F-L-N parameter based power density optimized design and implementation of a digitally controlled 1-kw interleaved DC-DC step down converter

Şahin, İlker
In power electronic conversion, interleaving technique, which can be considered as a special form of paralleling, is a widely utilized method due to the size and performance benefits it introduces. This thesis first compares interleaving to other forms of paralleling techniques and investigates the interleaving technique from both electrical (output voltage ripple, line current distortion, efficiency etc.) and physical (converter size, cost etc.) characteristics points of view. After the detailed description of interleaving, the subject of optimal converter design is stressed: by a careful selection of design parameters such as switching frequency (f), inductance (L) and phase number (N) optimum design points can be found. By means of a MATLAB code which calculates and reports converter efficiency, volume and cost for various f-L-N values, optimum design points targeting maximum efficiency, minimum volume, and maximum figure of merit which corresponds to smaller volume and higher efficiency together, are suggested for a 1-kW buck converter. For the physical demonstration of the benefits introduced by interleaving and to test the results of f-L-N based converter optimization, a 1-kW digitally controlled hard switched multi-phase buck converter is designed and implemented. Along the theoretical analyses and computer simulations, detailed laboratory tests are carried out and correlation of analysis, simulation, and implementation results are provided.