Common-Mode Conducted EMI Prediction for Dual Active Bridge Converter Based on Unterminated Behavioral Model

A dual active bridge (DAB) converter is widely used in electric vehicles due to its advantages of electrical isolation function and bidirectional energy flow. However, compared with other converters, the number of switching tubes is large; the internal structure is complex, and the electromagnetic interference (EMI) at the input and output ends is more serious. In this article, a predictive behavioral model is established to predict the common-mode (CM) conducted EMI on both sides of the DAB converter. First, the converter is treated as a linear two-port network. Second, the impedance of the two-port network in the CM loop is calculated from the extracted S-parameters of the converter. Then, an equivalent model is established to predict the conducted EMI combined with the CM current of the input and output buses. Finally, the proposed model is verified by experiments on a 140-W DAB converter system.