Electric vehicle fleet with charging infrastructure

To study the broad range of questions that electromobility presents and to translate a variety of research topics from theory into practice, Fraunhofer IAO operates an extensive fleet of electric vehicles and the necessary charging infrastructure. This consists of more than 30 alternating-current (AC) charge spots, each delivering a charging capacity of up to 22 kW per vehicle, as well as several direct-current (DC) charge spots for charging capacities of up to 150 kW per vehicle. In addition to the research vehicles, we offer electric vehicles for everyday use in the fleets of several institutes on campus.  

• Peak loads in the grid infrastructure 
  If electric vehicles are connected to all charging stations at the same time, peak outputs of over 2,000 kW are possible in principle. Parking garages are rarely designed for these high local loads, and retrofitting them to handle them would be very expensive. In practice, however, it is unlikely that vehicles will be plugged in at all charging stations simultaneously and charged at full power. The existing system is therefore being used to determine what the actual peak loads are in everyday operation and what maximum values an installation should reasonably be designed for.
• Load management systems 
  If parking garages are not designed for the maximum possible peak loads, a corresponding control system is recommended to avoid overloading the annexes in individual cases. Intelligent load management systems make it possible to distribute the charging of vehicles over time and to limit the charging currents according to the load situation. In addition, the peak loads of other consumers, e.g. connected office buildings and industrial plants, as well as the overarching grid and market situations, can be taken into account.
• Fleet management systems 
  While range is not a limiting factor for combustion-engine vehicles, it plays a significant role in fleet management for electric vehicles due to their longer charging times. When vehicles are booked, they must have a certain charge level to be able to fulfill the corresponding mobility needs. However, since the range depends to a large extent on the topography of the route, the percentage of full throttle driving and the use of heating and air conditioning, a certain degree of flexibility must be ensured when planning subsequent trips. To this end, backend systems have been developed and tested in practice that reconcile the mobility needs of users with the requirements and restrictions of the vehicles and energy infrastructure.
• Micro Smart Grid 
  The entire charging infrastructure is integrated into a micro smart grid as a controllable consumer. This means that the electric vehicles are not only supplied with environmentally friendly electricity from a photovoltaic system, but are also part of a higher-level energy management system. Flexibilities from different storage systems are used to efficiently and grid-friendly coordinate electricity generation with consumption.

The charging infrastructure consists of over 70 normal charging stations, each with a capacity of up to 22 kW, and several fast charging stations with a capacity of up to 150 kW per vehicle. The equipment of the higher-level energy infrastructure is described in our “Living Lab” Micro Smart Grid.

In addition to the research vehicles, additional electric vehicles are offered for regular operation in the company car fleets of several institutes on campus. Employees and visitors can also use the infrastructure.

You can also benefit from our experience, for example, through simulation-based charging infrastructure planning and customised backend systems for your electric vehicle fleet.