Dr. Lizana-Fuentes, Ricardo

The increasing power levels handled by electric vehicle (EV) dc fast chargers will impose additional challenges to the switching devices in order to cope with the efficiency requirements. A cost-effective alternative to achieve highly efficient power conversion is through the partial-power conversion concept. This article validates the advantages of a step-down Type II partial-power converter (PPC), based on the phase-shifted full-bridge converter, for EV fast chargers. By exploiting the reduced voltage range of an EV battery pack along with the reduced power ratio for a Type II PPC, an extremely efficient charging process can be achieved. The concept is validated with the development of a 7-kW demonstrator, and hence, realistic efficiency measurements are obtained. Results indicate the effectiveness of charging a battery by merely handling 13.32% of the power provided to it, with a peak efficiency of 99.11%.

This article provides a detailed analysis of the power electronics solutions enabling bipolar dc grids. The bipolar dc grid concept has proven to be more efficient, flexible, and higher in quality than the conventional unipolar one. However, despite its many features, these systems still have to overcome their issues with asymmetrical loading to avoid voltage imbalances, besides meeting regulatory and safety requirements that are still under development. Advances in power electronics and the large-scale deployment of dc consumer appliances have put this growing architecture in the spotlight, as it has drawn the attention of different research groups recently. The following provides an insightful discussion regarding the topologies that enable these architectures and their regulatory requirements, besides their features and level of development. In addition, some future trends and challenges in the further development of this technology are discussed to motivate future contributions that address open problems and explore new possibilities.