Research On The Mechanism Of Noise Filtering And Power Estimation In AEF Power Supply

With the development of high power density of switching power converters,caused by EMI problems more prominent,Active EMI Filter(AEF)with its small size,light weight of the great advantage,has begun to widely promote the use of.But the current AEF power supply problem is a major resistance to its promotion and use,AEF power supply noise affects the filtering performance of AEF,AEF power supply power configuration method blind,there is no quantitative basis,so the study of AEF power supply noise impact and power prediction problem,the AEF performance improvement and industrial promotion has great theoretical and practical significance.In response to the problem of not being able to describe the mechanism of the impact of AEF power supply noise on AEF filtering performance,the model of the impact of power supply noise on AEF filtering performance is established in this paper,which can quantitatively describe the effect of AEF power supply noise on the output of AEF and also the effect of AEF power supply noise on filtering performance.Firstly,the circuit and path of the influence of power supply noise on AEF system are analyzed.Secondly,the gain model of the power supply noise on the output of AEF is established and its gain characteristics are analyzed.Finally,based on the gain model of supply noise on the load side of the filtered system,a model of the influence of supply noise on the filtering perforuance of AEF is established,and the influence of the noise ratio coefficient of supply noise and system interference on the filterng performance is analyzed,and the model is extended to six basic AEF topologies,and the sensitivity of different AEF topologies to supply noise and the influence characteristics on their filtering performance are analyzed.In order to solve the problem of not being able to quantitatively design the power stipply of AEF,the power prediction model of AEF power supply is established in this paper,which can accurately and quantitatively predict the power supply of AEF based on the conducted EMI current generated by the filtered system.Firstly,the power flow path and power composition of the power supply are analyzed based on the filtering mechanism of AEF,and the static operating power and offset EMI power are clarified.Secondly,the static operating power model reflecting the operating characteristics of AEF amplifier and the offset EMI power estimation model reflecting the offset interference of AEF are established respectively.Finally,based on the established model,the power prediction model characteristics of AEF power supply are analyzed,and the model is extended to six basic AEF topologies,and the power demand characteristics of different AEF topologies are analyzed.Finally,the simulation and experimental validation platform of AEF power supply noise on filtering performance model was built.Both simulation and experimental results matched with the model prediction results,and the error of the whole frequency band was less than 3dB,which verified the correctness of the AEF power supply noise on filtering performance model;secondly,the simulation and experimental validation platform of AEF power supply prediction model was built.