CN112528580A

CN112528580A - Electromagnetic radiation simulation prediction method for flyback converter circuit board

Info

Publication number: CN112528580A
Application number: CN202011306564.XA
Authority: CN
Inventors: 杨汝; 吴键澄; 陈健玮; 欧嘉鸣; 杨红; 揭海; 刘浩祥; 朱旗; 王菁; 张宇帆; 钟振业; 陈浩
Original assignee: Guangzhou University
Current assignee: Guangzhou University
Priority date: 2020-11-19
Filing date: 2020-11-19
Publication date: 2021-03-19
Anticipated expiration: 2040-11-19
Also published as: CN112528580B

Abstract

The application relates to the technical field of electronic circuit simulation, in particular to an electromagnetic radiation simulation prediction method for a flyback converter circuit board. The method comprises the following steps: establishing an initial model of a flyback converter circuit board; setting parameters of a laminated layer and a passive device in the initial model to obtain a first model; setting a first excitation source port of a preset type device in the first model to obtain a second model; establishing a field effect transistor model; obtaining a third model according to the second model and the field effect transistor model; adding a model of the preset type device into the third model, and setting an excitation source for simulation to obtain simulation data; and obtaining the electromagnetic radiation distribution according to the simulation data. The electromagnetic radiation simulation prediction method saves the time cost of model machine debugging, and meanwhile, the whole electromagnetic radiation simulation prediction can be completed in a computer, so that the effects of quickly evaluating the design scheme and quickly giving the scheme correction and modification opinions are achieved, and a large amount of manpower and material resource costs are saved.

Description

Electromagnetic radiation simulation prediction method for flyback converter circuit board

Technical Field

The application relates to the technical field of electronic circuit simulation, in particular to an electromagnetic radiation simulation prediction method for a flyback converter circuit board.

Background

Flyback converters (also called Flyback converters) are the most widely used switching converter topologies in the current medium-small power switching power supply market. Common switching power supply products using Flyback converter topology include mobile phone chargers, notebook chargers, tablet chargers, desktop power supplies, desk lamp power supplies, and the like. With the development of high power density of power supply products, the operating frequency of switching power supply products is also continuously improved, and the problem of electromagnetic interference brought with the operating frequency is more and more emphasized by people. The existing research shows that the low-frequency-band conducted electromagnetic interference energy can flow back to the power grid through a transmission line to pollute the power grid and cause abnormal work of other peripheral electric equipment; the radiation electromagnetic interference of the high frequency band can affect the working state of the internal components of the power supply product in the near field range, thereby reducing the service life of the product; in the radiation far field range, the electrical appliances which generate high radiation electromagnetic interference energy can cause interference to the normal operation of peripheral precision instruments.

For safety reasons, relevant national standards such as GB 9254-. The products of the enterprise must pass these standards to be commercially available. According to the standard, the test of the radiation electromagnetic interference is generally required to be carried out in a 3-meter or 10-meter anechoic chamber, the cost of the test environment is extremely high, and common switching power supply manufacturers are difficult to bear the construction and operation costs. Today, products of enterprises are pre-certified by a third-party detection mechanism before being detected and identified by a quality control bureau. However, the detection period and the detection cost of the detection mechanism are important indexes to be considered by the production enterprise. Generally, when a product is required to reach a standard, the number of times of electromagnetic compatibility (EMC) test and rectification can be more than one, and the time cost and the design cost of the traditional development process of the switching power supply product are huge. The technology of performing EMC simulation prediction on the designed product by using computer software from the beginning of product design can greatly reduce the cost of the aspect for production enterprises.

The existing simulation prediction technology for the electromagnetic radiation of the switching power supply product regards the radiation generated by an input/output cable as a main radiation factor, neglects the radiation generated by a PCB, but actually, the part needing EMC correction is just the PCB, so that the existing technology has low prediction accuracy, and cannot provide a targeted correction suggestion for EMC correction of a switching converter PCB. In addition, the conventional simulation prediction technology for electromagnetic radiation of the PCB mainly performs simulation prediction on a circuit without magnetic elements, such as an IC circuit, and the like, but is not considered in the case of a PCB with a high-frequency transformer, such as a Flyback converter, and is also considered in the case of a three-dimensional package structure of a field effect transistor (MOSFET). In addition, the existing simulation prediction technology for electromagnetic radiation of switching power supply products regards radiation generated by an input/output cable as a main radiation factor, numerical simulation needs to be carried out on the radiation, a prototype is debugged, common-mode noise voltage generated by a PCB prototype is tested through equipment such as an LISN (laser induced noise) receiver and the like, and the established mathematical prediction model can be further introduced for simulation prediction, so that expensive test equipment such as an EMI receiver and the like is also needed for electromagnetic radiation prediction of the switching power supply, the prototype needs to be debugged stably, the prediction scheme is quite complex to implement, and the time period is long.

Disclosure of Invention

The invention aims to solve the technical problems that the existing simulation prediction technology for the electromagnetic radiation of the switch power supply product ignores the radiation generated by a PCB and has low prediction accuracy.

In order to solve the technical problem, an embodiment of the present application discloses an electromagnetic radiation simulation prediction method for a flyback converter circuit board, where the method includes:

establishing an initial model of a flyback converter circuit board according to the circuit board layout of the flyback converter;

setting a lamination layer, passive device parameters and an impedance network in the initial model to obtain a first model;

setting a first excitation source port of a preset type device in the first model to obtain a second model, wherein the first excitation source port is used for adding an excitation source; the preset type device at least comprises a rectifier bridge, a diode, a field effect transistor and a high-frequency transformer;

establishing a three-dimensional structure model of the field effect transistor;

obtaining a third model according to the second model and the three-dimensional structure model of the field effect transistor;

adding the model of the preset type device into the third model to obtain a fourth model;

simulating the fourth model by setting an excitation source to obtain simulation data, wherein the excitation source is voltage or current added to the first excitation source port;

and obtaining the electromagnetic radiation distribution according to the simulation data.

Furthermore, the model of the high-frequency transformer comprises a primary side winding inductance, a secondary side winding inductance, a primary side leakage inductance, a secondary side leakage inductance, a primary side interlayer parasitic capacitance, a secondary side interlayer parasitic capacitance and a primary and secondary side coupling parasitic capacitance;

the primary side leakage inductor is connected with the primary side winding inductor in series and then connected with the primary side interlayer parasitic capacitor in parallel;

the secondary side leakage inductor is connected in series with the secondary side winding inductor and then connected in parallel with the parasitic capacitor between the secondary side layers;

and the primary and secondary coupling parasitic capacitors are connected between the primary winding inductor and the secondary winding inductor.

Further, the setting a first excitation source port of a preset type device in the first model to obtain a second model includes:

setting a first excitation source port at a preset position of a bonding pad in the first model, wherein the preset position is a connection position of a pin of the preset type device and the bonding pad;

and setting a ground comparison network of the first excitation source port in the first model to obtain a second model.

Further, after setting the first excitation source port of the preset type device in the first model to obtain a second model, the method further includes:

and checking the circuit board trace network signals in the second model to obtain a first scattering parameter of the second model.

Further, the field effect transistor has three pins, and the establishing of the three-dimensional structure model of the field effect transistor comprises the following steps:

the three pins of the field effect transistor are equivalent to a dipole antenna model;

and setting a second excitation source port in the dipole antenna model to establish a three-dimensional structure model of the field effect transistor.

Further, after the establishing the three-dimensional structure model of the field effect transistor, the method further includes:

and performing frequency sweep analysis on the three-dimensional structure model of the field effect transistor to obtain the electromagnetic field radiation distribution and the second scattering parameter of the three-dimensional structure model of the field effect transistor in the space.

Further, obtaining a third model according to the second model and the three-dimensional structure model of the field effect transistor includes:

and connecting the three-dimensional structure model of the field effect transistor with a switch tube connecting port in the second model to obtain the third model.

Further, the adding the model of the preset type device to the third model to obtain a fourth model includes:

connecting a pin of the model of the preset device type with the first excitation source port in the third model to obtain a fourth model; the model of the preset device type is a model obtained according to a preset program or a model directly added by setting device parameters.

Further, the second excitation source port includes a gate pin port and a source pin port, and the fourth model includes an input wire; the simulation data obtained by simulating the fourth model by setting the excitation source comprises:

adding pulse width modulation signals on the gate pin port and the source pin port to serve as a switching tube excitation source;

adding mains voltage as an input excitation source on the input lead;

and simulating the fourth model according to the switching tube excitation source and the input excitation source to obtain simulation data.

Further, the obtaining of the electromagnetic radiation distribution according to the simulation data includes:

performing far field simulation according to the simulation data to obtain a far field electromagnetic radiation result;

and correcting the far-field electromagnetic radiation result to obtain the electromagnetic radiation distribution of the preset distance.

The electromagnetic radiation simulation prediction method for the flyback converter circuit board provided by the embodiment of the application has the following technical effects:

electromagnetic radiation of a PCB (printed Circuit Board) of the Flyback converter is predicted through simulation, and a high-frequency transformer equivalent model and a field effect transistor three-dimensional packaging model are added into the simulation prediction model, so that the characteristics of leakage inductance and the like of the high-frequency transformer and the influence of a three-dimensional packaging structure of the field effect transistor on the radiation can be fully considered. The electromagnetic radiation simulation prediction method can be realized at the beginning of product design, namely when a product PCB design drawing comes out, common mode noise voltage does not need to be extracted for simulation prediction after prototype debugging is finished, time cost of prototype debugging is saved, expensive test equipment is not needed, the whole electromagnetic radiation simulation prediction can be completed in a computer, the effects of rapidly evaluating a design scheme and rapidly giving scheme correction and improvement suggestions are achieved, and a large amount of manpower and material resource cost is saved.

Drawings

In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a flowchart of an electromagnetic radiation simulation prediction method for a flyback converter circuit board according to an embodiment of the present application;

FIG. 2 is a schematic diagram of the electric field distribution of a TO-220 packaged MOSFET on the ground according TO an embodiment of the present application;

FIG. 3 is a schematic diagram of scattering parameters of a MOSFET gate of a TO-220 package according TO an embodiment of the present application;

fig. 4 is a schematic diagram illustrating an excitation source port configuration provided in an embodiment of the present application;

fig. 5 is a schematic diagram of a high-frequency transformer model provided in an embodiment of the present application;

fig. 6 is a schematic diagram of an ANSYS Circuit Designer engineering interface after an active device and an excitation source are added according to an embodiment of the present disclosure;

fig. 7 is a schematic waveform diagram of an added excitation source Vgs provided in the embodiment of the present application;

fig. 8 is a schematic diagram of a far-field electromagnetic radiation simulation result provided in an embodiment of the present application;

fig. 9 is a schematic diagram of a far-field electromagnetic radiation simulation result with added mark points according to an embodiment of the present application;

FIG. 10 is a schematic diagram of a near-field magnetic field radiation distribution provided by an embodiment of the present application;

FIG. 11 is a schematic diagram of a near-field electric field radiation distribution provided by an embodiment of the present application;

FIG. 12 is a schematic diagram showing the horizontal results of a 3m anechoic chamber test according to an embodiment of the present application;

fig. 13 is a schematic diagram illustrating vertical results of a 3m anechoic chamber test according to an embodiment of the present disclosure.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or server that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

The technology of performing EMC simulation prediction on a designed product by utilizing computer software from the beginning of product design can greatly reduce the cost of the aspect for a production enterprise. The flyback converter is provided with a flyback transformer, and is different from a common PCB circuit product in simulation prediction.

The existing simulation prediction scheme for electromagnetic radiation of switching power supply products considers that the radiation interference of the switching power supply consists of differential mode radiation and common mode radiation, wherein the differential mode radiation

Common mode radiation

When θ is 90 ° and sin θ is 1, the common mode radiation and the differential mode radiation reach a maximum:

wherein E is_DMElectric field strength (V/m), E, representing differential mode radiation_cmThe electric field strength of common mode radiation is shown, f is the frequency (Hz) of an equivalent loop, S is the area (m2) surrounded by the magnetic dipole antenna, I is the current (A) passing through the loop, and r is the distance (m) from the observation point to the center point of the differential mode or common mode current loop.

Therefore, common-mode radiation of the switching power supply accounts for a dominant factor of radiation interference, and the input and output long cable is the most favorable carrier for emitting the common-mode radiation, so that most radiation interference prediction schemes are equivalent to a dipole antenna by the input and output long cable, and common-mode noise voltage of input and output obtained through testing is used as an excitation source of the antenna for simulation prediction. Although such a prediction scheme can evaluate the electromagnetic radiation level of the switching power supply product to a certain extent, the common mode noise voltage signal of the switching power supply product can be tested and extracted only after the prototype is successfully debugged, so that the electromagnetic compatibility of the product is not considered at the beginning of design in a strict sense, and considerable time cost is required for debugging the prototype. On the other hand, the common mode noise generated by the PCB is used as an excitation source of the equivalent antenna model of the input/output cable, which reflects that the PCB is a source of electromagnetic radiation of the switching power supply product, and the consideration of the electromagnetic compatibility of the PCB is a key point to be considered by a manufacturing enterprise at the beginning of design.

In addition, there are some schemes for simulating a PCB, which are effective in the analysis of the electromagnetic compatibility diagnosis of most PCB-level circuit products (such as high-speed signal control circuits, IC packages, etc.), but do not sufficiently consider the influence of the leakage characteristics of the magnetic elements such as the high-frequency transformer included in the switching power supply product such as the Flyback converter on the electromagnetic radiation.

Based on this, an embodiment of the present application discloses an electromagnetic radiation simulation prediction method for a flyback converter circuit board, and fig. 1 is a flowchart of the electromagnetic radiation simulation prediction method for the flyback converter circuit board provided in the embodiment of the present application, as shown in fig. 1, the method includes:

s101: establishing an initial model of a flyback converter circuit board according to the circuit board layout of the flyback converter;

in the embodiment of the application, the component packaging, the circuit schematic diagram of the Flyback converter to be designed and the PCB layout of the designed circuit are drawn in the aluminum Designer software. And then importing the drawn circuit PCB engineering file into ANSYS SIwave software for simulation. As an example, the drawn circuit PCB engineering output is converted into an anf file, which is imported into ANSYS SIwave software to obtain an initial model of the flyback converter circuit board.

S103: setting a lamination layer, passive device parameters and an impedance network in an initial model to obtain a first model;

in the embodiment of the application, the anf file after the PCB layout is converted is imported into ANSYS SIwave software, the validity Check of the PCB is firstly carried out, and if the result of the validity Check is wrong, the validity Check needs to be processed. And if no error exists, sequentially setting the lamination, the bonding pad and the via hole, the parameters of passive devices such as a resistance inductance capacitance (RLC) and the like, and the grounding impedance network, and obtaining a first model after setting is finished.

S105: setting a first excitation source port of a preset type device in the first model to obtain a second model;

in the embodiment of the application, a first excitation source port is arranged at a preset position of a bonding pad in a first model, and the preset position is a connecting position of a pin of a preset type device and the bonding pad; and setting a ground comparison network of the first excitation source port in the first model to obtain a second model. Specifically, an excitation source port is added first, and in electromagnetic simulation software such as ANSYS, if excitation source addition needs to be performed in combination with other software, the excitation source port needs to be set, which is represented by a port in the software, and the set port can play a role in information connection with an excitation source of external software or a component model, and the like. Adding ports on each concerned active device (such as a diode, a rectifier bridge and a MOSFET) and a bonding pad at a pin connection position of a high-frequency transformer, simultaneously setting a ground comparison network (Ref. Net) to GND, then simulating SYZ parameters between the added network ports, and checking the signal integrity of the concerned PCB trace network, wherein the obtained scattering parameter (S parameter) file is the key of subsequent simulation. As a preferred embodiment, when setting the excitation source port, the excitation source port is set only for the active device that needs attention, and for the Flyback converter, the excitation source port needs to be set: the reference comparison network of each excitation source port is GND.

S107: establishing a three-dimensional structure model of the field effect transistor;

in the embodiment of the application, three pins of a field effect transistor are equivalent to a dipole antenna model; and setting a second excitation source port in the dipole antenna model to establish a three-dimensional structure model of the field effect transistor. And then, carrying out frequency sweep analysis on the three-dimensional structure model of the field effect transistor to obtain the electromagnetic field radiation distribution and the second scattering parameter of the three-dimensional structure model of the field effect transistor in the space. As an example, the union ANSYS HFSS emulates a MOSFET three-dimensional package structure: the three pins of the MOSFET are equivalent to a dipole antenna, a MOSFET three-dimensional structure model is built on ANSYS HFSS, a simulator used is Terminal, and excitation source ports arranged at the grid (g), the drain (d) and the source(s) of the three pins of the MOSFET are Lumpedport. At ANSYS HFSS, there are two kinds of excitation source ports, one is Wave port and one is Lumped port, where Wave port refers to external port, usually defined as the cross section of transmission line, where the external means that there is field distribution only on one side, and generally only at the boundary of radiation boundary condition and background, and one side needs to be set on a plane attached to the device when used; the Lumpedport refers to an internal Port, signals need to be added to the structure through a test system, similar to a test probe of the test system, Lumpedport injects voltage and current signals into the structure, and in the embodiment of the application, the voltage or the current needs to be added externally as excitation signals, so the Lumpedport is set in the joint simulation.

In the embodiment of the application, the three-dimensional packaging structure of the MOSFET simulated in the HFSS increases the influence of the MOSFET packaging structure on the radiation electromagnetic interference. After the MOSFET chip is manufactured, a shell needs to be added to the MOSFET chip, which is the MOSFET package. The package housing serves primarily as support, protection and cooling, while also providing electrical connection and isolation for the chip, thereby completing the circuit between the MOSFET device and other components. Different packages and designs, the specification and dimensions of MOSFETs, various electrical parameters, etc. may be different, and their functions in the circuit may also be different. MOSFET packages are divided by the way they are mounted on a PCB board, and there are two main categories: plug-in (ThroughHole) and surface mount (SurfaceMount). As shown in fig. 2, the MOSFET package simulated in the embodiment of the present application is in the form of a plug-in package, specifically TO-220, and the three-dimensional model is established with reference TO package parameters of a component data manual. Setting the frequency sweep analysis frequency band to be 30MHz-1GHz, checking the distribution condition of electric field and magnetic field radiation of the packaging form in a three-dimensional space through simulation, and obtaining an S parameter curve of a port as shown in figure 3, wherein the S parameter curve is data required by subsequent simulation.

In the embodiment of the application, considering the influence of the three-dimensional packaging factor of the MOSFET of the switching tube on radiation, ANSYS HFSS, ANSYS Circuit design and ANSYS SIwave are combined to perform electromagnetic radiation simulation, wherein ANSYS HFSS simulates S parameters of a concerned MOSFET three-dimensional packaging structure, ANSYS SIwave simulates electromagnetic radiation of a PCB, and the ANSYS Circuit design is used as a key part for intermediate data interaction and excitation source and active device model addition.

S109: obtaining a third model according to the second model and the three-dimensional structure model of the field effect transistor;

in the embodiment of the application, the MOSFET three-dimensional model and the second model are led into the same simulation software, so that the MOSFET three-dimensional model is connected with the switch tube connecting port in the second model to obtain the third model. Specifically, joint ANSYS HFSS simulates a MOSFET three-dimensional package structure. An ANSYS SIwave engineering file (file suffix: siw) of the above second model was derived, and the above ANSYS SIwave engineering file was added to ANSYS Circuit Designer engineering by the import model function of ANSYS Circuit Designer software. Fig. 4 is a schematic diagram of an excitation source port setup provided in this embodiment of the present application, and as shown in fig. 4, it can be seen that ANSYS SIwave engineering is equivalent to a square, pins around the square model are the excitation source port ports set in the PCB board, and the names of each excitation source port correspond to the names of the PCB trace network where the excitation source port is located. Similarly, the MOSFET three-dimensional model obtained by simulation in the HFSS is imported into the Circuit Designer engineering through the import model function.

S111: adding a model of a preset type device into the third model to obtain a fourth model;

in the embodiment of the application, a pin of a model with a preset device type is connected with a first excitation source port in a third model to obtain a fourth model; the model of the preset device type is a model obtained according to a preset program or a model directly added by setting device parameters. As an example, a corresponding component model is added on each stimulus source port. Optionally, adding an active device model in the ANSYS Circuit Designer engineering has at least the following two ways: firstly, a Spice model of active devices such as an MOSFET, a driving chip, a diode and the like is downloaded on an official website of a component manufacturer and is directly imported; secondly, selecting a proper blank Component model from the Component according to a Component data manual, and then setting parameters of the blank Component model. In addition, when the high-frequency transformer model is added, the high-frequency equivalent model of the high-frequency transformer comprises parameters such as the primary and secondary inductances, the primary and secondary leakage inductances, the primary and secondary interlayer parasitic capacitances, the primary and secondary inter-winding parasitic capacitances and the like. In order to fully consider parameters of the high-frequency transformer under practical working conditions such as leakage inductance and the like, a three-capacitor high-frequency transformer model is adopted. Fig. 5 is a schematic diagram of a high-frequency transformer model provided in an embodiment of the present invention, as shown in fig. 5, parasitic parameters of the three-capacitor high-frequency transformer model are easily measured by an LCR tester, and the LCR tester can accurately and stably measure various component parameters, mainly a tester for testing inductance, capacitance, and resistance. As shown in fig. 5, Lp represents the inductance of the primary coil, Ls represents the inductance of the secondary coil, and the inductance setting is calculated by referring to a theory. In consideration of leakage inductance of the high-frequency transformer, small inductors are respectively connected in series with the primary winding inductance and the secondary winding inductance to serve as leakage inductances Lp _ Leak and Ls _ Leak, interlayer parasitic capacitances Cp and Cs of the primary side and the secondary side and parasitic capacitances Cps between windings are respectively connected in parallel, and Rp and Rs are parasitic resistances of a primary coil and a secondary coil of the transformer. When the design parameters of the transformer of the Flyback converter are determined, namely the turn ratio of the primary side and the secondary side of the high-frequency transformer and the inductance are determined, the parasitic parameters can be directly measured in the LCR instrument. Parasitic parameters of the high-frequency transformer equivalent model are easy to measure through an LCR instrument, application in practical engineering is facilitated, and if research needs, more complex high-frequency transformer equivalent models such as six capacitors and the like can be used for improving simulation precision.

S113: simulating the fourth model by setting an excitation source to obtain simulation data;

in the embodiment of the application, after the active device model and the high-frequency transformer model are added, the excitation source is added. In electromagnetic simulation software such as ANSYS, an excitation source refers to a voltage or a current added to an excitation source port. The excitation source is added to the two ends of the grid and source pins of the MOSFET serving as the switching tube and the input lead of the PCB in the embodiment of the application. Specifically, a simulated Pulse Width Modulation (PWM) signal is added to two ends of a GS pin of a switching tube MOSFET as an excitation source, a 220VAC mains voltage is added to a PCB input L, N line as an input excitation source signal, and three Lumpedport ports have been set in an HFSS in the introduced three-dimensional model of the MOSFET, and are connected to G, D, S three excitation source port ports, respectively. Fig. 6 is a schematic diagram of an ANSYS Circuit Designer engineering interface after an active device and an excitation source are added, as shown in fig. 6, a transient analysis (transient analysis) is set in the ANSYS Circuit Designer, and a simulation duration and a step length of a preset value are set to obtain a corresponding simulation data file. As an example, fig. 7 is a schematic diagram of a waveform of an added excitation source Vgs provided by an embodiment of the application, as shown in fig. 7, in an implementation case of a Flyback converter for outputting 5V/1A at 220VAC input, a simulation duration is set to be 50ms, a step size is set to be 10ns, and whether the waveform of the added excitation source is correct or not is verified through Vprobe check at the end of simulation. And then exporting the simulation result of the ANSYS Circuit Designer to the SIwave project through a Push execution instruction, and realizing data exchange between the two software, wherein the file name suffix is.tmp.

S115: and obtaining the electromagnetic radiation distribution according to the simulation data.

In the embodiment of the application, the electromagnetic radiation of the switch converter comprises near-Field radiation and Far-Field radiation, after the file of the simulation result is obtained, the file returns to ANSYS SIwave engineering, the Far-Field electromagnetic radiation is simulated and predicted through a computer Far Field simulation mode, the distribution condition of the near-Field electromagnetic Field is simulated through a computer near Field simulation mode, and the two simulation modes both need to specify an excitation source file and set a simulation frequency range and frequency point information. As an alternative embodiment, a sweep range of 30MHz to 1GHz is set. Note that the excitation source data files required by the two simulation modes are both obtained by simulation in ANSYS Circuit Designer in the previous step.

In the embodiment of the application, the simulation result is a spectrogram, the abscissa is frequency, the ordinate is radiation electric field intensity, the unit is dBuV/m, and the detection of the detection mechanism is 3m far field, so that the ordinate is divided by 3 in numerical value, then shifted up by 120 units to be converted into dBuV, then shifted up by 40 unit correction amounts, namely dB (maxetal/3) +120+40, and then logarithmic operation is performed on the X coordinate, and a standard limit line is set. Fig. 8 is a schematic diagram of a far-field electromagnetic radiation simulation result provided in this embodiment, in which several data points are labeled in the far-field electromagnetic radiation simulation result for comparison with measured data. Fig. 9 is a schematic diagram of a far-field electromagnetic radiation simulation result with added mark points according to an embodiment of the present application. As shown in fig. 8 and 9, the far-field electromagnetic radiation simulation result is checked, and it can be seen from the diagram that the low frequency band has the frequency points exceeding the standard.

In this embodiment of the present application, fig. 10 is a schematic diagram of a near-field magnetic field radiation distribution provided by an embodiment of the present application, and fig. 11 is a schematic diagram of a near-field electric field radiation distribution provided by an embodiment of the present application, as shown in fig. 10 and fig. 11, a simulation result of near-field electromagnetic radiation is checked, the simulation result is a cloud diagram corresponding to each different frequency point, electric field radiation intensity distribution and magnetic field radiation intensity distribution near the frequency point with higher radiation are respectively checked by selecting "E" and "H", and then a dominant factor of electric field or magnetic field radiation generated around which component near the frequency point is analyzed, so as to give a reference suggestion of PCB rectification.

In the embodiment of the application, a corresponding prototype is manufactured for the Flyback converter PCB board for which the electromagnetic radiation simulation result shown in fig. 8 to 11 is obtained, and the prototype is tested in a 3m anechoic chamber to verify the prediction accuracy of the electromagnetic radiation simulation prediction method for the Flyback converter circuit board in the embodiment of the application. Fig. 12 is a schematic diagram of a horizontal direction result of a 3m anechoic chamber test provided by an embodiment of the present application, and fig. 13 is a schematic diagram of a vertical direction result of the 3m anechoic chamber test provided by the embodiment of the present application, and as shown in fig. 12 and fig. 13, comparing the two laboratory test reports with the simulation results shown in fig. 8-9, it is found that the problem of excessive radiation exists in the vicinity of frequency points such as 50MHz, 70MHz, 100MHz, 125MHz, 157MHz, and the simulation result is basically consistent with the experimental test result. It should be noted that the actual laboratory test is divided into the vertical direction test and the horizontal direction test, the test results in the two directions are used as the judgment basis of the radiation electromagnetic interference level, and similarly, the simulation method is also used as a prediction scheme for evaluating the radiation electromagnetic interference level of the Flyback converter before debugging a prototype, so that a reference suggestion is provided for the EMC correction of the product in the actual engineering, and the effect of effectively shortening the product research and development period is achieved.

The electromagnetic radiation simulation prediction method for the flyback converter circuit board has the following advantages:

1. PCB radiation simulation of a flyback converter with magnetic elements such as a high-frequency transformer is considered, and the method is not only limited to electromagnetic radiation simulation of an IC digital circuit PCB;

2. the electromagnetic radiation simulation prediction of the Flyback converter and other switching power supplies can be realized by full computer simulation, an EMC correction scheme can be given before prototype debugging, complex processes such as parameter test extraction and simulation prediction are not required to be performed after the prototype debugging is finished, a large amount of prototype debugging time and the use frequency of EMI receivers and other high equipment are saved, the period of EMC correction of switching power supply products by production enterprises is shortened, and certain cost is saved;

3. parasitic parameters between a three-dimensional packaging structure of the MOSFET of the switching tube and the pin are considered, so that simulation is closer to actual test;

4. near field radiation can be very audio-visual with the radiation of each frequency point PCB board with the direct-viewing presentation of form of cloud picture, can inform the source of engineer PCB board radiation more directly perceivedly, can more efficient help the engineer carry out EMC rectification.

It should be noted that: the sequence of the embodiments of the present application is only for description, and does not represent the advantages and disadvantages of the embodiments. And specific embodiments thereof have been described above. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims may be performed in a different order than in the embodiments and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing may also be possible or may be advantageous.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the apparatus embodiment, since it is substantially similar to the method embodiment, the description is relatively simple, and for the relevant points, reference may be made to the partial description of the method embodiment.

It will be understood by those skilled in the art that all or part of the steps for implementing the above embodiments may be implemented by hardware, or may be implemented by a program instructing relevant hardware, where the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disk, etc.

The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. An electromagnetic radiation simulation prediction method for a flyback converter circuit board is characterized by comprising the following steps:

2. The simulation prediction method of claim 1, wherein the model of the high frequency transformer comprises a primary winding inductance, a secondary winding inductance, a primary leakage inductance, a secondary leakage inductance, a primary interlayer parasitic capacitance, a secondary interlayer parasitic capacitance, and a primary and secondary coupling parasitic capacitance;

3. The simulation prediction method of claim 1 or 2, wherein the setting of the first excitation source port of the preset type device in the first model to obtain a second model comprises:

4. The simulation prediction method of claim 3, wherein after setting the first excitation source port of the preset type device in the first model to obtain a second model, the method further comprises:

5. The simulation prediction method of claim 4, wherein the field effect transistor has three pins, and wherein the establishing a three-dimensional structure model of the field effect transistor comprises:

6. The simulation prediction method of claim 5, wherein after the establishing the three-dimensional structure model of the field effect transistor, the method further comprises:

7. The simulation prediction method of claim 6, wherein the deriving a third model from the second model and the three-dimensional structure model of the field effect transistor comprises:

8. The simulation prediction method of claim 7, wherein the adding the model of the preset type device to the third model to obtain a fourth model comprises:

9. The simulation prediction method of claim 8, wherein the second excitation source port comprises a gate pin port and a source pin port, and wherein the fourth model comprises an input wire; the simulation data obtained by simulating the fourth model by setting the excitation source comprises:

adding mains voltage as an input excitation source on the input lead;

10. The simulation prediction method of claim 1, wherein the deriving an electromagnetic radiation distribution from the simulation data comprises: