Modeling and stability analysis of power electronics based systems
Abstract
Systems consisting of power electronics based converters for power distribution have become increasingly prominent in the military as well as in industry. Stability analysis of all but the simplest of these systems is often based on model linearization (interpreted either in state-space or frequency domain) and time domain simulation. The information obtained with these tools is limited to small-signal behavior or to specific trajectories. The following research extends present theories and analysis tools enabling large-signal stability analysis of power-electronics-based systems. As an alternative to linear system analysis, nonlinear analysis may be conducted using Lyapunov techniques. The difficulty in such an approach is in calculating a suitable Lyapunov function candidate. The structure of polytopic models, which are based on convex combinations of linear or affine local models, provides a framework that can be used to establish a Lyapunov function candidate. Conditions for the polytopic model to be globally uniformly asymptotically stable are identified. Then the Lyapunov function candidate constructed using polytopic models is employed to estimate regions of attraction of the truth model. These methods are illustrated using second- and sixth-order nonlinear system examples. Finally, the extension of techniques proposed herein to decentralized analysis is addressed. Conversion of a decentralized polytopic model to a more tractable form is presented allowing techniques developed for the basic polytopic model structure to be utilized on interconnected polytopic models.
Degree
Ph.D.
Advisors
Zak, Purdue University.
Subject Area
Electrical engineering
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