Improved Bilinear Discrete-Time Modeling of the Single-Phase Dual active Bridge DC-DC Converter

Abstract

Single-Phase Dual active bridge converter (SPDABC) is a prominent topology for the bidirectional isolated dc-dc converter. SPDABC is widely used in the emerging power electronics system which as electric vehicle application, solid-state transformer, more electric aircraft, micro-grid. The conventional method of obtaining the modeling of a system is obtained through state-space averaging of the state variable. However, the process described above is not suitable for the resonant converter. Therefore, this paper proposes an improved bilinear discrete-time modeling method for the SPDABC. The technique utilizes Eigenvalue and vector-based new approximation of the matrix exponential involved in the exact discrete-time models. The proposed discrete-time model provides better accuracy and stability prediction than the conventional approximation. The proposed model is compared with the traditional bilinear and other discrete-time models in the literature. The proposed method applied on the closed-loop digitally controlled SPDABC can precisely estimate the converter’s stable region, which can be used for the controller design to ensure the converter does not cross a stable boundary.