Design And Research Of Power Supply System For Cube Sat Based On MPPT

CubeSat has become one of the mainstream technologies for micro-satellite design due to its high density,low cost and short development period.It has good development prospects in the field of aerospace technology.The power system is responsible for the acquisition,storage,distribution and control of satellite energy,which is the basis for the normal operation of other subsystems.According to the mission requirements of a CubeSat,a power system design scheme based on maximum power point tracking(MPPT)is proposed in this paper.Firstly,the overall design of the CubeSat power system is described from the solar array,battery pack and other modules.According to the analysis of satellite space operation environment,reliability design of power system,failure mode and impact analysis are carried out.Then based on the solar cell engineering model,the commonly used MPPT algorithm and its improved algorithm are analyzed and compared.A MPPT control strategy for cubic satellites is proposed.The perturbation period and step size of Perturbation and Observation(P&O)method are optimized by establishing small signal model of satellite photovoltaic control system.Then the Boost-type switching circuit is used as the power circuit of the MPPT module.By analyzing the loss of the circuit,a method for improving the conversion efficiency of the power circuit is put forward.The MPPT control system uses the ARM microprocessor of the Cortex-M4 core as the control core,and the driving circuit of MOSFET selects the NMOS lowside driving mode.The hardware circuit of MPPT module is tested,and the conversion efficiency is close to 90%.According to the theoretical analysis of MPPT algorithm,the optimal perturbation period and step size under different illumination intensity and temperature conditions are obtained.The testing of MPPT module tracing effect is carried out from two aspects: static tracing and dynamic tracing.The test results show that the tracking accuracy is higher than 98%,which takes into account the response speed and stability of the system,and effectively avoids the tracking misjudgment of traditional P&O under variable illumination conditions.The feasibility of the strategy is verified.