This thesis is concerned with some aspects of losses produced in the inductors and transformers of switched-mode power supplies (SMPS). The main subject of study is the eddy-current losses due to non-uniform current distribution across foil windings. These are calculated and measured for the cases when the foil constitutes an air-cored inductor, and when it is used as the secondary of a ferrite cored transformer. A coupled circuit model is used in which the foil inductor is subdivided into sets of mutually coupled filament coils. A formal method of solution of the resulting sets of equations is presented, and alternative mathematical methods of calculating self and mutual inductances are also compared. In addition to this work two other topics are addressed briefly. First, the magnetic fields in and around magnetic cores are measured, and compared with computed results using a 3D magnetostatic package, TOSCA. Secondly, core losses in ferrite cores due to sinusoidal and non-sinusoidal excitation are measured and calculated.
|Date of Award||1985|