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Status Quo: Electric vehicles currently available on the market have a real maximum range of approx. 400 - 500 km at low temperatures (source: Electric Vehicle Database). The shortest charging time of an electric vehicle is currently approx. 22 min. to charge the vehicle battery with max. 270KW from 5% to 80% (source: PAG).Problem: The range and the time required to refill the energy storage of electric vehicles are not yet as long as those of vehicles powered by internal combustion engines. For the user, these deficits are associated with a loss of comfort, especially on long-distance journeys.Method of Resolution: A promising approach is to significantly reduce the charging time by increasing the charging power with simultaneous and efficient dissipation of the waste heat. Technically, this is to be implemented with a vehicle-external cooling fluid, which is provided by the charging infrastructure. The question arises how the novel thermal interface then necessary can be physically integrated into the charging process, into the vehicle and into the charging infrastructure with special consideration of user requirements. The paper presents the design of three prototype connectors, using the standardized product development method described in VDI 2221. Requirements are defined from the analysis of the competitive environment and the required integration of a thermal interface. On the one hand, the focus lies on the technical and physical requirements related to the electrical and thermal power transmission, on the other hand, the human-product requirements related to the physical use are assigned special importance. For the conception, the derivation of Function Structures and subsequently the identification of all sub-functions serves as an essential basis. Partial functions of the interface that have proven themselves in the electrical power transmission of the standardized CCS interface (source: IEC 62196-3 / SAE J1772) are adopted. Essentially, the sub-functions "leakage-free coupling / decoupling", "overcoming closing resistances" and "user-friendly connector handling" are identified as design-critical. By defining and selecting suitable versions of the sub-functions, three interface concepts are systematically derived and evaluated against each other in test person studies. The result shows that vehicle ultrafast charging with electrical and thermal power transfer and with only one connector is possible for all users and all vehicle types from an ergonomic point of view. A test person study shows that the users prefer the handling of the new interface compared to the charging standard currently used on the market and a separate, hydraulic power transmission.

IntroductionThe CoolEV consortium, consisting of Porsche, Hydac, ZSW, IFS and the University of Applied Science Esslingen (UAS Esslingen) is currently working on the fast charging station of the future. In this context, the UAS Esslingen is developing a new type of charging interface, which, in addition to the electrical lines, also provides fluid lines for temperature control of the vehicle battery. Main research areas of the current work are a user-friendly physical charging interface and the overall operating concept of the charging process. The novel interface and the evaluation of user-friendliness are highlighted in this contribution.ProblemState of the art CCS charging connectors have added cooling to the contacts and the electrical lines, in order to prevent overheating within the connector [1]. The remaining bottleneck in charging speed now is the vehicle battery. To control its temperature, the novel charging interface, developed in the CoolEV consortium, provides two fluid lines, adding the capability of externally cooling the vehicle. Disadvantage of this addition is an increase in size, weight and line stiffness, compared to current charging connectors. This could cause problems concerning handling or carrying for a user. There needs to be a verification, if the interface is still usable for everyone and for all types of electric vehicles. Another question in need of an answer is, if a person would prefer the combination of fluid and electrical lines in one plug or a solution consisting of two separate plugs, keeping the CCS connection and adding a second line for the fluid.Method of ResolutionTwo different trials were held to answer the questions that were brought up while developing the physical interface. At first, a test rig with an adjustable ergonomics model of the new hand piece was built. The sockets, simulating the vehicle side of the rig, are arranged in two different heights, both on opposite ends of a comfort zone, determined by means of the digital human-model RAMSIS® [2]. Using this rig, 30 participants were guided through the experiment, each using the new interface and subsequently answering a questionnaire about their experience. For an objective review of the experience, every participant was also filmed while conducting the charging process. Using the videos different problems were identified, mostly involving body position and sight of the vehicle socket, giving inputs for improvement of the hand piece. For the second trial, the rig was extended with an assembly containing the dual line solution. The improved hand piece was 3D printed and added to the single line solution. In a comparison experiment, 30 participants used both variants and rated their experience, resulting in the identification of a user favourite. The experiment results prove that a one line solution is usable for everybody and preferred to a dual line solution. The significance of the results were statistically tested and secured.[1] PHOENIX CONTACT Deutschland GmbH, “High Power Charging – die Technologie für Schnellladestationen,” 2021. [Online]. Available: https://www.phoenixcontact.com/online/portal/de?1dmy&urile=wcm:path:/dede/web/main/products/technology_pages/subcategory_pages/High_power_charging/b1c8a245-f088-4fad-b144-cea31e7f9a82.[2] Human Solutions GmbH, “3D-Menschmodell & Ergonomiesimulation,” 2021. [Online]. Available: https://www.human-solutions.com/de/produkte/ramsis-allgemein/index.html.

In addition to the reduction of charging times, the optimization of the charging process and its integration into the primary vehicle use is a central approach to minimize the loss of comfort for the user. In a first step, design-critical vehicle users were identified and modelled in typical user scenarios. Then, on this basis and taking into account an analysis of the strengths and weaknesses of fast-charging technology currently available on the market, the requirements definition for the development of a system for "user-friendly support in the planning of a transport task for EVs" is carried out. The focus will be on the development of a multi input device operating system that is based on a different degree of connec-tivity and automation depending on the different user types. The focus of the evaluation lies in the discussion of the correlation between the degree of connec-tivity and automation and the user types. Systematically derived operating con-cepts are evaluated in the context of subject studies.