Closed-loop Implementation of a Non-isolated High Step-up Integrated SEPIC-CUK DC-DC Converter Structure with Single Switch

Abstract

Recently, the renewable energy applications require the development of highly efficient DC-DC converters with higher voltage transfer gain capability to meet out the increased global power demand. The non-isolated DC-DC converters are preferred due to certain drawbacks of isolated structures. The traditional boost, SEPIC (single-ended primary-inductor converter), and CUK based DC-DC converter structures are modified with additional power switches, diodes, and passive components in order to achieve high voltage gain. However, the modified structures with large number of active and passive elements suffer from the drawbacks of increased complexity of control algorithm, reduced power conversion efficiency and higher converter cost. Hence, the researchers started to explore more on single power switch configured non-isolated high step-up DC-DC converter topologies using hybrid concept. The research work presented in this paper explores such a high gain single-switch hybrid DC-DC converter structure that combines the conventional SEPIC and CUK topologies to achieve enhanced voltage gain. In the proposed hybrid topology, the input current is continuous during all modes of converter operation. Moreover, the power switch experiences only low voltage-current stress. The closed-loop configuration of the proposed hybrid converter is implemented using classic PID (Proportional+Integral+Derivative) and FOPID (Fractional Order PID) controllers, and simulated in MATLAB / SIMULINK environment with duty ratio D = 0.7 for the power switch. The results demonstrate that the dynamic performance of the converter with FOPID controller is much improved in terms of reduced settling time, overshoot, and ripples for the output voltage, as compared to that with classic PID controller.