The purpose of this work is to present a complete nonlinear analysis of the DC/DC Non-isolated Ćuk Converter in conjunction with a photovoltaic cell fractal model. Beginning with eigenvalues location and then using Lyapunov analysis to demonstrate stability, it is studied the input to state stability, input to output stability and finally passivity of the system. Then feedback controllers are designed: Sliding Mode Controller, Passivity Controller and a High Gain Observer for the control of the output voltage in continuous conduction mode (CCM). The proposed feedback controllers have been validated by simulations.