Electromobility: Checking charging points with mobile measurement tech
One million public charging points for electric cars are to be available by 2030 in Germany according to the government’s plans. Other countries have similarly ambitious plans. However, while at conventional filling stations the correct measurement and billing of the fuel refuelled is self-evident and reliable, a corresponding measurement technology is still new, especially for fast electric charging stations; the technology is in flux and generally accepted standards are lacking. The Physikalisch-Technische Bundesanstalt (PTB) has now developed a mobile measurement system for this purpose, which can be used to directly check charging columns that have already been installed – outside the laboratory at any location. The goal of the PTB scientists is to ensure that e-car charging will be just as trustworthy as conventional refuelling in the future.
Before they are approved, charging columns must first undergo a type test that confirms their suitability in principle. This takes place in the controlled environment of a laboratory. Flawless prototypes receive a certificate that allows them to charge the charging energy quantified by kWh. However, subsequent checks during operation, outside in the car park or at filling stations, are a challenge: not only environmental influences such as temperature and weather place special demands on the electrical measurement technology, but also the large number of different electric vehicle types with their respective different charging characteristics.
PTB has developed a precise measurement system especially for this purpose, which is inserted into the charging section between the charging pole and the electric vehicle on site. It has two benefits: On the one hand, it is conceivable to use the measuring system within the framework of market monitoring – at least for some of the charging columns installed in Germany: Does the charging pole measure as reliably in everyday use as it does in the laboratory? On the other hand, the new measurement system can be used to verify the previous testing of fast charging points (with currents of up to 450 amps). The results can be used to develop relevant control documents.
PTB’s measurement system is based on a power analyser that is traced back to PTB’s national standards – and thus ultimately to the International System of Units (SI). This reference to the SI ensures the international comparability of the measured values. The development of the measurement system was funded, among other things, as part of the European research project “DC Grids”, which was launched in 2021 and investigates factors influencing the measurement accuracy of charging stations.