OF
The Challenge
A Series B EV charging startup was developing a 350kW DC fast charger for highway deployment. Their existing design was experiencing thermal runaway under peak load conditions, with IGBT junction temperatures exceeding safe operating limits by 15°C during 10-minute sustained charging sessions. This was blocking their UL certification process and delaying commercial deployment by 3+ months. The client needed a solution that could handle the full power range from -30°C to +50°C ambient while maintaining IP65 protection for outdoor installation.
Our Approach
- Conducted comprehensive CFD analysis of existing power module layout and airflow patterns
- Identified critical hot spots at IGBT mounting interfaces and DC bus bar connections
- Redesigned the liquid cooling cold plate with optimized serpentine flow channels
- Selected high-performance thermal interface materials (6 W/mK gap pads) for uneven surfaces
- Implemented thermal spreading copper inserts at high heat flux locations
- Validated design through prototype testing across full ambient temperature range
Results
38%
Junction Temp Reduction
Peak Tj reduced from 165°C to 102°C
+23°C
Thermal Margin
Added safety margin for derating
3 weeks
Timeline
From analysis to validated prototype