用稳定内压估算氢镍电池荷电态的研究及应用

Nickel-metal hydride (Ni-MH) batteries, as a power supply of hybrid vehicles (HEV), have been and will be further widely used. Currently, the values of the battery state of charge (SOC) are estimated by measuring several parameters including voltage, current, battery resistance, and temperature, possessing low accuracy and big accumulative errors. These methods can cause the decreases of the battery lifetime and energy efficiency. Therefore, how to estimate SOC with better accuracy has been a tough question and critical technology in practical applications. In this project, we develop a novel approach for the estimation of SOC to overcome the problems mention above, by accurately measuring the built-in pressure in nickel-metal hydride batteries.. Specifically, a built-in pressure sensors is sealed within a type D nickel-metal hydride battery and is used to accurately measure the internal pressure of the battery. According to the direct relation between the hydrogen balance pressure and alloy discharge capacity of the hydrogen storage alloy, SOC can be accurately estimated by measuring the built-in pressure. In order to better understand the changes of the built-in pressure, several typical factors such as the battery temperature, negative charge electricity state, and cycles of battery are investigated to find out their effects on the internal pressure. Then the relationship between the built-in pressure and the actual SOC is systemically studied at various temperatures and cycles numbers.. The more accurate SOC can therefore be achieved by measuring the built-in pressure of the battery. The proposed method avoids the complicated charging and discharging working state and is able to correct accumulative error resulting from the current sensor, sampling , self- charging and discharging efficiency. Finally, the practical use of our method will be explored in the 288V - 6Ah battery system.

氢镍（MH-Ni）电池作为混合动力汽车（HEV）的电源已经且必将进一步得到广泛应用。目前通过电压、电流、电池内阻、温度等参数估算电池荷电态(SOC)的方法精度低且累积误差大，不仅大大缩短电池寿命，而且其能量效率也降低。这一直是实际应用中的棘手问题，也是核心技术。本项目提出一种基于氢镍电池内压的SOC估算方法，其核心创新点是依据贮氢合金的氢平衡压力与合金可逆储氢量一一对应的理论，综合考虑电池温度、负极荷电态、循环次数等因素对电池稳定内压的影响，系统研究不同温度、不同循环次数下电池的稳定内压与电池实际SOC的关系，以便通过一定温度下可精确测量的电池稳定内压获知其更为准确的SOC。该方法巧妙地避开了复杂的充放电工况，而且可以校正由于电流传感器与采样精度、自放电以及充电效率引起的积分电量累计误差。项目还将这一估算SOC的新方法在实际的288V-6Ah氢镍电池系统中进行探索性应用。

氢镍电池是目前混合电动汽车中得到最大规模使用的电池。电池的荷电态作为电池管理系统的核心技术，成为制约车用电池系统使用寿命的重要因素。目前通过电压、电流、电池内阻、温度等参数估算其荷电态的方法，存在精度低且累积误差大。项目依据储氢合金的氢平衡压力与合金可逆储氢量一一对应的理论，提出一种基于电池稳定内压估算其荷电态的新方法。项目通过含压力传感器电池的设计和高精度在线电池内压测试系统开发，建立了一种在线定量检测氢镍电池稳定内压的方法，并具有普适性。研究了电池在不同倍率和温度等条件下充放电过程中的内压特性，明确了氢镍电池内压的规律性和机理。研究了电池在不同荷电态、不同温度下搁置和不同循环次数下，稳定内压与荷电态的关系，结果表明电池的实际荷电态与稳定内压都有一一对应的关系，并拟合得到相应的关系式，为采用数学建模的方法建立相应的数据库打下基础。在此基础上，将基于稳定内压的荷电态估算方法在车用氢镍电池中进行初步应用，验证了该方法的可行性，有望成为估算氢镍电池荷电态的一种新方法。通过项目的实施在学术期刊上发表论文8篇，其中SCI收录3篇；2篇会议论文参加技术交流；申请专利4项，其中3项已授权；出版专著1本；培养了硕士2名，博士1名。