Formulation of DC Energy Factor and Energy-based Control Method for High Efficiency Power Electronics Conversion Systems

This thesis is to examine the energy handling in DC-DC converter systems. The management of the energy in terms of energy factor is the core area of the examination. The theory derived is extended to the family of DC-DC power converters from which the efficiency and its implication in power factor as that in the AC counterpart are studied.;The conventional AC power factor is a start point. Its exploration to DC system, mainly the DC-DC power converters are thoroughly done. There are a number of new concepts that have been explored.;Five main aspects of works carried out in this thesis have been clarified below.;A series of novel concepts such as Energy Storage (ES), Energy Factor (FE), Buffer Energy (E B) and Buffer Energy Factor (FEB) are reviewed and presented to quantitatively describe the energy behaviour in DC-DC converters.;The definitions of buffer energy and buffer energy factor are further extended on the basis of theory of non-active power. Through the extended definitions buffer energy and buffer energy factor can be applied not only to DC systems but also to AC systems. The correlations and distinctions among buffer energy and reactive energy, buffer energy factor and power factor have been clarified.;On the basis of energy factors and buffer energy factors, comparison study has been carried out for basic topologies of DC-DC converters. In general, efficiency of DC-DC converter decreases when buffer energy factor increases.;Tapped-inductor converters have been researched carefully by this thesis. Static performances of tapped-inductor Boost converter have been examined. Comprehensive comparisons between tapped-inductor Boost converter and conventional Boost converter have been carried out.;This thesis has researched the buffer energy factors during transient time. The application of one famous energy-based control method: passivity-based control to tapped-inductor Boost converter has been researched. The overall performances of control are analyzed. These researches can provide useful references for the controller design of tapped-inductor DC-DC converters.