Charging Made Easy

Plug & Charge and eRoaming should simplify life with electric cars – and put more of them onto the road

For electric car drivers, recharging the battery is still a hassle – particularly if you have to juggle various cards when logging on to the charging station and have to key in some of the details by hand,which is time-consuming. IAV is therefore forging ahead with the Plug & Charge concept: In future, data exchange is to take place automatically and with eRoaming it won't matter which provider operates a specific charging station.

If you want to recharge your electric car at a public charging station today, you need several cards for the different power suppliers. "The driver has to hold the right card to the display and follow a menu to key in various details. Then and only then does the power flow – if he's lucky",says Ursel Willrett, Senior Technical Consultant for Infrastructure Systems and Electric Mobility at IAV, in describing the unsatisfactory status quo. "Our aim is for the vehicle to begin communicating automatically with the charging station, negotiating among others the charging conditions, such as costs."

This is followed by a brief confirmation query with the driver (e.g. using an app on the driver's smartphone) and then charging can begin. The idea is called “Plug & Charge” with reference to the convenient “Plug & Play” mechanism in the IT world.

It would then no longer be necessary to key in user data manually. Juggling with various cards for the individual power suppliers would also become a thing of the past because IAV is also forging ahead with eRoaming. Instead of concluding contracts with different energy providers, in future customers would be billed by just one central entity. This is a similar concept to telephone roaming: People using their phone abroad pay the incurred fees later on through their home provider, rather than directly to another cell phone service provider.

Full implementation of ISO 15118

Before Plug & Charge and eRoaming can make life with an electric car much easier, a number of obstacles have to be eliminated by electricity providers, OEMs and suppliers. These begin with communication between vehicle and charging station. "Standard ISO 15118 already covers a broad scope of functions, but it is still quite new, being completed only in summer 2015", explains Willrett. "Many functions still have to be implemented in the vehicles and charging stations or haven't completed the test phase yet."

At the moment, they fulfill DIN Spec 70121, the "little brother" of the major ISO standard, which only deals with charging control. It does not support load management and the related call-up of tariff tables, so that load-dependent billing is not possible. Nor does it include any functions for secure billing between customer and power supplier. The first prerequisite for Plug & Charge and eRoaming therefore consists in full implementation of standard ISO 15118 in vehicles and charging infrastructure. "It contains algorithms for encrypting the exchanged data and defines the structure for the digital certificates that act as the customer's signature during communication", says Willrett.

But many questions still remain in this respect: Who manages the certificates in the long term? What happens to the certificates if a customer sells his car or wants to change the power provider? "All these questions need to be dealt with and are currently being discussed", says Willrett. "IAV wants to make progress in this field and is making an active contribution to working on standards related to ISO 15118."

Shared backend for billing

Besides standardization, it is also important for all stakeholders to use the same infrastructure. "Power and mobility providers as well as OEMs should operate a shared backend for billing and set up a central clearing house for sending the invoices and managing the certificates", proposes Willrett. "This system should work at least throughout Europe." Among others, the OEMs should issue a certificate for each vehicle and forward this information to the shared backend. As well as supplying the electric energy, power providers would also have to enter their current tariffs in the shared infrastructure. Mobility providers would be responsible for producing certificates for their contracts with customers and managing them accordingly.

Finally, the shared backend would manage the certificate information, provide contract certificates and bill customers with the incurred costs. Here again, there is a need for standardization in terms of uniform communication protocols for transmitting data between the charging station and the various secondary actors connected to the backend.

One important aspect in implementing a shared backend will consist in protecting personal, security-relevant data. During the charging process, the vehicle and charging station exchange large amounts of information, including log-on details (customer name, certificates, contract numbers), user settings such as the method of payment, vehicle information (including an ID number and technical parameters such as maximum charging power) and information about the status of the charging station. All this information has to be securely protected from unauthorized access and alteration, both during data exchange between vehicle and charging station and during communication between charging station and backend.

Need for consistent ICT concept

For years IAV has been forging ahead with eMobility as an overall concept, also looking at the requirements made of the infrastructure as well as data protection issues. "What's needed is a consistent ICT concept", says Willrett, who has already held numerous training courses on this subject. "That's the only way to achieve greater acceptance of electric mobility and put more electric cars on the road."