A simulation calculation method and terminal for conducted noise

Abstract

This invention provides a simulation calculation method and terminal for conducted noise. The method establishes a power transmission principle diagram of the power system of the target device to be analyzed, identifying each interference source and coupling path. Within the frequency range to be analyzed, discretized amplitude expressions for each interference source are defined, and transfer functions for the coupling paths from each interference source to each electromagnetic compatibility conducted interference detection point are established. An equivalent model expression for conducted noise evaluation is constructed, and a simulation model is established. Based on the constructed simulation model, combined with the actual parameters of the target device and the conducted interference test spectra of each interference source operating independently under full load and no load, simulation calculations are performed. Evaluation results can be obtained based on the simulation calculation results and preset standard limits, enabling more effective electromagnetic compatibility conducted interference evaluation.

Description

[0001] This case is a divisional application based on the invention patent filed on September 6, 2024, with application number 202411246812.4 and titled "A Method and Terminal for Evaluating Electromagnetic Compatibility Conducted Interference in a Power Supply System". Technical Field

[0002] This invention relates to the field of conducted interference assessment technology, and in particular to a simulation calculation method and terminal for conducted noise. Background Technology

[0003] As a crucial component of the new energy industry, energy storage systems and distributed generation are widely used to regulate and supplement the power grid. Most energy storage systems require connection to either AC or DC power grids. Unlike traditional rotating generators, the electromagnetic interference generated by numerous high-frequency power converters after the integration of new energy sources is coupled to user equipment through transmission lines, affecting equipment safety and reliability and placing higher demands on the immunity of electrical appliances. Particularly for complete sets of equipment in industrial, commercial, or residential energy storage systems, which often consist of multiple power electronic converters located close to users, conducted interference on AC (DC) buses is increasingly severe, becoming a new bottleneck restricting the electrification of the power grid.

[0004] According to the product access requirements of the energy storage industry, complete equipment systems must pass electromagnetic compatibility (EMC) testing and meet corresponding indicators. For assessing the conducted interference level at the power ports of medium and large-sized complete equipment systems, the overall testing and rectification approach is limited in terms of testing cycle, cost, and site conditions. Although individual power conversion devices within the complete equipment system are also required to pass EMC testing, the EMC status of the assembled system may change, and it may not necessarily pass the test. Furthermore, the overall results during rectification cannot pinpoint the problematic unit within the complete equipment system, lacking guidance for rectification. Currently, there is a lack of effective interference modeling and analysis methods for the energy storage industry, increasing the cost and time required for overall EMC assessment. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a simulation calculation method and terminal for conducted noise, so as to achieve more effective electromagnetic compatibility conducted interference assessment.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A method for evaluating conducted electromagnetic compatibility interference in a power supply system, comprising the following steps:

[0008] S1. Establish the power transmission principle diagram of the power system of the target device to be analyzed, and identify the interference sources and coupling paths therein;

[0009] S2. Within the frequency range to be analyzed, define discretized amplitude expressions for each interference source and establish transfer functions for the coupling paths between each interference source and each electromagnetic compatibility conducted interference detection point.

[0010] S3. Construct an equivalent model expression for conducted noise assessment and establish a simulation model;

[0011] S4. Obtain the actual parameters of the target device and the conducted interference test spectrum of each interference source when working independently under full load and no load, and perform simulation calculations in conjunction with the simulation model.

[0012] S5. Based on the simulation results and the preset standard limits, the evaluation results are obtained.

[0013] A simulation calculation method for conducted noise includes the following steps:

[0014] S1. Establish the power transmission principle diagram of the power system of the target device to be analyzed, and identify the interference sources and coupling paths therein;

[0015] S2. Within the frequency range to be analyzed, define discretized amplitude expressions for each interference source and establish transfer functions for the coupling paths between each interference source and each electromagnetic compatibility conducted interference detection point.

[0016] In step S2, the discretized amplitude expression for each interference source is defined as follows:

[0017] The complete form of the expression for the amplitude of the nth interference source in the form of a current source is:

[0018]

[0019] This represents noise as a superposition of signals at x frequency points. When the frequency points are selected as multiples of the fundamental frequency ω0, the frequency of the i-th frequency point is denoted as iω0, and the peak value of the instantaneous noise amplitude at the i-th frequency point is A. i The frequency is iω0, and the initial phase angle is... a periodic function that varies with time t A0 represents the DC component of the signal;

[0020] Because the common-mode interference coupling path is AC, A0 cannot pass through and can be ignored. Furthermore, in electromagnetic compatibility testing, the signal phase does not affect the judgment of the interference amplitude; therefore, the phase is set to a fixed value, I. mn The expression (t) simplifies to:

[0021]

[0022] When x is not selected as a regular multiple of the fundamental frequency ω0, the test frequency range (fmin , ..., f max x frequency points (a1, ..., a) within ) x Then we have:

[0023]

[0024] Where (A1, ..., A x (f) represents the interference amplitude at each frequency point. min f max () indicates the test frequency range;

[0025] The transfer function for establishing the coupling path between each interference source and each electromagnetic compatibility conducted interference detection point in step S2 is as follows:

[0026] Based on the common-mode interference transmission characteristics analysis, the coupling path from the interference source n to the detection point k can be equivalent to the conductor impedance Z. n_wire and ground impedance Z n_GND Part of this interference, after passing through the equivalent network impedance, constitutes external interference, and the current value is expressed as:

[0027]

[0028] For the propagation of common-mode interference, the conductor impedance Z n_wire Much smaller than the ground impedance Z n_GND Therefore, we can ignore this and obtain the coupling path transfer function G of the path nk from any interference source to any detection point. nk (jω):

[0029]

[0030] Among them, Z LISN Z is the preset standard value. n_GND The series RCL circuit is equivalent to:

[0031] Z n_GND =R nk +jωL nk +1 / jωC nk ;

[0032] Rnk, Lnk, and Cnk represent the resistance, inductance, and capacitance values ​​of the ground impedance, respectively; j represents the imaginary unit; and ω represents the frequency.

[0033] S3. Construct an equivalent model expression for conducted noise assessment and establish a simulation model;

[0034] S4. Obtain the actual parameters of the target device and the conducted interference test spectrum of each interference source when working independently under full load and no load, and perform simulation calculations in conjunction with the simulation model.

[0035] To solve the above-mentioned technical problems, another technical solution adopted by the present invention is as follows:

[0036] A power system electromagnetic compatibility conducted interference assessment terminal includes a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps in the power system electromagnetic compatibility conducted interference assessment method described above.

[0037] A simulation computing terminal for conducted noise includes a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps in the simulation computing method for conducted noise described above.

[0038] The beneficial effects of this invention are as follows: The simulation calculation method and terminal for conducted noise of this invention identify interference sources and coupling paths based on the equipment schematic diagram, establish the amplitude expression of the interference source and the transfer function of the coupling path, and establish a simulation model. Combined with the actual equipment parameters, the simulation operation is carried out to evaluate the electromagnetic compatibility conducted interference of the power supply system. This can obtain a relatively accurate trend of system conducted interference superposition, identify frequency bands exceeding the specifications, locate problematic converter units, make rectification more targeted, accelerate the electromagnetic compatibility testing process, and reduce the testing workload of engineers. Attached Figure Description

[0039] Figure 1 This is an example diagram illustrating the power transmission principle of the power system of the target device in a power system electromagnetic compatibility conducted interference assessment method according to an embodiment of the present invention.

[0040] Figure 2 This is an example diagram showing the connection between the interference source and the monitoring point of the target device in a power system electromagnetic compatibility conducted interference assessment method according to an embodiment of the present invention;

[0041] Figure 3 This is a test result curve of a converter under full load conditions in a power system electromagnetic compatibility conducted interference evaluation method according to an embodiment of the present invention;

[0042] Figure 4 This is a simulation result of the interference spectrum of a target device at a certain detection point in a power system electromagnetic compatibility conducted interference evaluation method according to an embodiment of the present invention.

[0043] Figure 5 This is a flowchart of a method for evaluating electromagnetic compatibility conducted interference in a power supply system according to an embodiment of the present invention;

[0044] Figure 6 This is a structural diagram of a power system electromagnetic compatibility conducted interference assessment terminal according to an embodiment of the present invention;

[0045] Label Explanation:

[0046] 1. A power system electromagnetic compatibility conducted interference assessment terminal; 2. Processor; 3. Memory. Detailed Implementation

[0047] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0048] Please refer to Figure 5 A method for evaluating conducted electromagnetic compatibility interference in a power supply system, comprising the following steps:

[0049] S1. Establish the power transmission principle diagram of the power system of the target device to be analyzed, and identify the interference sources and coupling paths therein;

[0050] S2. Within the frequency range to be analyzed, define discretized amplitude expressions for each interference source and establish transfer functions for the coupling paths between each interference source and each electromagnetic compatibility conducted interference detection point.

[0051] S3. Construct an equivalent model expression for conducted noise assessment and establish a simulation model;

[0052] S4. Obtain the actual parameters of the target device and the conducted interference test spectrum of each interference source when working independently under full load and no load, and perform simulation calculations in conjunction with the simulation model.

[0053] S5. Based on the simulation results and the preset standard limits, the evaluation results are obtained.

[0054] As can be seen from the above description, the beneficial effects of the present invention are as follows: The present invention provides a method for evaluating electromagnetic compatibility conducted interference in a power supply system. It identifies interference sources and coupling paths based on the equipment schematic, establishes the amplitude expression of the interference source and the transfer function of the coupling path, and builds a simulation model. This model is then combined with actual equipment parameters for simulation operation to evaluate electromagnetic compatibility conducted interference in the power supply system. This method can obtain a relatively accurate trend of system conducted interference superposition, identify frequency bands exceeding the specified limits, locate problematic converter units, make rectification more targeted, accelerate the electromagnetic compatibility testing process, and reduce the workload of engineers.

[0055] Furthermore, in step S2, the discretized amplitude expression for each interference source is defined as follows:

[0056] The complete form of the expression for the amplitude of the nth interference source in the form of a current source is:

[0057]

[0058] This represents noise as a superposition of signals at x frequency points. When the frequency points are selected as multiples of the fundamental frequency ω0, the frequency of the i-th frequency point is denoted as iω0, and the peak value of the instantaneous noise amplitude at the i-th frequency point is A. i The frequency is iω0, and the initial phase angle is φ. i A periodic function A that varies with time t i sin(iω0t+φ i A0 is the DC component of the signal;

[0059] Because the common-mode interference coupling path is AC, A0 cannot pass through and can be ignored. Furthermore, in electromagnetic compatibility testing, the signal phase does not affect the judgment of the interference amplitude; therefore, the phase is set to a fixed value, I. mn The expression (t) simplifies to:

[0060]

[0061] When x is not selected as a regular multiple of the fundamental frequency ω0, in the test frequency range (f min ,f max (x frequency points a1..a) x ∈(f min ,f max Then we have:

[0062] I mn (t)=A1sin(2πa1t+φ)+A2sin(2πa2t+φ)......A x sin(2πa x t+φ);

[0063] Among them, A1...A x This represents the interference amplitude at each frequency point.

[0064] As described above, based on the above steps, the discretized amplitude expression of each interference source is defined.

[0065] Furthermore, the transfer function for establishing the coupling path between each interference source and each electromagnetic compatibility conducted interference detection point in step S2 is specifically as follows:

[0066] Based on the common-mode interference transmission characteristics analysis, the coupling path from the interference source n to the detection point k can be equivalent to the conductor impedance Z. n_wire and ground impedance Z n_GND Part of this interference, after passing through the equivalent network impedance, constitutes external interference, and the current value is expressed as:

[0067]

[0068] For the propagation of common-mode interference, the conductor impedance Z n_wireMuch smaller than the ground impedance Z n_GND Therefore, we can ignore this and obtain the transfer function G of the path nk from any interference source to any detection point. nk (jω):

[0069]

[0070] Among them, Z LISN Z is the preset standard value. n_GND The series RCL circuit is equivalent to:

[0071] Z n_GND =R nk +jωL nk +1 / jωC nk ;

[0072] R nk L nk C nk These represent the resistance, inductance, and capacitance values ​​of the ground impedance, respectively, where j represents the imaginary unit and ω represents the frequency.

[0073] As described above, based on the above steps, the transfer function of the coupling path between each interference source and each electromagnetic compatibility conducted interference detection point is defined.

[0074] Furthermore, the construction of the equivalent model expression for conducted noise evaluation in step S3 is specifically as follows:

[0075] For n interference sources, after flowing through n coupling paths, the conducted interference voltage noise V generated at detection point k is... noise_k (jω) is:

[0076]

[0077] Among them, R LISN For Z LISN The sampling resistor part in the diagram.

[0078] As described above, the equivalent model expression for conducted noise assessment is constructed as shown above.

[0079] Furthermore, step S3, establishing the simulation model, includes the following steps:

[0080] In circuit simulation software, create a simulation model that includes all interference sources, coupling paths, and detection points of the target device:

[0081] Based on the definition of the discretized interference source amplitude expression in step S2, in the test frequency range (f min ,f max Take x frequency points (a1, ..., a) within the range x In the simulation model, all interference current sources are established.

[0082] Based on the definition of the transfer function of the coupling path between each interference source and each electromagnetic compatibility conducted interference detection point in step S2, an impedance model of all coupling paths is established in the simulation model.

[0083] Based on the equivalent model expression for conducted noise evaluation in step S3, an evaluation of noise V is added at each detection point of the simulation model. noise_k Spectral analysis of (jω).

[0084] As described above, a circuit simulation model of the target device is constructed based on the above steps.

[0085] Furthermore, the specific steps in step S4 for obtaining the actual parameters of the target device are as follows:

[0086] Measure the ground impedance of each coupling path from the interference source to the detection point in the target device and obtain the corresponding parameter R. nk L nk C nk .

[0087] As described above, the ground impedance parameters in the coupling path from the interference source to the detection point are obtained by measuring each parameter individually, thus ensuring accuracy.

[0088] Furthermore, the specific details of obtaining the conducted interference test spectrum of the target device under full load and no load when each interference source operates independently in step S4 are as follows:

[0089] Obtain the peak envelope dBV of the conducted interference noise at the power port of each interference source under no-load and full-load conditions. mp (jω).

[0090] As described above, the peak envelope of conducted interference noise can be obtained by actual measurement at the power port.

[0091] Furthermore, step S4, which involves performing simulation calculations using the simulation model, includes the following steps:

[0092] Based on the frequency points (a1,…,a) x Interference voltage set {dBV} mp (j2πa1), ..., dBV mp (j2πa x )} and interference current set {I mp (j2πa1),...I mp (j2πa x The transformation relationship of )} is:

[0093]

[0094] For each interference source, a discretized expression for the interference source amplitude is defined, where:

[0095] A1 = I mp (j2πa1); ...

[0097] A x =I mp (j2πa x );

[0098] The expression for the amplitude of the discretized nth interference current source is:

[0099]

[0100] I was obtained under both no-load and full-load conditions. mn (t) expression;

[0101] The expression for the amplitude of all interference current sources I mn (t), Coupled path transfer function G nk (jω) is substituted into the simulation model, and spectrum analysis is set at all k detection points;

[0102] Select different interference sources based on the actual operating conditions of the target equipment, and use full-load I / O. mn The expression (t) is used to obtain the interference amplitude of the detection point from the spectrum analysis of the detection point.

[0103] As described above, the envelope of each independent converter is dbV mp The set of interference voltages at the set frequency point (jω) is extracted and converted into the corresponding set of interference currents. Further discretized expressions for the amplitudes of n interference current sources are obtained. All the amplitude expressions for the interference current sources are then combined into I... mn (t), Coupled path transfer function G nk (jω) is substituted into the simulation model for analysis.

[0104] Further, step S5 includes the following steps:

[0105] S51. Compare the interference amplitude of each detection point with the standard limit when using different interference sources, and locate the frequency points that exceed the standard limit.

[0106] It also includes the following steps:

[0107] Switch all interference sources to idle I one by one in sequence mn The expression (t) records the changes in interference amplitude during the switching process and compares them with the standard limit until all frequency points meet the standard limit, and locates the abnormal interference source and coupling path;

[0108] Switch all interference current sources to no-load Imn If the spectrum analysis of the detection point still exceeds the standard limit after the expression (t), all interference current sources are turned off one by one in sequence, the change of interference amplitude during the shutdown process is recorded and compared with the standard limit, until all frequency points meet the standard limit, and the abnormal interference source and coupling path are located.

[0109] As described above, based on the above steps, the interference current source and coupling path that have a significant impact on the result can be located, thereby enabling the converter corresponding to the located interference source to be modified to reduce its conducted interference emission level; or the corresponding coupling path can be processed to increase the ability to suppress interference.

[0110] Please refer to Figure 6 A power system electromagnetic compatibility conducted interference assessment terminal includes a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps in the power system electromagnetic compatibility conducted interference assessment method described above.

[0111] This invention provides a method and terminal for evaluating electromagnetic compatibility conducted interference in power systems, applicable to evaluating electromagnetic compatibility conducted interference in power systems of energy storage equipment.

[0112] Please refer to Figures 1 to 5 Embodiment 1 of the present invention is as follows:

[0113] A method for evaluating conducted electromagnetic compatibility interference in a power supply system, comprising the following steps:

[0114] S1. Establish the power transmission principle diagram of the power system of the target device to be analyzed, and identify the interference sources and coupling paths.

[0115] In this embodiment, a power transmission schematic diagram of the power supply system of the complete set of equipment to be analyzed is established, showing the connection relationship between all s high-frequency power converters (hereinafter referred to as "converters") and the power transmission lines of the external power supply port of the complete set of equipment. The noise current transmitted outward from the n interference sources of the s converters is defined as I. m1 (jω) to I mn (jω), see reference Figure 1 .

[0116] This step involves identifying all interference sources from the n power converters and treating them as independent electromagnetic interference sources, with the line from each interference source to each detection port identified as a coupling path.

[0117] S2. Within the frequency range to be analyzed, define discretized amplitude expressions for each interference source and establish transfer functions for the coupling paths between each interference source and each electromagnetic compatibility conducted interference detection point.

[0118] In this embodiment, the expression for the amplitude of the noise current of the nth interference source is listed in series form, and then simplified and discretized to obtain the expression within the test frequency range.

[0119] In step S2, the discretized amplitude expression for each interference source is defined as follows:

[0120] The complete form of the expression for the amplitude of the nth interference source in the form of a current source is:

[0121]

[0122] This expression describes noise as a superposition of signals at x frequency points. When the frequency points are chosen as multiples of the fundamental frequency ω0, the frequency of the i-th point among the x frequency points is represented as i*ω0, or simply iω0. The instantaneous amplitude of the noise at this point is expressed in A. i The peak value is iω0, and the initial phase angle is φ. i A periodic function A that varies with time t i sin(iω0t+φ i A0 is the DC component of the signal.

[0123] Because the common-mode interference coupling path is AC, A0 cannot pass through and can be ignored; furthermore, in electromagnetic compatibility testing, the signal phase does not affect the judgment of the interference amplitude, so the phase is set to a fixed value, I. mn The expression (t) simplifies to:

[0124]

[0125] When x is not selected as a regular multiple of the fundamental frequency ω0, the test frequency range (f min ,f max The x frequency points a1..a1 within the range of ) x Then we have:

[0126] I mn (t)=A1sin(2πa1t+φ)+A2sin(2πa2t+φ)......A x sin(2πa x t+φ);

[0127] Among them, A1...A x This represents the interference amplitude at each frequency point.

[0128] In this embodiment, the connection relationship between the power transmission lines and grounding points of each converter and the grounding lines of the complete set of equipment is established. Each of the n interference sources, relative to one of the k electromagnetic compatibility detection points (hereinafter referred to as "detection points"), constitutes an interference coupling path. The transfer function of all paths is denoted as G. 11 (jω) to Gnk (jω), see reference Figure 1 .

[0129] To simulate a real electromagnetic compatibility conducted interference detection process, a set of equipment may contain k detection points, such as the DC input port detection point and the AC input port detection point of the equipment.

[0130] This step involves identifying and defining all coupling paths between all common-mode conducted interference sources and all detection points.

[0131] The actual transmission path from a certain interference source n to a certain detection point k may be more than one, but it can be equivalent to one, denoted as the transfer function G of path nk. nk (jω).

[0132] Let G be the transfer function of the path nk from any interference source to any detection point. nk (jω) Creates an expression.

[0133] The transfer function for establishing the coupling path between each interference source and each electromagnetic compatibility conducted interference detection point in step S2 is as follows:

[0134] Based on the common-mode interference transmission characteristics analysis, the coupling path from the interference source n to the detection point k can be equivalent to the conductor impedance Z. n_wire and ground impedance Z n_GND In this embodiment, it can be referred to Figure 2 A portion of the interference current flowing from interference source n passes through Z. n_GND A portion flows into the system grounding point, and a portion flows into point A through the power port, passing through the equivalent network impedance Z. LISN This constitutes external interference.

[0135] Part of this, after passing through the equivalent network impedance, constitutes external interference, and the current value is expressed as:

[0136]

[0137] For the propagation of common-mode interference, the conductor impedance Z n_wire Much smaller than the ground impedance Z n_GND Therefore, we can ignore this and obtain the transfer function G of the path nk from any interference source to any detection point. nk (jω):

[0138]

[0139] Among them, Z LISN To meet the standard values ​​specified in GB / T6113.102, Z n_GND The series RCL circuit is equivalent to:

[0140] Z n_GND =Rnk +jωL nk +1 / jωC nk ;

[0141] R nk L nk C nk These represent the resistance, inductance, and capacitance values ​​of the ground impedance, respectively; j is the imaginary unit; ω represents the frequency; and I... mn_LISN (jω) and G nk (jω) are all complex frequency domain functions, and the same applies below.

[0142] S3. Construct an equivalent model expression for conducted noise assessment and establish a simulation model.

[0143] In this embodiment, under the condition of conducting interference detection at the external power port of the complete set of equipment, when the equivalent resistance of the test impedance stabilization network at detection point k is R_ LISN When, the equivalent model expression for conducted interference noise assessment.

[0144] The construction of the equivalent model expression for conducted noise evaluation in step S3 is as follows:

[0145] For n interference sources, after flowing through n coupling paths, the conducted interference voltage noise V generated at detection point k is... noise_k (jω) is:

[0146]

[0147] Among them, R LISN For Z LISN The sampling resistor part in the expression is used to calculate the spectral value obtained on the detection instrument when interference is measured at detection point k.

[0148] Step S3, establishing the simulation model, includes the following steps:

[0149] Create a circuit simulation software containing the target device (such as...) Figure 1 Simulation model of all interference sources, coupling paths, and detection points (as shown):

[0150] Based on the definition of the discretized interference source amplitude expression in step S2, in the test frequency range (f min ,f max Take x frequency points (a1, ..., a) within the range x In the simulation model, all interference current sources are established. Where A1...A x ,a1..a x And φ can be set, and each interference source generator can be set to enable or disable.

[0151] Based on the definition of the transfer function of the coupling path between each interference source and each electromagnetic compatibility conducted interference detection point in step S2, an impedance model for all coupling paths is established in the simulation model. Where R... nk L nk C nk It can be configured.

[0152] Based on the equivalent model expression for conducted noise evaluation in step S3, an evaluation of noise V is added at each detection point of the simulation model. noise_k The spectrum analysis of (jω) simulates the test of this point by an actual electromagnetic compatibility testing device.

[0153] S4. Obtain the actual parameters of the target device and the conducted interference test spectrum of each interference source when working independently under full load and no load, and perform simulation calculations in conjunction with the simulation model.

[0154] The specific steps in step S4 to obtain the actual parameters of the target device are as follows:

[0155] Measure the ground impedance of each coupling path from the interference source to the detection point in the target device and obtain the corresponding parameter R. nk L nk C nk .

[0156] (1) Turn off the converter connected to the coupling path 1-k under test and disconnect the connection. Disconnect switches K1 to Kn. Use a bridge or other equipment to measure the resistance R between C and D. nk Inductor L nk and capacitor C nk The value of .

[0157] (2) Measure the parameters corresponding to all paths in sequence.

[0158] In step S4, the conducted interference test spectra of the target device under full load and no load when each interference source is working independently are obtained as follows:

[0159] Obtain the peak envelope dBV of the conducted interference noise at the power port of each interference source under no-load and full-load conditions. mp (jω).

[0160] In this embodiment, standalone power converters are generally required to undergo electromagnetic compatibility testing before being integrated into a system, and this spectral characteristic is obtainable. This step is to obtain the actual level of electromagnetic interference generated under the condition that the converter operates independently. Figure 3 The curve represents the test results of a converter under full load conditions, where f min =150kHz,f max =30MHz.

[0161] Step S4, which involves performing simulation calculations using the simulation model, includes the following steps:

[0162] In this embodiment, the envelope of each independent converter is dbV mp The set of interference voltages at the set point of frequency (jω) is extracted and converted into the corresponding set of interference currents, and then the discretized amplitude expressions of n interference current sources are obtained.

[0163] In this embodiment, as can be seen from the conducted interference measurement standard, the sampling resistance for detecting network impedance is 50Ω.

[0164] According to the frequency points (a1,…,a) set in step S2 x Interference voltage set {dBV} mp (j2πa1), ..., dBV mp (j2πa x )} and interference current set {I mp (j2πa1),...I mp (j2πa x The transformation relationship of )} is:

[0165]

[0166] Unit (μA). Figure 3 The diagram shows several representative frequency points selected, covering the entire test frequency range of 150kHz to 30MHz.

[0167] For each interference source set in step S2, define a discretized expression for the interference source amplitude, where:

[0168] A k =I mp (j2πa k );

[0169] k∈[1,x];

[0170] Right now:

[0171] A1 = I mp (j2πa1); ...

[0173] A x =I mp (j2πa x );

[0174] The expression for the amplitude of the discretized nth interference current source is:

[0175]

[0176] I was obtained under both no-load and full-load conditions.mn (t) expression.

[0177] The expression for the amplitude of all interference current sources I mn (t), Coupled path transfer function G nk (jω) is substituted into the simulation model, and spectrum analysis is set at all k detection points;

[0178] Select different interference sources based on the actual operating conditions of the target equipment, and use full-load I / O. mn The expression (t) is used to obtain the interference amplitude of the detection point from the spectrum analysis of the detection point.

[0179] S5. Based on the simulation results and the preset standard limits, the evaluation results are obtained.

[0180] Step S5 includes the following steps:

[0181] S51. Compare the interference amplitude of each detection point with the standard limit when using different interference sources, and locate the frequency point that exceeds the standard limit.

[0182] In this embodiment, the interference amplitude of the acquired detection point is compared with the standard limit to locate the frequency point that exceeds the standard limit. Figure 4 The simulation results of the interference spectrum at a certain detection point for the complete set of equipment.

[0183] Step S5 is followed by the following steps:

[0184] Switch all interference sources to idle I one by one in sequence mn The expression (t) records the changes in interference amplitude during the switching process and compares them with the standard limit until all frequency points meet the standard limit, and locates the abnormal (i.e., the interference source and coupling path that have a significant impact on the result);

[0185] Switch all interference current sources to no-load I mn If the spectral analysis of the detection point still exceeds the standard limit after the expression (t), all interference current sources are turned off one by one in sequence, the change of interference amplitude during the shutdown process is recorded and compared with the standard limit, until all frequency points meet the standard limit, and the abnormal (i.e., the interference source and coupling path that have a greater impact on the result) are located.

[0186] Please refer to Figure 6 Embodiment two of the present invention is as follows:

[0187] A power system electromagnetic compatibility conducted interference assessment terminal 1 includes a processor 2, a memory 3, and a computer program stored in the memory 3 and executable on the processor 2. When the processor 2 executes the computer program, it implements the steps in the power system electromagnetic compatibility conducted interference assessment method described in Embodiment 1 above.

[0188] In summary, the present invention provides a method and terminal for evaluating electromagnetic compatibility (EMC) conducted interference in a power system. Based on the equipment schematic, it identifies interference sources and coupling paths, establishes the amplitude expression of the interference source and the transfer function of the coupling path, and builds a simulation model. This model is then used in conjunction with actual equipment parameters to simulate and evaluate the EMC conducted interference in the power system. This method can obtain a relatively accurate trend of conducted interference superposition, identify frequency bands exceeding the specified limits, locate problematic converter units, and make rectification more targeted. It also accelerates the EMC testing process and reduces the workload of engineers.

[0189] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A simulation calculation method for conducted noise, characterized in that, Including the following steps: S1. Establish the power transmission principle diagram of the power system of the target device to be analyzed, and identify the interference sources and coupling paths therein; S2. Within the frequency range to be analyzed, define discretized amplitude expressions for each interference source and establish transfer functions for the coupling paths between each interference source and each electromagnetic compatibility conducted interference detection point. In step S2, the discretized amplitude expression for each interference source is defined as follows: The complete form of the expression for the amplitude of the nth interference source in the form of a current source is: This represents noise as a superposition of signals at x frequency points. When the frequency points are selected as multiples of the fundamental frequency ω0, the frequency of the i-th frequency point is denoted as iω0, and the peak value of the instantaneous noise amplitude at the i-th frequency point is A. i The frequency is iω0, and the initial phase angle is... a periodic function that varies with time t A0 represents the DC component of the signal; Because the common-mode interference coupling path is AC, A0 cannot pass through and can be ignored. Furthermore, in electromagnetic compatibility testing, the signal phase does not affect the judgment of the interference amplitude; therefore, the phase is set to a fixed value, I. mn The expression (t) simplifies to: When x is not selected as a regular multiple of the fundamental frequency ω0, the test frequency range (f min f max x frequency points (a1, ..., a) within ) x Then we have: Where (A1, ..., A x (f) represents the interference amplitude at each frequency point. min f max () indicates the test frequency range; The transfer function for establishing the coupling path between each interference source and each electromagnetic compatibility conducted interference detection point in step S2 is as follows: Based on the common-mode interference transmission characteristics analysis, the coupling path from the interference source n to the detection point k can be equivalent to the conductor impedance Z. n_wire and ground impedance Z n_GND Part of this interference, after passing through the equivalent network impedance, constitutes external interference, and the current value is expressed as: For the propagation of common-mode interference, the conductor impedance Z n_wire Much smaller than the ground impedance Z n_GND Therefore, we can ignore this and obtain the coupling path transfer function G of the path nk from any interference source to any detection point. nk (jω): Among them, Z LISN Z is the preset standard value. n_GND The series RCL circuit is equivalent to: Z n_GND =R nk +jωL nk +1 / jωC nk ; Rnk, Lnk, and Cnk represent the resistance, inductance, and capacitance values ​​of the ground impedance, respectively; j represents the imaginary unit; and ω represents the frequency. S3. Construct an equivalent model expression for conducted noise assessment and establish a simulation model; S4. Obtain the actual parameters of the target device and the conducted interference test spectrum of each interference source when working independently under full load and no load, and perform simulation calculations in conjunction with the simulation model.

2. The simulation calculation method for conducted noise according to claim 1, characterized in that, The specific steps in step S4 to obtain the actual parameters of the target device are as follows: Measure the ground impedance of each coupling path from the interference source to the detection point in the target device and obtain the corresponding parameter R. nk L nk C nk .

3. The simulation calculation method for conducted noise according to claim 2, characterized in that, Parameter R nk L nk C nk The specific acquisition is as follows: Turn off the converter connected to the coupling path under test and disconnect the wiring and switch. Use a measuring device to measure the resistance R. nk Inductor L nk and capacitor C nk The value of .

4. The simulation calculation method for conducted noise according to claim 1, characterized in that, In step S4, the conducted interference test spectra of the target device under full load and no load when each interference source is working independently are obtained as follows: Obtain the peak envelope dBV of the conducted interference noise at the power port of each interference source under no-load and full-load conditions. mp (jω).

5. The simulation calculation method for conducted noise according to claim 1, characterized in that, The construction of the equivalent model expression for conducted noise evaluation in step S3 is as follows: For n interference sources, after flowing through n coupling paths, the conducted interference voltage noise V generated at detection point k is... noise_k (jω) is: RLISN is the sampling resistor part in ZLISN.

6. The simulation calculation method for conducted noise according to claim 1, characterized in that, Step S3, establishing the simulation model, includes the following steps: In circuit simulation software, create a simulation model that includes all interference sources, coupling paths, and detection points of the target device: Based on the definition of the discretized interference source amplitude expression in step S2, in the test frequency range (f min f max Take x frequency points (a1, ..., a2) within a given range. x In the simulation model, all interference current sources are established. Based on the definition of the transfer function of the coupling path between each interference source and each electromagnetic compatibility conducted interference detection point in step S2, an impedance model of all coupling paths is established in the simulation model. Based on the equivalent model expression for conducted noise evaluation in step S3, an evaluation of noise V is added at each detection point of the simulation model. noise_k Spectral analysis of (jω).

7. The simulation calculation method for conducted noise according to claim 1, characterized in that, In step S4, the conducted interference test spectra of the target device under full load and no load when each interference source is working independently are obtained as follows: Obtain the peak envelope dBV of the conducted interference noise at the power port of each interference source under no-load and full-load conditions. mp (jω).

8. The simulation calculation method for conducted noise according to claim 7, characterized in that, Step S4, which involves performing simulation calculations using the simulation model, includes the following steps: Based on the frequency points (a1, ..., a1) x Interference voltage set {dBV} mp (j2πa1), ..., dBV mp (j2πa x The conversion relationship between the set of interference currents {Imp(ja1), ..., Imp(jax)} and the set of interference currents {Imp(ja1), ..., Imp(jax)} is as follows: For each interference source, a discretized expression for the amplitude of the interference source is defined, where: THE k =I mp (j2πa k ); k∈[1,x]; Then the amplitude expression of the nth interference source is I mn The discretized form of (t) is expressed as: I was obtained under both no-load and full-load conditions. mn (t) expression; All the aforementioned interference source amplitude expressions and coupling path transfer functions G nk (jω) is substituted into the simulation model, and spectrum analysis is set at all k detection points; Select different interference sources based on the actual operating conditions of the target equipment, and use full-load I... mn The expression (t) is used to obtain the interference amplitude of the detection point from the spectrum analysis of the detection point.

9. The simulation calculation method for conducted noise according to claim 1, characterized in that, Z LISN The preset standard values ​​are as follows: Z LISN The test requirements are the standard values ​​specified in GB / T6113.

102.

10. A simulation computing terminal for conducted noise, comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps in the simulation calculation method for conducted noise as described in any one of claims 1-9.

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