Design And Test Of CubeSat Power System

Power system as a key part of CubeSat, responsible for the acquisition, storage, and distribution of energy, is the guarantee of the good operation of the other subsystems.A new design of power system based on MPPT is presented. The energy source of the CubeSat is the solar adopts three Junction GaAs solar cells, and the storage energy of the power is lithium-ion battery with 18650 shape, and the MPPT module is realized with the algorithm of variable-step perturbation and observation method, and the voltage converter and over-current protection circuit is designed with commercial integrated devices. The reliability design of power system has been taken into consideration in the MPPT module, battery pack, over-current protection circuit and the MCU system, also through the power system management the power system increases the reliability.The principle prototype of the power system has been accomplished according to the above design, and the following conclusion is obtained by related function test. The MPPT module of the power system has a good stability and dynamic tracking performance, and the tracking accuracy reached 2%. The efficiency of power conversion module is 90%, and the highest one can amount to 95%. Short circuit protection circuit realizes quick short-circuit protection for outputs to improve the reliability. The software over-current protection achieves 200 ms level response, at the same time realizes the intelligent management of output ports.The analysis of the CubeSat energy balance has been done by establishing the simulation system with Simulink tool, in order to test if the power system suits the application of NJUST-1 CubeSat in orbit. The simulation results present that the CubeSat gets energy balance in normal mode with a certain power margin, not in scientific load mode, and the scientific load must be opened periodically to achieve energy balance. The semi-physical simulation test platform is built with the power system prototype involved, and the solar cell array output simulated by solar emulator. The test result consists with the simulation results, shows that the CubeSat can realize long-term stable operation in orbit according to the current design.So the power supply system in accordance with the design requirements of low cost, high efficiency, low consumption, satisfies the CubeSat application.