Whitepaper
DC Contactors and EMI Filters for EV Charging Stations
This Altran Magnetics whitepaper covers the roles of DC contactors and EMI filters in EV charging stations. DC contactors are high-voltage switches that handle power connection/disconnection, overcurrent protection, and charge flow control. They must be designed for appropriate voltage/current ratings, fast switching to minimize arcing, effective thermal management, and durability under repeated cycling. EMI filters are required at two points in the charging system: on the AC input side to protect the grid (and any solar or battery storage sources), and on the DC output side to protect the vehicle's battery and electronics. Their design must account for the correct frequency range, low insertion loss, compact form factor, and temperature stability. Together these filters ensure compliance with standards like FCC and CE. The paper also touches on broader integration challenges: heat management (addressed through liquid cooling or heat sinks), miniaturization to fit within tight station enclosures, and balancing cost against performance. Standardization per IEC 61851-1 and SAE J1772, rigorous testing, and modular design are highlighted as key to ensuring long-term reliability and upgradeability.