Saving electricity is one of the most important challenges for science, but also for each of us. For the individual user, the simplest habit to save energy is to switch off appliances that are not being used at the moment. However, much more can be done in this respect by designers of electronic devices. In the design of such devices, an important component is their power supply or charger. Designers should therefore ensure that they are highly efficient, i.e. that energy losses in such a system are minimised. The design of such systems is computer-aided, so it is necessary to formulate mathematical equations that help the designer to select the system parameters in such a way as to achieve the highest possible efficiency while maintaining the assumed geometrical dimensions of the systems. In the project, which dr Paweł Górecki from the Faculty of Electrical Engineering at the Gdynia Maritime University is carrying out together with the team of prof. Vincenzo d'Alessandro from the University of Naples, the key is to develop an averaged modelling method for DC-DC converters, which will allow a significant reduction in the time needed to obtain the calculation result - from several hours to single seconds. The method being developed also allows the elimination of convergence problems, which in the classical method often prevent the calculation result from being obtained. From the point of view of designing DC-DC converters, the prediction of the internal temperature of the transistor present is particularly important. Statistically, every 10 degrees C increase in its operating temperature results in a doubling of its failure-free time. Therefore, proper modelling of the thermal properties of the device is of particular importance. The value of the temperature rise inside a transistor is proportional to the power dissipated in it. A significant part of the power dissipated in it during each operating period is related to the switching of this element. "The issue of modelling the power dissipated in the transistor during its switching and relating it to the design of the printed circuit of the converter and the parameters of its other components will be the focus of prof. d'Alessandro's team during my stay in Naples," - says Dr Górecki.