Modeling and stability analysis of buck-boost dc-dc converter based on Z-transform

Abstract

In this paper, the stability of the buck-boost dc-dc converter in the continuous conduction mode (CCM) is investigated by using a modeling method. The proposed method is based on the two Laplace and Z-transforms. The Laplace transform is used for determination of the general relations of the inductor current and the output voltage. Also the Z-transform is used for obtaining the transfer function of the buck-boost dc-dc converter. Then by using the transfer function which is in the Z domain, the stability of the buck-boost dc-dc converter is investigated and the effect of the converter elements on its stability is analyzed. Finally, the results of the theoretical analysis are compared with the results of the simulation in the PSCAD/EMTDC to prove the validity of the presented theoretical subjects.