随着能源需求增长和环境污染恶化，电动汽车将逐步占领汽车市场。作为电动汽车动力心脏的锂离子电池，在使用过程中剩余电量的不一致性不断扩大，直接影响电动汽车的续航里程，因此电池均衡控制系统成为电动汽车领域的研究热点。本文以18650三元锂离子电池为研究对象，开展以下研究：

首先，采用扩展卡尔曼滤波算法对电池进行SOC估算。搭建二阶RC电路模型，采用HPPC脉冲测试法进行电池参数识别，在MATLAB/Simulink中对该电路模型的精确性进行仿真验证。在1C放电倍率直流放电和1C、1/3C放电倍率间歇放电工况下，通过仿真得到的工作电压数据与实验数据进行对比，误差值在0.05V之内，验证电路模型的有效性。在MATLAB中分别进行直流放电工况和间歇放电工况下的SOC估算仿真，并与实验数据进行对比，误差值控制在3%左右，验证扩展卡尔曼滤波算法的可行性。

其次，设计短路式均衡拓扑结构及其控制策略。以SOC作为均衡变量，通过继电器通断实现不同电池之间的交替重组，形成串联电池组进行充放电，以达到整个电池组SOC均衡的目的。在Simulink中进行相对应充放电仿真，验证该系统的可行性。仿真结果表明，在正常工况下，单体电池在充放电过程中的不一致性控制在1.556%以内；故障工况下，电池组依然能够选择性放电，直至电池组不满足放电需求。

最后，搭建交替式均衡控制系统实验平台，进行电池组电压采集，SOC估算及不同工况下的充放电实验。实验结果表明，该系统采集到的电压值及SOC估算值均与真实值变化趋势相同，具有可行性；在正常工况下的放电实验中，延时时间由20s缩短为10s，电池之间的不一致性缩小至1.27%，能明显改善系统的均衡效果。实验结果与仿真结果相一致，证明该系统对电池均衡控制的有效性。

With the energy demand increasing and environment deteriorating, electronic vehicles will become the dominate player in the vehicle market. As the key power source of electric vehicles, the inconsistency of state of charge between lithium-ion batteries is increasing while being used, which directly affects the cruising range of electric vehicles. Therefore, the battery balance control system has become a hot research topic in the field of electric vehicles. In this paper, the 18650 ternary lithium battery is taken as the research object, and the following research is carried out:

Firstly, the extended Kalman filter algorithm is used to estimate the SOC for the battery. The second-order RC circuit model has been built, and the experiment of HPPC has been conducted to identify the battery parameters. The accuracy of the circuit model had been verified by the simulation in MATLAB/Simulink. Under the condition of 1C discharge rate and 1C, 1/3C discharge rate, the working voltage data obtained by the circuit model is compared with the experimental data, and the error value is within 0.05V, verifying the validity of the circuit model. Under the condition of DC discharge and intermittent discharge, the programming simulations are carried out in MATLAB to estimate the SOC. Finally, the value of SOC is compared with experimental data, and the error value is controlled at about 3%, which verify the feasibility of the extended Kalman filter algorithm.

Then, the short-circuit balanced topology and its control strategies are proposed. Taking SOC as the balance variable, the alternate recombination between different batteries is realized through turning on and off the relays to form a battery group in series, and charging and discharging experiments of the battery group are conducted to achieve the balance of SOC of all batteries. The simulations of corresponding charge and discharge are conducted to verify the feasibility of this system. The simulation results show that under normal working conditions, the inconsistency of single cells during charging and discharging is controlled within 1.556%; under fault working conditions, the battery pack can still be selectively discharged until the battery pack does not meet the discharge requirements.

Finally, an experimental platform of alternate balance control system is built, and the experiment of voltage collection, SOC estimation and charging and discharging experiments under different working conditions are carried out. The experiment results show that the trend of change between the value of collected voltage and estimated SOC by the system are the same with the real value, which shows the methods adopted are feasible. In the discharge experiment, the delay time is shortened from 20s to 10s, the inconsistency was reduced to 1.27% under normal operating conditions, which can obviously improve the balance effect of this system. The experimental results are consistent with the simulation results, proving the effectiveness of the system proposed for battery balancing control.

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