Experimental validation with a control point of view analysis of the SEPIC converter

This paper presents a theoretical study with experimental validation carried out on a DC-DC SEPIC converter operating in continuous conduction mode (CCM). Two dynamic modeling techniques are adopted and various aspects of the converter´s operating modes are analyzed. Simulations of transient and frequency responses are verified with experimental results. A PI control law is used to validate responses to load and reference voltage variations with parasitic losses taken into account. An in-depth analysis of the effects of unstable zeros of the transfer function, from the duty cycle to the output voltage, on the implementation of control laws is also presented. The frequency behavior of the converter along with the stability margins are found to be widely influenced by load resistance and duty cycle variations.