开关电源传导EMI分析及抑制技术的研究

发布时间：2018-05-13 07:31

本文选题：开关电源 + 共模传导EMI　；参考：《西安理工大学》2017年硕士论文

【摘要】：随着开关电源开关频率及功率密度的提高,开关电源的传导EMI问题尤为突出与重要。作为耦合通道环节的开关电源中的变压器分布电容参数以及接地阻抗会对传导EMI产生影响。本文针对这两个问题进行研究。首先对开关电源的传导EMI流通路径进行了分析,建立了开关电源共模传导EMI模型。通过该模型分析了变压器原副边分布电容以及接地阻抗对共模传导EMI电流的影响。可以看出,随着分布电容的增大,共模电流增大。而随着接地阻抗的增大,共模干扰电流在减小。所以,需要研究如何减小分布电容及其接地阻抗对传导EMI的影响。本文建立了考虑到变压器原副边所有匝数之间的分布电容的变压器分布电容网络结构模型。并且提出了一种基于MAXWELL软件的变压器分布电容网络模型参数提取方法,通过该方法与建模方法结合可以求出变压器的分布电容。然后通过二端口网络法实验提取出变压器的分布电容,将两者进行对比,验证了该建模方法的正确性。并采用分段绕制方法减小变压器的原副边之间分布电容,进而降低开关电源传导EMI。分别通过仿真与实验验证了分段绕制方法可以减小开关电源的传导EMI。同时,本文针对大功率电源柜体作为接地体,仿真分析了其面板上的阻抗,分别验证了频率对其阻抗的影响,面板上开孔形状与尺寸对阻抗的影响,以及面板上开孔位置布局不同对接地柜体上阻抗的影响。通过对比不同的面板上的布局情况下的接地阻抗,分析了面板上开孔布局对接地阻抗的影响。
[Abstract]:With the increase of switching frequency and power density, the conduction EMI problem of switching power supply is becoming more and more important. The distributed capacitance parameters and grounding impedance of the transformer in the switching power supply, which is the link of the coupling channel, will affect the conduction EMI. This paper studies these two problems. Firstly, the conduction EMI circulation path of switching power supply is analyzed, and the common-mode conduction EMI model of switching power supply is established. Based on the model, the influence of the primary side capacitance and grounding impedance of transformer on the common-mode conduction EMI current is analyzed. It can be seen that the common-mode current increases with the increase of the distributed capacitance. The common-mode interference current decreases with the increase of grounding impedance. Therefore, it is necessary to study how to reduce the influence of distributed capacitance and grounding impedance on conductive EMI. In this paper, a distributed capacitance network model of transformer considering the distributed capacitance between all turns of the primary and secondary edges of a transformer is established. A method of extracting the parameters of transformer distributed capacitance network model based on MAXWELL software is proposed. The distributed capacitance of transformer can be obtained by combining this method with the modeling method. Then the distributed capacitance of transformer is extracted by two-port network method, and the correctness of the modeling method is verified by comparing the two methods. The distributed capacitance between the primary and secondary edges of the transformer is reduced by using the piecewise winding method, and then the conduction EMIs of the switching power supply are reduced. The results of simulation and experiment show that the piecewise winding method can reduce the conduction EMIs of the switching power supply. At the same time, the impedance on the panel is simulated and analyzed, and the influence of frequency on the impedance is verified, and the influence of the shape and size of the opening hole on the impedance of the panel is verified. And the influence of the location of the opening on the panel on the impedance of the earthing cabinet. By comparing the grounding impedance of different panel configurations, the influence of the hole layout on the earthing impedance is analyzed.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN86

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