Derivation of Small-Signal Model of Boost-SEPIC Interleaved Converter Based on PWM Switch Model

Small-signal model is essential in ensuring the quality and performance of dc-dc converters. An insight into dynamics is a fundamental requirement to select and design the controller of converters correctly. The dc-dc boost-SEPIC interleaved (BSI) converter has the potential for wide application but the small-signal model has not been thoroughly studied. This paper presents a method to establish the small-signal model of the high-order BSI converter based on the circuit averaging and averaged switch techniques. The transfer function model obtained in factorized form with three complex poles, two complex zeros, and one real zero makes it convenient to analyze characteristics and evaluate the impact of components and working conditions on the dynamic of the converter. The obtained model is verified by simulation and experimental results on the frequency domain.