Conducted Common Mode Emission Analysis of a Three-Port Modular Multiactive Bridge System

The modular multi-active bridge (MMAB) DC–DC converter is increasingly considered for multiport power conversion; however, its conducted electromagnetic interference (EMI) behavior has received limited attention. In particular, the presence of multiple switching bridges, transformer parasitic capacitances, and high <tex-math notation="LaTeX">$dV/dt$</tex-math> transitions can introduce significant common mode cm currents. This paper investigates the conducted CM EMI characteristics of MMAB systems, with emphasis on the influence of topology selection and transformer parasitic elements. The effects of transformer leakage inductance, winding parasitic capacitances, and port configuration on CM emissions are analysed using experimentally validated time- and frequency-domain measurements. Several MMAB configurations, including the fundamental topology and a hardware-level decoupled variant, are evaluated and compared. The results demonstrate that the conducted CM emission is strongly dependent on MMAB topology, phase-shift operation, leakage inductance, and winding parasitic capacitances. While hardware-level decoupling effectively mitigates power cross-coupling, it is shown to increase conducted CM emission.