A Power Management and Distribution Concept for Space Station

It is expected that utilization of the space environment will increase significantly when a manned low-Earth-orbit Space Station becomes operational. To properly and adequately support this user community, communications from the Space Station to Earth stations will be necessary. The various data forms expected include video and audio and are expected to reach 300 Mbps. The video portion, especially, requires a large bandwidth and high power for transmission. In general, the housekeeping power levels for the Space Station subsystems will be much higher than in previous programs. The expected power levels for the Space Station range from 75 kW to 300 kW for both housekeeping and users/payloads, a large portion of which is telecommunications. Because of this high power level, it becomes impractical to continue the current use of a 28-V dc bus for power distribution. The current concept to supplant this low-voltage bus system is to go to a higher voltage and thereby to increase performance and efficiency. The two technology options available are high-voltage dc and high-voltage, high-frequency ac. Up to approximately 100 kW of bus power, both technologies are competitive. At higher power levels, ac is increasingly attractive. As part of the Space Station effort at the NASA Lyndon B. Johnson Space Center (JSC), a high-voltage, high-frequency ac system has been studied and a design concept generated. This system has a 200-V, 20-kHz primary bus.