Issue link: https://iconnect007.uberflip.com/i/1542458
50 SMT007 MAGAZINE I JANUARY 2026 ROA D TO R E L I A B I L IT Y S ER I ES BY S TA N TO N R A K , S F R A K C O M PA N Y High Voltage Auxiliaries on the Road T hus far, this series has focused on power elec- tronics and controls that propel the vehicle. However, EVs are not solely defined by their pro- pulsion system. While much attention is placed on inverters, traction motors, and battery cells, an eco- system of high-voltage (HV) auxiliary systems sus- tains safety, comfort, and functionality. These systems, including compressors, heaters, coolant pumps, and the associated cabling, have evolved into critical components that ensure the vehicle functions reliably under a wide range of operating conditions. With this evolution comes a new set of challenges in terms of design, materi- als, reliability, and manufacturability. Failure can dis- able or degrade EV performance, reduce consumer trust, and inflate warranty costs. As a result, auxiliary system design and packaging are rapidly becoming focal points for innovation, integration, and reliabil- ity engineering. Beyond the Powertrain: The Auxiliary Backbone EV auxiliary loads initially operated at 12V or 48V, supporting lighting, infotainment, and small actua- tors. But to reduce energy conversion losses and support more demanding thermal management loads, many auxiliaries have now moved into the HV domain operating at 400V or even 800V supply levels for greater efficiency. Key auxiliary HV components include compres- sors for cabin cooling, positive temperature coef- ficient (PTC) heaters or HV coolant heaters for cabin and battery thermal management, coolant and refrigerant pumps, electric brake boosters and steering actuators, and HV harnesses, contactors, and connectors. Each serves as a critical node in the functional ecosystem, ensuring driver comfort, battery safety, or chassis control, even when the traction motor is idle. These components are not