Analysis And Calculations Of10KVA High Frequency Transformer’ Winding Losses And Stress

With the development of the technology of power electronics, module power supplies putforward more intensive requests for transformers, for instance smaller size, less cross areas,larger output currents as well as heat dissipating properties, reasonable parameters and so on. Toreduce the switching power supplies’ sizes and enhance their power densities, their workingfrequency has to be boosted, which inevitably makes the Proximity Effect and the Skin Effectmore remarkable. As a result, that will lead to a series of changes of the resistances, inductancesand distributed capacitances in the high frequency power transformers. Therefore, in theoptimized design of the high frequency power transformers used in switching power supplies,researches focused on diminishing coil losses and searching for rational parameters reserveprominent theoretical significance and practical application value. On account of an immensecurrent flowing through the windings, resulting in impact of electromagnetic forces, part orentire of the windings are likely to be distorted, which will disturb the normal operation of thehigh frequency power transformers and even make it break down, therefore, it is essential tocalculate and analyze the electromagnetic forces on them.The thesis has adapted FEM analysis method to calculate the losses caused by the ProximityEffect and the Skin Effect in the copper foils and analyzed distinctive losses under currents witha series of diverse frequencies flowing through copper foils of different thicknesses with the helpof "Magnet" software produced by "Infolytica" incorporation. On the basis of survey on thephenomenon that currents flow unevenly through parallels connected windings, the maxthickness of copper foils which can be accepted under the operation of a10Kva high frequencypower transformer with a working frequency of40Khz is obtained through calculation.Moreover, the thesis has calculated and analyzed the losses of differently structured parallelwindings and drawn a conclusion that taking advantage of interleaving techniques in the primaryand secondary windings contributes to decrease the losses of the high frequency powertransformers. Afterwards, the thesis has illustrated in detail how to use the techniques to reducelosses in different types of transformers. Eventually, influences of the windings’ Edge Effect onhigh frequency losses and leakage inductances are analyzed. The thesis has calculated and analyzed four types of high frequency power transformerswith different winding layout and proved their credibility through contrast with experiments’results, which indicates benefiting from the interleaving techniques in the primary and secondarywindings, the performances of high frequency power transformers will be better, and theoperating efficiency will be higher.