James J. Liu

Date of Award


Document Type


Degree Name

Master of Science


Department of Aeronautics and Astronautics

First Advisor

Eric D. Swenson, PhD.


Failure of the electrical power system (EPS) to meet mission requirements is a common problem in nano-size satellites commonly referred to as CubeSats. The motivation for this research stems from the desire to prevent EPS failure through a process of testing and space qualification of components. Utilizing models to predict the behavior of an EPS before it is designed, built, and tested for space can provide critical insight in areas of limitation in performance and survivability. Modeling an entire EPS system is challenging because it requires extensive knowledge of all components and their behavior. This research focuses specifically on the storage component of the EPS often referred to as secondary batteries. The secondary batteries, such as Li-Ion battery cells, are modeled to predict the performance of the storage component in the space environment. Experimental test data is collected under a simulated space environment through the use of a Thermal Vacuum Chamber (TVAC). Data collected from battery testing in the space environment is used to validate a modified Thevenin Equivalent Circuit model. The experimental test data and battery model are compared and evaluated resulting in a promising model that can reasonably predict performance of a battery pack in a two-series two-parallel configuration.

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DTIC Accession Number