Control and Thermal Design of a Bi-Directional Grid Interface Converter for Fast-Recharging Stations Developed in the Framework of the Italian PNRR Research Activities.

Multi-level converters are a possible solution for increasing the power density and efficiency in many power electronic systems. The increase in the number of switching components on a single device leads to a growth both in the cost of the converter and in its complexity compared to two-level solutions. However, these drawbacks are counterbalanced by a better harmonic content on the AC quantities, allowing a significant decrease in the size of the output filters and reactive power as well. Thus, three-level converters represent a good compromise between costs, system complexity and efficiency. More specifically, this paper focuses on the development of a bidirectional control for a three-phase three-level T-type converter working as an active front end to be coupled with DC/DC converters in off-board recharging stations or in renewable power plants. Moreover, a thermal analysis of the power electronics is carried out aimed to the design and the development of an ad hoc cooling system for a prototype working at 80 kW.