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This paper is aimed to present an experimental criterion that allows researchers and designers to evaluate the performance of DC micro-grids dedicated to charging operations of full EV. The laboratory methodology is explained through tests on a demonstrator of power architecture, specifically designed as simplified case study of a DC charging station for fully-electrified low-power two-wheeler, such as: electric scooters and bikes. This experimental prototype is composed by a 20. kW AC/DC bidirectional grid-tied converter, which realizes the DC conversion stage, and two DC/DC power converters, interconnected with the micro-grid through a DC bus. The power architecture provides on one hand the charging operations of electric two-wheeler battery packs and on the other hand the integration of the micro-grid with an ES buffer, which has the main function of supporting the main grid while an electric vehicle is on charge. The performance of the considered architecture is characterized and analyzed in different operative conditions, through a specific management of the energy fluxes. The laboratory tests evaluate efficiency, charging times and impact on the main grid, with specific reference to the DC charging operations of electric scooters. The obtained experimental results show the advantages of adopting the DC buffer architecture, compared with an AC commercial battery charger, considered as reference in this work. Finally, the numerical data of this paper, related to the single power components and to the experimental results evaluated for the whole demonstrator, effectively support the lack of knowledge in the literature about charging stations for EVs. In fact, these pieces of information, based on experimental tests, are expected to support the building of simulation models and the identification of the best energy management and control strategies to be adopted in a smart-grid scenario, characterized by distributed generation systems including renewable energy sources.

Abstract This paper is focused on the evaluation of theoretical and experimental aspects related to the different operation modes of a laboratory power architecture, which realizes a micro grid for the charging of road electric and plug-in hybrid vehicles. The analyzed power configuration is based on a {DC} bus architecture, which presents the main advantage of an easy integration of renewable energy sources and buffered storage systems. A first phase of simulations is aimed to evaluate the main energy fluxes within the studied architecture and to identify the energy management strategies, which optimize simultaneously the power requirements from the main grid and charging times of different electric vehicles. A second phase is based on the experimental characterization of the analyzed power architecture, implementing the control strategies evaluated in the simulation environment, through a laboratory acquisition and control system. Then the experimental results coming from the laboratory prototype are compared with the simulation results, in order to achieve a better parameter setting of the simulation model for the analyzed structure. This preliminary analysis makes possible other simulations to be carried out on more complex architecture of micro-grids, taking into account the integration of renewable energy sources and high power buffer storage systems. Particular attention is also given to the analysis of ultra-fast charging operations and the related performance in terms of total efficiency, charging times, total power factor and power requirements from the main grid. This study represents a further step toward the new concept of smart grid scenario for electric vehicles.

The paper presents a laboratory test bench specifically designed for sea wave generation systems. In particular a DC Micro Grid is realized to experimentally validate the energy performance of a PM Brushless ball screw actuator, during motor-regenerative operative conditions, which is representative of an oscillating body wave generation system. The proposed architecture is based on a DC bus, which features the integration of renewable energy sources and buffered storage systems, with the aim of smoothing the natural power fluctuations of wave energy generation systems. The wave generation is simulated in laboratory by controlling an electric motor, which is directly coupled with the PM brushless generator. The experimental validation phase is mainly devoted to verify the design criteria of the architecture scheme and the control strategies of the power fluxes related to power converters.

This paper presents an overview of issues and technologies related to the proper design of charging infrastructures for road electric vehicles. The analysis is carried out taking into account that the recharging stations of electric vehicles might be integrated in smart grids, which interconnect the main grid with distributed power plants, different kinds of renewable energy sources, stationary electrical storage systems and electric loads. The study is introduced by an analysis of the main characteristics concerning different kinds of storage systems to be used for stationary and on-board applications. Then, different charging devices, modes and architectures are presented and described showing their characteristics and potentialities. DC and AC configurations of charging stations are compared in terms of the issues related to their impact on the main grid and the design of their main components. Specific attention was devoted also to the ultra-fast DC architecture, which appears a possible solution to positively affect a wide spread of plug-in hybrid and full electric road vehicles.