Steady-State Modeling of a Matrix-Type AC-DC DAB Converter Considering AC-Side Capacitor Voltage Ripple

The matrix-type dual-active-bridge (DAB) converter is attractive for single-stage ac-dc power conversion, known for its high efficiency and reliability. Unlike conventional dc-dc DAB converters, which typically feature large dc-side filter capacitance to maintain constant dc voltage throughout each switching cycle, the matrix-type ac-dc converter employs small ac-side capacitance. This design achieves a high power factor and optimize both power density and cost. However, the small ac-side capacitance results in noticeable capacitor voltage ripple during the switching cycle, which cannot be ignored. This paper develops a time-domain steady-state model to accurately characterize the steady-state performance of the converter. It is revealed for the first time that the ac-side capacitor voltage ripple can substantially impact the performance of the converter, particularly by potentially compromising zero-voltage-switching (ZVS) operation, thereby reducing power conversion efficiency and worsening electromagnetic interference (EMI) issues. Both simulation and experimental results validate the theoretical analysis and the findings.