The use of power electronics DC/DC converters in aircraft has increased due to the state-of-art converters developments. However, the volume, efficiency and mass of such converters are critical issues. Each component of the DC/DC converters contributes to the total mass of the system. By designing each component, optimized to have small volume, high efficiency and small mass, the total system can have small volume, small mass and high efficiency. This master project explores design optimization of dual active bridge (DAB) DC/DC converter components: the capacitors, the cooling system and the transformer. Different types of capacitors are compared in terms of mass, volume and loss for the input and output capacitors. After selecting the types of capacitors, the number, volume and mass of the input and output filter capacitors are optimized by interleaving two and three dual active bridge DC/DC converters. The thermal resistance of external cooling system for the selected switches is optimized by a trade-off between the junction temperature of the switches and the losses induced. The transformer is optimized by an evolutionary algorithm, particle swarm optimization, for volume, power loss and required maximum allowable thermal resistance for cooling. The three interleaved DAB is found to be attractive in terms of less capacitor number which leads to a small volume and mass. It is also found to be attractive in terms of thermal management of the transformers designed using the particle swarm optimization. This decreases the volume of cooling systems needed for the transformer. Interleaved three DAB is selected as best in terms of volume, mass and thermal management.