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dc.contributorMulti-disciplinary Studiesen_US
dc.contributorDepartment of Applied Physicsen_US
dc.creatorLai, Chi-wing-
dc.identifier.urihttps://theses.lib.polyu.edu.hk/handle/200/1017-
dc.languageEnglishen_US
dc.publisherHong Kong Polytechnic University-
dc.rightsAll rights reserveden_US
dc.titleOptimization of the efficiency of switched-mode power transformersen_US
dcterms.abstractSwitched-mode power supplies are widely used nowadays. Nearly all power supplies are working in switched-mode because of its higher efficiency and smaller size. In this project, the efficiency optimization of the switched-mode power transformers (SMPT) is investigated, consideration taking into the temperature rise limit, the safety requirement and the size of the transformers. The dissertation starts with a study and delineation of the origin of the core losses (hysteresis loss and eddy-current loss) and the conductor losses (a.c. power loss and d.c. power loss). The core losses of some ETD (Efficient Transformer Design) type cores (5 different sizes and 2 different materials) are measured within a temperature-controlling chamber at different operating frequencies and magnetic flux densities. The actual core losses are then compared with the calculated values, in which the calculations are based on the power loss formula provided by the cores' manufacturer. The conductor losses of the enamelled copper wires with different wire gauge are measured at different operating frequencies under constant ambient temperature. The results obtained are then compared with the predicted values. Finally, the procedures for core selection and winding design are given. The core selection methods based on the cores' nomograms and the area product factor are introduced. The essential background information behind the design rules for high-frequency transformer winding is discussed first and then a practical winding design procedure is proposed.en_US
dcterms.extentiv, 100 leaves : ill. ; 30 cmen_US
dcterms.issued1999en_US
dcterms.educationalLevelAll Masteren_US
dcterms.educationalLevelM.Sc.en_US
dcterms.LCSHElectric transformersen_US
dcterms.LCSHSwitching circuitsen_US
dcterms.LCSHHong Kong Polytechnic University -- Dissertationsen_US
dcterms.accessRightsrestricted accessen_US

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Please use this identifier to cite or link to this item: https://theses.lib.polyu.edu.hk/handle/200/1017