Battery Technology Center
Picture of the SKALE processKIT

SKALE – Scalable Charging System for Electric Vehicles



Objectives and Results

In order to be able to shape the transition to electromobility, appropriate charging infrastructure is needed. The problem of large load peaks caused by a large number of simultaneously charging electric cars could be solved by coupling the charging points with decentralized renewable energy sources and stationary storage.

A corresponding charging infrastructure with the claim of high scalability and the ability for bidirectional charging is being built and operated at Robert Bosch GmbH. The charging system, a PV system, and a stationary lithium-ion storage unit are connected via a DC power distribution network with a central inverter. Additional vehicles can be charged AC-side. The aforementioned infrastructure is developed and optimized by the cooperation partners Robert Bosch GmbH, PowerInnovation Stromversorgungstechnik GmbH and the Institute of Electrical Engineering (ETI) at KIT for semi-public to private use.

In the project, the ETI at Campus North has the goal and task of developing a simulation and design tool for the charging infrastructure. At the South Campus, the project will conduct studies on the stability of distributed DC networks. In addition, the direct connection to the medium-voltage AC grid will be investigated.


Contents and Approach

First, the system requirements and effective chain interrelationships are implemented in a simulation. The simulation takes into account the electrical variables as well as the characteristic curves and limit values of the components and can simulate site-specific operating strategies. The economic efficiency of the system will also be considered.
On the basis of the simulation, system interrelationships, efficiencies and simultaneity factors will be analyzed and thus a design recommendation for the demonstrator, which will be set up at Robert Bosch GmbH, will be created. Subsequently, based on the previous work, a design tool will be developed that can design and optimize the charging infrastructure including its components for a specific location.
Finally, the simulation and design tool will be validated and optimized and the overall system efficiency will be evaluated using real measured characteristic diagrams acquired by the demonstrator. The evaluation takes into account the efficient use of renewable energies.

An accurate simulation model will be created to investigate the novel DC grid in terms of robust and reliable operation. The simulation model shall include all connected components so that the behavior under normal operation and fault conditions can be evaluated. The results of the investigation shall be considered for the design of the prototype.

In addition, a medium-voltage converter is to be designed for direct connection of the charging infrastructure to the medium-voltage grid. In particular, the converter must meet the requirements in terms of efficiency, redundancy and conformity with the grid code. In addition, a small installation space is required for integration in parking garages. The developed concept is to be validated by building a downscaled laboratory demonstrator.

 

Project Volume

4,3 mio. €
 


Further Information