Power Distribution Study for 10-100 kW Baseload Space Power Systems

Power distribution designs for various space power systems are driven by source characteristics, load requirements, and subsystem functional requirements. The primary considerations in the selection of a power distribution type is minimization of the system mass and power losses. Additional criteria used in the selection of power distribution schemes are survivability, cost, reliability, and power quality. The objective of this power distribution paper was to define the optimum power distribution topology for a 10 kW photovoltaic array source, a 20 kW space nuclear reactor thermionic source, a 50 kW solar thermal dynamic brayton source, and a 100 kW space nuclear reactor thermoelectric source. The problems associated with distributing power to a spacecraft user vary greatly depending upon source characteristics and load profile considerations. In order to properly evaluate and select power distribution options for each selected power system, it became necessary to analyze the effects of bus voltage, AC vs. DC, regulated vs. unregulated, and central vs. distributed power distribution on power distribution system performance. Parametric studies of cabling masses, converter masses, and source masses were performed which input into system mass calculation models. Numerous assumptions about platform size, load profiles, source weights, and design criteria were made in order to allow for the parametric evaluations present in the various trade studies. A description of these assumptions is included in this paper. The results of this study suggests that it, is advantageous to design an unregulated, centrally distributed high voltage bus between 120 and 200 VDC for distribution on power systems between 10 and 100 kWe.