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80 SMT007 MAGAZINE I NOVEMBER 2025 Onboard Charger (OBC): Gateway to the Grid Closely related to the DC-DC converter is the OBC, which converts AC input from a wall or public char- ger into regulated DC voltage for battery charging. Depending on market and grid specs, OBCs must accept 120–240 V AC input, and provide 3–22 kW output. OBCs face unique stresses like grid volt- age fluctuation, lightning-induced surges, and long idle periods punctuated by high-power operation. Galvanic isolation and power factor correction are required by standards, but implementation strate- gies vary. Newer bi-directional OBCs (for vehicle- to-grid applications) face even higher reliability demands due to frequent mode switching. DFR in OBCs involves high-voltage isolation design, common-mode EMI filtering, creepage management, and protection against harmonic dis- tortion from poor grid conditions. Weatherproofing is essential in externally mounted chargers, and liq- uid cooling is often integrated for 11 kW+ units 15 . Conclusion: A Systematic Path to Durable Propulsion The propulsion electronics of an EV are more than a collection of components; they're an orches- trated system where failure in one area cascades across others. As performance demands grow, DFR becomes a strategic pillar. Techniques like predic- tive analytics, hardware-in-the-loop testing, and digital twin simulation are allowing designers the opportunity to foresee and prevent failures, instead of just reacting to them. Long-term field reliability is now inseparable from design methodology, espe- cially for power electronics. As automakers compress development cycles and scale across multiple platforms, all while fac- ing fierce cost competition, only those who factor in reliability from the outset will see consistent perfor- mance on the road. Please note the importance of reliability in EV/ automotive/power electronics will be highlighted at the upcoming APEX EXPO Technical Conference in March 2026, where over 30 contributions have been received that delve into the advancement of reliability for these applications through design, materials, assembly, test, and metrology best prac- tices. Be sure to attend. SMT007 References 1. Alternative Fuel Data Center, U.S. Department of Energy. 2. Mitsubishi iMiEV (System Diagram) F. 3. "Scalable, Decentralized Battery Management System Based on Self-organizing Nodes," by A. Reindl, H. Meier, M. Niemetz, Architecture of Computing Systems, 2020. 4. "High-Accuracy Battery Monitor ICs," Applica- tion Note, Texas Instruments, 2023. 5. Nine EV BMS & battery pack field incidents reported by NHTSA and other sources were reviewed. Additional information can be pro- vided separately. 6. "Thermal Design Considerations for Traction Inverters," White Paper, Infineon, 2022. 7. "Designing with SiC Power Modules for EV Traction Inverters," Application Guide, Wolf- speed, 2023. 8. "Road to Reliability Webinar Series: Design for Manufacturing," by Michael Schleicher, Global Electronics Association, July 24, 2025. 9. "Road to Reliability Webinar Series: Design for Reliability," by A. Mackie, Global Electronics Association, May 22, 2025. 10. "Multiphysics Simulation for Electric Drive System Design," White Paper, ANSYS, 2021. 11. "Extended Mission Profile Model," by Lewitschnig, et al, AECRW, Oct. 4, 2023. 12. "The Importance of Reliable Charging Station Electronics for Building a Sustainable EV Eco- system: 'R' YOU READY?" by Brian Chislea, EV Quality and Reliability Group, Global Elec- tronics Association, July 2025. 13. IPC-2221B, Generic Standard on Printed Board Design, Global Electronics Association. 14. "Digital Control of DC/DC Converters in Auto- motive Applications," App Note, STMicroelec- tronics, 2022. 15. "OBC Test Challenges in EV Power Electronics," Tech Paper, Chroma Systems, 2023. Stanton Rak is principal consultant of SF Rak Company and co-chair of the APEX EXPO Technical Committee.