Order Diminution of SEPIC Converters: Direct Truncation Methodology and Application

SEPIC converter is a versatile DC-to-DC converter that can adjust voltage levels both upwards and downwards. By featuring two inductors and two capacitors, the SEPIC converter operates as a fourth-order converter. Initially, a continuous conduction mode of operation (CCM) is taken into consideration when modeling SEPIC converter using the state space analysis (SSA) technique. A linearized interval model of SEPIC is obtained by putting SSA into execution and interval constituting of 10% variations is considered. For reducing the complexity of analysis process, an approximation of higher-order(HO) SEPIC converter is carried out. Direct truncation method is used to approximate the linearized transfer function of the HO system to a third order model and subsequently to a second order model. All of these models’ step, Bode, and impulse responses are provided for comparison, along with those for system. Based on evaluation of these responses, conclusion is derived on the efficiency and applicability of proposed method.