Stability Analysis and Control of Non-Ideal SEPIC Converters Using Leverrier's Algorithm and PI Controller Considering Parasitic Elements

This paper presents the modelling of a fourth-order dc-dc converter, introduces a simple systematic approach to calculate the resolvent matrix in order to obtain the small signal transfer function of the dc-dc converter and the implementation of a PI controller to synchronize its output voltage with input voltage and load disturbances. A SEPIC (Single Ended Primary Inductance Converter) dc-dc converter with uncoupled inductors rated 100- Watt power has been designed specifically for battery charging applications. In certain applications, a SEPIC converter is used where the input voltage can be either higher or lower than the required output voltage. A SEPIC consists of two inductors and two capacitors for this reason, its mathematical model is of the fourth-order differential equations. The dynamic model of the converter is obtained through the State Space Averaging (SSA) technique in the presence of non-idealities specially source resistance which has been overlooked by researchers. Leverrier's Algorithm-based approach is applied here to calculate the resolvent matrix. The tuning of the PI controller parameter is done using the Ziegler-Nichols method. At last, the derived dynamic model and calculated PI controller parameters are verified through MATLAB Simulation.