Feature: Electric Vehicles
EMI/RFI filters for fast DC EV charging stations
By Felix Raj, GM of Operations, EMIS Global T
he surge in demand for electric vehicles (EVs) is a significant part of global efforts to reduce pollution and reliance on fossil fuels. As more people adopt
EVs, the need for efficient and accessible charging infrastructure has grown. Early slow chargers, which required long wait times, are being replaced by fast charging stations that offer quicker charging times and enhanced efficiency, contributing to greater EV adoption. Smart DC fast charging stations are
crucial to facilitating this transition, especially for long-distance EV travel. However, their increased power demands, high switching frequencies and sophisticated electronics create significant challenges. One of the most pressing being electromagnetic interference (EMI).
EMI effects in smart fast chargers EMI presents serious challenges in the design and operation of electric vehicle (EV) fast chargers, particularly due to high power levels, fast switching frequencies and the presence of sensitive electrical and electronic systems within the charging units.
16 March 2025
www.electronicsworld.co.uk One key source of EMI in smart fast
chargers is the power converters used, such as DC-DC converters. These converters often employ high-speed switching components like Insulated- Gate Bipolar Transistors (IGBTs), operating at frequencies between 20 kHz and 200 kHz. Advanced semiconductor materials such as silicon carbide (SiC) and gallium nitride (GaN) push these switching frequencies even higher, into the MHz range, leading to even greater EMI.
EMI can affect both the charger itself and its surrounding environment: • Internal disruptions: These may include signal interference, power supply disturbances and component stress within the charger.
• External disruptions: Nearby devices may experience crosstalk, wireless communication interference or malfunction due to radiated EMI.
• Conduction and radiation: EMI can manifest through both conducted (via power lines) and radiated (through electromagnetic waves) interference,
impacting the charger’s electromagnetic compatibility (EMC), the performance of the vehicle being charged and the functionality of other sensitive equipment in the area.
Standards and regulations for EV chargers To address these challenges, various international standards and regulations have been set for both EMI mitigation and the overall safety of EV chargers. These standards ensure chargers meet electromagnetic emission limits and other safety requirements, protecting users and the environment.
Key standards include • IEC 61851 Series (IEC 61851-1, IEC 61851-23, IEC 61851-21-2) for the EMC and operational safety of EV chargers.
• UL 2202 and UL 2251 for safety requirements concerning EV chargers and related connection components. These standards are vital for ensuring
that charging stations do not generate excessive EMI, thus safeguarding nearby electronic devices and ensuring the safe operation of EV charging infrastructure.
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