The Grace Follow-On Quiet Electrical Power System

Abstract

This paper provides and overview of the GRACE-FO Electrical System and an in depth discussion of the Electrical Power System (EPS). The EPS elements are presented and their features described by their key parameters. These components are inclusive of the body-mounted Solar Array Panels for Power Generation, the Power Control Unit (PCU) and Power Distribution Unit (PDU), a Li-Ion Battery and the Thermal Control System's Heater Control Electronics (HCE's) acting as active current control front-ends. The latter is explained more in detail with respect to its purpose and implementation. The GRACE-FO EPS has been given the designation of "quiet" EPS due to the function of the HCE within the thermal control Subsystem. The final portion of the paper provides information about the power and energy budgeting and operational aspects of the EPS such as undervoltage and overcurrent H/W features of the PCU/PDU design, and the EPS related On-board Software and On-Board Control Procedures. Finally, the system level power analysis is provided to provide the reader with a better understanding of the expected behaviour of the electrical power parameters.