Multi-port converter integrating boost and switched capacitor converters for single-cell battery power system in small satellite

In small satellite development, building and testing batteries that comprise several small commercial off-the-shelf lithium-ion cells is cumbersome due to the need for mounting tests to ensure that batteries can withstand the harsh space environment. Space-qualified lithium-ion cells are available but they are too large for small satellites; one space-qualified cell is sufficient to power a whole small satellite. In this paper, a multi-port converter integrating boost and switched capacitor converters is proposed to realize the power system architecture consisting of a single-cell battery and a single power converter. The proposed power system architecture is compared to traditional alternatives, and the advantages of the proposed multi-port converter are mathematically presented based on a comparison with a traditional boost converter. A 20-W prototype of the multi-port converter was built for a 14-V unregulated power system. The measured power conversion efficiencies for battery charging and discharging modes were 97% and 84.5%, respectively. An experimental charge-discharge cycling test was performed for a single lithium-ion cell. The cell was cycled within the range of 3.0-4.1 V while the bus voltage variation was within the acceptable range of 11.0-16.8 V, demonstrating the proposed concept as well as performance.