Issue link: https://iconnect007.uberflip.com/i/1542458
54 SMT007 MAGAZINE I JANUARY 2026 Design for Reliability (DFR) in the Auxiliary Space To increase field reliability, a few key DFR strate- gies are emerging that include: 17,18 • System-level multiphysics simulation, which models thermal, electrical, and mechanical stresses across complex thermal systems • Robustness validation testing of HV heaters and pumps under combined environmental exposures such as thermal shock, salt fog, and vibration • Connector standardization, with growing convergence around defined pin spacing, ingress protection ratings (e.g., IP6K9K), and HV interlock functionality • Creepage and clearance verification, partic- ularly for edge cases like high-altitude oper- ation or condensation events, where insula- tion margins must remain safe and compliant HV insulation design in EVs must account for real- world environmental variables, especially in regions where vehicles are deployed at high altitudes. At elevations above 2,000 meters, the dielectric strength of air decreases due to reduced atmo- spheric pressure and air density, increasing the risk of partial discharge and electrical breakdown in HV systems. This phenomenon is particularly critical for EVs operating in mountainous regions, where high- voltage components such as heaters, compressors, and power distribution units may experience a loss of isolation margin.19 OEM product literature for electric buses explic- itly references operation in high-altitude regions as a design consideration, suggesting that some OEMs already recognize and engineer for this fail- ure mode.20 Reliability is Sustainability HV auxiliary components, though smaller, are increasingly part of a larger reliability conversation. They are frequently "always on" in the background, helping maintain battery temperatures, monitoring isolation faults, or adjusting cabin air even when the vehicle is stationary. Reliability strategies now include advanced fault diagnostics and predictive maintenance algorithms, use of automotive-grade conformal coatings for moisture protection, thermal derating and smart power control under high-load events, and inte- grated sensing (e.g., temperature, current, dielec- tric breakdown) directly in auxiliary modules. In the context of sustainability, failure of an auxil- iary control unit can trigger costly repairs, full battery disconnects, or even towing events, under- mining EV cost of ownership goals. Manufactur- ers are beginning to apply mission-profile based design and accelerated life testing to auxiliaries, just as they have done for traction inverters and DC-DC converters. A recent industry white paper described the "Connect-Clean-Coat" concept and its importance in achieving reliability and sustainability for charg- ing electronics.21 The same principles apply for auxiliary systems. The Road Ahead: Standards and Cross- Domain Collaboration While some propulsion components are covered by mature standards, e.g., ISO 26262 for functional safety, IEC 61851 for charging, the auxiliary compo- nents often exist in a fragmented regulatory land- scape.