Optimisation of the Energy Harvesting and Management Systems of the Nanosatellite OUFTI-2 and Design of its Electrical Power Supply

Abstract

The aim of this thesis is to design a part of the Electrical Power Supply (EPS) board of the nanosatellite OUFTI-2. The parameters to be fixed are the solar panels’ configuration and management, the Battery Management System (BMS), and their connection to the DC-DC converters distributing the power to all sub-systems. The battery pack, the solar panels and the DC-DC converters are already chosen from previous works on the satellite. The limitations and requirements imposed by the choice of these components are analysed. The state of the art of Maximum Power Point Tracking (MPPT)technology as well as Battery Management Systems (BMS) of Lithium-Polymer (LiPo) are summarised and compared. From this knowledge, several relevant EPS designs combining different MPPT controllers and BMS configurations are discussed and tested as well as their power paths. The final design is chosen to be a semi-regulated bus architecture connecting two SPV1040 MPPT controllers in series and an MCP73213 linear BCR to the DC-DC converters. Finally, the power budget of the satellite’s consumption and harvested power based on the chosen design is discussed. This first analysis ensures a net power margin of 300mW in the worst case orbit scenario, for a standard mode operation.