This project has been oriented to the development of an energy system unit for powering tramways during shorts periods of time. The aim of this work is to present the results obtained for a high frequency DC-DC converter which is included in the energy unit. The energy unit will consist on two type of energy storage devices: a battery stack and a supercapacitor stack. A comparison of the simulated model of the DC-DC converter and the real measurement on both topologies, resonant switching and hard switching, has been done. The system works at high frequencies to reduce the weight. In addition, the efficiency should be optimized to reduce the heat sink area and the volume of the whole system. In this case, a 5kW - 100 kHz bidirectional DC-DC converter was developed and the results of the first stage are presented.