A Solid State Power Controller Module for the International Space Station EXPRESS Rack

Abstract

The Solid State Power Controller Module (SSPCM) designed For the International Space Station (ISS) EXPRESS Rack is a remote-controlled power switching unit with both 120 V DC and 28 V DC solid state power controllers (SSPCs). The SSPCs distribute and protect power to the various loads within the EXPRESS Rack. The SSPCM is designed with two 120 V DC inputs (main and auxiliary) and includes three 1100 W DC/DC converters to provide the payload 28 V DC. The main 120 V DC bus normally provides the 120 V DC for the payloads and the DC/DC converters. In the event of an undervoltage condition on the main 120 V DC bus, the SSPCM automatically switches the payloads and the DC/DC converters to the auxiliary 120 V DC bus. The SSPCM can be configured on orbit to control which payloads are powered during auxiliary 120 V DC operations. This allows an experiment system to run without crew actions during numerous mission profiles. The SSPCM also provides payload analog and discrete inputs/outputs for experiment use. The SSPCM provides sampling rates up to 1 kHz and data formatting for payload data. Two additional configurations consisting of more power channels and less payload analog and discrete inputs/outputs are also under development for the International Space Station Furnace Facility.