MPPT Finite-State Supervisor for Electrical Power System Management in LEO Satellites

Implementation of maximum power point tracking (MPPT) and optimization of battery charging in low Earth orbit (LEO) satellites are interleaved problems which both depend on the state in which the satellite is operating. In this paper a finite-state supervisor for energy management in electrical power systems (EPS) with unregulated bus is proposed. The supervisor design is based on a hybrid dynamic model of the system and it discriminates among the different operating modes of the satellite. Conditions for the transitions among the different modes of the supervisor are discussed and formulated in terms of the battery state of charge (SOC), power loads and irradiance. The supervisor determines for each mode the duty cycle required between the photovoltaic panel and the battery voltages, which is implemented by means of a DC-DC buck converter. The model is reproduced in the Simulink/Stateflow environment and simulation results show the representativeness of the model in different operating conditions.