Surge protection for electromobility

The electromobility market is on the move. Alternative drives are registering a steadily increasing number of registrations, and special attention is also being paid to the need for nationwide charging points. According to calculations by the BDEW association, 70,000 normal charging points and 7,000 fast charging points are needed for 1 million e-cars. Three different charging principles can be found on the market. In addition to wireless charging based on the induction principle, which is still not very widespread in Germany, battery exchange stations have been developed as a further alternative as the most convenient charging variant for the user. The most widespread, however, is cable-based conductive charging ...
And it is precisely here that attention must be paid to reliable and carefully designed lightning and surge protection. If the car is considered a safe place to stay during thunderstorms due to its metal body and thus following the principle of Faraday's cage, and if the electronics are also relatively safe from hardware damage, the conditions change during conductive charging.
During conductive charging, the vehicle electronics are now connected to the charging electronics, fed by the power supply system. Overvoltages can now also couple into the vehicle via this galvanic connection to the energy supply network.

Wired charging

A typical installation location of such charging facilities is in the private environment in the garages of homes or underground garages. The charging station is part of the building. The typical charging power per charging point is up to 22 kW, the so-called normal charging, whereby according to the current application rule VDE-AR-N 4100, charging facilities for electric vehicles with rated powers ≥ 3.6 kVA must be registered with the grid operator, and even require prior approval if the total rated power to be installed is > 12 kVA. DIN VDE 0100-443 should be specifically mentioned here as the basis for determining the requirements of the surge protection to be provided. It describes the "protection against transient overvoltages due to atmospheric influences or switching operations". For the selection of the components to be installed here, we refer to DIN VDE 0100-534. A selection aid prepared by CITEL facilitates the selection of the arresters in question.

Charging mode 4

Last but not least, charging mode 4 describes the so-called fast charging method with > 22 kW, mostly with DC up to currently typically 350kW (in the future 400kW and more). Such charging stations are mainly found in public areas. This is where DIN VDE 0100-722 "Requirements for special types of premises, rooms and installations - power supply for electric vehicles" applies. Explicitly for charging points in publicly accessible facilities, overvoltage protection against transient overvoltages due to atmospheric influences or switching operations is required. If the charging stations are installed outside the building in the form of charging columns, the selection of the required lightning and surge protection is based on the selected installation site. The application of the lightning protection zone concept according to DIN EN 62305-4 (VDE 0185-305-4) provides further important information on the correct design of the lightning and surge arresters.

Parallel attention must be paid to the protection of the communication interface, especially in the case of wallboxes and charging columns. This extremely important interface should be considered not only because of the recommendation of DIN VDE 0100-443, as it represents the link between the vehicle, the charging infrastructure and the energy system. Protection modules tailored to the application ensure the reliable and safe operation of electromobility here as well.

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