- Charging Technologies
Charging electric vehicles involves more than pure energy supply. Communication before and during the charging operation needs to be taken into consideration, as well as all kinds of requirements. These include aspirations regarding safety, suitability for daily use and user-friendliness, which, in turn, create a basis for customer acceptance. Therefore, FKFS is conducting in-depth research into inductive charging of electric vehicles, preferring to take a holistic approach.
The communication interface between the charging station and the vehicle battery is well-defined by the standard ISO 15118. At the same time, there are practical problems concerning charging communication. FKFS is in an excellent position as a development partner, since the Institute has in-depth knowledge about standardization and the charging infrastructure of a variety of automotive manufacturers. One result of this expertise is our FKFS Conformance Tester, which enables testing of the ability of electric vehicle product families to communicate with all available charging stations. The system includes the hardware setup with its control system, as well as automatically-generated test cases including test procedures. When carrying out tests, the test system can consider both the vehicle and the charging equipment sides separately.
Inductive charging is regarded as a particularly user-friendly way to charge electric vehicles, because there is no need for a cable connection between the charging station and the vehicle. At the same time there are technical problems to be solved: to ensure optimum charging (also regarding efficiency), the relative positions of the charging coil and the vehicle coil must be located accurately. FKFS is actively involved in providing solution approaches to these problems – both in research and in development work for customer applications. One highlight here is the Magnetic Pulse Positioning System, developed and patented by FKFS. This is an assistance system which optimizes detection of the charging coil and the positioning of the electric vehicle over the charging coil – even with poor visibility (e.g. snow) or for critical materials such as reinforced concrete.
Using its research charging station, FKFS is conducting in-depth work on AC and DC charging, fast charging and inductive charging. Current research work and studies for automotive customers arise from this context. The central focus is the development of electric vehicle fleets which are suitable for daily use. A variety of factors play a role in this, which may also be vital for the further expansion of e-mobility: starting with battery cells and the possibilities for balancing dissimilar voltage states ("cell balancing"), efficiency is of primary importance. The objective is always a charging operation which is as efficient and as fast as possible. Here FKFS considers all the entities involved: vehicle, user and energy supplier. FKFS studies also investigate the payment process and usability from a user perspective (human-machine interface).
With the increasing electrification of Germany's vehicle fleet, integration of these vehicles into the network poses a challenge. Relative to Germany's total electricity requirements, the energy quantity which will need to be supplied for this is not predicted to present too great a burden. However, the power requirements – especially those needed for fast-charging electric vehicles – pose a huge challenge for our existing infrastructure.
FKFS is considering all kinds of scenarios concerning e.g. car-sharing fleet operation, private vehicles in single-family households and apartment blocks, as well as commercial vehicles. Building on this, we are investigating the influence of individual mobility needs on the charging requirement. Since the charging requirement can be spread over a period of time, strategies for spreading the burden are possible: e.g. via scheduling or incentive models using tariff models, which enable the resulting influence on the network load to be determined.
The combination of electrical energy for vehicle propulsion and renewable energy offers potential for synergies, which can be exploited using suitable strategies for supplying electric vehicles and local electricity demands. The burden on the distribution network can be reduced by increasing local self-sufficiency.