电动汽车动力电池分数阶阻抗模型和健康状态估计的研究

Aiming at the safety issue and service life issue for traction batteries of electric vehicle (EV), the state of health (SOH) estimation method based on fractional order impedance model would be researched in this project. Firstly, the electrochemical impedance spectra (EIS) analysis would be carried out for different state of charge (SOC) of the battery. The impedance equivalent circuit model would be deduced according to the electrochemical theories and circuit theories. The fractional order calculus theories would be utilized to explain the impedance equivalent circuit model, and the fractional order impedance model would be obtained. Secondly, based on the researches of discrete methods for fractional order calculus and the researches of model based state estimation methods, the SOH estimation method based on the fractional order impedance model would be analyzed and obtained. The relationships between the SOH of battery cells and the SOH of the battery string would be studied, and the method to obtain the SOH of the battery string from the SOH of the battery cells would be obtained. Finally, the realization methods and principles of the fractional impedance model and the SOH estimation method with hardware circuits, such as FPGA, would be studied, and the obtained circuits would run fast and the results would be accurate. The research results of this project would provide new theoretical foundation for SOH estimation method for battery management system of EVs, and the results to improve the computation complexity and accuracy would be very important, both in theory and in application.

针对电动汽车动力电池安全性和使用寿命这一科学问题，本项目拟开展基于电池分数阶阻抗模型的健康状态估计方法的研究。首先通过电化学阻抗谱分析方法获得电池在不同荷电状态下的阻抗谱，并综合电化学理论和电路理论推导得到电池阻抗等效电路模型；利用分数阶微积分理论对电池阻抗等效电路进行数学解释，获得电池分数阶阻抗模型。其次通过分数阶微积分离散方法和基于模型的状态估计方法的研究，明确基于电池分数阶阻抗模型的健康状态估计方法；研究电池单体健康状态与电池组健康状态之间的联系，获得由单体健康状态推测电池组健康状态的方法。最后，研究FPGA等硬件电路对分数阶阻抗模型和健康状态估计的实现方法和原理，获得运算速度快而精度高的电池健康状态估计硬件电路。研究成果将为电动汽车电池管理系统的健康状态估计提供新的理论基础，对提高健康状态估计的精度和运算速度等具有重要的理论意义和应用价值。

针对电动汽车动力电池安全性和使用寿命这一科学问题，本项目开展了基于电池分数阶阻抗模型的健康状态估计方法的研究。研究的主要内容包括：电动汽车动力电池精确分数阶阻抗模型建立的研究，基于模型的健康状态估计的研究，电池组不均衡特性对电池组状态估计影响与应对策略的研究，硬件在环仿真测试与实车验证研究。项目组首先对电动汽车动力电池进行时频特性测试，通过理论分析、模拟仿真和实验验证的方法，开展分数阶阻抗模型建立的研究，深入解释了电池时域与频域特性，探索分数阶阻抗模型构型与参数辨识方法。基于自适应控制算法，在建立锂离子动力电池精确模型的基础上，开展电池健康状态在线实时估算方法的研究。分析电池组的不均衡特性对电池组健康状态估计的影响，研究锂离子动力电池组均衡拓扑与控制策略。针对电动汽车实时工况，搭建了基于dSPACE的电动汽车动力电池测试实验硬件在环实验平台，并结合整车实验平台，实现对应方法的综合验证与评估。