Design of Output Feedback Sliding Mode Controller for Sepic Converter for Robustness

Abstract

This paper presents an output feedback sliding mode control (SMC) of a SEPIC converter whose utilisation areas include MPPT and PFC in industrial applications. Owing to their discrete nature, DC-DC converters represent challenges in modelling therefore special linearisation techniques are required. In this study, state space averaging method, which is one of those linearisation methods, is employed in the modelling phase of the design process. Since SEPIC has non-minimum phase and non-linear characteristics, conventional linear control algorithms offer unsatisfactory performance in the face of disturbances, thereby requiring more advanced control strategies. Recently, SMC technique has gained popularity due to whose robust nature against parameter variations, modelling uncertainties and disturbances. Output Feedback Discrete Sliding Mode Control (ODSMC) is a SMC control algorithm that requires only output to be measured instead of full state vector, thereby eliminating the observer design process. To validate the superiority of the non-linear controller in the case of supply voltage and load current variations with sensor noise, results of numerical simulations that are carried are also given.