Modeling and analysis of spacecraft power systems

Abstract

A comprehensive large-scale power system modeling is developed to facilitate the design and analysis of present and future spacecraft power systems. A two-port coupling method is utilized to provide a modularity in model building and analysis of the system. The modular approach allows the model to be flexible, verifiable and computationally efficient. A methodology for the system level analysis is presented with the ability to focus on the performance characteristics of an arbitrary component or subsystem.The system performance parameters are derived explicitly in terms of the two-port hybrid g-parameter representation of the component or subsystem, and impedances of its terminating subsystems. From this, the stability of the system is analytically determined and the subsystem interaction criteria is observed. Also presented is a model development from the empirical data employing the complex curve fitting technique.The technique is especially powerful for large scale system modeling and analysis where certain components and subsystems are viewed as black boxes with measurable terminal characteristics. The technique can also be used to realize a reduced order model of a complex subsystem.The Direct Energy Transfer (DET) spacecraft power system is modeled Z to demonstrate the versatility of the comprehensive system model by performing various DC, small-signal and large-signal analyses.Of particular interest is the analysis of the large-signal behavior of the nonlinear solar array system by employing the state-plane method. The analysis of the solar array system operation focused on the transition mode between the shunt mode and the battery discharging mode is presented.The subsystem interaction problems in the local component and global system are illustrated. A methodology for the design and trouble-shooting of a system dealing with the interaction problems using the g-parameters is described. Finally, a system level analysis of the DET system using an empirical data modeling technique is performed. ACKNOWLEDGEMENTS iv

Non-linear, hybrid terminal behavioral modeling of a dc-based nanogrid system

“…The dynamic model of the dc-dc converter can be built using the two-port network model with inverse hybrid gparameters [19][20][21][22], by linearizing the converter around desired operating point. As shown in the (3), the four unterminated transfer functions have to be defined: …”

Simple Modeling and Identification Procedures for “Black-Box” Behavioral Modeling of Power Converters Based on Transient Response Analysis

“…T ODAY, power electronics systems with multiple converters and loads are growing dramatically (e.g., onboard power electronics-based systems for aircrafts) [1]- [7]. The system level analysis is complex [8]- [10], and simulation tools are needed to carry it out.…”

Analysis and design of multi-stage distributed power systems

“…9@)), the stability and dynamic performance of the unterminated line conditioner can be optimized. It is particularly important to minimize the output impedance of the unterminated line conditioner, denoted as Zou, to ensure the stability after integration and minimal interactions with load converters [6]. It can be shown that this approach results in compensation parameters similar to those of Section 2.2.…”

“…If both Zoo and ZAc are stable, the sufficient condition for the stability of the integrated system is for all frequencies. If the impedances do not meet this condition, the Nyquist criterion should be applied to T,,, to determine the stability [6]. indicating the instability of the integrated system.…”

“…As demonstrated in [6], the stability of the integrated system can be analyzed using impedances at the interface of two subsystems.…”