Power Line Communication integrates EVs with the Smart Grid

Electric vehicles are gaining momentum on a worldwide basis. A compatible charging infrastructure and communication between the vehicle and the "charging spots" is required for ease of use on the end user side. The already established Power Line Communication (PLC) standard in the Smart Power Grid area offers a robust and long term available setup.

Electric cars, with a history ranging back more than hundred years, are experiencing a renaissance. The rise in fuel costs, improved battery technologies and government incentives are just some of the factors that make electric vehicles (EVs) a great choice especially for individual mobility in the growing megacities.

China shows an impressive rollout plan, but also European countries are driving this trend. Germany has a plan for 1 million EVs by 2020; France is moving ahead even faster with massive government funding for a plan to install 1 million EV charging spots by 2015 and 2 million EVs by 2020. The increased distribution of EVs also offers new business opportunities for utility providers creating new income sources and also allows grid stabilization (cut of peak loads) via the EV's battery as buffer feeding energy back into the power grid.

The charging of these EV batteries can be done in different ways. The majority of the charging cycles will certainly happen at home or at work (estimated at 80%), but public charging spots are required as well to ensure an adequate supply grid.

There are different possibilities for charging. The most basic one is to use a single phase power supply of 230V and up to 32A AC via a typical 3 kW on-board-charger, but also via a 3 phase 400V with up to 63A AC (typical 20 kW charger). Charging with these currents is typically taking hours and is combined with parking times of the car (home, work, shopping). A closer equivalent of a gas station for conventional combustion engine cars is the DC charging (or also called fast charging) ranging up to 100 kW power, but this has to be possible without damaging the battery pack.

Ease of use

All of these charging situations in public drive the need for user interaction at the charging spot. For advanced features, the identification of the vehicle itself at the charging spot is required, which is typically realized via Power Line Communication (PLC). In these cases, a variety of data, including vehicle identification, current battery status, maximum allowed charge current and number of phases, charging times (e.g. delayed charging start), and overall 'charged' electricity amount with associated costs are exchanged. The identification of the car in the network opens up a cross utility provider usage of the electricity, similar like roaming in a mobile phone network.

However, this brings up one of the most important requirements: every car has to work with every charging spot. So the standardization does not only apply to the used plug standard, but also to the method of communication of the car with the charging infrastructure.

The PLC is a well suited choice as the connection cable is needed anyway for charging (excluding the possibility for inductive charging, which is lower power but under consideration). PLC is robust and does not normally require any additional user interaction.

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