Much more than just a socket

E-mobility is a market of the future. But before electric vehicles can be accepted, a broadly-based privately owned charging infrastructure accessible to the public will be needed. Standardisation in the area of e-mobility is of particular importance. Clear standards offer both protection and convenience during use. They protect investments and ensure environmental objectives are achieved. The focus of interest is in the charging socket. This applies both to the physical plug connection itself, which is used to connect the car and the charging socket via a charging cable, and to the bidirectional data communication between the car and the charging point.

Alternating current (AC) charging: standard in Europe

One success of the standardisation process is the standard for the type 2 connector. As a standard for safe, rapid and smart charging, it has become widespread in northern, central and southern Europe. In early 2013, the European Commission proposed this type 2 plug as the uniform plug for Europe, and in March 2014 the standard was established.

Unlike the familiar domestic sockets, the type 2 e-mobility connector is not always live. The charger plug is not live when first connected; current flows only once four conditions are satisfied: firstly, the full plug-in depth must be recognised (proximity function), after which the plug is locked. The vehicle must respond to the signal from the charging infrastructure to monitor the earth (“control pilot”) and – in the case of a publicly available charging infrastructure – the driver of the electric car must provide authentication. The charging process starts only at that point.

The type 2 plug standard also provides for a bidirectional data exchange and thus forms the bridge to the key international standard for vehicle-to-grid communication.

As a result, the plug face for the type 2 connector was also included in the proposed standard for the Combined Charging System for Europe, given its high charging potential (meaning shorter charging times for customers), its safety features and its data communication ability.

Direct current (DC) charging along arterial roads
DC charging using an external charging device (offboard charger) complements the AC charging option. As a means of driving forward the development of a charging infrastructure, both economically and with minimal disruption to the grid, it makes sense to provide additional DC charging stations mainly on motorways and highways. It is to be expected that all vehicles with the option of DC charging will be fitted with an onboard charger as a second charging strategy. This would make it possible for standard charging to be performed using an AC socket anyway.

Leading automakers in the US and Germany began the work of developing a combination AC/DC plug in the autumn of 2011. Development of this Combined Charging System (CCS) was based on the type 1 (North America) and type 2 (Europe) plugs, with two further powerful DC contacts added.

New models from German automakers, such as the BMW i3 or VW e-Up, now include both the type 2 plug connection (AC) and the DC plug connection behind just one compact “fuel filler flap”.

Data communication: environmentally friendly and convenient electric mobility
The pilot signal sent by electric vehicles to a charging point to ensure recognition was set down in standard IEC 61851-1 as early as 2011, guaranteeing electrical safety for high charging capacities in particular.

Now, in 2013 and 2014, the area of application and the data formats for data exchanges at the charging point have been set down as a uniform global standard, ISO/IEC 15118.

In the context of the transformation of the energy market, electric vehicles help preserve resources. Smart charging and thus the integration of electric vehicles into the grids of the future will, however, be one of the preconditions for being able to use renewables as a fuel. Smart charging also makes it possible to make the greatest possible use of “own-generated”, decentralised, renewable energy, in addition to the opportunities for active load management to avoid overload situations.

The standardised exchange of data during the charging process can make use of automatic identification opportunities offered by the vehicle at the charging point (i.e. Plug & Charge). Drivers would not need to take any further action and could charge their vehicles almost incidentally during normal parking hours. Activation at the public charging point via a Smartphone or a charging point status display would also draw on standardised data communication. This is one way in which a smooth exchange of information will provide the prerequisites for convenient mobility.

Torsten Günter
Head of Operations
RWE Effizienz GmbH


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