Simulation Analysis And Suppression Method Research Of Conducted Interference For Half-bridge Switching Converter

Switching power supply is applied widely, but the high-frequency switching powersupply results in large transient voltage, current. The voltage and current form conductedinterference. The mechanism and propagation path of conducted interference are analyzedaccording to electromagnetic and circuit theory in order to suppress it. To improve theperformance of suppressing conducted interference, all factors about interference suppressionare required to be analyzed. The dissertation analyzes conducted interference coupling path,EMI filter design and the elimination of parasitic parameters through half-bridge switchingconverter and electromagnetic interference (EMI) filters.In order to study the performance of high-frequency passive components， the cellstructure and mechanism of parasitic parameters are studied to analyze the characteristics ofinductors, capacitors, resistors and wires by circuit theory. The selection and application ofcomponents in conducted interference suppression are discussed through the analysis ofmathematical models， and the effect and influence of passive components in conductedinterference generation, dissemination and inhibition are analyzed.The working principle of half-bridge switching converter is analyzed and the effect ofcomponents in interference suppression is elaborated. The mechanism generating interferenceis analyzed to determine conducted interference sources of half-bridge switching converter.According to the basic coupling path, the main circuit is simplified on condition that allparasitic parameters and main factors about conducted interference are considered. Thecoupling interference is considered to draw the coupling path of mixed mode interference,intrinsic differential mode interference and common mode interference. The determination ofinterference source and coupling path facilitates the accurate suppression of conductedinterference.The performance of EMI filters is analyzed and insertion loss is defined with two-portnetwork T parameters in order to study the impact of interference source impedance and loadimpedance better. In order to reduce the impact of interference source impedance on filteringperformance, EMI filters are designed in accordance with the procedure of conductedinterference measurement, attenuation amount calculation, topology choice, corner frequencydetermination. No matter the interference source impedance is considered or not, the designmeets the requirements of interference suppression.Due to the impact of passive component parasitic parameters, the performance of EMIfilters can hardly meet design requirements. In order to analyze the impact of self-parasiticand mutual parasitic parameters on insertion loss of differential and common mode filters, the mechanism that parasitic parameters affect performance of filters is analyzed byelectromagnetic and circuit theory, and the improvement of EMI filter performance is verifiedby personal simulation program with integrated circuit emphasis (PSpice) when parasiticparameters are cancelled. Circuits are designed to cancel parasitic parameters and the effect ofadditional circuit is analyzed from the point of secondary parasitic parameters. Analysis ofcircuit shows that reasonable circuit design can eliminate parasitic parameters, avoidredundant design and improve performance price ratio and degree of integration.