Nanosatellite Power System with A Variable DC Bus Voltage for Improved System Efficiency

The electrical power system of nanosatellites are challenging because they must be very small and lightweight, yet highly efficient and reliable since they cannot be repaired after launch from Earth. This work has designed a nanosatellite power system using GaN switches operating at high switching frequency. In order to optimize system efficiency, a dynamic dc-link bus voltage control method is being developed, but first the efficiency of the nanosatellite system at different dc-link bus voltages must be analyzed. Experimental data of the individual converters and overall efficiency are investigated and used to estimate system efficiency at different dc-link bus voltage combinations with loading current conditions. Experimental results point to the lowest dc-link voltage of 6 V as yielding the highest system efficiency for this nanosatellite design. The goal is to adjust the bus voltage to maximize system efficiency at any operating condition.