Simulation analysis method for near-field radiation characteristics of power supply module

Abstract

The invention discloses a power module near-field radiation characteristic simulation analysis method, and belongs to the technical field of electromagnetic compatibility. According to the method, aiming at the near-field radiation characteristic problem of the power supply module, a power supply module PCB full-wave three-dimensional numerical simulation model is built by using CST, and the near-field radiation characteristics of the power supply module PCB under different output end parameter configurations are obtained through simulation by changing the filter inductance and capacitance values of the output end of the power supply module. And the influence of different PCB grounding layer segmentation modes on the near-field radiation characteristics of the power supply module is analyzed, and a reference basis is provided for subsequent CAN node module PCB optimization.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic compatibility, and in particular to a method for simulating and analyzing near-field radiation characteristics of a power module. Background Art

[0002] Electromagnetic noise, electromagnetic pulses (EMP), and other electromagnetic signals that can have a harmful effect on the operation of electronic equipment are collectively referred to as electromagnetic interference. Electromagnetic interference signals often produce transient surges in circuits through coupling with metal media, thereby coupling into electronic equipment and seriously affecting its internal functional circuits. As a core component of the CAN bus electronic control system, the CAN node module mainly includes the minimum system, CAN transceiver circuit, and other functional circuits. Since the CAN node module PCB is usually encapsulated in a metal box with electromagnetic shielding, electromagnetic interference signals can be coupled into the box through antennas, cables, holes, and gaps. Cables are generally connected to the PCB through connectors with metal terminals, allowing electromagnetic interference signals to affect the internal functional circuits.

[0003] In the engine CAN bus distributed electronic control system, the operating voltage of the minimum system circuit and signal conditioning circuit on the CAN node module PCB is 5V. Therefore, a step-down converter circuit is required to convert the 12V voltage provided by the battery to 5V to power both. DC / DC switching power supply chips offer the advantages of high conversion efficiency, a wide input range, and excellent stability under load changes and input voltage fluctuations. The switching power supply circuit uses the switching elements within the power supply chip to switch current at a high frequency, generating high-frequency switching signals, which in turn generate high-frequency electromagnetic fields, generating near-field radiation effects on the functional circuits on the PCB. By performing near-field radiation simulation analysis on the DC / DC switching power supply module PCB, the noise source can be quickly located. By analyzing the frequency domain characteristics of the power supply module's near-field radiation, the frequency band in which the near-field radiation energy is concentrated can be determined. Summary of the Invention

[0004] The present invention provides a simulation and analysis method for the near-field radiation characteristics of a power module. Aiming at the problem of the near-field radiation characteristics of the power module, the present invention analyzes the influence of different output filter inductor and capacitor parameters and PCB ground layer segmentation methods on the near-field radiation characteristics of the switching power module, providing a reference basis for the optimization of the PCB of the CAN node module.

[0005] An embodiment of the present invention provides a method for simulating and analyzing near-field radiation characteristics of a power module, comprising the following steps:

[0006] Step 1: Use simulation software to build a full-wave three-dimensional numerical simulation model of the LC filter circuit at the output end of the power module PCB, and apply the output signal of pin 3 of the power chip to the corresponding position of the full-wave three-dimensional numerical simulation model;

[0007] Step 2: Analyze the near-field radiation characteristics of the power module PCB using simulations for different values ​​of the filter inductor and capacitor at the output end of the power module PCB.

[0008] Step 3: Analyze the near-field radiation characteristics of the power module PCB under different power module PCB ground layer segmentation methods through simulation.

[0009] Optionally, in one embodiment of the present invention, in step 1, the power module PCB is a DC / DC switching power supply chip MP2225, the core circuit is a step-down DC / DC converter, and the basic topology structure is a power semiconductor switch tube controlled by a PWM signal output by a pulse width modulator inside the power chip.

[0010] Optionally, in one embodiment of the present invention, in step 1, in step 1, a power module PCB is designed based on a DC / DC switching power supply chip, the DC / DC switching power supply chip is a DC / DC step-down converter with a maximum input voltage of 22V and a load current of 9A, and the chip has a built-in short-circuit protection working mode.

[0011] Optionally, in one embodiment of the present invention, in step 1, by setting the simulation frequency range, boundary conditions, grid, electric field time domain solver and field detector in the simulation software, a complete full-wave three-dimensional numerical simulation model is built, and an external port input excitation signal is added at the key pins of the power module PCB.

[0012] Optionally, in one embodiment of the present invention, in step 1, the sampling period of the oscilloscope is set to 10 ns, and the time domain waveform of the output voltage signal of pin 3 of the power module PCB is obtained.

[0013] Optionally, in one embodiment of the present invention, in step 2, the output end filter capacitor of the power module PCB is set to 10 μF, and the filter inductance is set to 4.7 μH, 15 μH, and 22 μH respectively under the initial conditions, and the near-field radiation intensity of the power module PCB is simulated and calculated respectively; the output end filter inductance of the power module PCB is set to 4.7 μH, and under the initial conditions that the filter capacitor values ​​are 10 μF, 100 μF, and 220 μF respectively, the near-field radiation intensity of the power module PCB is simulated and calculated respectively.

[0014] Optionally, in one embodiment of the present invention, in step 3, the PCB ground layer is reasonably divided to distinguish between signal ground and power ground, and the two ground layer division methods of the same power module PCB are used to simulate and calculate the effects of different PCB ground layer division methods on the near-field radiation characteristics of the power module.

[0015] The simulation and analysis method of the near-field radiation characteristics of the power module in an embodiment of the present invention addresses the problem of the near-field radiation characteristics of the power module. Simulation software is used to build a full-wave three-dimensional numerical simulation model of the power module PCB. By changing the values ​​of the filter inductance and capacitance at the output end of the power module, the near-field radiation characteristics of the power module PCB under different output end parameter configurations are simulated and obtained. The influence of different PCB ground layer segmentation methods on the near-field radiation characteristics of the power module is analyzed, providing a reference basis for subsequent CAN node module PCB optimization.

[0016] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0018] Figure 1 This is a flow chart of a method for simulating and analyzing near-field radiation characteristics of a power module according to an embodiment of the present invention;

[0019] Figure 2 Schematic diagram of the topology of a step-down switching power converter according to an embodiment of the present invention;

[0020] Figure 3 Schematic diagram of the working principle of a step-down DC / DC converter according to an embodiment of the present invention;

[0021] Figure 4 This is the time domain waveform of the output signal from pin 3 of the power chip according to an embodiment of the present invention;

[0022] Figure 5 This is a diagram of a full-wave three-dimensional numerical simulation model of a power module PCB according to an embodiment of the present invention;

[0023] Figure 6 This is a diagram showing the simulation results of the near-field radiation characteristics of the power module corresponding to the 4.7μH, 15μH, and 22μH filter inductors according to an embodiment of the present invention;

[0024] Figure 7 This is a diagram showing the simulation results of the near-field radiation characteristics of the power module corresponding to 10μF, 100μF, and 220μF filter capacitors according to an embodiment of the present invention;

[0025] Figure 8 Schematic diagram of two ground layer segmentation methods for a power module PCB according to an embodiment of the present invention;

[0026] Figure 9 Graph showing simulation results of near-field radiation characteristics of the power module PCB under two PCB ground layer segmentation methods according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0028] Figure 1 The present invention provides a flowchart of a method for simulating and analyzing near-field radiation characteristics of a power module according to an embodiment of the present invention.

[0029] like Figure 1 As shown, the power module near-field radiation characteristics simulation analysis method includes the following steps:

[0030] Step 1: Use CST simulation software to build a full-wave three-dimensional numerical simulation model of the output end LC filter circuit of the power module PCB, and apply the output signal of pin 3 of the power chip at the corresponding position of the full-wave three-dimensional numerical simulation model.

[0031] Step 2: Through simulation analysis, the near-field radiation characteristics of the power module PCB are analyzed under different values ​​of the filter inductor and capacitor at the output end of the power module PCB.

[0032] Step 3: Analyze the near-field radiation characteristics of the power module PCB under different power module PCB ground layer segmentation methods through simulation.

[0033] In one embodiment of the present application, Figure 2 and Figure 3 As shown, Figure 3 (a) is the current path when the switch is turned on. Figure 3 (b) is the current path when the switch is off. In step 1, the power module PCB contains the MP2225 DC / DC switching power supply chip. The core circuit of this DC / DC switching power supply chip is a step-down DC / DC converter with high conversion efficiency and low power loss. Its basic topology consists of a power semiconductor switch controlled by the PWM signal output by the chip's internal pulse width modulator. In actual chips, this is typically a triode or MOS transistor. To better illustrate the operating principle of a step-down DC / DC converter, the power switch in its topology can be equated to a controlled switch.

[0034] The power module PCB is designed based on the MP2225 switching power supply chip. The MP2225 chip is a DC / DC step-down converter with a maximum input voltage of 22V and a load current of 9A. It has a strong load capacity and a built-in short-circuit protection working mode.

[0035] In one embodiment of the present invention, in step 1, to build a complete full-wave 3D numerical simulation model of the power module PCB, the simulation frequency range, boundary conditions, grid, electric field time-domain solver, and field detector must be set in CST MWS. External ports are added to key pins of the chip to input excitation signals.

[0036] In one embodiment of the present invention, Figure 4 As shown, in step 1, due to the lack of an electrical model for the MP2225 power chip, the measured results of its key pins were used as stimulus. The output signals of the chip's other pins are relatively flat, so the signal at pin 3 is the primary stimulus signal for the near-field radiation of the DC / DC switching power module. The oscilloscope's sampling period was set to 10ns to obtain the time domain waveform of the output voltage signal at pin 3 of the MP2225 chip.

[0037] In one embodiment of the present invention, in step 2, the near-field radiation intensity of the power module PCB is simulated and calculated under the initial conditions that the filter capacitor at the output end of the DC / DC power module is set to 10 μF and the filter inductor is set to 4.7 μH, 15 μH, and 22 μH, respectively. Furthermore, the near-field radiation intensity of the power module PCB is simulated and calculated under the initial conditions that the filter inductor at the output end of the DC / DC power module is set to 4.7 μH and the filter capacitor is set to 10 μF, 100 μF, and 220 μF, respectively.

[0038] In one embodiment of the present invention, in step 3, the PCB ground layer is rationally segmented to distinguish between "signal ground" and "power ground." This is crucial for improving PCB signal integrity, reducing ground loop noise interference, optimizing power and signal return paths, and enhancing power output quality and system stability. Here, two ground layer segmentation methods for the same power module PCB are simulated to calculate their effects on the near-field radiation characteristics of the power module.

[0039] The proposed method for simulating and analyzing the near-field radiation characteristics of a DC / DC power supply module, based on an embodiment of the present invention, analyzes the impact of varying output filter inductor and capacitor parameters and PCB ground layer segmentation on the near-field radiation characteristics of a switching power supply module, providing a reference for optimizing the PCB for CAN node modules. This method is not only applicable for locating electromagnetic noise sources, but also provides a reference for optimizing the PCB for CAN node modules.

[0040] The following describes in detail the method for analyzing the electric field strength inside the engine nacelle under strong electromagnetic pulses of the present invention through specific examples.

[0041] Step 1: Build a full-wave three-dimensional numerical simulation model of the output LC filter circuit of the DC / DC switching power supply chip MP2225. Apply the output signal of pin 3 of the power supply chip at the corresponding position of the three-dimensional model. The full-wave three-dimensional numerical simulation model is as follows: Figure 5 shown.

[0042] Step 2: Set the filter capacitor value at the output of the DC / DC power module to 10μF, and the filter inductor values ​​to 4.7μH, 15μH, and 22μH respectively. Under the initial conditions, simulate and calculate the near-field radiation intensity of the power module PCB. In addition, set the filter inductor value at the output of the DC / DC power module to 4.7μH, and under the initial conditions that the filter capacitor values ​​are 10μF, 100μF, and 220μF respectively, simulate and calculate the near-field radiation intensity of the power module PCB. The simulation results are shown in the figure below. Figure 6 and Figure 7 As shown in the figure, it is found that as the filter inductance and capacitance of the power module increase, the electric field strength at the detection point decreases, and the near-field radiation energy is mainly concentrated within 20MHz.

[0043] Step 3: Simulate and analyze the near-field radiation characteristics of the power module PCB under different power module PCB ground layer division methods. For the two ground layer division methods of the same power module PCB, such as Figure 8 The simulation results are shown in (a) and (b). Figure 9 As shown in the figure, by comparing the near-field radiation simulation results of the power module obtained by two different division methods of the PCB ground layer, it can be concluded that reasonable division of the PCB ground layer can reduce the near-field radiation intensity of the power module.

[0044] According to the simulation and analysis method for the near-field radiation characteristics of a power module proposed in an embodiment of the present invention, CST software is first used to build a full-wave three-dimensional numerical simulation model of the LC filter circuit at the output end of the DC / DC switching power supply chip MP2225. The output signal of pin 3 of the power supply chip is applied to the corresponding position of the three-dimensional model. The near-field radiation characteristics of the power module PCB are then simulated and analyzed under different values ​​of the filter inductor and capacitor at the output end of the power circuit. The near-field radiation characteristics of the power module PCB are also simulated and analyzed under different power module PCB ground layer segmentation methods, providing a reference for subsequent optimization of the CAN node module PCB.

[0045] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0046] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this application, "N" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0047] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing a custom logical function or process step, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may be performed in a different order than shown or discussed, including performing functions in a substantially simultaneous manner or in a reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present application pertain.

Claims

1. A method for simulating and analyzing the near-field radiation characteristics of a power module, characterized in that: The following steps are involved: Step 1: Use simulation software to build a full-wave three-dimensional numerical simulation model of the LC filter circuit at the output end of the power module PCB, and apply the output signal of pin 3 of the power chip to the corresponding position of the full-wave three-dimensional numerical simulation model; Step 2: Analyze the near-field radiation characteristics of the power module PCB using simulations for different values ​​of the filter inductor and capacitor at the output end of the power module PCB. Step 3: Analyze the near-field radiation characteristics of the power module PCB under different power module PCB ground layer segmentation methods through simulation.

2. The method according to claim 1, characterized in that In step 1, the power module PCB is a DC / DC switching power supply chip MP2225, the core circuit is a step-down DC / DC converter, and the basic topology is a power semiconductor switch tube controlled by a PWM signal output by a pulse width modulator inside the power chip.

3. The method according to claim 2, characterized in that In step 1, the power module PCB is designed based on the DC / DC switching power supply chip. The DC / DC switching power supply chip is a DC / DC step-down converter with a maximum input voltage of 22V and a load current of 9A. The chip has a built-in short-circuit protection working mode.

4. The method according to claim 1, wherein In step 1, a complete full-wave three-dimensional numerical simulation model is built by setting the simulation frequency range, boundary conditions, grid, electric field time domain solver and field detector in the simulation software, and an external port input excitation signal is added to the key pins of the power module PCB.

5. The method according to claim 1, wherein In step 1, the sampling period of the oscilloscope is set to 10 ns, and the time domain waveform of the output voltage signal of pin 3 of the power module PCB is obtained.

6. The method according to claim 1, characterized in that In step 2, the output filter capacitor of the power module PCB is set to 10 μF, and the filter inductance is set to 4.7 μH, 15 μH, and 22 μH respectively. Under the initial conditions, the near-field radiation intensity of the power module PCB is simulated and calculated respectively. The output filter inductance of the power module PCB is set to 4.7 μH, and under the initial conditions that the filter capacitor values ​​are 10 μF, 100 μF, and 220 μF respectively, the near-field radiation intensity of the power module PCB is simulated and calculated respectively.

7. The method according to claim 1, characterized in that In step 3, the PCB ground layer is reasonably divided to distinguish between the signal ground and the power ground. For the two ground layer division methods of the same power module PCB, the effects of different PCB ground layer division methods on the near-field radiation characteristics of the power module are simulated and calculated.

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