Charging stations for more electric mobility

Starting point

The growing number of electric vehicles and the increasingly dense network of charging stations present major challenges. A huge amount of power is needed to charge many electric vehicles at the same time. This can overload the power grid, especially if a large number of vehicles are charging in the same place at the same time. Grid operators nevertheless also see the opportunity presented by electric vehicles in relation to the energy transition with an increasing share of renewable energies.

Approach

Many electric vehicle batteries store a considerable amount of energy. These batteries can be used as energy storage, enabling power to be fed back into the grid when levels are low. Implementing such a system requires interaction between the vehicle, charging station and grid as well as the option of feeding battery energy into the grid via the charging stations. It also requires a bidirectional converter which allows electricity to flow in both directions. However, most charging stations are not currently bidirectional, and relatively few vehicles possess the intelligence required.

In collaboration with the company Green Motion, which develops and manufactures charging stations for electric vehicles, the team from the Power Electronics Laboratory at the Institute for Energy and Mobility Research (IEM) at Bern University of Applied Sciences is able to contribute to solutions in this area in various ways.

Solution

A highly efficient isolated modular converter was developed to equip a family of high-performance fast-charging stations. They are capable of both charging a vehicle and feeding battery energy back into the grid if required. While the topologies used to produce bidirectional converters for the charging station are complex to implement, they are reasonably well established in power electronics. The solution’s innovation lies in its compactness, its low costs and the efficiency attained. These qualities were made possible by the improvements in the modelling of the converter’s elements.

The bidirectional converter system means Green Motion is one of the first companies able to provide a solution that supports the vehicle-to-grid (V2G) function. This enables it to provide services for the energy management of power grids.