Sigmoid function model of Zeta converter considering sneak circuits

With the continuous development of industry, the application of DC/DC converters is becoming increasingly widespread. Zeta converter, as a fundamental DC/DC converter, has a wide range of applications in practical engineering fields. In the Zeta converter, the presence of switching elements causes the mode of the converter to change with the on and off of the switching elements. Due to the presence of switching elements, the zeta converter becomes a segmented smooth system, which increases the difficulty of its Sneak circuit analysis. The emergence of Sneak circuits can lead to more complex working modes and modes of the converter, which poses great challenges to system modeling. Therefore, this article proposes a new modeling method that uses a smooth Sigmoid function to approximate the switching process of the switching element, thereby establishing a smooth continuous time system model of the converter. This model can uniformly describe the CCM, DCM, and Sneak operating modes of the Zeta converter, effectively reducing the difficulty of analyzing the converter.