Generic Lithium ion battery model for energy balance estimation in spacecraft

Spacecraft is generally powered by solar array and battery. The design of power system considers that the energy supported by battery is put back in sunlit while catering to other spacecraft loads. The energy balance estimation over multiple cycles is essential to ensure proper functioning of spacecraft. In this paper, a generic model is developed for estimation of energy balance. Proposed model takes battery configuration, cell open circuit voltage characteristics, resistance characteristics, load profile, generation profile as inputs. Battery voltage, resultant battery current, State of Charge (SOC) and instantaneous internal resistance are output. In a two-step procedure, battery health parameters are estimated and then estimated parameters are used to check energy balance over new load and generation profiles. The load and generation profiles are run in loop helping in establishing stabilized battery voltage (positive energy balance) or voltage walk down over several cycles (negative energy balance). The proposed model is verified with experimental data and is in close agreement.