ZVS modulation strategy for a 3 - 5 level bidirectional Dual Active Bridge DC - DC converter

This paper presents a Zero Voltage Switching (ZVS) modulation strategy for the 3 Level - 5 Level (3-5L) Dual Active Bridge (DAB) DC-DC converter. The DAB accommodates a full bridge in the primary side and two 3-level T-Type bridge legs in the secondary side, linked by a high-frequency transformer and an inductor. A ZVS modulation strategy is presented, in which commutation inductances are utilized to extend the ZVS region to the entire operating range of the converter. The configuration of the secondary-side bridge allows further flexibility, compared to a full bridge configuration, to minimize the RMS current in the inductor. The nominal power of the converter is 2.8 kW with input voltage range from 8 V to 16 V, and output voltage range from 175 V to 450 V. The RMS currents of the 3-5L DAB are compared with those of a typical 3-3L full bridge - full bridge DAB, by applying the proposed modulation strategy in the 3-5L DAB, and a strategy proposed in literature in the 3-3L DAB.