• • • ELECTRIC VEHICLES • • •
The roads of the future are electric
John Harrison, who was recently appointed managing director of Schaffner UK, looks at EMC considerations for EV charging points
N
ew electric car models are being introduced almost daily. The market forecast for battery electric vehicles (BEV)
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 two million units for the first time. By 2030, the number is expected to increase ten-
fold, up to 60%, which will correspond to 20 million cars sold per year worldwide. It is notable that around 80 % of electric vehicle sales today are for purely electric vehicles (BEVs). The charging infrastructure currently seems to
be receiving little consideration in the rush to design and develop new electric car models. However, this is at least as important as the cars themselves in order to successfully implement the eMobility rollout in prospect. Approximately 77,000 charging stations are
required for one million electric vehicles, including 7,000 DC rapid charging stations. 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 point of view. Electromagnetic compatibility (EMC) plays a key
role in products designed for charging BEV (Battery Electric Vehicles) and HEV (hybrid electric vehicles).
What is electromagnetic
compatibility? Electromagnetic compatibility (EMC) is concerned with the emission and immunity of products connected to the mains supply. The emitted interference or emission generated by lossy switching operations must not exceed specified limits. If non-compliant products are brought onto the
market, problems may arise in operation with other consumers connected to the main power grid. Immunity to interference describes the ability of products to withstand external influences without error. The immunity of products can be verified by various tests, for example by means of the surge, burst or flicker test. EMC filters, as developed by Schaffner, are
available to enable compliance with emission limit standards. These filters are designed to operate in the frequency range between 9 kHz and 30 MHz in order to suppress conducted interference. This prevents other devices in the environment from being negatively affected. All standard filters should be designed in accordance with the IEC
26 ELECTRICAL ENGINEERING • JUNE 2022 Filter safety requirements for
BEV/HEV charging stations The ‘norms’ on the subject of EMC are 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 1 uF at the DC output, i.e., with a filter in the system, the filter can be provided with 500 nF capacitance on positive and negative conductor; if several filters
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. Schaffner works on the premise of “first time
right“ saving valuable waiting time for our customers before series production can take place. Example product descriptions based on
standard DC filters: FN2200Q1*-250-99-R66* - FN2200 Standard filter
for 250 A with 220 nF (Q1) capacitors with increased discharge resistances (R66 - 1.5 MOhm in parallel to X and Y capacitors) FN2211-400-99-C23*-R99*- FN2211 Standard
filter for 400 A with 500 nF (C23) capacitors with increased discharge resistances (R99 - 10 MOhm in parallel to X and Y capacitors)
*further variations possible
electricalengineeringmagazine.co.uk
60939-3 standard (“Passive filter units for electromagnetic interference suppression”) and other international standards and are therefore readily available for use in a potential customer system. 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.
are used in parallel, the size must be r educed accordingly. In addition, the discharge resistors must be at
least 1 MOhm to enable insulation measurement in the system. The design of Schaffner standard filters provide the opportunity to modify the components used to meet customer specifications within the scope of the existing safety certificates. DC filters about to be launched to the market
are the models FN2220 or FN2230, which can be adapted as required and identified with a unique suffix. Customer specific modifications are also
possible for standard AC filters, but there are different requirements for the design of these filters (>1 MOhm leakage resistors remain). The great advantage of modification of a standard filter is that it has already been certified. This means
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52
