R744热管理系统在实车电动汽车测试中的能量流动态分析与区间次优控制

Abstract R744 thermal management systems (TMS) are regarded as promising for electric vehicles (EVs) due to environmental friendliness and excellent performance of CO 2 as refrigerant. However, current research remains limited to bench tests and simulations, failing to comprehensively evaluate their dynamic application effects in real-world vehicle scenarios, making it challenging to extend driving range. This study established an energy flow testing system and operated experiments for real electric vehicles in EVs environmental test laboratory. Using dynamic energy flow analysis approach, the study summarized the specific impacts of ambient temperature, thermal management demands, vehicle speed, and driving time on energy flow distribution. Through the analysis process with gradually refined time scales, richer energy flow information for electric vehicles was obtained, revealing the detailed performance of the R744 TMS. The test was operated at ambient temperature of −7°C, 0 °C, 35 °C, 40 °C and 45 °C and the energy flow system nearly stabilizes after the third CLTC cycle. The energy consumption of the TMS decreases by 30 % from the low-speed to medium-speed, and decreased by 20 % to high-speed intervals of the CLTC cycle. The study evaluated the influence of dynamic outside conditions of electric vehicles and proposed an interval suboptimal control method to manage the discharge pressure of R744 TMS, which balances the difficulty of dynamic control with the requirements for optimal performance, thereby enhancing the practical feasibility of R744 TMS. Using the control method, thermodynamic parameter fluctuations only result in a driving range fluctuation of only 3 to 7 km. Overall, this study could significantly advance research progress in TMS of EVs by real vehicle testing, dynamic analytical approaches, and systematic robustness validation.