航空锂离子电池组过放电工作特性研究

Study on Operating Characteristics of Over-discharging Aero Lithium-ion Battery Packs

航空锂离子电池组工作不同于通常动力锂离子电池组,是长时间搁置、间歇补充电和瞬时大电流放电的工作状态,其过放电工作特性对能量管理和航空安全至关重要。基于反应机理分析和过放电实验研究,通过电池等效模型构建和状态空间描述,实现过放电过程分析,获得极限条件下的电池工作特性。通过使用7串45 Ah航空锂离子电池组进行测试验证该方法的可行性和精度。实验结果表明,在电池组过放电过程中,输出电压存在缓慢变化、快速变化和陡坡变化3个阶段,输出电压跟踪误差低于5%,确定放电截至电压(拐点)为20.14 V;通过宽温度范围工作特性的研究,确立最佳工作温度范围为5~35℃,基于加热片和散热器的方式实现了其最佳温度范围控制。该方法能够实现对过放电特性准确数学描述,有效分析航空锂离子电池组的工作特性,提供工作特征突变关键点监测方法,为航空安全的关键性突破奠定基础。

With the operating characteristics of long time abeyance, intermittent recharge and instantaneously large current discharge, the operation of aero lithium-ion battery packs is different from that of the conventional power lithium batteries. Therefore, its over-discharging characteristics are essential for the energy management and aviation security. In this paper, based on the analysis of reaction mechanism and the experimental study on over-discharge, the overdischarging process was analyzed through the establishment of a battery equivalent model and the description of statespace, and the operating characteristics of batteries under extreme conditions were obtained. The feasibility and accuracy of the proposed method were verified through tests on 45 Ah aero lithium-ion battery packs of 7 cells. Experimental results showed that, in the over-discharging process of battery packs, the output voltage was divided into three stages,i.e., slow, rapid and steep changes; the output voltage tracking error was less than 5%, and the discharge cut-off voltage（i.e., inflection point） was determined as 20.14 V; through studying the operating characteristics in a wide temperature range, the optimum operating temperature range was identified as 5 ～35 ℃, the control of which can be achieved by means of heater bands and radiators. This method can realize an accurate mathematical description of the overdischarging characteristics and an effective analysis of the operating characteristics of aero lithium-ion battery packs,which provides a monitoring method for key mutations in operating characteristics and lays a foundation for breakthroughs in aviation security.