Energy Consumption Proportions of High Voltage System in Battery Electric Vehicle (BEV) under Different Driving Conditions

The energy consumption of battery electric vehicles (BEV) is not only determined by the powertrain system but also by auxiliary subsystems powered by the high-voltage battery such as the heating ventilation and air conditioning (HVAC) system and the DC-DC converter. Previous studies have shown that BEV energy demand is strongly affected by climatic and driving conditions, with consumption increasing under extreme hot or cold environments. This study aims to (1) evaluate the effects of standardized driving cycles and ambient temperatures on BEV energy consumption under laboratory conditions, and (2) analyze the real-world distribution of energy usage among the powertrain, HVAC, and DC-DC converter during urban and suburban driving in Bangkok. The experiments were conducted on a 2022 MG EZS using a chassis dynamometer with microcontroller-based acceleration control integrated with LabVIEW software. Standard driving cycles included WLTC Class 1 and UDDS profiles, tested under ambient conditions of 30 °C, 35 °C, and 40 °C. Results indicated that increasing the ambient temperature from 30 °C to 40 °C led to higher energy consumption. The WLTC cycle showed a 13.13% increase, while UDDS rose by 12.30%. Real-world tests further revealed that urban routes consumed more energy than suburban routes. At approximately 35 °C, the energy distribution was 53.43% for the powertrain, 25.80% for HVAC, and 20.77% for the DC-DC converter. Notably, HVAC demand was influenced by both cabin cooling and battery thermal management. These findings highlight the significant impact of temperature and driving conditions on BEV efficiency, emphasizing the importance of optimizing HVAC and auxiliary systems to improve overall vehicle energy performance in hot climates.