Simulation method of transient loss of copper bar / busbar in high-power converter

Abstract

The present application relates to the technical field of high-power converter, in particular to high-voltage copper bar / bus in the converter, and more particularly to a simulation method for transient loss of copper bar / bus in high-power converter. In order to solve the problem that the simulation result of the simulation method for transient loss of copper bar / bus in high-power converter is inaccurate, a new simulation method for transient loss of copper bar / bus in high-power converter considering high-frequency parasitic parameters is provided. The simulation is realized based on three-dimensional structure to extract parasitic distribution parameters of high-voltage and high-current copper bar / bus in high-power converter, and a high-frequency parasitic parameter circuit model is generated. The high-frequency parasitic parameter circuit model is embedded in the main circuit simulation to obtain working current containing high-frequency harmonics. Through multi-software joint simulation, the working current containing high-frequency harmonics close to the actual working current is used as an excitation source to calculate the real-time transient loss of copper bar / bus, which can well reproduce the field conditions and guide the design and rectification of actual products.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-power converter, in particular to high-voltage copper bar / bus in the converter, and specifically to a simulation method for transient loss of copper bar / bus in a high-power converter. BACKGROUND

[0002] A high-power converter is a large device integrating mechanical, electrical and electronic equipment. In order to improve the space utilization, the interconnection structure between electronic and electrical systems and between devices is complex, the structure is compact, and many types of cables are used, including copper bar / bus, power cable, control signal line and communication line, which bear high-voltage and large current. Thus, the high-frequency electromagnetic environment inside the converter becomes more and more complex.

[0003] In a high-power converter, we usually use copper bar / bus to bear positive and negative power alternating current and IGBT transient impact, which inevitably faces the mutual influence of conductor resistance and current to generate Joule heat, and the excessive temperature is easy to accelerate the aging and damage of other parts of the box.

[0004] Alternating large current conductors will generate alternating large electromagnetic fields. According to Faraday's law of electromagnetic induction, the conductor in the alternating field will generate eddy current, resulting in uneven magnetic field inside the conductor material, which is the skin effect. The higher the frequency, the more obvious the skin effect. The existence of skin effect makes the impedance of the conductor itself increase with the increase of high-order harmonics, resulting in larger loss. The skin effect calculation formula is as follows:

[0005]

[0006] Where: μr is the relative permeability, μ0 is the vacuum permeability, σ is the electrical conductivity, and w is the angular frequency.

[0007] The conductor resistance calculation formula is: R = p (L / S), where p is the resistivity, L is the length of the conductor, and S is the current flowing through the cross-sectional area.

[0008] The copper bar Joule heat calculation formula is: Q = I 2 R, where Q is the Joule heat, I is the current through the conductor, and R is the resistance of the conductor.

[0009] As can be seen from the above, the parasitic parameters of copper bar / bus itself and each other, the parasitic capacitance formed by IGBT module and heat sink, and the mutual coupling effect between parasitic capacitance and inductance, the actual converter will superimpose many high-frequency harmonics when working. Under the influence of high-frequency harmonics, the high-voltage copper bar / bus will form obvious skin effect, thus increasing its own resistance and loss, and causing excessive temperature rise.

[0010] In order to further guide the design and rectification of the product, the simulation technology is usually used to simulate the transient loss of the copper bar / busbar in the high-power converter, and the existing simulation method of the transient loss of the copper bar / busbar in the high-power converter does not consider the influence of high-frequency harmonics, that is, the ideal power source is used as the excitation source, the copper bar loss obtained is greatly different from the actual situation, the real-time transient loss cannot be reflected, the parasitic parameters of the high-voltage and high-current copper bar / busbar system are not considered and the influence of the parasitic parameters on the loss is not analyzed, so that the simulation result cannot truly simulate the actual working condition of the converter. SUMMARY

[0011] In order to solve the problem that the simulation result obtained by the simulation method of the transient loss of the copper bar / busbar in the high-power converter is inaccurate, a new simulation method of the transient loss of the copper bar / busbar in the high-power converter considering high-frequency parasitic parameters is provided.

[0012] The application is implemented by adopting the following technical scheme: the simulation method of the transient loss of the copper bar / busbar in the high-power converter, comprising the following steps:

[0013] 1) a three-dimensional model of the copper bar / busbar of the high-power converter is established by using a three-dimensional mechanical software, and is imported into a finite element analysis software AnsysQ3DExtractor, the three-dimensional model of the copper bar / busbar of the high-power converter imported into the AnsysQ3DExtractor is divided into different networks according to the interconnection connection relationship between the copper bar / busbar and according to the conductor conduction relationship, and in the division process, it is necessary to clearly define each network in the section set corresponding to the main circuit schematic diagram;

[0014] 2) an ideal model of the main circuit of the converter is established by using a main circuit simulation software Ansyssimplorer, and a part of the ideal model of the main circuit of the converter existing in the high-frequency parasitic parameter section is separated, each section is named by defining two port name combinations, and each section contains two ports;

[0015] 3) according to the network division, the high-frequency parasitic parameter section separated from the ideal model of the main circuit of the converter is mapped into the three-dimensional model of the copper bar / busbar of the high-power converter imported into the AnsysQ3DExtractor (that is, the port corresponding to the ideal model of the main circuit of the converter is correspondingly defined under each grid according to the specific position of the three-dimensional model of the copper bar / busbar of the high-power converter imported into the AnsysQ3DExtractor, and the same port name as the ideal model of the main circuit of the converter is defined one by one);

[0016] 4) High-frequency parasitic parameter extraction simulation settings are made for finite element analysis software AnsysQ3DExtractor (simulation settings can be set according to experience, such as setting the parasitic parameter extraction sweep range to 50Hz-10MHz with a step of 100KHz according to the FFT analysis experience of the measured waveform of a certain type of high-power converter), and then simulation analysis is performed to obtain a multi-dimensional matrix of high-frequency parasitic parameters of the copper bar / busbar (the matrix includes the high-frequency parasitic parameters of each section itself and the multi-stage coupling parasitic parameters between the ports and the ports), and a high-frequency parasitic parameter extraction three-dimensional model of the converter in the high-frequency harmonic frequency range is exported;

[0017] 5) In the main circuit simulation software Ansyssimplorer, the high-frequency parasitic parameter extraction three-dimensional model of the converter in the high-frequency harmonic frequency range in step 4) is imported, main circuit simulation is performed (the simulation time can be set to 500ms with a step of 10ns), and a main circuit model embedded with high-frequency parasitic parameters is formed;

[0018] 6) The copper bar / busbar transient loss simulation is completed based on finite element analysis software AnsysMaxwell (AnsysMaxwell and AnsysQ3DExtractor are two different finite element analysis software), a copper bar / busbar transient loss simulation model of the converter is established by using AnsysMaxwell software, the conductor material (copper) is defined, the solution domain is set, the grid subdivision is self-defined, the main circuit model embedded with high-frequency parasitic parameters in step 5) is imported into the transient loss simulation model AnsysMaxwell software as an external circuit, the working current corresponding to the copper bar / busbar containing high-frequency harmonics is collected in real time and used as the input excitation of the transient loss, the material is defined, the solution domain is set, the simulation time is set, the transient real-time loss simulation of the copper bar / busbar is performed, and thus the transient real-time loss waveform and distribution cloud diagram of the copper bar / busbar are obtained.

[0019] The beneficial effects of the present application are as follows: (1) a specific implementation method of high-frequency parasitic parameter extraction simulation of high-power converter high-voltage copper bar / busbar based on three-dimensional structure is proposed, the real and complex multi-stage coupling parasitic parameters existing in the converter can be introduced into ideal main circuit simulation in a field-circuit parallel manner, and a working current containing high-frequency harmonics closer to the actual working current can be obtained;

[0020] (2) through multi-software joint simulation, the working current containing high-frequency harmonics close to the actual working current is used as the excitation source, the real-time calculation of the transient loss of the copper bar / busbar is performed, the on-site working condition can be well reproduced, the design and rectification of the actual product can be better guided, and more valuable data support can be provided for solving the on-site fault. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Flow chart of the present application;

[0022] Figure 2 High-frequency parasitic parameter section diagram based on ideal model of main circuit of certain type of converter;

[0023] Figure 3 Main circuit model diagram embedded with high-frequency parasitic parameters;

[0024] Figure 4 Copper bar transient loss real-time waveform diagram of a certain time period;

[0025] Figure 5 Copper bar transient loss distribution cloud diagram at a certain time. DETAILED DESCRIPTION

[0026] As shown in Figure 1 , 2 , the copper bar / busbar transient loss simulation method in a high-power converter includes the following steps:

[0027] 1) A three-dimensional mechanical software is used to establish a three-dimensional model of the copper bar / busbar of a certain type of high-power converter, and the model is imported into the finite element analysis software AnsysQ3DExtractor. According to the interconnection connection relationship between the copper bar / busbar and the conductor conduction relationship, the three-dimensional model of the copper bar / busbar of the high-power converter imported into AnsysQ3DExtractor is divided into seven networks, and each component is as follows:

[0028] Net1: Four-quadrant input positive network (4QC+): contains four-quadrant input copper bar and middle layer busbar of rectifier module 1;

[0029] Net2: Four-quadrant output negative network (4QC-): contains four-quadrant output copper bar and middle layer busbar of rectifier module 2;

[0030] Net3: Positive busbar network (busbar+): includes positive busbar containing support capacitor, positive busbar of power module composite, positive busbar of intermediate DC transition, and positive busbar of intermediate DC copper bar;

[0031] Net4: Negative busbar network (busbar+): includes negative busbar containing support capacitor, negative busbar of power module composite, negative busbar of intermediate DC transition, and negative busbar of intermediate DC copper bar;

[0032] Net5: U-phase output network (U): includes U-phase output busbar and copper bar of inverter module;

[0033] Net6: U-phase output network (U): includes V-phase output busbar and copper bar of inverter module;

[0034] Net7: W-phase output network (W): including the inverter module W-phase output busbar and copper bar;

[0035] 2) Using the main circuit simulation software Ansyssimplorer, an ideal model of the converter main circuit is established, and based on the main circuit topology graph, the part with high-frequency parasitic parameter section is separated, each section is named with the defined combination of two port names, and each section contains two ports. For example, as shown in Figure 2

[0036] Collector of upper tube of rectifier 1 module bridge arm 1-collector of upper tube of rectifier 1 module bridge arm 2 (4QC1-4QC2);

[0037] Collector of upper tube of rectifier 1 module bridge arm 2-positive electrode of support capacitor 1 (4QC2-CAP1+);

[0038] Positive electrode of support capacitor 1-collector of upper tube of rectifier 2 module bridge arm 1 (CAP1+-CPC1);

[0039] Collector of upper tube of rectifier 2 module bridge arm 1-collector of upper tube of rectifier 2 module bridge arm 2 (CPC1-CPC2);

[0040] Collector of upper tube of rectifier 2 module bridge arm 2-collector of upper tube of rectifier 2 module bridge arm 3 (CPC2-CPC3);

[0041] Collector of upper tube of rectifier 2 module bridge arm 3-positive electrode of support capacitor 2 (CPC3-CAP2+);

[0042] Positive electrode of support capacitor 2-positive electrode of filter inductor (CAP2+-FTL+);

[0043] Positive electrode of filter inductor-positive electrode of support capacitor 3 (FTL+-CAP3+);

[0044] Positive electrode of support capacitor 3-collector of upper tube of inverter module bridge arm 1 (CAP3+-INVC1);

[0045] Collector of upper tube of inverter module bridge arm 1-collector of upper tube of inverter module bridge arm 2 (INVC1-INVC2);

[0046] Collector of upper tube of inverter module bridge arm 2-collector of upper tube of inverter module bridge arm 3 (INVC2-INVC3);

[0047] ​Net3 busbar+ network can be divided into 11 sections containing high-frequency parasitic parameters, and other networks are the same, Net1 four-quadrant input positive network (4QC+) is divided into 3 sections; Net2 four-quadrant output negative network (4QC-) is divided into 3 sections, Net4 busbar- network is divided into 10 sections; Net5 U-phase output network (U), Net6 U-phase output network (U), Net7 W-phase output network (W) are each divided into 1 section, a total of 36 ports.

[0048] 3) According to the network division, the high-frequency parasitic parameter section separated from the ideal model of the main circuit of the converter is mapped to the three-dimensional model of the copper bar / busbar of the high-power converter imported into AnsysQ3DExtractor (that is, the ports corresponding to the ideal model of the main circuit of the converter are defined one by one under each grid in correspondence with the specific position of the high-frequency parasitic parameter extraction three-dimensional model, with the same port name as the ideal model of the main circuit of the converter), taking the main circuit corresponding to Net3 busbar+ as an example, the mapping relationship between the ideal model of the main circuit of the converter and the high-frequency parasitic parameter extraction three-dimensional model is explained, and 12 ports are defined in Net3, including 4QC1, 4QC2, CAP1+, CAP2+, CAP3+, CPC1, CPC2, CPC3, FTL+, INVC1, INVC2, and INVC3;

[0049] 4) Set the high-frequency parasitic parameter extraction simulation of the finite element analysis software AnsysQ3DExtractor (the simulation settings can be set according to experience, such as setting the parasitic parameter extraction frequency sweep range to 50Hz-10MHz with a step of 100KHz based on the FFT analysis experience of the measured waveform of a certain type of high-power converter), and then perform simulation analysis to obtain a 30*30 copper bar / busbar high-frequency parasitic parameter multi-dimensional matrix (the matrix contains the high-frequency parasitic parameters of each section and the multi-level coupling parasitic parameters between ports), and the multi-dimensional matrix is exported in a packaged form to form a high-frequency parasitic parameter extraction three-dimensional model containing an external interface in the high-frequency harmonic frequency range of the converter;

[0050] 5) In the main circuit simulation software Ansyssimplorer, import the high-frequency parasitic parameter extraction three-dimensional model containing an external interface in the high-frequency harmonic frequency range of the converter in step 4), perform main circuit simulation to form a main circuit model embedded with high-frequency parasitic parameters, as shown in Figure 3 The simulation step is set to 10ns and the simulation duration is set to 500ms, and then the main circuit simulation is performed (the simulation duration can be set to 500ms and the step is 10ns);

[0051] 6) The copper bar / bus transient loss simulation is completed based on the finite element analysis software Ansys Maxwell. A transient loss simulation model of the converter copper bar / bus is established using the Ansys Maxwell software, the conductor material (copper) is defined, the solution domain is set, the mesh is divided, the input / output ports are set according to the current flow direction of the copper bar / bus, and the winding is loaded. The current excitation is imported through the winding. The main circuit model embedded with the high-frequency parasitic parameters in step 5) is imported into the transient loss simulation model Ansys Maxwell software in the form of an external circuit. The simulation duration is set to 550 ms (the simulation duration of the copper bar / bus transient loss simulation in step 6 is longer than the simulation duration of the main circuit simulation in step 5). The working current containing high-frequency harmonics corresponding to the copper bar / bus is collected in real time, and the working current is used as the input excitation of the transient loss, so as to obtain the transient real-time loss waveform and distribution cloud diagram of the copper bar / bus, as shown in FIGS. 10 and 11. Figure 4 and Figure 5 ​

Claims

1. A simulation method for transient losses of copper busbars / busbars in high-power converters, characterized in that, Includes the following steps: 1) Using 3D mechanical software, establish a 3D model of the copper busbar / busbar of the high-power converter and import it into the finite element analysis software AnsysQ3DExtractor. According to the interconnection relationship between the copper busbar / busbar and the conductor conduction relationship, divide the 3D model of the copper busbar / busbar of the high-power converter imported into AnsysQ3DExtractor into different networks. During the division process, it is necessary to clarify the segment set corresponding to the main circuit schematic diagram for each network. 2) Using the main circuit simulation software Ansyssimplorer, an ideal model of the converter main circuit is established and the part with high-frequency parasitic parameters is separated. Each part is named by a combination of two defined port names. 3) Based on the network partitioning, the high-frequency parasitic parameter segments separated from the ideal model of the converter main circuit are mapped to the copper busbar / busbar 3D model of the high-power converter imported into AnsysQ3DExtractor; 4) The high-frequency parasitic parameter extraction simulation settings were performed on the finite element analysis software AnsysQ3DExtractor, and then the simulation analysis was carried out to obtain the multi-dimensional matrix of high-frequency parasitic parameters of copper busbar / busbar, and the three-dimensional model of high-frequency parasitic parameter extraction in the high-frequency harmonic frequency range of the converter including the external interface was exported. 5) In the main circuit simulation software Ansyssimplorer, import the three-dimensional model of high-frequency parasitic parameters extracted from the converter with external interfaces in step 4) within the high-frequency harmonic frequency range, and perform main circuit simulation to form a main circuit model with embedded high-frequency parasitic parameters. 6) The transient loss simulation of the copper busbar / busbar was completed using the finite element analysis software AnsysMaxwell. An AnsysMaxwell software was used to establish a transient loss simulation model of the converter copper busbar / busbar, define the conductor material, set the solution domain, and customize the mesh. The main circuit model with embedded high-frequency parasitic parameters in step 5) was imported into the transient loss simulation model AnsysMaxwell software as an external circuit. The operating current containing high-frequency harmonics corresponding to the copper busbar / busbar was collected in real time and used as the input excitation for transient loss, thereby obtaining the transient real-time loss waveform and distribution cloud map of the copper busbar / busbar.

2. The method for simulating transient losses of copper busbars / busbars in a high-power converter according to claim 1, characterized in that, The simulation time for the transient loss simulation of the copper busbar / busbar in step 6) is longer than the simulation time for the main circuit simulation in step 5).

3. The method for simulating transient losses of copper busbars / busbars in a high-power converter according to claim 2, characterized in that, The simulation time for the main circuit simulation in step 5) is 500ms.

4. The method for simulating transient losses of copper busbars / busbars in a high-power converter according to claim 3, characterized in that, The simulation duration for the transient loss simulation of the copper busbar / busbar in step 6) is 550ms.

5. The method for simulating transient losses of copper busbars / busbars in a high-power converter according to claim 4, characterized in that, In step 5), the step size for the main circuit simulation is 10ns.

6. The method for simulating transient losses of copper busbars / busbars in a high-power converter according to claim 5, characterized in that, In step 4), the frequency step size for extracting high-frequency parasitic parameters during simulation is 100kHz.

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