UBCS Underbody Charging System

To operate electric vehicles efficiently, large amounts of energy must  be transferred in a very short time, similar to conventional fueling

For this purpose, Fraunhofer IVI has developed a compact, safe underbody charging system meant specifically for vehicle fleets in logistics, municipal operators, and even in the private sphere. The charging process starts and ends at the push of a button – no manual plugging in is needed. The automated contact system connects vehicles and infrastructure in a space-saving way, is capable of high-current charging and complies will all safety standards.

A range of different systems for charging electric vehicles are available at the market today. If high power levels are to be transmitted, only conductive, i. e., contect-based systems (charging cable with plug) are currently an option. These solutions are flexible, but they limit the performance of the system to ca. 130 to 150 kW charging power and are therefore not suited for fast charging systems with higher power levels.  

Fraunhofer IVI has developed a fully automated charging system for this specific operation scenario that overcomes the limitations of conventional plug-and-cable devices.

With this new technology, it is possible to transmit up to one MW of electrical power for passenger cars and up to three MW for trucks. Alls of this happens without the intervention of an operator and in a fully automated, safe and reliable way. The system is distinguished by 

• only one interface for different charging power levels, 
• no limitations regarding charging power, as well as 
• high operating comfort through full automation.

This means that handling charging cables will soon be a thing of the past.

During the development process, special attention was paid to the technology's simplicity and maintenance-friendliness. In accordance with the manufacturers, the vehicle component had to be particularly small, lightweight, and cost-effective due to the high number of units expected to be produced.

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If the charging intervals are to be short, high system voltages of up to 1250 VDC and high charging currents of up to 2000 A and above are required. As aconsequence, the contact systems must be constructed in an especially safe and reliable way.

This applies to touch protection, the prevention of arcing or unwanted heating, and to safe and secure charging process control. In addition, fundemantal safety regulations regarding, e. g., getting caught and slipping, were observed.

Fraunhofer IVI supports the further development of their systems by active participation in the following standarization bodies and interest groups on a national and international level: 

• Founding member of the DKE working group 353.0.13 (Automated Conductive Charging)
• Member of the international IEC-TC69-WG14 mirror body (EV supply equipment with automated connection of a vehicle coupler), standardization mandate issued for IEC 61851-26 / -27 
• Solution proposal "Automated Charging Device Underbody (ACD-U)" for private and public charging (Annex D of future IEC 61851-26 standard, currently in draft stage)
• Deputy manager of working group "ACD-U" within Charging Interface Initiative e. V. (CharIn)
• Founding member of DKE working group 542.4.8 (ACD-U interface) for IEC 61851-26
• TS IEC 61851-27 published for comments, publishing of TS IEC 61851-26 imminent
• Participation in DKE working group 353.0.02 (Mega Charging System MCS)
• Member of project group IEC PT63644 (ACD-U Interface) for IEC 61851-26