Mode Analysis and Optimal Design of GaN-Based Three-Phase Bidirectional Dual Active Bridge DC/DC Converters for E-Vehicles Applications

The common grid structure of a battery electric vehicle consists of a high-voltage (HV) and a low-voltage (LV) on-board power system. The HV one, with voltage levels up to 800 V, is responsible for supplying the vehicle›s powertrain. The LV system, with a rated voltage of 14 V, supplies most electrical consumers. The increase in on-board power with the addition of new electrical components motivates the introduction of a third voltage level of 48 V, which allows the supply of high power consumers while remaining below the automotive HV threshold of 60 V. The topologies studied in this dissertation are suitable for interconnecting the HV and 48 V networks, providing the required galvanic isolation between them. To this end, two approaches based on the three-phase dual active bridge converter are proposed. An optimization procedure, based on comprehensive analytical models of the studied topologies, has been developed and leads to the optimal parameters to achieve the best compromise between compactness and efficiency. Finally, three 4 kW prototypes based on gallium nitride semiconductors are constructed and experimentally validated.