Introduction to Power Electronic Converters Modeling
This chapter deals with a brief presentation of the main modeling aspects of power electronic converters. The chapter overviews modeling basics, provides useful hints about the main modeling methodologies, accompanied by some illustrative examples, and su
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Introduction to Power Electronic Converters Modeling
This chapter deals with a brief presentation of the main modeling aspects of power electronic converters. The chapter overviews modeling basics, provides useful hints about the main modeling methodologies, accompanied by some illustrative examples, and suggests some possible uses of models.
2.1 2.1.1
Models What Is a Model?
Modeling of a phenomenon or process is based on its observation and relies upon capturing into an approximate, but sufficiently comprehensive, representation, its most significant features from the point of view of a given application. Modeling requires generalization in the sense that the studied phenomenon must be regarded in the context of similar phenomena so common features may be extracted. Generally speaking, there are two main modeling approaches: one that uses black-box models, based on the process behavior observation of its response to some known input signals, and one based on the known information about the system to be modeled (i.e., representation centered on the behavior laws). The latter approach is employed not only to model physical processes, but also biological, economics or even social systems. Mixing between the two approaches is also encountered, leading to the so-called gray-box models. The interest of this textbook is on power electronic converter modeling using the “information” approach. This means that model representations will be made using the available physical knowledge about the considered converter. In general, physical knowledge about system results in mathematical description of mass and energy conservation laws. Thus, energy accumulation variations within the system are described by so-called state variables. In the particular case of power converters, information is embodied in Kirchhoff’s laws of the converter circuit, Ohm’s laws for the various loads and, finally, in the states of various solid-state switches. S. Bacha et al., Power Electronic Converters Modeling and Control: with Case Studies, Advanced Textbooks in Control and Signal Processing, DOI 10.1007/978-1-4471-5478-5_2, © Springer-Verlag London 2014
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2 Introduction to Power Electronic Converters Modeling u
+
Σ +
Plant ∼ u
High-pass filter
y∼ y∼ gain = ∼ u
Fig. 2.1 Basic idea of linear identification approach, where u and ue are input’s low-frequency and high-frequency components, respectively
2.1.2
Scope of Modeling
Next within this textbook one seeks to obtain quasi-general power electronic converter dynamical models to simulate converter dynamic behavior and to construct various control laws. Steady-state converter behavior (static models) can also be obtained, either by zeroing the time derivatives in the dynamical models in the case of DC variables, or by zeroing the derivative of both magnitude and phase in the case of AC variables. Concerning simulation, a plethora of software renders power converter timedomain behavior in a very precise and reliable way (see, for example, SPICE®, SABER®, MATLAB®). With these program
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