Abstract: Technology is disclosed herein for a power control and distribution unit (PCDU) of a spacecraft that has a microcontroller to control battery charging from solar arrays. Using a microcontroller within the PCDU reduces the complexity of the PCDU. The microcontroller may be programmable and reprogrammable, which allows the charging of the battery to be adapted to various conditions. For example, the microcontroller can be programmed in accordance with the mission to optimize battery charging for that mission.

Abstract: Technology is disclosed herein for reverse current protection for a photovoltaic module string. An apparatus has a switch connected between each respective PV module string and a power bus. A control circuit closes a set of the switches to connect a set of the PV module strings to the power bus to transfer power from the set of the photovoltaic PV module strings to the power bus. The control circuit determines whether a reverse current flows in the direction from the power bus to any of the PV module strings. The control circuit maintains the switch associated with a particular PV module string in an open state to prevent reverse current from flowing in the particular PV module string responsive to a determination that a reverse current flows in the particular PV module string when the particular PV module string is connected to the power bus.

Abstract: Technology is disclosed herein for reverse current protection for a photovoltaic module string. An apparatus has a switch connected between each respective PV module string and a power bus. A control circuit closes a set of the switches to connect a set of the PV module strings to the power bus to transfer power from the set of the photovoltaic PV module strings to the power bus. The control circuit determines whether a reverse current flows in the direction from the power bus to any of the PV module strings. The control circuit maintains the switch associated with a particular PV module string in an open state to prevent reverse current from flowing in the particular PV module string responsive to a determination that a reverse current flows in the particular PV module string when the particular PV module string is connected to the power bus.

Abstract: Described herein is a power processing unit (PPU) for use with a Hall Effect Thruster (HET) and a Propellant Management Assembly (PMA) of a spacecraft. The PPU comprises an anode and ignitor supply subsystem that provides anode and ignitor signals to an anode and an ignitor circuit of the HET. The PPU also comprises a valve control subsystem that provides valve control signal(s) to valve(s) of the PMA. The anode and ignitor supply subsystem and the valve control subsystem are each coupled to a low voltage (LV) bus of an electrical power subsystem of the spacecraft. The anode and ignitor supply subsystem includes a step-up DC-DC converter having a transformer that steps-up a voltage of the LV bus to a higher voltage used to produce the anode and ignitor signals. The valve control subsystem is devoid of a transformer. An Electric Propulsion System (EPS) includes the PPU, HET and PMA.