Effective control & software techniques for high efficiency GaN FET based flexible electrical power system for cube-satellites

This paper investigates an intelligent and configurable electric power system (EPS) for CubeSats and small satellites built using Silicon and GaN FETs at high switching frequency. The EPS is the power source of CubeSat which harnesses power from solar panels and includes battery charging and multi-domain voltage output regulation within the CubeSat. The electrical power system of a Cube-Satellite is developed and is used as a test bed for implementation of the various control algorithms necessary for such photovoltaic - battery based power management systems. The introduction of a digital controller to such power systems provides the system added flexibility and intelligence but also introduces controller design challenges with many control loops running simultaneously and being controlled by a single controller. Efficiency of power converter is increased using pulse frequency modulation (PFM) at light load. For moderate load, higher efficiency can be achieved with comparatively lower Rds-ON based GaN FETs. In this paper we have implemented a control scheme that takes into account various parameters like load transients, control loop update rate and sampling intervals that have an effect on the system performance. Power loss analysis is done for EPS using silicon devices. Simulation and experimental results are presented in this paper using both Silicon and 100V EPC Gallium Nitride Mosfets in PFM and PWM mode for EPS.