The acceptance and marketing of the electric car are continuously progressing, however with the inconsistent charging infrastructure many motorists are still shying away from purchasing electric cars. There are increased DC fast charge stations at and near motorways which make it possible to fast charge the vehicle battery. But in built-up areas the cost-effective AC charging stations which require significantly longer charging times with single- or three-phase alternating current are more widespread.
There is also the fact that not all electric cars are equipped with the corresponding technology for direct current charging. In the majority of cases the vehicle has a so-called on-board charger. Alternating current is converted into the required direct current using a DC rectifier. This technology also enables charging at a conventional household socket (single-phase, 230 volt) with a maximum charging capacity of 3.6 kilowatts. In theory, higher capacities of up to 43 kilowatts and shorter charging times are also possible at AC charging stations with three-phase alternating current (three-phase current, 400 volt), but the vehicle often lacks the necessary technology for this purpose.
The electric powertrain as a "universal charger"
In order to solve this problem, one option is to install additional charging technology in the vehicle to make it compatible with all charging stations. But the engineers from Continental had another, surprisingly simple idea: They further developed the electric powertrain into the "universal charger". The clever thing about this is that the technical components required are already available. Because direct and alternating current of different voltage levels is already constantly being converted in the electric powertrain.
The innovation of Continental: The electric motor and the inverter (converter between direct and alternating current) are simply part of the charging system. Only minimal changes had to be made to the electric powertrain and a DC/DC converter which ensures the optimal voltage for the battery was added. Outside the electric vehicle there is a single cable connection from which two current paths lead to the battery: If alternating current is available, it first flows through the electric motor to the inverter where it is converted into direct current and then from there to the battery. If direct current charging is possible, the direct current is fed directly to the battery by the DC/DC converter.
In addition to the flexible use of direct and alternating current charging stations, this technology also boasts another decisive advantage: With the AllCharge system the electric car can be charged with up to 800 volts and up to 350 kilowatts of charging capacity. "350 kilowatts of DC charging capacity covers roughly 150 kilometres with a 5-minute charging time", states Dr. Martin Brü̈ll, expert responsible for the new charging system at Continental. "This shows what is possible in the future with our charging system. It doesn't matter how fast the infrastructure develops in the future, a vehicle with AllCharge charging technology will always make the most of the charging station."
The car as 230 volt socket
The new AllCharge charging system not only allows optimal use of the currently inconsistent charging infrastructure. It also works in the opposite direction and can supply mobile electrical devices with 230 volt of alternating current from the vehicle battery. The so-called bidirectional charging allows the electric car to be used as a high-performance power source for a fridge on a campsite. A connection to the public grid is also not always possible on construction sites or at events. This situation can be quickly remedied with the bidirectional charging system.
Innovative charging system receives award from AUTO TEST
The new AllCharge charging system is to be installed in the future generation of electric cars and is expected to be available on the free market from 2022. Continental has been able to impress with its innovative charging technology in advance: For instance, the editorial team of the trade journal AUTO TEST presented a special award in the "Connectivity" category to the automotive supplier for the AllCharge system.