The purpose of this thesis is to develop the theory for analysing and designing the non-isolated and isolated type of SEPIC converters for continuous conduction mode (CCM). The non-isolated converter has single output. The isolated converter considered has two cases: single output and multi-output. The principle of operation of each circuit is explained during different time intervals of the switching cycle. The analytical expressions for various characteristics of the circuits are derived, such
as: MV DC and MIDC of the lossless and lossy converter; average and peak-to-peak currents through the inductors, primary and secondary windings of the transformer; average and peak-to-peak voltages across the capacitors; boundary conditions between CCM and DCM; minimum inductance of the inductors and magnetizing inductance of the transformer and minimum capacitances of the capacitors to operate the converter in CCM; power losses of all the components and efficiency of the converter. The converters analyzed are supported by a design example and also simulated using
Saber software. The simulation results for each circuit are in good agreement with the theoretically calculated values for an assumed specifications of the converter. For instance, the respective η(theoretical), η(assumed), and η(simulated) of the non-isolated, single output and multi-output isolated converters are 89.84%, 90%, and 91.448%; 87.54%, 90%, and 90.076%; and 86.78%, 90%, and 87.76%.