Modelling and Controller Design of Sepic Converter

The SEPIC converter has gained significant attention in renewable energy applications due its unique ability to provide up and down voltage level conversion. For closed loop controlled applications mathematical modelling of converter is essential for describing converter behaviour. In this context, mathematical modelling of SEPIC converter is presented here. At first, the large signal model is developed with state space equations and later steady state model is constructed. The perturbations are introduced in the average large signal model to obtain the small signal model and finally, the transfer functions are obtained by MATLAB programming to describe open loop relations between output and control variable and output and input voltage. The bode diagram and root locus is constructed from the transfer function and SISO tool is used to obtain PI controller gain values. This PI controller is deployed for regulating the output of SEPIC converter. The stability analysis is also discussed.