Development and Qualification of a Scalable and Modular COTS-based Li-Ion Battery System for Satellites in Low Earth Orbit

Kurzfassung

This paper introduces a commercial-of-the-shelf (COTS) - based lithium ion battery system for satellites in low Earth orbit (LEO). The aspects of modularity and scalability in system design are outlined. Further, a market study of existing battery systems for satellites was analysed to compare the specifications and functionality. The fundamental building block of the presented battery system is a cell module that consists of eight battery cells. By stacking multiple battery modules either the electrical capacity and current capability or the terminal voltage can be adapted to the satellite’s requirements. This modular approach also makes the battery system redundant. The software is also responsible for communication between battery modules and analysis of the state of the battery cells with sensors for temperature, current and voltage of each cell. The COTS battery system is developed to reduce manufacturing price and increase functionality of future satellites. Development and testing of the battery system are supported by the fundamental knowledge of batteries at the DLR’s Institute of Engineering Thermodynamics. The approach of using mostly COTS components including the battery cells influences system architecture, electronic design, software and the qualification process. The battery system has the ability to measure temperature, voltage and current of each battery cell. This allows for further functions like adaptive cell balancing, state of charge and state of health estimation. The goal of a highly functional battery system is to give the operator knowledge of the remaining useful life of the satellite.