Modeling and design of power conditioning unit of CubeSat electrical power subsystem with robust nonlinear MPPT controller.

Two non-inverting buck-boost converters, one for each solar panel of the X and Y axes of CubeSat have been used to condition the power with a common output capacitor on DC bus. The power generated from each axis of the solar panel is added to the DC-bus along with the power generated by the less illuminated solar panels. For the proposed model, Synergetic control, Sliding Mode Control, and Super Twisting Sliding Mode Control algorithms have been implemented for the MPPT, and their results are compared with each other. The results indicate that the ST-SMC performs well and gives the best dynamic performance and robustness under varying load conditions of temperature, irradiance, and disturbance. Moreover, the stability of the system is validated by using the Lyapunov stability criterion.