Study and Development of Innovative Capacitevely Isolated Low Power DC-DC Converter

In the last decades electronics is getting into everyone's life. A great impact in this sense is due to the huge increase in the consumer electronics devices market: among the research fields about this topic, an important one is dedicated to the design of more compact, reliable and powerful energy suppliers. The main goals are: to increase the delivered power, guarantee internal galvanic isolation and maximise the power density. For over a century galvanic isolation was obtained with inductive coupling. This physical phenomenon exploits magnetic field as an interaction media between two or more copper coils, that become inevitably lossy and bulky as soon as the system power increases. Among all the possible alternatives, capacitive coupling appears to be the most promising: in this case the interaction is obtained by means of electric fields between two metal plates. An interface made of plates or discrete capacitors (like in the case of a compact power adapter) may increase a lot the compactness of the final system and the achievable power density. In this thesis, a capacitively isolated and innovative power converter architecture is proposed. The final circuit is intended to be a consumer electronics power adapter, able to provide 60 W of power and a level of efficiency of 90%. According to the application, the output voltage is set to 20 V(DC) derived from the power grid voltage (220 V(AC) at the input side. The entire circuitry is tough to be mounted on PCB, where discrete capacitors are employed to ensure the galvanic isolation. A key aspect in the analysis performed is to evaluate the architecture validity in terms of efficiency and power density. The project is carried out by both simulation and practical approaches: the goodness of the results is assessed with a final prototype.