EMIS Adds Advanced EMI Filtering for High-Power EV Charging

High-power DC fast chargers for electric vehicles introduce electromagnetic interference (EMI) due to high-frequency switching and large power levels. This EMI can affect charger performance, disrupt nearby electronics, and cause regulatory compliance issues.

The EMIS MF 620 series is a dual-stage DC EMI/EMC filter designed to suppress conducted and radiated emissions in EV fast-charging infrastructure. With voltage ratings up to 1600 VDC and current handling from 150 A to 1600 A, this filter range addresses electromagnetic compatibility (EMC) challenges in modern power electronics.

How does EMI affect charger performance? Image used courtesy of EMIS

Electromagnetic Interference in DC Fast Charging

DC fast chargers rely on power converters and high-speed switching to deliver efficient energy transfer. Technologies such as IGBTs, SiC MOSFETs, and GaN transistors operate at frequencies from 20 kHz to several MHz, generating substantial EMI. Without proper filtering, this interference can degrade system performance in multiple ways:

• Internal disturbances affect power supplies, communication circuits, and sensitive components inside the charger.
• External EMI can disrupt wireless signals, impact nearby electronics, and interfere with other charging stations.
• Regulatory non-compliance may lead to failures in meeting IEC 61851-23, UL 2202, and EN 55032 standards, preventing market approval.

EMIS MF 620 Series for EV Fast Charging

The MF 620 series covers 500 VDC, 1000 VDC, and 1500 VDC applications with a transient voltage tolerance of 1600 VDC. Current ratings range from 150 A to 1600 A, providing scalability for different charger power levels. The filter also features an overload capability of 135% of rated current for up to 15 minutes, handling short-term demand surges in public fast-charging networks.

The dual-stage filter topology suppresses common mode and differential mode noise, targeting interference sources in DC-DC converters, switched-mode power supplies, and interleaved PFC stages. Its >60 dB insertion loss in the 150 kHz-30 MHz range makes it highly effective for compliance with FCC Part 15B and automotive EMC standards.

The MF 620 series is engineered for reliable operation in high-power environments, incorporating thermal resilience, space efficiency, and modular connectivity.

The EMIS MF 260 Series DC EMI filter for EV charging stations. Image used courtesy of EMIS

Thermal and Environmental Tolerance

The filter operates in environments ranging from -40°C to +100°C. Its UL 94 V-0 flame-resistant design and IP20-rated enclosure provide basic particulate protection. Derating curves are optimized for high-temperature operation inside enclosed charger cabinets.

Compact and Scalable Architecture

Despite its high power ratings, the 150 A model measures just 200×122×128 mm, while the 1600 A variant scales to 270×140×130 mm. Nickel-plated copper busbars reduce the footprint, allowing seamless integration into existing charger cabinets without structural modifications.

Modular Electrical Connections

The filter uses laser-welded, tin-plated copper lugs for secure connections. Cross-sectional dimensions range from 25×3 mm at 150 A to 60×12mm at 1600 A, supporting a wide range of high-current applications.

Applications Beyond DC Fast Charging

The MF 620 series meets IEC/EN 61851-23 and UL 2202, confirming its compatibility with DC fast chargers worldwide. It also complies with EN 55032 Class B, ensuring minimal emissions in residential-adjacent charging installations.

High-potential testing confirms 2000-6000 VDC isolation between live conductors and ground, exceeding standard safety requirements. The series also incorporates galvanic isolation monitoring circuits, supporting ISO 21434 cybersecurity protocols for connected chargers.

Although primarily designed for DC fast charging, the MF 620 series provides effective EMI suppression in other high-power applications, including renewable energy systems, industrial automation, and telecommunications and data centers. The MF 620 series has been benchmarked against competing EMI filters, such as the Schaffner FN3280 and TDK Lambda ZAS35, and shows advantages in attenuation, thermal management, and overall efficiency.