In the ‘NEFTON’ project, a charging current of 3,000 amps was achieved for the first time, paving the way for charging at over one megawatt in the future. To this end, in addition to a highly efficient, bidirectional megawatt charging station, components capable of handling charging currents of up to 3,000 amperes were developed and successfully tested. The consortium has summarised the results in a report.
Whilst a charging capacity of 11 kilowatts is sufficient for normal charging of passenger cars and 120 to 400 kW for fast charging, electric lorries require considerably larger amounts of energy. This poses a particular challenge for the energy system and the associated charging infrastructure. The Megawatt Charging Standard (MCS), with 1,250 volts and 3,000 amps, applies to this power class. Technically speaking, this has not yet been fully utilised at charging stations; the current state of the art is around 1 MW of charging capacity.
Simulation models
The partners in the collaborative project ‘NEFTON – Electrification of commercial vehicles for the transport sector – Optimised grid connection’ have developed a user-specific, cost-optimised concept for commercial vehicles and the associated drive and charging system in accordance with the MCS standard. To this end, data was first collected and converted into user and requirements profiles. Based on this, simulation models for the design of the vehicle and the drive system were drawn up to enable the analysis and evaluation of various concepts. In addition to technical feasibility, the systems were compared in terms of efficiency, costs and sustainability.
Future charging
From MAN Truck & Bus’s perspective, the result achieved in the NEFTON project represents a significant milestone for the future of commercial vehicle charging. For the first time, a complete charging cycle was carried out stably at 3,000 amps in a test setup close to the vehicle. “This will eventually make it possible to charge enough energy for a range of over 400 kilometres in around 10 to 15 minutes,” explains Fabian Schweizer, project manager at MAN. However, this requires a new generation of battery systems specifically designed for very high charging capacities. The project results are being directly incorporated into the further development of production-ready high-current charging solutions.
Thermal load capacity
A test rig for high-current testing has been set up at the Technical University of Munich (TUM) to experimentally investigate the charging of electric lorries in the megawatt range. In the process, both individual components and the entire charging system were tested at currents of up to 3,000 amperes and assessed for their thermal capacity. The tests confirmed that the systems used can function reliably even under high electrical and thermal loads. “With the successful construction of our low-voltage test rig and the achievement of 3,000 amperes, we have been able to make a significant contribution to the further development of megawatt charging technology. This lays an essential foundation for making 3 MW charging ready for industrial use,” explains Prof. Malte Jaensch.
New laboratory infrastructure
The higher power classes in the megawatt range require not only new charging and vehicle technology, but also new testing technology with higher connection capacities. Fraunhofer ISE has 40 MW of connection capacity available at its low- and medium-voltage test sites. As part of the NEFTON project, Fraunhofer ISE’s megawatt laboratory has expanded its portfolio to enable the testing of high-power charging system installations with regard to the required grid connection conditions. Fraunhofer ISE’s test facilities were used in the project, in collaboration with the Technical University of Munich and MAN, to investigate prototypes of DC circuit breakers with short-circuit currents of up to 12 kA and to ensure that the entire electromechanical system – comprising the charging cable, plug and distribution system right up to the vehicle batteries under nominal operating conditions of 3,000 A and up to 1,250 V.
Safety measures
Due to the high short-circuit currents, particularly in combination with battery systems, special structural safety measures are required for these tests: because of the risk of electric arcs, shock waves and flying debris, the tests are carried out remotely and in shielded areas. “The new test set-ups have been integrated into the existing laboratory infrastructure of the megawatt laboratory, enabling us to test not only individual charging points but also larger systems,” explains Dirk Kranzer, project manager at Fraunhofer ISE.
Source: Fraunhofer ISE Featured image : As part of the project, the complete system – from charging cable, plug and distribution to the vehicles’ batteries – has been successfully tested at currents of up to 3,000 A and voltages of up to 1,250 V. (photo: Fraunhofer ISE)
See also: Vattenfall, Kia and Hyundai launch Dutch pilot project for bidirectional charging
