Medium Voltage DC (MVDC) Microgrid Power System for Megawatt (MW)-Scale Spacecrafts

This paper proposes a medium voltage direct-current (MVDC) electric power and propulsion system for megawatt (MW)-scale spacecrafts. The core component of this system is a nuclear electric propulsion (NEP) system, which serves as the primary in-space power source for an electric thruster. By utilizing the NEP system as a heat source, a fixed speed alternating-current (AC) electric generator converts the mechanical energy on its shaft into electrical energy at its output. This electrical output is then rectified by a diode rectifier converting it into DC before connecting it to the spacecraft’s MVDC bus through a DC-DC boost converter stage. The MVDC bus voltage in the spacecraft is fixed at 1000V by controlling the DC-DC boost converter. In addition to the NEP system, the spacecraft incorporates solar photovoltaic (PV) panels and batteries to support its power system and payload. The solar PV panels are connected to the MVDC bus via a unidirectional DC-DC boost converter, while batteries interface with the bus through a bidirectional DC-DC boost converter, regulating the charge and discharge processes. The integration of multiple power sources allows for efficient power management and ensures a continuous and reliable power supply during the spacecraft’s mission. In the proposed design, two control modes of the DC-DC boost converter are presented: voltage mode and current mode. Simulation studies are conducted to verify the feasibility and performance of the system.