关键词: 紧凑型电动乘用车；动力电池系统；能量密度；热管理技术；电池管理系统

Abstract: To address the trade-offs between energy density, thermal safety, and system cost in compact electric passenger cars, this paper proposes a system design method based on multidimensional performance balancing, and designs and implements a highly integrated energy storage device for the drive system. This device is based on high-energy-density ternary lithium-ion cells, employing a modular structure and laser welding technology to achieve low-resistance connections between battery modules. Through a layered insulation structure and a multi-sensor monitoring network, the thermal runaway warning response time is reduced to less than 2 s. Combining finite element analysis and topology optimization methods, the topology-optimized aluminum alloy housing achieves a 12.3% weight reduction, and the liquid cooling system controls the module temperature difference to within 3 ℃. Real-world vehicle verification shows that the system maintains good stability at 45 ℃, achieving a capacity retention rate of 95.3% after 200 cycles, with the vehicle completing the cycle without any failures. This paper systematically elucidates the design principles and optimization path, providing a theoretical basis and reusable engineering path for the design of high-performance battery systems for compact electric vehicles.

Key words: compact electric passenger cars; power battery system; energy density; thermal management technology; battery management system