The project focuses on the development of a holistic system which cools the charging system and the vehicle while at the same time enabling the waste heat generated during fast charging to be utilised. The aim is to facilitate user-friendly fast charging of up to 400 kW DC and to significantly enhance the overall energy balance of electric vehicles

Starting point

In the near future, the market demand for electric vehicles with greater range and shorter charging times will be increasingly fulfilled by long-range vehicles with fast-charging capability and the corresponding charging infrastructure. The charging power of 50 kW, which was designated as fast charging only a few years ago, has meanwhile been superseded several times over, at least as far as the expansion of the infrastructure is concerned.

Fast charging with up to 400 kW DC is possible using new battery concepts, albeit with charging losses of up to 40 kW. Removing the dissipative heat thus created from the vehicle requires a cooling system which is too big, too heavy and too expensive to be economical to use in series production according to the current state of the art. Further research is needed to reduce the charging times further or at least keep the charging times for bigger batteries at their present level.

Project idea

The CoolEV research project is investigating future possibilities and limits of fast charging with regard to heat removal, efficiency, user-friendliness and economic aspects. Its aim is to develop an innovative cooling system using a holistic approach which takes into account the different demands made by the individual components of the vehicle and the charging infrastructure.

A portion of the requisite cooling power is to be shifted from the vehicle to the charging station via a special thermal interface, because it is much easier to integrate more powerful cooling units into the station. The different requirements of battery, electric powertrain and power electronics in respect of flow rate and temperature level of the coolant are a great challenge here. The individual components must be cooled according to their individual requirement.

A further aim is to utilise the waste heat generated during fast charging. Improving the total energy balance of electric vehicles could thus make a crucial contribution to the competitiveness, economic efficiency and market penetration of electric vehicles in the future.

Objectives

The goal of the CoolEV research project is to facilitate user-friendly rapid charging with up to 400 kW by using efficient and economic cooling systems. It will employ two approaches:

Holistic vehicle cooling concept: Battery, electric powertrain and power electronics are to be cooled directly by means of a shared cooling circuit with a non-conducting coolant.

Improved total energy balance: Using the waste heat generated during fast charging will improve the total energy balance of electric vehicles. To this end, a concept which includes a business model and charging logistics is to be developed

Practical applications

A demonstrator vehicle with optimised cooling of the battery and the electric powertrain components will be built in the course of the project. Moreover, a prototype charging infrastructure will be used to simulate how the dissipative heat generated during fast charging can be utilised.

The research results will serve as the basis for the further development of concepts for batteries with long-range capability towards mass production. These concepts are of great relevance, especially for vehicles in the premium segment, but also for electrification in the commercial vehicle segment.

Project findings are incorporated into the teaching.

Project manager Prof. Dr. Alexander Müller from Esslingen: “The results are exploited scientifically by making the findings available to the public at large by showcasing our work at conferences and events. Our findings are also incorporated into our teaching and contribute to the topicality of the courses offered by the Faculty.”

Consortium

Dr. Ing. h.c. F. Porsche AG (consortium leader), Institute of Automotive Engineering Stuttgart (IFS), Esslingen University of Applied Sciences, Center for Solar Energy and Hydrogen Research (ZSW), HYDAC COOLING GmbH

Contact Esslingen University of Applied Sciences

Prof. Dr. Alexander Müller