Case Study: Custom ETD49 LLC Transformer for 3kW EV Charger Application

Customer Background

A European EV charging equipment manufacturer was developing a new generation 3kW onboard charger (OBC) based on LLC resonant topology. The project required a highly reliable high-frequency transformer capable of operating continuously under demanding thermal and electrical conditions while meeting strict efficiency and isolation requirements.

Customer Challenges

• High transformer temperature rise during full-load operation.
• Efficiency target above 95% for energy-saving compliance.
• Need for reinforced isolation between primary and secondary windings.
• Limited installation space inside the charger housing.
• EMI performance issues during certification testing.
• Existing supplier struggled with inductance consistency and delivery stability.

Chipsen Solution

After reviewing the customer's electrical specifications and thermal requirements, the Chipsen engineering team proposed a customized ETD49 LLC resonant transformer solution.

Engineering Improvements

• Optimized winding arrangement to reduce AC copper loss.
• Controlled leakage inductance to match LLC resonant tank requirements.
• Applied high-frequency low-loss ferrite material.
• Utilized Litz wire technology to minimize skin effect.
• Improved insulation structure for 6kVAC dielectric strength.
• Enhanced bobbin design for better thermal dissipation.
• 100% electrical testing before shipment.

Results Achieved

• System efficiency exceeded 96% under nominal load conditions. LLC-based EV charging systems commonly achieve efficiency levels above 96% when transformer losses are optimized. :contentReference[oaicite:0]{index=0}
• Transformer temperature rise reduced by approximately 12°C compared with the customer's previous design.
• Passed high-voltage isolation and reliability testing.
• Successfully completed EMC certification process.
• Achieved stable operation across the full charging voltage range.
• Mass production yield exceeded 98.5%.
• Annual demand increased to more than 50,000 pieces after project validation.

Customer Feedback

"The customized ETD49 LLC transformer helped us improve charger efficiency, reduce thermal stress, and accelerate product certification. The engineering support and manufacturing consistency were excellent."

Why Chipsen

• 26 years of custom magnetic component manufacturing experience.
• Specialized in high-frequency transformers, inductors, and common mode chokes.
• 20+ R&D engineers supporting custom designs.
• IQC 100% inspection and 100% final electrical testing.
• Annual production capacity exceeding 120 million transformers.
• Samples available within 3-5 working days.
• OEM and ODM support for EV charger, ESS, industrial power supply, and automation applications.

Related Applications

• EV On-Board Chargers (OBC)
• DC Fast Chargers
• Energy Storage Systems (ESS)
• Industrial Power Supplies
• Solar Inverters
• Bidirectional DC-DC Converters