Analysis of Nanosatellite Impedance Interaction and Stability Based on System Operation Mode

Low orbit nanosatellites are gaining popularity due to their small volume and low cost. However, these constraints also make power system design challenging. In this paper, a distributed power system consisting of four buck converters is described to be used with solar panels as the input source along with a rechargeable battery. Multiple operation modes are identified, and the dynamic performance of the system during operation Mode I is analyzed with an emphasis on system stability. The relationship between the open-loop and closed-loop input impedances is discussed and Middlebrook’s Extra Element Theorem and minor loop gain analysis are utilized to address stability concerns. Since the mismatched impedance of each converter under different conditions is known to cause instabilities, the affects of the bus capacitor sizing on system stability is investigated using ac analysis and Nyquist plotting.