Abstarct: In this thesis, the sepic converter is controlled by the singular perturbation method. baxsed on the sepic converter characteristics, it is used in photovoltaic applications. The mathematical modeling of the system is performed by the Stat-space Average model. By considering noise, nonlinear properties and disturbances, some limitations are discussed in designing the controller where the conventional controllers do not have an appropriate performance. Thus, to control the converter system, three sequential controllers are designed. For the inner controller, sliding mode method is used, for the middle controller, singular perturbation method is applied and for the outer controller, the integrated controller is designed. Finally, the simulation results and the comparison between the proposed controller with PI controller show the effectiveness of the proposed controller. This controlling method causes the converter to be stable, while in comparison with PI controllers contains a lower settling time and overshoot which has a better performance Compared with classical controllers.