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Mobile measuring system for electric vehicle charging stations

Measurement technology for real-world validation of conformity assessments for charging stations

PTB-News 2.2022
Especially interesting for


legal metrology

German government planning foresees the installation of one million public charging stations for electric vehicles in Germany by 2030. Whereas the correct metering and billing of fuel is reliable and a matter of course at conventional filling stations, the measurement technology used in particular for fast charging stations is still new and constantly being improved. A mobile measuring system allows those charging stations already in place to be checked in the field.

Charging an electric vehicle at a fast charging station with the measuring system inserted between the station and the vehicle.

Before being granted approval, charging stations must first pass a type examination confirming that they are fit for purpose. This is done in the controlled environment of a laboratory. Flawless specimens of the approved type obtain a certificate allowing them to be placed on the market and to bill energy in kWh. Subsequent tests in routine operation in the field on carparks or at filling stations, however, are a challenge. Not only environmental factors such as temperature and weather conditions, but also the sheer number of different types of electric vehicles with their different charging behaviors place particular demands on the electric measuring equipment.

PTB has developed a precise measuring system specifically for this application. It is inserted into the charging circuit between the charging station and the electric vehicle. It is based on a power analyzer that is traced to PTB’s national standards and that can also deliver information on the form and the frequency components of electric signals.

The new measuring system thus provides the essential technical foundation for validating the test of fast charging stations with currents of up to 450 A. This is a prerequisite for certified charging stations to meter and bill the quantities of charging energy correctly and reliably despite the great number of influencing factors involved. The measuring system ensures not only smooth charging but also correct energy metering, and it does so without affecting either the data communication between the charging station and the electric vehicle or the electrical power flow.

Sources of support for this development work included the DC Grids European research project that was launched in 2021. This project investigates the factors that affect the measurement trueness of charging stations.

Depending on the technical implementation of the charging station, the new system could be used for tests performed when placing devices on the market and for market surveillance purposes. PTB is accompanying the development of the pertinent regulatory documents in Germany.


Jannes Langemann
Department 2.3
Electrical Energy Measuring Techniques
Phone: +49 531 592-2342
Opens local program for sending emailjannes.langemann(at)ptb.de