Modeling and analysis of DC-DC SEPIC converter with coupled inductors

Nowadays, DC/DC converters are widely used in industrial applications and renewable energy systems. A SEPIC (single-ended primary inductance converter) DC-DC converter is capable of operating in either step-up or step-down mode and commonly used in a battery charger system. This paper presents the modeling and analyzing of the SEPIC with coupled and uncoupled inductors. In this study, the state-space averaged (SSA) model is established and built in MATLAB/Simulink environment. The obtained SEPIC model was simulated for different input parameters, and results of coupled and uncoupled are compared. Moreover, the small signal model is used for linearization of the SSA model of the SEPIC with coupled and uncoupled inductors, hence the transfer function of control (duty cycle) to output voltage is formulated. Bode plots of the duty cycle to output voltage transfer functions are constructed, and the result can be used in various applications to design a closed-loop controller to regulate the output voltage.