engleski

Design methodology for improved electromagnetic compatibility of switched-mode power converters

Switched-mode power converters are used in various applications, such as computer and office equipment, consumer electronics, networking and telecom equipment and industrial electronics. The main advantage of switched-mode power converters is the high conversion efficiency they provide. One of their most important disadvantages is the high level of electromagnetic emissions they generate, which can exceed the limits specified in the regulations. The objective of this dissertation is to develop a design methodology for switched-mode power converters with an improved electromagnetic compatibility. The methodology consists of combining the circuit and electromagnetic simulations to predict the generated emissions of the analyzed converter. The input decoupling network of a switched-mode power converter is the critical part for its electromagnetic compatibility. Therefore, it is analyzed with the aid of electromagnetic simulations and the methodology for its design is developed. Placing a conductive plane close to the source of the radiation is an effective way of reducing the radiated fields. The image theory is extended to model the impact of the finite ground planes, such as those used in switched-mode power converters. A procedure for calculation of radiated emissions of a converter based on the measurements performed by a transverse electromagnetic cell and a hybrid coupler is developed. The procedure consists of positioning the converter in multiple orientations inside the transverse electromagnetic cell. For the positioning, two card-edge connectors are used. The connectors are modeled by a generalized capacitance matrix of widely separated conductors. The methodology is applied to synchronous buck converters. A good agreement between the predicted radiated emissions and the measurements performed by a transverse electromagnetic cell is obtained.

card-edge connectors, electromagnetic simulations, generalized capacitance matrix, hybrid coupler, image theory, impedance mismatch, input decoupling network, radiated emissions, small loop, synchronous buck converters, transverse electromagnetic (TEM) cell

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