Repositori URV

Identifier: TDX:1013

Handle: https://hdl.handle.net/20.500.11797/TDX1013

Authors:
Peláez Restrepo, Julián

Abstract:
This work is a contribution to the study of the stability of a DC-DC two-cell buck converter using different control strategies. Chapter 1 provides a general introduction to power electronics and its different applications in the efficient management of electrical energy. Then, some typical topologies of DC-DC switched converters and their main modulation strategies are presented. Chapter 2 gives an overview of multi-cell converters, explaining why they are useful for high voltage applications. Below, the different kind of topologies of multi-cell converters that can be developed are shown. Chapter 3 presents three ways of modeling a DC-DC switched-mode two-cell converter, starting with the natural switched model from which the widely used averaged model is derived. Next, we discuss the discrete-time model obtained from the Poincaré section technique. Finally the dynamic phasor model of the converter is presented. At the end of this chapter a comparison, among the waveforms of the system obtained from each model in transient and in steady state, is carried out. Chapter 4 presents a study of the converter using the averaged model and the discrete-time mode under proportional (P) and Proportional Integral (PI) controllers. An analytical study of the system using each model is carried out defining the stable region in the parameter space. Chapter 5 uses only the discrete-time model of a two-cell buck converter and proposes two control algorithms able to stabilize the system and to expand the range of working parameters with a stable behavior. These algorithms are: TDFC control that can extend the parameter space but has a stable steady-state error and the GTDFC which also can stabilize the system over a wide range of parameter space, and has the advantage of obtaining a ze