开关电源（SMPS）电磁干扰（EMI）问题的研究

摘要

同传统的线性电源相比较,开关电源具有效率高,体积小,重量轻等优势.然而,由于开关电源工作在高频状态,其产生的瞬态脉冲包含有能够发射电磁干扰(EMI)的的高频谐波.EMI不仅影响开关电源的电磁兼容(EMC)性能,而且影响开关电源的工作成本.该文侧重研究了典型开关电源中的几种EMI形式,即传导干扰(包括差模和共模噪声)和辐射干扰.抑制开关电源中的EMI需要系统地研究变换器各成分的噪声发射.为了评估开关电源中电感对传导EMI的影响,该文调查了在一个Boost电路中的电感绕组分布电容所产生的传导共模电流.为了减少修改开关电源设计的成本,该文提出了一套规则用于建立一个简单而广泛适用的开关电路传导EMI模型.这些规则是基于抽取PCB的敷线和器件模型的所有寄生参数而建立的,寄生参数的抽取考虑到了瞬态行为,不同材料的高频特性,PCB不同导体和各导体对地间的静电耦合.对于该课题组提出的反相共模抑制技术,使用一个简化的等效电路,该文进一步研究了寄生电容在其中的影响.因此,反相绕组寄生电容对该技术效能的影响在该文中得到了确认.

目录

文摘

英文文摘

ACKNOWLEDGMENTS

Chapter1Introduction

1.1 Introduction to Electromagnetic Interference (EMI) and Electromagnetic environment

1.2 EMI regulations

1.3 EMI measurement for verification of compliance

1.4 Power Electronics and Electromagnetic interference (EMI)

1.5 Purposes and achievements of this dissertation

Chapter 2 The influence of magnetic component on commonmode current in a converter

2.1 Study of sensitive parameters of inductors

2.2 Physical analysis of magnetic materials

2.3 EMI sources generated in switching mode power supplies

2.4 Study of common mode (CM) noise generated by the magnetic components

2.4.1 Experimental Setup and Measurement of common mode current

2.4.2 Influence of winding arrangement

2.4.2 Emission map of the inductor windings

2.4.4 Reduction of Emission from the inductor

2.4.5 Summary

Chapter 3 Modeling for radiated and Conducted EMC/EMI predictions

3.1 Radiated emission prediction

3.2 Elemental dipole antennas

3.3 Simple models for wires and PCB lands

3.4 Radiated emission model in SMPS

3.5 EMC/EMI computer program

3.6 Simple modelling for conducted common-mode current in switching circuits

3.6.1 Assumptions for simplification

3.6.2 Modelling

3.6.3 EMI prediction of common mode currents

3.6.4 Simulation and experimental results

3.6.5 Proposed model perspective

3.6.6 Summary

Chapter 4 Study and design of EMI suppression techniques in SMPS

4.1 EMI reduction techniques

4.2 Circuit characteristics influence on EMI reduction

4.3 Filtering

4.4 Study on Novel boost converter with anti-phase winding

4.4.1 The influences of parasitic capacitances on the effectiveness of anti-phase technique for common mode noise suppression

4.4.2 Analysis of conducted common mode circuit model

4.4.3 Brief analysis of anti-phase winding techniques

4.4.4 Winding stray capacitance effect on conducted CM noise

4.4.5 Winding stray capacitance effect on conducted DM noise

4.4.6 Summary

Conclusion

References

Publications