Research On The Conducted Interference Suppression For LED Driver Power Supply In Certification

As the requirements of EMC standard are increasing day by day, the test failure ofthe conducted interference in the power supply certification became the main problem.The researchs on the conducted interference suppression in the LED driver powersupply certification are done in this article.The working principle, certification standards and related conduction interferencetheoretical knowledge of LED drive power supply are firstly introduced in this article.The common mode noise is generally the more difficult noise to deal with. The origin ofthe common mode noise is the chargeing and dischargeing of the parasitic capacitanceswhich come from the heat sink and transformer interwinding primarily. The conductioninterference suppression in the class1LED drive power supply are analyzed, lincludingthe analysis of grounding and shielding of heat sink on MOSFET and output diodeshielding techniques, and the analysis of EMI filter interference suppression.Theconduction interference suppression is more difficult in the class2LED drive powersupply without EMI filter. The conduction interference suppression in the class2LEDdrive power supply are secondly analyzed, including transformer shielding design,shielded transformer winding design,, the analysis of RCD-R snubber circuitinterference suppression, the analysis of the Y capacitor and ferrite beads interferencesuppression.All the conduction interference suppression technologies that can be appliedto the the class2LED drive power supply also can be applied to the class1LED drivepower supply.There are many test projects in the LED drive power supply products certification.The impact of conduction interference suppression technologies on the other testprojects must be paied attation when making the rectification technology of LED drivepower conduction interference. In this paper, the impact is analyzed in the specific asfollows: the influence of transformer shield design on transformer creepage and theelectric distance; the influence of circuit design of powering for the power supply chip inthe buffer circuit e design on power surge test; The influence of the design of radiator onthe MOSFET and output diode on the power creepage and clearance test;Y in the designof EMI filter capacitance values affect the power leakage current test. In this paper, eachimprovement technology and the technology impact on the rest of the test project areanalyzed in theory, at the same time, experimental verification.The experimental results proved the correctness of the theoretical analysis.