FEATURE EMC & THERMAL MANAGEMENT POWERING N
ew electric car models are introduced almost daily. The market forecast for
the BEV (Battery Electric Vehicle) predicts very strong growth in the coming years. In 2018, the market share of electric cars reached approximately 2.5%, and the number of electric cars built worldwide rose to more than 2 million units for the first time. By 2030, the number is expected to increase tenfold, up to 60%, which will correspond to 20 million cars sold per year worldwide. Incidentally, around 80% of electric vehicle sales today refer to purely electric vehicles (BEVs). The charging infrastructure currently
seems to be a minor factor in the design and development of electric car models. However, this is at least as important as the cars themselves in order to successfully implement the eMobility concept. Approximately 77,000 charging stations
are required for 1 million electric vehicles, including 7000 DC rapid charging stations (source: Bundesverband Freier Tankstellen -bft). With 20 million cars sold per year, 140,000 DC fast charging stations would have to be installed by 2030. This is a challenge not only from an economic point of view, but also from a technical view.
CHARGING INFRASTRUCTURE Above all, electromagnetic compatibility (EMC) plays an important role in charging BEV (Battery Electric Vehicles) and HEV (hybrid electric vehicles). If noncompliant products are brought onto the market, problems may arise in operation with other consumers connected to the main power grid. Schaffner develops EMC filters that
enable compliance with emission limit standards. These filters are designed to operate in the frequency range between 9kHz and 30MHz in order to suppress conducted interference. This prevents
36 JULY/AUGUST 2020 | ELECTRONICS
E-MOBILITY EMC considerations for EV Charging and how the latest filters from Schaffner are playing their part in creating complaint EV charging stations
other devices in the environment from being negatively affected. All standard filters are designed in accordance with the IEC 60939-3 standard (“Passive filter units for electromagnetic
interference suppression”) and other international standards and are therefore quickly ready for use in a potential customer system.
NETWORK OPERATIONS In the case of EV charging stations, electromagnetic compatibility is particularly important, because, without filters any interference that occurs during rectification in charging stations operated directly from a low-voltage network on the input side could have an effect on the entire network. On the output side, i.e. on the side where the car is charged, the safety of the operator and the interoperability between different charging stations and car manufacturers are of primary importance. Both factors must therefore also be taken into account in the design of the EMC filters. Normatively, the subject of EMC is
completely defined in the area of charging stations. The IEC 61851-23 standard defines the safety-relevant aspects for DC charging stations (fast charging stations). For EMC filters, the definition of the capacitors on the DC side (output side) is particularly important. The maximum capacitor size is set to 1uF at the DC output, i.e. with a filter in the system, the filter can be provided with 500nF capacitance on positive and negative conductor. If several filters are used in parallel, the size must be reduced accordingly. In addition, the discharge resistors must be at least 1MOhm to enable insulation measurement in the system. Schaffner standard filters offer the opportunity to adapt the component
specification in the standard product based on the existing safety certificates. Typical DC filters are the models FN2200 or FN2211, which can be adapted accordingly with the help of a suffix. Adaptations are of course also possible
for the AC standard filters, but there are different requirements for the design of these filters. (>1 MOhm leakage resistors remain). The great advantage of this modification
of the standard filter is that it has already been certified. This means that even after modification, all certifications remain in place, which considerably reduces the time-to-market. If the mechanics remain the same, samples ready for series production can be rapidly made available and initial delivery can take place quickly. Since not only the functionality but also
the design of the charging stations is important, the size of the filters is often also decisive. Furthermore, the cost factor is playing an increasingly important role. This often results in oversized filters. The
first major wave of industrialisation is typically followed by a consolidation of manufacturers, and thus also by an increase in production capacity. At this time, cost factors also play an important role. At the time of consolidation an application-specific solution must be available so customers can continue to be satisfactorily served in the future. This application-specific solution must also be optimised in terms of cost and size. Schaffner has released a White Paper on
Safety and EMC Considerations for EV Charging and is available to download in full by visiting:
https://products.schaffner.com/en/ev- charging-whitepaper
Schaffner
www.schaffner.com
/ ELECTRONICS
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