Abstract
This paper investigates, analyses and presents a control scheme for a modified SEPIC converter. High voltage conversion ratio is accomplished by using fewer passive components. The modified SEPIC converter is a combination of two different circuits. The first part is a standard SEPIC converter circuit, and the second part is a switched capacitor circuit. A high voltage conversion ratio is achieved up to 29 times by the input voltage, if the duty ratio is kept 0.9. However, high performance control of DC-DC converters is a difficult task due to nonlinearities and higher order behaviour. Control methods, such as PI controller or linear state space approaches cannot achieve the goal in a wide operating range. Instead, Sliding Mode Control (SMC) method is a suitable solution in such circumtances. Since it is insensitive to parameter deviations and free from system dynamics. This study accomplishes a SMC to the modified SEPIC converter and also maintains the constant switching frequency. The complete DC-DC converter along with the control algorithm using Matlab/Simulink simulation software is demonstrated. Simulations show impressive results with the expectations for different perturbation scenarios and matches the developed theoretical background.