Design and analysis of SMC for second order DC-DC flyback converter

Flyback converter has RHPZ (right half plane zero) in its voltage transfer function when operating in CCM. This unstable zero dynamics produces some tough limitation to achieve required output characteristic using classical control techniques. In this paper second order flyback converter is implemented with Sliding Mode Control (a non-linear control) to get regulated output voltage in response to line, load and set point variation. It is convenient to linearly model the flyback converter for better circuit understanding. For this purpose, averaged state space model is obtained for both states of the switch over one switching period. Then Sliding Mode Control is implemented using voltage and current error to get regulated output voltage and better dynamic response. The MATLAB / Simulink environment is used to implement the proposed control scheme. Results give the response of SMC for load, line and reference value variation. Obtained results provide a reference picture for the designers to practically implement SMC for flyback converter.