Fraunhofer Institute for Transportation and Infrastructure Systems IVIConcept and functioning of the underbody charging system.
Road-Integrated Charging Unit
for vehicle fleets, filling stations and charging lots
Underbody charging system applied in logistics operation at Westhafen Berlin.
The road-integrated charging solution is a so-called Automated Charging Device - Underbody (ACD-U). Due to the system's high transmittable charging capacity, the charging process is similar in length as conventional refueling.
Therefore, conventional gas stations are well-suited installation sites for the road-integrated charging interface. The charging actuator is embedded in a compact shaft system and dug ca. 1 meter deep into the ground. Vehicles can easily drive over it for recharging. 10 to 20 charging processes per hour and contact unit can be performed at this electric charging station.
Key design aspects such as simplicity, robustness, durability and maintenance-friendliness guarantee that the system will work smoothly over a period of several years:
- 1.2 MW charging capacity for passenger cars (up to 3.5 t)
- 600 km range achieved within 5 minutes
- 4.5 MW charging capacity for trucks
- 100 km range achieved in 3 minutes
- Fully automated charging process
- Integrated electromagnet for maintaining the contact forces during the charging process
- Integrated compensaiotn of positioning tolerances:
- 140 x 140 x 60 … 320 mm; ±10°
- Traversable by cars, load class DIN EN 124 D400
- Dimensions of road integration:
- 920 mm x 552 mm
- Depth 1080 mm
FAQ
What is the core technology behind the system and how does the energy transmission work? What are the advantages?
The system is a conductive energy transmission system. This means that electrical contacts are physically connected to each other. The Underbody Charging System (UBCS) uses the front-end contacting principle. By way of this principle, the electrical contacts are pressed together with great force. To ensure that this electric connection is maintained throughout the entire charging process, an electromagnetic locking mechanism between the charging unit's road component and the UBCS vehicle interface is activated.
This innovative technology significantly reduces transmission losses, which allows much more current to be transmitted via a contact point without active cooling.
What are the main advantages for users?
Due to its integration into the raod, the system basically requires no installation surface and is therefore especially well-suited for depots and other environments where space is critical.
In addition, it is a discreet solution for areas where no above-ground charging stations can be installed for reasons of urban planning (historical monument protection, sightlines). Because it is traversable, it cannot be crashed into.
The system is securely protected against vandalism and cable theft. Due to its automated character, it is especially well-suited for automated vehicle applications.
It is a safe investment into future applications because of its high potential charging capacity.
What performance specifications and electrical standards does the system meet? What options are available for adapting it to different vehicle types or charging capacities?
The system complies with the the newly published IEC 61851-26 standard. The electrical interface's capacity exceeds the requirements of a Megawatt charging system (MCS). The system is capable of carrying out charging scenarios with capacities of 22 kW to 4.5 MW and can be integrated in any vehicle.
How is the system integrated into the road surface? What are the requirements for the integration environment?
The charging unit is integrated into the road via a plastic cable duct or shaft. The civil engineering work does not differ from conventional installation, for example in the area of broadband cable expansion. Drainage pipes and cable ducts also need to be planned for at the shaft.
The road surface cover including the cover flaps is a special custom component. It has to be fitted in horizontal level into the road surface.
How is the electrical connection to the charging infrastructure established?
The charging interface connects directly to the charging station. This means that conventional charging cables are not needed.
Can I step on or drive over the system with my vehicle? How is it protected against vandalism?
The system features a road cover with integrated cover flaps. The assembly was tested in conformity with DIN EN 124 for the D400 load class, which proves its suitability for road surfaces in public spaces. Depending on the specific use case, other load classes can also be achieved.
The cover flaps are locked in idle state and protect the system from unauthorized access. Due to the fact that the charging cables lie securely under the road surface, cable theft is impossible.
How is the system protected against environmental factors? What happens in case of flooding?
The system is equipped with a drainage system that extracts rain water and dirt from the cable duct. The road cover is designed to prevent the accumulation of dirt in the area around the cover flaps. In case of strong contamination, the road cover can be easily cleaned with a broom.
A heating unit also protects the road cover from freezing. In the event of flooding, critical water levels will be detected via an integrated float switch and the system will be shut down.
With how much precision do I need to position my vehicle above the charging system? Can I access the system from different directions? How about vehicles with different ground clearance?
The charging system can compensate positioning tolerances of 70 mm and angle tolerances of 10 ° in each direction. It can be accessed from two opposite directions.
Vehicles with ground clearances of 80 to 320 mm can be charged, which includes all vehicle classes from sports cars to trucks.
Which requirements must be met in order for the charging process to start?
Vehicles must be in the correct position above the charging system and the parking brake must be engaged.
Wireless communication between vehicles and charging station will initiate the charging process. The communication can either be carried out fully automatically or via the push of a button located inside the vehicle or on the charging station.
What happens if the charging process is aborted due to an emergency shutdown or a blackout?
If the charging process is aborted, the charging contactors open automatically and the electromagnetic lock is disengaged.
The road-integrated charging interface will retract into the charging duct and the road cover will close and lock automatically so that the vehicles can evacuate the charging area. During this process, the prescribed sequence for disconnecting the electrical contacts is observed.
Can passengers enter or exit the vehicle, can cargo be loaded into or unloaded from the vehicle during the electric charging process?
Yes. The road-integrated charging interface stays connected to the UBCS vehicle interface via the electromagnetic locking mechanism. The system will compensate for all dynamic movements of the vehicle that occur during the charging process.
What development and cooperation options does Fraunhofer IVI offer industry partners?
Fraunhofer IVI offers their industry partners diverse development and cooperation options. This includes:
- Joint research projects: Development of innovative technology in the fields of transport engineering, mobility and automation.
- Technology transfer: Support for the transfer of research findings into industrial application, including attractive licensing plans for our patented technologies.
- Access to an expert network: We promote synergies and cooperation through our access to a broad network of experts and other enterprises.
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