Small Signal Modeling of a Synchronous Isolated Cuk Converter used in Photovoltaic Systems

This paper presents the small-signal modeling of a synchronous Cuk converter using state-space averaging method. In the proposed isolated converter, the conduction and switching losses reduced by replacing the traditional diode with transistor and employing an auxiliary circuit. It causes the conversion efficiency of the photovoltaic system to be increased and better matching of the supplied load. Also this circuit has significant advantage over other topologies since it enables low voltage ripple on both input/output sides of the converter and better dynamic response. The low frequency small-signal model is done using state space averaging technique and two main power-stage transfer functions are derived, which are control-to-output voltage transfer function and input-to-output voltage transfer function. Using the proposed model of the converter we can analyze and simulate the time domain transient behavior of the system accurately and intuitively. Finally, the accuracy and validity of the proposed system model is verified by simulation results.