基于插入损耗法的噪声源内阻抗建模及误差分析

针对传导电磁干扰滤波器设计中人工电源网络阻抗、噪声源内阻抗、负载阻抗与EMI滤波器的阻抗匹配问题,建立了插入损耗法的误差理论模型及其等效电路.分别分析了串联和并联插入损耗法的测量精度及其系统误差,据此提出了相应的测试条件和测试方法,即当被测阻抗远大于负载阻抗时,采用串联插入损耗法；当被测阻抗远小于负载阻抗时,采用并联插入损耗法；当被测阻抗与负载阻抗相当时,可改变负载阻抗.理论与试验研究表明,该方法在适用范围内能够快速有效地提取EMI噪声源内阻抗,从而实现噪声源与EMI滤波器之间的最大阻抗适配,为EMI滤波器的设计及传导电磁干扰噪声抑制提供理论依据.

Noise source impedance modeling and measurement error analysis based on insertion loss method

In order to solve the impedance matching problem for conducted EMI filter designing of artificial mains network(AMN) impedance,noise source impedance,load impedance and EMI filter impedance,the error theoretical model and equivalent circuits of insertion loss(IL) method were established.The measurement accuracy and system error of series and parallel IL methods were analyzed to provide improved test condition and methods.Series IL method was used when the measured impedance was much larger than load impedance.Parallel IL method was utilized when the measured impedance was much smaller than load impedance.The load impedance was altered when the measured impedance approximately equaled to load impedance.Theoretical analysis and experimental results show that the proposed method can extract EMI noise impedance effectively in certain range,where it can also realize the maximum impedance adapter between noise impedance and EMI filter.The proposed method has good validity for EMI filter design and conducted EMI noise suppression.