Integration of Stationary Batteries for Fast Charge EV Charging Stations

Abstract

One of the biggest issues preventing the spread of electric vehicles is the difficulty in supporting distributed fast charging stations by actual distribution grids. Indeed, a significant amount of power is required for fast charging, especially if multiple vehicles must be supplied simultaneously. A possible solution to mitigate this problem is the installation of auxiliary batteries in the charging station to support the grid during high peak power demands. Nevertheless, the integration of high-voltage batteries with significant power is not a trivial task. This paper proposes the configuration and control of a converter to integrate batteries in a fast charging station. The proposed configuration makes it possible to decouple the grid power from the vehicle power using several auxiliary battery modules. At the same time, the converter makes it possible to draw different amounts of power from the battery modules, allowing the use of second life batteries performing in different ways. This paper discusses the design, control, and operation of the converter. Moreover, the effectiveness of the proposed control is shown by means of numerical results.

Hydrogen Fuel Cell Implementation for the Transportation Sector

“…Supplement a battery to a fast charging station is a feasible approach to alleviate the oversizing installed power. This electric storage system acts as a buffer to decrease the peak power request on the network without increasing EV charging time [75]. In this situation, the redox flow battery charges installed power during low electricity demand periods to supply electricity for the fast charging.…”

Reconfigurable Stationary Battery with Adaptive Cell Switching for Electric Vehicle Fast-Charging

“…With respect to the whole charging process, these conditions are met at the beginning of the current ramp- In contrast to the voltage, the deviations of the actual current from its reference seem considerably larger. According to (5), the current is a function of the voltage difference V BESS oc,batt − V EV oc,batt divided by the total resistance. Consequently, the voltage steps caused by the cell switching are directly affecting the charging current.…”

“…The output voltage of the converter could be controlled by the BMS in order to compensate the deviations between V batt and V ref . According to (5), the charging current can further be controlled by adjusting an additional series-connected variable impedance. Based on the introduced Simulink model, future studies could aim at comparing different approaches for complementing the reconfigurable battery concept in order to achieve a sufficient current control.…”

“…However, the rising numbers of EVs pose new challenges for the electric power system, such as an overall increased energy demand, as well as congestion and voltage unbalances in the distribution grid [3], [4]. Specifically, fast-charging processes are impacting the grid due to the high peak-load demand and the inflexible charging times [5]. As part of the H2020 INSULAE project, we deploy and test a local DC microgrid consisting of renewable energy sources (wind, photovoltaics), a BESS, and a DC fast-charging station [6].…”

“…In the present work we investigate, if the reconfigurable design of a stationary battery can further be used to directly follow the charging request of an EV by adapting the cell topology in a real-time fashion. While the concept of battery buffered fast-charging stations has already been analysed in literature, an external DC-DC converter is commonly used as a controllable interface to the EV [5]. To the best of our knowledge, no study has yet explored the option of charging an EV directly with a reconfigurable BESS, without any power converter interconnecting the two units.…”