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78 SMT007 MAGAZINE I NOVEMBER 2025 state of health (SOH), cell voltages, current flow, and thermal conditions across hundreds of individ- ual cells. Anomalies detected by the BMS can trig- ger balancing operations, cooling commands, or system shutdowns. Reliability begins with accurate sensing and robust communication between the BMS controller and its distributed sensor network. In centralized architectures, the controller resides within the pack, offering compactness and reduced latency, but increasing exposure to heat and vibration. Distrib- uted BMS architectures, in contrast, place smaller modules near individual cell groups, easing thermal burden but increasing the complexity of wiring and communication protocols 3 . DFR efforts in BMS design now include the use of high-accuracy redundant voltage measure- ment ICs, fault-tolerant communication buses, and advanced diagnostics and early failure detection 4 . Physical separation of analog sensing from digital processing can mitigate crosstalk and EMI, while predictive analytics help forecast aging behavior. Failures in BMS operation, whether due to software faults, moisture ingress, or sensor drift, can disable an EV or lead to battery safety incidents, making its robustness non-negotiable 5 . Thermal Management System: Keeping Cool Under Pressure Thermal regulation of the battery is inextricably linked to BMS performance. BMS thermal manage- ment typically aligns with broader battery thermal management systems (BTMS) and includes indi- rect liquid cooling, passive and active air cool- ing, and hybrid cooling technologies. Indirect liq- uid cooling, consisting of cold plates and gly- col-based solvents, is the predominant technol- ogy used in EVs. Passive and active air cooling is widely deployed in lower-cost EVs and two-wheel- ers, especially in entry-level vehicles in emerging markets. Hybrid cooling solutions such as active liquid cooling plus phase change materials (PCMs) comprise the smallest percentage of the BTMS cooling units today but are faster growing, espe- cially in high-performance EVs, because they can smooth temperature spikes. Newer BTMS designs are co-optimized with mechanical pack architecture and DFR techniques, including thermal simulations under mission pro- file conditions, high-cycle temperature testing, and degradation modeling at connector interfaces 6 . Power Inverter: Bridging Battery and Motor The power inverter is the real-time translator between the battery's DC output and the motor's AC needs. Using silicon carbide (SiC) or gallium nitride (GaN) switches, modern inverters pulse energy at high frequencies to optimize motor torque and effi- ciency. However, this switching creates immense thermal and electrical stress, requiring careful bal- ancing of materials, geometry, and controls 7 . Internally, the inverter contains a gate driver board, power module, capacitor bank, and heat sink or cold plate assembly. Each interface pres- ents reliability challenges, from delamination at die " " Reliability begins with accurate sensing and robust communication between the BMS controller and its distributed sensor network. ▼ E V p owe r t ra i n a rc h i te ct u re s h ow i n g t h e B M S , i nve r te r, D C - D C c o nve r te r, a n d O B C ( S o u rc e : W i k i m e d i a C o m m o n s , Le e C o l l eto n )