Simulation calculation method and terminal for conducted noise

Abstract

The invention discloses a simulation calculation method and terminal for conducted noise, and the method comprises the steps: building a power transmission schematic diagram of a power system of to-be-analyzed target equipment, and recognizing all interference sources and coupling paths in the schematic diagram; in a frequency range to be analyzed, a discretized interference source amplitude expression is defined for each interference source, and a transfer function of a coupling path between each interference source and each electromagnetic compatibility conducted interference detection point is established; constructing a conducted noise evaluation equivalent model expression, establishing a simulation model, and based on the constructed simulation model, performing simulation operation in combination with the actual parameters of the target equipment and the full-load and no-load conducted interference test spectrums when each interference source works independently; an evaluation result can be obtained according to the simulation operation result and a preset standard limit value; and more effective electromagnetic compatibility conducted interference evaluation can be realized.

Description

[0001] This case is a divisional application based on the invention patent with application date of September 6, 2024, application number 202411246812.4, and name “A method and terminal for evaluating electromagnetic compatibility conducted interference of a power supply system” as the parent case. Technical Field

[0002] The present invention relates to the technical field of conducted interference evaluation, and in particular to a simulation calculation method and a terminal for conducted noise. Background Art

[0003] As an important part of the new energy industry, energy storage systems and distributed power generation have been widely used to regulate and supplement the power supply of the power grid. Most energy storage systems need to be connected to the AC power grid or the DC power grid. Unlike traditional rotating generators, after the access of new energy, the electromagnetic interference generated by the operation of a large number of high-frequency power converters is coupled to the user's equipment through the transmission line, which affects the safety and reliability of the equipment operation and also puts higher requirements on the anti-interference of electrical appliances. Especially for complete sets of equipment in industrial and commercial energy storage or household energy storage, which are often composed of a combination of multiple power electronic converters and are close to users, the conducted interference formed on the AC (DC) bus is becoming more and more serious, becoming a new bottleneck restricting the power electronics of the power grid.

[0004] According to the product access requirements of the energy storage industry, the entire complete set of equipment system needs to pass the electromagnetic compatibility test and meet the corresponding indicators. For the determination of the degree of conducted interference of the power port of medium and large complete sets of equipment, if the overall test and rectification method is adopted, the detection cycle, cost, and site conditions are all limited; although each independent power conversion device in the complete set of equipment is also required to pass the electromagnetic compatibility test, the electromagnetic compatibility status of the combined complete system changes and may not necessarily pass the test; the overall results during the rectification process cannot locate the problem units in the complete set of equipment, and lack guidance for rectification. At present, there is a lack of effective interference modeling and analysis methods for the energy storage industry, which increases the cost and cycle of the overall electromagnetic compatibility 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 evaluation.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

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

[0008] S1. Establish a power transmission schematic diagram of the power supply 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 a discretized interference source amplitude expression for each interference source, and establish a transfer function of the coupling path between each interference source and each electromagnetic compatibility conducted interference detection point;

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

[0011] S4, obtaining actual parameters of the target device and the full-load and no-load conducted interference test spectra of each interference source working independently, and performing simulation calculations in combination with the simulation model;

[0012] S5. Obtain evaluation results based on simulation results and preset standard limits.

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

[0014] S1. Establish a power transmission schematic diagram of the power supply 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 a discretized interference source amplitude expression for each interference source, and establish a transfer function of the coupling path between each interference source and each electromagnetic compatibility conducted interference detection point;

[0016] In step S2, the discrete interference source amplitude expression defined for each interference source is specifically:

[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] Indicates that the noise is expressed as the superposition of signals at x frequency points. When the frequency point is selected as a multiple of the regular base frequency ω0, the frequency of the i-th point among the x frequency points is expressed as iω0, and the peak value of the instantaneous amplitude of the noise at the i-th point is A i , the frequency is iω0, and the initial phase angle is The periodic function of A0 is the DC component of the signal;

[0020] Because the common mode interference coupling path is AC, A0 cannot pass and can be ignored. In the electromagnetic compatibility test, the signal phase does not affect the judgment of the interference amplitude, so the phase is set to a fixed value, I mn (t)The expression is simplified to:

[0021]

[0022] When x is not a multiple of the regular base frequency ω0, the test frequency range (fmin , ..., f max ) within x frequency points (a1, ..., a x ) then:

[0023]

[0024] Among them, (A1, ..., A x ) is the interference amplitude at each frequency point, (f min , f max ) indicates the test frequency band;

[0025] The transfer function of the coupling path between each interference source and each electromagnetic compatibility conducted interference detection point established in step S2 is specifically:

[0026] According to 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 wire impedance Z n_wire and ground impedance Z n_GND , part of which passes through the equivalent network impedance to form 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 ground impedance Z n_GND , so it is ignored, and the coupling path transfer function G of the path nk from any interference source to any detection point can be obtained nk (jω):

[0029]

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

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

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

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

[0034] S4. Acquire actual parameters of the target device and full-load and no-load conducted interference test spectra when each interference source works independently, and perform simulation operations in combination with the simulation model.

[0035] In order to solve the above technical problems, another technical solution adopted by the present invention is:

[0036] A power supply system electromagnetic compatibility conducted interference assessment terminal comprises a processor, a memory and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps in the above-mentioned power supply system electromagnetic compatibility conducted interference assessment method are implemented.

[0037] A simulation calculation terminal for conducted noise comprises a processor, a memory and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps in the simulation calculation method for conducted noise described above are implemented.

[0038] The beneficial effects of the present invention are as follows: a simulation calculation method and terminal for conducted noise of the present invention identify interference sources and coupling paths according to the device schematic diagram, establish an interference source amplitude expression and a transfer function of the coupling path, and establish a simulation model, and perform simulation operation in combination with actual device parameters to evaluate the electromagnetic compatibility conducted interference of the power supply system, thereby obtaining a relatively accurate superposition trend of system conducted interference, troubleshooting the frequency band range that exceeds the index, locating the problematic converter unit, making rectification targeted, accelerating the electromagnetic compatibility test process, and reducing the testing workload of engineering personnel. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0040] Figure 2 This is an example diagram of connecting interference sources and monitoring points of a target device in a method for evaluating electromagnetic compatibility conducted interference of a power supply system according to an embodiment of the present invention;

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

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

[0043] Figure 5 A flowchart of a method for evaluating electromagnetic compatibility conducted interference of 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] Description of labels:

[0046] 1. A power system electromagnetic compatibility conducted interference assessment terminal; 2. A processor; 3. A memory. DETAILED DESCRIPTION

[0047] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in combination with the implementation modes and the accompanying drawings.

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

[0049] S1. Establish a power transmission schematic diagram of the power supply 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 a discretized interference source amplitude expression for each interference source, and establish a transfer function of the coupling path between each interference source and each electromagnetic compatibility conducted interference detection point;

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

[0052] S4, obtaining actual parameters of the target device and the full-load and no-load conducted interference test spectra of each interference source working independently, and performing simulation calculations in combination with the simulation model;

[0053] S5. Obtain evaluation results based on simulation results and preset standard limits.

[0054] From the above description, it can be seen that the beneficial effects of the present invention are: a method for evaluating electromagnetic compatibility conducted interference of a power supply system of the present invention identifies interference sources and coupling paths according to the device schematic diagram, establishes interference source amplitude expressions and transfer functions of coupling paths, and establishes simulation models, and combines simulation operations with actual device parameters to perform electromagnetic compatibility conducted interference evaluation of the power supply system, which can obtain relatively accurate system conducted interference superposition trends, check frequency bands that exceed indicators, locate problematic converter units, make rectifications targeted, speed up the electromagnetic compatibility test process, and reduce the testing workload of engineering personnel.

[0055] Furthermore, in step S2, the discrete interference source amplitude expression is defined for each interference source 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] Indicates that the noise is expressed as the superposition of signals at x frequency points. When the frequency point is selected as a multiple of the regular base frequency ω0, the frequency of the i-th point among the x frequency points is expressed as iω0, and the peak value of the instantaneous amplitude of the noise at the i-th point is A i , the frequency is iω0, and the initial phase angle is φ i The periodic function A that changes 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 and can be ignored. In the electromagnetic compatibility test, the signal phase does not affect the judgment of the interference amplitude, so the phase is set to a fixed value, I mn (t)The expression is simplified to:

[0060]

[0061] When x is not a multiple of the regular base frequency ω0, in the test frequency range (f min ,f max ) within x frequency points a1..a x ∈(f min ,f max ) then:

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

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

[0064] It can be seen from the above description that based on the above steps, the definition of the discrete interference source amplitude expression of each interference source is achieved.

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

[0066] According to 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 wire impedance Z n_wire and ground impedance Z n_GND , part of which passes through the equivalent network impedance to form 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 ground impedance Z n_GND , so we ignore it, and we can get the transfer function G of the path nk from any interference source to any detection point nk (jω):

[0069]

[0070] Among them, Z LISN is the preset standard value, Z 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 are the resistance, inductance and capacitance of the ground impedance respectively, j represents the imaginary unit, and ω represents the frequency.

[0073] It can be seen from the above description that based on the above steps, the definition of the transfer function of the coupling path between each interference source and each electromagnetic compatibility conducted interference detection point is achieved.

[0074] Furthermore, the construction of the equivalent model expression for conducting 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 the detection point k is noise_k (jω) is:

[0076]

[0077] Among them, R LISN Z LISN The sampling resistor part.

[0078] From the above description, it can be seen that the construction of the equivalent model expression for conducted noise evaluation is as shown above.

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

[0080] In the circuit simulation software, a simulation model including all interference sources, coupling paths and detection points of the target device is established:

[0081] According to the definition of the discretized interference source amplitude expression in step S2, in the test frequency range (f min ,f max ) to select x frequency points (a1,…,a x ), establish all interference current sources in the simulation model;

[0082] According to 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, a ground impedance model of all coupling paths is established in the simulation model;

[0083] According to the conduction noise evaluation equivalent model expression in step S3, the noise V is added to each detection point of the simulation model. noise_k Spectral analysis of (jω).

[0084] It can be seen from the above description that based on the above steps, a circuit simulation model of the target device is constructed.

[0085] Furthermore, the actual parameters of the target device are obtained in step S4 as follows:

[0086] Measure the ground impedance of all coupling paths from the interference source to the detection point in the target device one by one and obtain the corresponding parameter R nk , L nk , C nk .

[0087] It can be seen from the above description that the ground impedance parameters in the coupling path from the interference source to the detection point are obtained by measuring one by one to ensure accuracy.

[0088] Furthermore, the full-load and no-load conducted interference test spectra obtained in step S4 when each interference source of the target device works independently are specifically:

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

[0090] It can be seen from the above description that the spectrum peak envelope of the conducted interference noise is obtained by actually measuring at the power port.

[0091] Furthermore, the simulation operation performed in combination with the simulation model in step S4 includes the following steps:

[0092] According to the frequency point (a1,…,a x ), interference voltage set {dBV mp (j2πa1), ..., dBV mp (j2πa x )} and the interference current set {I mp (j2πa1),...I mp (j2πa x )} is:

[0093]

[0094] For each interference source, define a discretized interference source amplitude expression, where:

[0095] A1=I mp (j2πa1); ...

[0097] A x =I mp (j2πa x );

[0098] Then the discretized nth interference current source amplitude expression is:

[0099]

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

[0101] The total interference current source amplitude expression I mn (t), coupling path transfer function G nk (jω) is brought into the simulation model, and spectrum analysis is set at all k detection points;

[0102] Select different interference sources according to the actual working conditions of the target equipment, and use full load I mn (t) expression, and obtain the interference amplitude of the detection point from the spectrum analysis of the detection point.

[0103] From the above description, it can be seen that the envelope dbV of each independent converter mp The interference voltage set at the frequency setting point is intercepted on (jω) and converted into the corresponding interference current set, and then the discrete n interference current source amplitude expressions are obtained. The amplitude expressions of all interference current sources I mn (t), coupling path transfer function G nk (jω) is brought into the simulation model for analysis.

[0104] Further, step S5 comprises the steps of:

[0105] S51, comparing the interference amplitude of each detection point when using different interference sources with the standard limit, and locating the frequency point that exceeds the standard limit;

[0106] Also includes the steps:

[0107] Switch all interference sources to no-load I one by one mn (t) expression, record the change of interference amplitude during the switching process, and compare it with the standard limit until all frequency points meet the standard limit, and locate the abnormal interference source and coupling path;

[0108] All interference current sources are switched to no-load Imn (t) expression, if the spectrum analysis of the detection point still exceeds the standard limit, turn off all interference current sources one by one, record the change of interference amplitude during the shutdown process, and compare it with the standard limit until all frequency points meet the standard limit, and locate the abnormal interference source and coupling path.

[0109] From the above description, it can be seen that based on the above steps, the interference current sources and coupling paths that have a greater impact on the results are located, so that the converter corresponding to the located interference source can be rectified 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 supply system electromagnetic compatibility conducted interference assessment terminal, comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps in the above-mentioned power supply system electromagnetic compatibility conducted interference assessment method when executing the computer program.

[0111] A method and terminal for evaluating electromagnetic compatibility conducted interference of a power system according to an embodiment of the present invention are applicable to evaluating electromagnetic compatibility conducted interference of a power system of an energy storage complete set of equipment.

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

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

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

[0115] In this embodiment, a power transmission principle 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") contained therein and the power transmission line of the complete set of equipment to the external power supply port. The noise current transmitted to the outside by the n interference sources of the s converters is defined as I m1 (jω) to I mn (jω), refer to Figure 1 .

[0116] This step is to identify all interference sources of the n power converters and regard them as independent electromagnetic interference sources, and identify the line from each interference source to each detection port as a coupling path.

[0117] S2. Within the frequency range to be analyzed, define a discretized interference source amplitude expression for each interference source, and establish a transfer function of the coupling path between each interference source and each electromagnetic compatibility conducted interference detection point.

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

[0119] In step S2, the discrete interference source amplitude expression defined for each interference source is specifically:

[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 is used to express noise as the superposition of signals at x frequency points. When the frequency point is selected as a multiple of the regular base frequency ω0, the frequency of the i-th point among the x frequency points is expressed as i*ω0, abbreviated as iω0. The instantaneous amplitude of the noise at this point is expressed as A i is the peak value, the frequency is iω0, and the initial phase angle is φ i The periodic function A that changes 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 and can be ignored; and in the electromagnetic compatibility test, the signal phase does not affect the judgment of the interference amplitude, so the phase is set to a fixed value, I mn (t)The expression is simplified to:

[0124]

[0125] When x is not a multiple of the regular base frequency ω0, the test frequency range (f min ,f max ) within x frequency points a1..a x , then:

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

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

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

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

[0130] This step is to identify and define all coupling paths between all common-mode conducted interference sources and all detection points.

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

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

[0133] The transfer function of the coupling path between each interference source and each electromagnetic compatibility conducted interference detection point established in step S2 is specifically:

[0134] According to 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 wire impedance Z n_wire and ground impedance Z n_GND In this embodiment, reference may be made to Figure 2 A part of the interference current flowing from the interference source n passes through Z n_GND Flows into the system grounding point, and part flows into point A through the power port, passing through the equivalent network impedance Z LISN constitutes external interference.

[0135] Part of it passes through the equivalent network impedance to form 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 ground impedance Z n_GND , so we ignore it, and we can get 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 test the standard value 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 are the resistance, inductance and capacitance of the ground impedance respectively, j is an imaginary unit, ω represents the frequency, I mn_LISN (jω) and G nk (jω) are all complex frequency domain functions, and the same applies to the following text.

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

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

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

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

[0146]

[0147] Among them, R LISN Z LISN The sampling resistor part in . This expression is used to calculate the spectrum value obtained on the detection instrument when performing interference measurement on the detection point k.

[0148] The step S3 of establishing the simulation model includes the following steps:

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

[0150] According to the definition of the discretized interference source amplitude expression in step S2, in the test frequency range (f min ,f max ) to select x frequency points (a1,…,a x ), establish all interference current sources in the simulation model. Among them, A1...A x , a1..a x , and φ can be set, and each interference source generator can be set whether to be enabled.

[0151] According to 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, the impedance model of all coupling paths is established in the simulation model. nk , L nk , C nk Can be set.

[0152] According to the conduction noise evaluation equivalent model expression in step S3, the noise V is added to each detection point of the simulation model. noise_k The spectrum analysis of (jω) simulates the actual electromagnetic compatibility testing equipment to test this point.

[0153] S4. Acquire actual parameters of the target device and full-load and no-load conducted interference test spectra when each interference source works independently, and perform simulation operations in combination with the simulation model.

[0154] The actual parameters of the target device obtained in step S4 are specifically:

[0155] Measure the ground impedance of all coupling paths from the interference source to the detection point in the target device one by one and obtain the corresponding parameter R nk , L nk , C nk .

[0156] (1) Turn off the converter connected to the coupling path 1-k to be measured and disconnect the connection, open the switches K1 to Kn, and use a bridge or other device to measure the resistance R between C and D. nk 、Inductance L nk and capacitor C nk The value of .

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

[0158] The conducted interference test spectra of the target device at full load and no load when each interference source works independently in step S4 are specifically:

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

[0160] In this embodiment, independent power converters are generally required to undergo electromagnetic compatibility testing before forming a system, and this spectrum characteristic is available. This step is to obtain the actual electromagnetic interference level generated by the converter under independent working conditions. Figure 3 is the test result curve of a converter under full load condition, where f min =150kHz,f max =30MHz.

[0161] The simulation operation performed in combination with the simulation model in step S4 includes the following steps:

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

[0163] In this embodiment, it is known from the conducted interference measurement standard that the sampling resistor for detecting the network impedance is 50Ω.

[0164] According to the frequency points (a1,…,a x ), interference voltage set {dBV mp (j2πa1), ..., dBV mp (j2πa x )} and the interference current set {I mp (j2πa1),...I mp (j2πa x )} is:

[0165]

[0166] Unit (μA). Figure 3 It is shown in the figure that several representative frequency points are selected, and the entire test frequency range of 150kHz to 30MHz is covered.

[0167] For each interference source set in step S2, a discretized interference source amplitude expression is defined, 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] Then the discretized nth interference current source amplitude expression is:

[0175]

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

[0177] The total interference current source amplitude expression I mn (t), coupling path transfer function G nk (jω) is brought into the simulation model, and spectrum analysis is set at all k detection points;

[0178] Select different interference sources according to the actual working conditions of the target equipment, and use full load I mn (t) expression, and obtain the interference amplitude of the detection point from the spectrum analysis of the detection point.

[0179] S5. Obtain evaluation results based on simulation results and preset standard limits.

[0180] Step S5 comprises the steps of:

[0181] S51. Compare the interference amplitude of each detection point when using different interference sources with the standard limit, 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 value to locate the frequency point exceeding the standard limit value. Figure 4 The interference spectrum simulation results for the complete set of equipment at a certain detection point.

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

[0184] Switch all interference sources to no-load I one by one mn (t) expression, record the change of interference amplitude during the switching process, and compare it with the standard limit until all frequency points meet the standard limit, and locate the abnormal interference source and coupling path (i.e., the one that has a greater impact on the result);

[0185] All interference current sources are switched to no-load I mn (t) After the expression is completed, if the spectrum analysis of the detection point still exceeds the standard limit, turn off all interference current sources one by one, record the change of interference amplitude during the shutdown process, and compare it with the standard limit until all frequency points meet the standard limit, and locate the abnormal interference source (i.e., the one that has a greater impact on the result) and coupling path.

[0186] Please refer to Figure 6 , Embodiment 2 of the present invention is:

[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, the steps of a power system electromagnetic compatibility conducted interference assessment method described in the first embodiment are implemented.

[0188] In summary, the present invention provides a method and terminal for evaluating electromagnetic compatibility conducted interference of a power supply system, identifies interference sources and coupling paths according to the device schematic diagram, establishes interference source amplitude expressions and transfer functions of coupling paths, and establishes a simulation model, and performs simulation operation in combination with actual device parameters to evaluate electromagnetic compatibility conducted interference of the power supply system. A relatively accurate trend of system conducted interference superposition can be obtained, the frequency band range exceeding the index can be checked, and the problematic converter unit can be located, so that rectification is targeted, the electromagnetic compatibility test process can be accelerated, and the testing workload of engineering personnel can be reduced.

[0189] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A simulation calculation method for conducted noise, characterized in that: Includes steps: S1. Establish a power transmission schematic diagram of the power supply 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 a discretized interference source amplitude expression for each interference source, and establish a transfer function of the coupling path between each interference source and each electromagnetic compatibility conducted interference detection point; In step S2, the discrete interference source amplitude expression defined for each interference source is specifically: The complete form of the expression for the amplitude of the nth interference source in the form of a current source is: Indicates that the noise is expressed as the superposition of signals at x frequency points. When the frequency point is selected as a multiple of the regular base frequency ω0, the frequency of the i-th point among the x frequency points is expressed as iω0, and the peak value of the instantaneous amplitude of the noise at the i-th point is A i , the frequency is iω0, and the initial phase angle is The periodic function of A0 is the DC component of the signal; Because the common mode interference coupling path is AC, A0 cannot pass and can be ignored. In the electromagnetic compatibility test, the signal phase does not affect the judgment of the interference amplitude, so the phase is set to a fixed value, I mn (t)The expression is simplified to: When x is not a multiple of the regular base frequency ω0, the test frequency range (f min , f max ) within x frequency points (a1, ..., a x ) then: Among them, (A1, ..., A x ) is the interference amplitude at each frequency point, (f min , f max ) indicates the test frequency band; The transfer function of the coupling path between each interference source and each electromagnetic compatibility conducted interference detection point established in step S2 is specifically: According to 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 wire impedance Z n_wire and ground impedance Z n_GND , part of which passes through the equivalent network impedance to form 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 ground impedance Z n_GND , so it is ignored, and the coupling path transfer function G of the path nk from any interference source to any detection point can be obtained nk (jω): Among them, Z LISN is the preset standard value, Z n_GND The series RCL circuit is equivalent to: Z n_GND =R nk +jωL nk +1 / jωC nk ; Rnk, Lnk, Cnk are the resistance, inductance and capacitance of the ground impedance respectively, j represents the imaginary unit, and ω represents the frequency; S3. Construct an equivalent model expression for conducting noise evaluation and establish a simulation model; S4. Acquire actual parameters of the target device and full-load and no-load conducted interference test spectra when each interference source works independently, and perform simulation operations in combination with the simulation model.

2. A simulation calculation method for conduction noise according to claim 1, characterized in that: The actual parameters of the target device obtained in step S4 are specifically: Measure the ground impedance of all coupling paths from the interference source to the detection point in the target device one by one and obtain the corresponding parameter R nk , L nk , C nk .

3. A simulation calculation method for conduction noise according to claim 2, characterized in that: Parameter R nk , L nk , C nk The specific acquisition is: Turn off the converter connected to the coupling path to be measured and disconnect the wires and switches. Use the measuring equipment to measure the resistance R nk 、Inductance L nk and capacitor C nk The value of .

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

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

6. The simulation calculation method for conduction noise according to claim 1, characterized in that: The step S3 of establishing the simulation model includes the following steps: In the circuit simulation software, a simulation model including all interference sources, coupling paths and detection points of the target device is established: According to the definition of the discretized interference source amplitude expression in step S2, in the test frequency range (f min , f max ) to select x frequency points (a1, ..., a x ), establish all interference current sources in the simulation model; According to 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, a ground impedance model of all coupling paths is established in the simulation model; According to the conduction noise evaluation equivalent model expression in step S3, the noise V is added to each detection point of the simulation model. noise_k Spectral analysis of (jω).

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

8. The simulation calculation method for conduction noise according to claim 7, characterized in that: The simulation operation performed in combination with the simulation model in step S4 includes the following steps: According to the frequency point (a1, ..., a x ), interference voltage set {dBV mp (j2πa1), ..., dBV mp (j2πa x )} and the interference current set {Imp(ja1), ..., Imp(jax)} is: For each interference source, a discretized interference source amplitude expression is defined, where: THE k =I mp (j2πa k ); k∈[1,x]; Then the amplitude expression of the nth interference source is mn The discretized form of (t) is expressed as: I was obtained under no-load and full-load conditions respectively. mn (t) expression; All the interference source amplitude expressions, coupling path transfer functions G nk (jω) is brought into the simulation model, and spectrum analysis is set at all k detection points; Select different interference sources according to the actual working conditions of the target equipment, and use full load I mn (t) expression, and obtain the interference amplitude of the detection point from the spectrum analysis of the detection point.

9. The simulation calculation method for conduction 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, the steps in the simulation calculation method for conducted noise described in any one of claims 1 to 9 are implemented.

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