基于模糊神经网络优化扩展卡尔曼滤波的锂离子电池荷电状态估计
State of charge estimation for lithium-ion batteries based on extended Kalman filter optimized by fuzzy neural network

电池荷电状态(state of charge, SOC)的精确估计是判断电池是否过充或过放的重要依据, 是电动汽车安 全、可靠运行的重要保障. 传统基于扩展卡尔曼滤波(extended Kalman filter, EKF)的SOC估计方法过度依赖于精确 的电池模型, 并且要求系统噪声必须服从高斯白噪声分布. 为解决上述问题, 基于模糊神经网络(fuzzy neural network, FNN)建立模型误差预测模型, 并藉此修正扩展卡尔曼滤波测量噪声协方差, 以实现当模型误差较小时对 状态估计进行测量更新, 而当模型误差较大时只进行过程更新. 仿真和实验结果表明, 该算法能有效消除由于模型 误差和测量噪声统计特性不确定而引入的SOC估计误差, 误差在1:2%以内, 并且具有较好的收敛性和鲁棒性, 适用 于电动汽车的各种复杂工况, 应用价值较高.
The accurate estimation for state of charge (SOC) is the important basis to prevent overcharge or overdischarge of batteries, and is the important guarantee for the electric vehicle safety and reliability. In the traditional SOC estimation methods based on extended Kalman filter (EKF), the SOC estimation precision was highly dependent on an accurate battery model. To solve the above problems, an error prediction model was built based on fuzzy neural network (FNN), by which the measurement noise covariance of EKF was real-time revised. When the predicted model error was small, the measurement model was updated, otherwise, the process model was updated only. The simulation and experimental results show that the proposed algorithm can effectively eliminate the SOC estimation error caused by the model error and the uncertain noise statistical properties, with the maximum error of less than 1:2%. The proposed algorithm has good convergence and robustness, and is applicable to various complicated driving cycles for electric vehicles, with high application value.