Un-terminated frequency response measurements and model order reduction for black-box terminal characterization models

Abstract

Black-box terminal characterization models are constructed from "un-terminated" frequency response functions (FRF) measured at the converter terminals without requiring explicit knowledge of any of the converter parameters; however to some extent, these measurements are always coupled with the source and load dynamics which reduces the fidelity of the final models obtained. This paper analyzes this problem and proposes a methodology to obtain un-terminated FRFs for dc-dc converters in the presence of source and load coupled FRF measurements. Furthermore, it presents a model order reduction technique to enable the simulation of dc distributed power systems with a large number of converters, applied to the calculated un-terminated FRFs that constitute the black-box models in question. Experimental results are presented to verify the theoretical analysis and the high accuracy obtained with the black-box models built.

Non-Linear Behavioral Modeling for DC-DC Converters and Dynamic Analysis of Distributed Energy Systems

“…To achieve this the measurement setup should have almost no interaction either with the source or load. This is possible if the converter is fed from a low output impedance voltage source and connected to an electronic load in constant current sink mode [27]. Using such a decoupling procedure the influence of external elements such as filters and other converters can be removed from the measurements.…”

Un-terminated, low-frequency terminal-behavioral d-q model of three-phase converters

“…This modeling is very well understood and applied to dc-dc converters [6][7][8][9][10] due to the easiness of performing small-signal measurements and existence of the operating point. This concept has even been further extended to address nonlinear behavior [11,12] and EMI [13,14].…”

Easy Modeling and Identification Procedure for "Black Box" Behavioral Models of Power Electronics Converters with Reduced Order Based on Transient Response Analysis

“…1). Reduced-order models are suitable to analyze distributed systems with a high number of converters, since the required computational cost is optimized [2], [14]. The proposed method has been applied to identify a "black box" behavioral model of a line commutated rectifier, which provides a DC bus for an experimental test bench of an aircraft power system.…”

“…Behavioral modeling of power converters can be carried out in terms of a "white box" approach [3][4][5][6][7][8][9], or a "black box" approach [10][11][12][13][14]:…”

“…Each parameter is composed of LTI (linear time invariant) models, or nonlinear polytopic models [14]. A network analyzer and a linear amplifier are used to capture the frequency response of the converter, and system identification procedures [17] are applied to identify each parameter of the model.…”