example 3: The initial protection structure includes: TVS clamping structure, resistor current limiting structure, ferrite bead filtering structure and capacitor decoupling structure; wherein, the initial protection structure is based on the initial protection characteristics, and the protection sequence of the protection structure is determined by the interference sequence of the RS485 interface in the industrial environment.

[0041] In one embodiment of this application, the TVS clamping structure is composed of a transient voltage suppressor diode (TVS diode) connected in parallel between the RS485 signal line and ground. When transient high-voltage interference such as surges or static electricity occurs, the TVS diode changes from a high-resistance state to a low-resistance state within nanoseconds, clamping the signal line voltage below the chip's safe withstand voltage. After absorbing the interference energy, it returns to the high-resistance state without affecting normal signal transmission. As the first line of defense, it preferentially suppresses high-voltage transient interference such as surges and static electricity, preventing them from damaging subsequent circuit components. In one embodiment of this application, the resistor current-limiting structure consists of a current-limiting resistor connected in series in the RS485 signal line, which limits the current flowing through the circuit based on Ohm's law. When a large current still exists after TVS clamping (surge energy not fully absorbed) or continuous overcurrent interference (line short circuit), the current-limiting resistor reduces the loop current through voltage division, preventing excessive current from burning out the chip I / O ports.

[0042] In one embodiment of this application, the ferrite bead filter structure consists of ferrite beads connected in series in the signal line. Utilizing the high-frequency impedance characteristics of the ferrite beads, the impedance increases significantly with increasing frequency, resulting in significant attenuation of high-frequency EFT pulse groups, while the impedance for low-frequency normal communication signals is extremely low, with almost no attenuation. The capacitor decoupling structure consists of a decoupling capacitor (typically a ceramic capacitor) connected in parallel between the RS485 chip's power supply pin and ground. Utilizing the charging and discharging characteristics of the capacitor, it provides a locally stable power supply voltage to the chip. When noise (high-frequency ripple, voltage fluctuations) exists on the power line, the decoupling capacitor absorbs noise energy or releases stored charge, suppressing power supply voltage fluctuations and preventing noise from coupling to the signal link through the power supply.

[0043] In one embodiment of this application, based on the order of interference conduction coupling determined in step 2, such as surge-static discharge-high-frequency EFT-power supply noise, the four protection modules are arranged in the order of TVS clamping-resistor current limiting-ferrite bead filtering-capacitor decoupling. Specifically, TVS clamping prioritizes handling the earliest occurring surge / static discharge interference, resistor current limiting follows to limit current, ferrite bead filtering targets subsequent high-frequency EFT, and capacitor decoupling ultimately stabilizes the power supply, forming a one-to-one correspondence between interference timing and protection functions.

[0044] The beneficial effects of the above technical solution are as follows: The initial protection structure of this application determines the protection sequence through the interference sequence, thereby improving the protection efficiency against dynamic interference.

[0045] Example 4: Step 2 includes: Based on the industrial environment, identify typical abnormal data of the RS485 interface to be designed in the industrial field; Based on typical anomaly data, determine the types of anomalies faced by the RS485 interface to be designed, as well as the initial protection characteristics of different anomalies; Based on the initial protection characteristics, the conduction coupling order of different anomalies is determined; whereby the conduction coupling order characterizes the order in which different anomalies appear in association. The initial protection structure is determined based on the anomaly type and the order of conductive coupling; wherein, the order of conductive coupling is used to characterize the modular structural sequence of the target protection structure.

[0046] In one embodiment of this application, by collecting historical fault records and real-time monitoring data of the RS485 interface in the industrial field, recurring typical anomalies are filtered out to form a structured typical anomaly dataset. For example, historical fault records include equipment maintenance logs and communication error reports; real-time monitoring data includes waveform distortion and bit error rate statistics recorded by a signal analyzer; typical anomalies include frequent communication interruptions, data frame loss, chip resets, etc.

[0047] In one embodiment of this application, typical abnormal data is classified, and corresponding initial protection characteristics are matched by determining the key parameters for each type of abnormality. For example, typical abnormal data can be classified by interference source into surge, EFT, and electrostatic discharge, and by manifestation into overvoltage, overcurrent, and signal distortion. Key parameters include the voltage amplitude of the surge and the pulse frequency of the EFT.

[0048] In one embodiment of this application, the correlation patterns of anomaly types in an industrial environment are analyzed, and the conduction coupling order of anomalies is determined based on electromagnetic conduction theory, i.e., the timing relationship of which occurs first and which is triggered later. For example, the correlation patterns include surges usually arriving at the interface before EFT pulses, and electrostatic discharge may trigger subsequent common-mode interference; electromagnetic conduction theory includes common-mode to differential-mode conversion in cables and the superposition effect of time-domain pulses.

[0049] In one embodiment of this application, the protection characteristics corresponding to the anomaly type are mapped to specific protection modules, and the modules are arranged in order of conduction coupling to form a modular initial protection structure that is functionally independent and time-coordinated, ensuring that each module corresponds to a specific anomaly type and takes effect in the order in which the interference occurs.

[0050] In one possible implementation, the conducted coupling sequence is used to analyze the conduction paths and priorities of interference in the interface system, preventing ineffective protection in the design. During the conducted path analysis, the main paths of interference conduction are determined by TDR measurements using a time domain reflectometer. For example, after the interference source is identified, the first path can be determined: power line conduction combined with the interface power terminal; the second path can be determined: signal line coupling combined with the interface signal terminal; and the third path can be determined: ground loop combined with common-mode interference. Priority is calculated by multiplying the conducted path length by the ratio of the interference amplitude to the path impedance multiplied by the frequency.

[0051] The beneficial effects of the above technical solution are as follows: This application combines conductive coupling sequence with dynamic protection structure design to enable the abnormal correlation to dynamically match the protection topology in sequence, thereby achieving the effect of time-series adaptation and improving protection efficiency.

[0052] Example 5: Determining the protection zone benchmark in step 3 includes: Based on the interference ratio of common-mode interference components and differential-mode interference components in the interference characteristics, the common-mode protection zone and the differential-mode protection zone are dynamically divided. Determine the coupling coefficient between the common-mode protection zone and the differential-mode protection zone, and set a zone overlap threshold so that the target protection structure gradually transitions between the common-mode protection and differential-mode protection frequency bands.

[0053] In one embodiment of this application, the real-time proportion of common-mode and differential-mode interference is obtained through interference characteristic analysis. The frequency boundary of the protection zone is dynamically adjusted based on the proportion weight to match the zone division with the actual interference energy distribution. For example, when the common-mode proportion is high, the common-mode zone is expanded to a higher frequency band, and when the differential-mode proportion is high, the common-mode zone is compressed.

[0054] In one embodiment of this application, the coupling coefficient between the common-mode and differential-mode regions in the switching frequency band is calculated using electromagnetic coupling theory. An overlap threshold is set based on the magnitude of the coupling coefficient, causing the common-mode protection characteristic to linearly decrease with increasing frequency within the overlap region, while the differential-mode protection characteristic synchronously and linearly increases, forming a common-mode to differential-mode gradual transition band. For example, the coupling coefficient characterizes the energy conversion efficiency of both; setting an overlap threshold indicates that a higher coupling coefficient increases the overlap bandwidth.

[0055] The beneficial effects of the above scheme are as follows: This application combines interval overlap with parameter gradient control to ensure that the efficiency of the switching frequency band does not change abruptly during fixed interval protection.

[0056] Example 6: The optimization of the initial protective structure into the target protective structure in step 3 includes: A multi-objective genetic algorithm is employed to optimize the parameters of the TVS clamping voltage, resistor current limit, ferrite bead impedance characteristics, and capacitor value. With protection response time and signal transmission loss as dual objective functions, a Pareto optimal solution set is generated, and the optimal parameter combination is dynamically selected based on real-time interference spectrum data from the industrial environment. In this application, the multi-objective genetic algorithm simultaneously optimizes multiple protection parameters, balancing interference suppression effect, cost, and size. The optimized parameters include the ferrite bead inductance L, capacitance C, and the number of turns N of the common-mode choke, etc.

[0057] In one embodiment of this application, parameters such as TVS clamping voltage and resistor current limiting value are encoded using a simulated selection-crossover-mutation mechanism. With protection response time (the smaller the better) and signal transmission loss (the smaller the better) as dual objective functions, multiple iterations are used to select parameter combinations that simultaneously optimize both objectives, forming a Pareto optimal solution set containing multiple non-dominated solutions. For example, the Pareto optimal solution set represents the set of solutions for which improving one protection structure cannot worsen the effect of another.

[0058] In one embodiment of this application, the protection response time characterizes the startup speed of the protection structure after interference occurs, and the signal transmission loss characterizes the attenuation degree of normal communication signals passing through the protection structure. These two are used as mutually constraining objective functions, and a genetic algorithm is used to find a balance point in the parameter space to avoid performance imbalance caused by optimizing a single objective. For example, startup speed represents the TVS diode clamping delay time; attenuation degree characterizes the amplitude reduction caused by resistor voltage division; and performance imbalance characterizes sacrificing signal integrity in pursuit of the ultimate response time.

[0059] In one embodiment of this application, the Pareto optimal solution set includes multiple parameter combinations with balanced performance. By real-time acquisition of interference spectrum data from the industrial environment, the parameter combination that best matches the current spectrum characteristics is matched from the solution set, achieving dynamic parameter switching. For example, the interference spectrum data indicates that the currently dominant interference is either high-frequency EFT or low-frequency surge; the parameter combination indicates that for high-frequency interference, high-impedance ferrite bead parameters are preferentially selected, while for low-frequency interference, TVS parameters with low clamping voltage are selected.

[0060] The beneficial effects of the above technical solution are as follows: This application achieves dynamic parameter matching through real-time feedback of the interference spectrum, enabling automatic switching of high-impedance ferrite bead parameters when high-frequency interference intensifies, thereby improving dynamic protection effectiveness.

[0061] Example 7: The surge test and EFT electrical fast transient / burst test in step 4 are performed as follows: Segmented EFT electrical fast transient burst testing based on interference spectrum data, gradually increasing the pulse intensity to the interface critical failure threshold in each frequency band; When the failure threshold is reached, a surge test is performed, and the injection polarity and waveform parameters of the surge test are dynamically adjusted according to the abnormal frequency band characteristics that appear in the segmented EFT electrical fast transient burst test.

[0062] In one embodiment of this application, based on industrial environmental interference spectrum data, the EFT (Electronic Fast Transient) burst test frequency band is divided into multiple sub-bands. Within each sub-band, the pulse intensity is gradually increased from a low level, and the interface output signal is monitored in real time until a critical failure occurs. The failure threshold of that frequency band is then recorded. For example, the interference spectrum data represents the frequency band distribution data where interference energy is concentrated; the sub-bands include low-frequency, mid-frequency, and high-frequency bands; the interface output signal represents the bit error rate and chip reset; and the critical failure phenomenon represents communication interruption.

[0063] In one embodiment of this application, after a certain frequency band reaches the failure threshold during segmented EFT (Electrical Fast Transient) burst testing, the characteristics of the abnormal frequency band are analyzed, and surge test parameters are adjusted accordingly: the type of interference component is injected to match the polarity, and the waveform parameters are matched to the frequency band characteristics. Then, a surge test is performed to verify the surge protection capability after EFT pre-damage. For example, the failure threshold is such as 1500V failure in the high-frequency band; the characteristics of the abnormal frequency band include, but are not limited to, high-frequency EFT typically accompanied by common-mode interference components. Interference component types include, for example, common-mode interference corresponding to line-to-ground polarity, and differential-mode interference corresponding to line-to-line polarity; waveform parameters are matched to the frequency band characteristics, such as high-frequency anomalies corresponding to short-width waveforms, and low-frequency anomalies corresponding to long-width waveforms.

[0064] The beneficial effects of the above scheme are as follows: This application optimizes surge test parameters by reverse-engineering the characteristics of abnormal frequency bands in the EFT, such as high-frequency sensitivity, to achieve fast rise-edge surges, thereby improving test efficiency and accuracy.

[0065] Example 8: The abnormal items identified in step 5 include: Based on the anomalies, an anomaly tracing model based on Bayesian networks is constructed, and the output anomalies are used as observation nodes. Based on the observation nodes, the parameter drift range of each component in the target protection structure is used as a latent variable. The failure probability ranking of each component is calculated by Markov chain Monte Carlo sampling, and the protection characteristic parameters with the highest failure probability are optimized first.

[0066] In one embodiment of this application, a Bayesian network is a model that uses a directed acyclic graph to represent the probabilistic relationships between variables.

[0067] In one embodiment of this application, the output anomaly of the RS485 interface is defined as an observable observation node, and the parameter states of each component in the target protection structure are defined as latent variable nodes. Conditional probabilities between nodes are set using historical fault data or expert experience to construct a causal relationship model between the anomaly and component parameter drift. For example, the output anomaly may represent communication interruption, signal jitter, or increased bit error rate. The components in the target protection structure include TVS diodes, current-limiting resistors, and ferrite beads. Parameter states represent phenomena such as normal operation and drift; conditional probabilities represent the probability that an increase in TVS leakage current leads to signal jitter.

[0068] In one embodiment of this application, the component parameter drift range is treated as a latent variable that cannot be directly observed. The probability distribution of parameter drift is simulated using Markov chain Monte Carlo sampling: starting from the prior probability, the possible values ​​of the latent variable are iteratively sampled, and combined with the actual abnormal data of the observed nodes, the posterior probability of each latent variable is corrected, ultimately outputting a ranking of the failure probabilities of each component. For example, the prior probability represents the probability of the component operating normally; the actual abnormal data represents the signal waveform during communication interruption.

[0069] In one embodiment of this application, the failure probability ranking of each component is calculated using Markov chain Monte Carlo sampling, which can accurately predict the component failure probability and guide the design and replacement cycle of the modular protection unit. The failure probability model is as follows: ; In the specific process of substituting components and performing calculations... ; The beneficial effects of the above scheme are as follows: This application uses the component parameter drift range as a hidden variable of a Bayesian network and combines it with priority optimization after fault probability ranking to achieve accurate localization of gradual faults.

[0070] Example 9: The optimization of the target protection structure in step 5 includes: When the proportion of common-mode interference corresponding to the abnormal item exceeds the target preset value, a common-mode choke is inserted between the ferrite bead filter structure and the capacitor decoupling structure. The number of turns of the choke and the permeability of the core material are dynamically adjusted according to the center frequency of the abnormal frequency band, so that the common-mode impedance is increased in the abnormal frequency band until the abnormal frequency band disappears.

[0071] In one embodiment of this application, a target preset value for the common-mode interference ratio is determined through interference characteristic analysis. When anomaly detection shows that the common-mode ratio exceeds this value, it is determined that the existing ferrite bead filter cannot meet the common-mode protection requirements. A common-mode choke is then inserted between the ferrite bead filter structure and the capacitor decoupling structure—utilizing its high common-mode impedance and low differential-mode impedance characteristics to specifically block the conduction of common-mode interference to subsequent circuits, while simultaneously avoiding attenuation of the differential-mode signal. For example, the target preset value represents a typical interference threshold based on an industrial environment; the existing ferrite bead filter represents a filtering method focusing on high-frequency differential-mode / common-mode suppression; the ferrite bead filter structure represents the initial suppression of some high-frequency interference; and the capacitor decoupling structure represents the final stable power supply structure.

[0072] In one embodiment of this application, the impedance characteristics of the common-mode choke are jointly determined by the inductance and the core permeability: high inductance is required to increase impedance in the low-frequency range, while a high-permeability core is required in the high-frequency range to reduce high-frequency losses. The inductance is proportional to the square of the number of turns. The core permeability is frequency-dependent. High inductance is found in structures with many turns. High-permeability cores are found in cores made of nanocrystalline materials.

[0073] In one embodiment of this application, the center frequency of the abnormal frequency band is determined by spectrum analysis, and the number of turns and the core material are adjusted accordingly (ferrite cores are selected for low frequencies, and nanocrystalline cores are selected for high frequencies) so that the choke exhibits high impedance characteristics in the target frequency band. For example, adjusting the number of turns can increase the inductance; the core material is preferably selected as ferrite cores for low frequencies and nanocrystalline cores for high frequencies.

[0074] In one embodiment of this application, the high impedance of the common-mode choke in the abnormal frequency band will impede the passage of common-mode interference current. With the dynamic adjustment of the number of turns and core parameters, the common-mode impedance gradually increases, and the amplitude of the common-mode interference is continuously attenuated until the interference energy in the abnormal frequency band is found to have dropped below the threshold for normal interface operation through spectrum monitoring, such as the disappearance of the abnormal frequency band. Impeding the passage of common-mode interference current is based on Lenz's law, and the high-frequency common-mode current will generate a back electromotive force to cancel the interference. The beneficial effects of the above scheme are as follows: This application eliminates interference by dynamically matching the center frequency of the abnormal frequency band with the number of turns / permeability.

[0075] Example 10: After determining the final protective structure in step 6, the following steps are also included: A virtual model of the RS485 interface is constructed based on digital twin technology. The long-term electromagnetic aging effect in the industrial environment is simulated in the virtual environment to predict the life decay curve of the protective components. Based on the life decay curve, replaceable modular protection units are added to the final protection structure; wherein the replacement cycle of the modular protection units is set based on the life prediction results.

[0076] In one embodiment of this application, digital twin technology constructs a high-precision virtual model using material parameters, structural parameters, and industrial environment parameters from a physical interface. This virtual model recreates long-term electromagnetic aging scenarios, such as simulating temperature and humidity cycles and high-frequency electromagnetic radiation accumulation over a decade. Multiphysics simulation is used to calculate the decay patterns of key performance parameters of protective components over time, generating a lifetime decay curve. For example, material parameters include TVS diode semiconductor materials and ferrite bead materials; structural parameters include component size and layout; and industrial environment parameters include temperature fluctuation range and electromagnetic radiation intensity. Key performance parameters of the protective components include TVS clamping voltage, ferrite bead impedance, and capacitance value. The lifetime decay curve represents the time history from the initial performance value to the failure threshold. The construction of the virtual model includes the hardware layer (ANSYS), electromagnetic field simulation (MATLAB) for real-time data acquisition, and the data layer (Unity 3D visualization). It also incorporates industrial environment simulation of temperature, electromagnetic stress, and mechanical stress to achieve lifetime prediction and output the lifetime decay curve.

[0077] In one embodiment of this application, the remaining lifespan of each protective component is determined based on its lifespan decay curve. Easily aging components are integrated into independent modular protective units, such as pluggable modules. The module replacement cycle is set according to the principle of prioritizing components with the shortest lifespan, ensuring that only the corresponding module needs to be replaced during replacement, without requiring reconstruction of the entire protective structure. For example, the remaining lifespan is five years for TVS diodes, eight years for current-limiting resistors, and six years for ferrite beads. Easily aging components include TVS diodes and ferrite beads, etc.

[0078] The beneficial effects of the above scheme are as follows: This application combines virtual aging prediction using digital twins with the dynamic replacement cycle of modular units, ensuring that the protection design avoids excessive maintenance and prevents sudden failures.

[0079] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A design optimization method for surge protection and EFT (Electronic Fast Transient / Bulk Transmission) of an RS485 interface, characterized in that, include: Step 1: Determine the industrial environment in which the RS485 interface to be designed will be used, and the corresponding interference characteristics of the industrial environment; Step 2: Determine the initial protection characteristics and the corresponding initial protection structure based on the industrial environment; Step 3: Based on the interference characteristics, determine the protection zone benchmark and optimize the initial protection structure into a target protection structure that conforms to the protection zone benchmark; Step 4: Test the RS485 interface that conforms to the target protection structure under surge test and EFT electrical fast transient / burst test in an industrial environment to determine whether there is any output abnormality in the RS485 interface; Step 5: When an output anomaly exists, identify the anomaly item and the corresponding protection characteristics, optimize the target protection structure, and repeat step 4. Step 6: When there is no output anomaly, use the target protection structure as the final structure of the RS485 interface to be designed.

2. The design optimization method for surge protection and EFT (Electronic Fast Transient / Bulk Transient) of an RS485 interface as described in claim 1, characterized in that, Step 1 includes: Identify high electromagnetic interference and conventional electromagnetic interference in industrial environments, as well as interference spectrum data for industrial environments; Based on the interference spectrum data, determine the interference injection path, the common-mode conducted coupling path between the RS485 interface and the protective ground, and the differential-mode conducted coupling path between the signal lines, and distinguish the interference ratio of common-mode interference components and differential-mode interference components. Based on high electromagnetic interference and conventional electromagnetic interference, an association model based on differential-mode conducted coupling path is constructed; The interference percentage is introduced into the correlation model to determine the interference characteristics corresponding to the industrial environment.

3. The design optimization method for surge protection and EFT (Electronic Fast Transient / Bulk Transient) of an RS485 interface as described in claim 1, characterized in that, The initial protection structure includes: a TVS clamping structure, a resistor current limiting structure, a ferrite bead filtering structure, and a capacitor decoupling structure; wherein, based on the initial protection characteristics, the protection sequence of the protection structure is determined by the order of interference received by the RS485 interface in the industrial environment.

4. The design optimization method for surge protection and EFT (Electronic Fast Transient / Bulk Transient) of an RS485 interface as described in claim 1, characterized in that, Step 2 includes: Based on the industrial environment, identify typical abnormal data of the RS485 interface to be designed in the industrial field; Based on typical anomaly data, determine the types of anomalies faced by the RS485 interface to be designed, as well as the initial protection characteristics of different anomalies; Based on the initial protection characteristics, the conduction coupling order of different anomalies is determined; whereby the conduction coupling order characterizes the order in which different anomalies appear in association. The initial protection structure is determined based on the anomaly type and the order of conduction coupling; among which, the order of conduction coupling is used to characterize the modular structural sequence of the target protection structure.

5. The design optimization method for surge protection and EFT (Electronic Fast Transient / Bulk Transmission) of an RS485 interface as described in claim 1, characterized in that, Determining the protection zone benchmark in step 3 includes: Based on the interference ratio of common-mode interference components and differential-mode interference components in the interference characteristics, the common-mode protection zone and the differential-mode protection zone are dynamically divided. Determine the coupling coefficient between the common-mode protection zone and the differential-mode protection zone, and set the zone overlap threshold so that the target protection structure gradually transitions between the common-mode protection and differential-mode protection frequency bands.

6. The design optimization method for surge protection and EFT (Electronic Fast Transient / Bulk Transient) of an RS485 interface as described in claim 1, characterized in that, The optimization of the initial protective structure into the target protective structure in step 3 includes: A multi-objective genetic algorithm is used to optimize the parameters of TVS clamping voltage, resistor current limit value, ferrite bead impedance characteristics and capacitor value. With protection response time and signal transmission loss as dual objective functions, a Pareto optimal solution set is generated and the optimal parameter combination is dynamically selected based on real-time interference spectrum data of the industrial environment.

7. The design optimization method for surge protection and EFT (Electronic Fast Transient / Bulk Transient) of an RS485 interface as described in claim 1, characterized in that, The surge test and EFT electrical fast transient / burst test in step 4 are performed as follows: Segmented EFT electrical fast transient burst testing based on interference spectrum data, gradually increasing the pulse intensity to the interface critical failure threshold in each frequency band; When the failure threshold is reached, a surge test is performed, and the injection polarity and waveform parameters of the surge test are dynamically adjusted according to the abnormal frequency band characteristics that appear in the segmented EFT electrical fast transient burst test.

8. The design optimization method for surge protection and EFT (Electronic Fast Transient / Bulk Transient) of an RS485 interface as described in claim 1, characterized in that, The abnormal items identified in step 5 include: Based on the anomalies, an anomaly tracing model based on Bayesian networks is constructed, and the output anomalies are used as observation nodes. Based on the observation nodes, the parameter drift range of each component in the target protection structure is used as a latent variable. The failure probability ranking of each component is calculated by Markov chain Monte Carlo sampling, and the protection characteristic parameters with the highest failure probability are optimized first.

9. The design optimization method for surge protection and EFT (Electronic Fast Transient / Bulk Transient) of an RS485 interface as described in claim 1, characterized in that, Step 5, optimizing the target protection structure, includes: When the proportion of common-mode interference corresponding to the abnormal item exceeds the target preset value, a common-mode choke is inserted between the ferrite bead filter structure and the capacitor decoupling structure. The number of turns of the choke and the permeability of the core material are dynamically adjusted according to the center frequency of the abnormal frequency band, so that the common-mode impedance is increased in the abnormal frequency band until the abnormal frequency band disappears.

10. The design optimization method for surge protection and EFT (Electronic Fast Transient / Bulk Transient) of an RS485 interface as described in claim 1, characterized in that, After determining the final protective structure in step 6, the following steps are also included: A virtual model of the RS485 interface is constructed based on digital twin technology. The long-term electromagnetic aging effect in the industrial environment is simulated in the virtual environment to predict the life decay curve of the protective components. Based on the life decay curve, replaceable modular protection units are added to the final protection structure; the replacement cycle of the modular protection units is set based on the life prediction results.

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