A novel modeling method, namely, the mixed logical dynamical model(MLD) based on discrete evolution mapping theory by integrating the Hamilton''s principle and hybrid system theory, for DC/DC converter has been proposed. In this paper, without loss of generality, the MLD of Buck converter is achieved by unifying the discrete evolution mapping model, which is obtained by variational integrators, in continuous current mode(CCM) and discontinuous current mode(DCM) under the hybrid system theory framework. The simulation shows that the new model has many advantages, such as, less calculation needed, high precision and it can completely describe the various working state of the system and reflects inductor current ripple etc, over those conventional ways, which means this novel model could be more useful for analysis and controller designing of DC/DC converters.
