The ‘FastCharge’ research project has demonstrated a three-minute charge on a 450 kW ultra-fast prototype charging station can keep an electric-drive vehicle going for some 100 km.
The demonstration project, run by an industry consortium under the leadership of the BMW Group and including Allego, Phoenix Contact E-Mobility, Porsche and Siemens, showed a full charge (10-80% State of Charge (SOC)) could be achieved with the same prototype in 15 minutes.
This prototype was inaugurated in Jettingen-Scheppach, Bavaria, Germany, recently, and can now be used free of charge, BMW Group said. It is suitable for “electric models of all brands with the Type 2 version of the internationally widespread Combined Charging System (CCS), as is commonly used in Europe”, the auto manufacturer said.
This demonstration was clearly for the car market, yet the results of these trials are expected to impact charging times and systems for the current crop of battery-electric vehicles being developed in the mining industry.
The FastCharge project is receiving total funding of €7.8 million ($8.9 million) from Germany’s Federal Ministry of Transport and Digital Infrastructure.
“Fast and convenient charging will enhance the appeal of electromobility,” BMW says. “The increase in charging capacity up to 450 kW – between three and nine times the capacity available at DC fast-charging stations to date – enables a substantial reduction in charging times.”
The project is now investigating the technical requirements that need to be met in order to be able to tap into these extremely high charging capacities, the company said.
The essence of this system is a high-performance charging infrastructure; the Siemens energy supply system (pictured) being used in the project enables researchers to test the limits of the fast-charging capacity demonstrated by vehicle batteries. It can already handle higher voltages of up to 920 V – the level anticipated in future electrically powered vehicles – and integrates both the high-power electronics for the charging connections as well as the communication interface to the electric vehicles.
“This charge controller ensures the output is automatically adapted so that different electric cars can be charged using a single infrastructure,” the company said.
Thanks to high-current, high-voltage charging, the system is suitable for several applications, including fleet charging solutions and, as in the test case, charging along highways. In order to link the system to the public power grid in Jettingen-Scheppach as part of the project, a charging container was set up with two charging connections: one provides an unprecedented charging capacity of a maximum of 450 kW and the second delivers up to 175 kW. Both charging stations are now available for use free of charge for all vehicles which are CCS-compatible.
The Allego charging station prototypes now presented use the European Type 2 version of the well-established CCS charging connectors. This standard has already proved successful in numerous electrically-powered vehicles and is widely used internationally, BMW Group said.
In order to meet the demands of fast charging at high capacity, cooled high power charging cables made by Phoenix Contact are used, which are fully CCS-compatible. The cooling fluid is an environmentally-friendly mixture of water and glycol, allowing the cooling circuit to be half open. This makes maintenance comparatively straightforward compared with hermetically-sealed systems that use oil, eg in terms of refilling the cooling fluid.
One challenge was ensuring the cooling hoses in the charging line were not squeezed when connected to the charging station, as would happen with a conventional cable gland. This problem was solved by Phoenix Contact with a specially developed wall duct with defined interfaces for power transmission, communication and cooling as well as integrated tension relief.
“Depending on the model, the new ultra-fast charging station can be used for vehicles fitted with both 400 V and 800 V battery systems. Its charging capacity automatically adapts to the maximum permitted charging capacity on the vehicle side,” BMW Group said.
“The time saved as a result of the increased charging capacities is demonstrated in the example of the BMW i3 research vehicle. A single 10-80% SOC charging operation now only takes 15 minutes for the high-voltage battery, which has a net capacity of 57 kWh. This can be achieved on the vehicle side by means of a specially developed high-voltage battery combined with an intelligent charging strategy. The latter includes precise preconditioning of the storage temperature at the start of charging, temperature management during the charging operation itself and a perfectly coordinated charging capacity profile over time,” the company added.
The charging operation is carried out via a multi-voltage network on the vehicle side using a high-voltage DC/DC (HV-DC/DC) converter, transforming the required 800 V input voltage of the charging station to the lower 400 V system voltage of the BMW i3 research vehicle. The HV-DC/DC system also gives the vehicle reverse compatibility, allowing it to be charged at both old and future charging stations.
BMW Group said a key factor in ensuring reliable operation is secure communication between the vehicle and the charging station. For this reason, standardisation issues relating to interoperability are also being investigated and submitted to standardisation bodies.
The Porsche research vehicle, with a net battery capacity of around 90 kWh, achieved a charging capacity of more than 400 kW, thereby allowing charging times of less than three minutes for the first 100 km of range.
IM will be hosting The Electric Mine conference in Toronto, Canada, on April 4-5, 2019, where developments in this fast-evolving sector will be discussed. For more information on the event, click here.