锂电池荷电状态(state of charge,SOC)估计技术是保证电力储能和电动汽车合理应用的核心技术,也是锂电池系统控制运营、监测维护的基础。在锂电池实际应用中,其表现出非线性、时变性、影响因素复杂性和不确定性的问题,造成了荷电状态估...锂电池荷电状态(state of charge,SOC)估计技术是保证电力储能和电动汽车合理应用的核心技术,也是锂电池系统控制运营、监测维护的基础。在锂电池实际应用中,其表现出非线性、时变性、影响因素复杂性和不确定性的问题,造成了荷电状态估计难度大、精度不高和适应能力不足。为此,众多锂电池荷电状态估计算法及改进策略应运而生。与此同时,部分研究人员针对不同估计方法和改进策略的实现方式和优缺点开展了分析与对比,但相关综述对估计方法的技术特点和适用性方面的论述不足且缺乏系统性总结。本文首先分析了锂电池荷电状态估计的影响因素和测试标准;然后从基于实验计算的传统方法、基于电池模型的滤波类算法、基于数据驱动的机器学习技术以及数模混合估计方法四个方面开展对比分析,归纳总结各类方法的技术特点、实现过程、适用条件、难题痛点以及应用优势,系统全面地论述了现有锂电池荷电状态估计技术的研究重点和应用现状;最后,展望了锂电池荷电状态估计算法的未来研究方向。展开更多
The mathematical model of 4He quantum interferometer gyroscope is presented. The model includes the driven equation, the current equation and the position equation. Therefore, it can sufficiently describe the gyro- sc...The mathematical model of 4He quantum interferometer gyroscope is presented. The model includes the driven equation, the current equation and the position equation. Therefore, it can sufficiently describe the gyro- scope system. The driven equation shows the thermally driven gyroscope can work for a long time but the pres- sure driven one cannot. From the current equation, the superfluid currents passing through the weak link contain the AC currents which show the rotation flux, and other currents caused by drive. As shown in the position equa- tion, the displacement of diaphragm is the only detectable parameter in the gyroscope system. The model is tested by the simulations based on experimental parameters, and can be used to research performance of the gyroscope and analyse the gyroscope error.展开更多
A mathematical model was developed to analyze the characteristics of the wet clutch during engagement. The lubricant squeeze action was simulated with Patir and Cheng average flow model in which the permeability of fr...A mathematical model was developed to analyze the characteristics of the wet clutch during engagement. The lubricant squeeze action was simulated with Patir and Cheng average flow model in which the permeability of friction material is taken into account, and the asperity load is calculated according to the Greenwood and Tripp approach. In this model, effects of friction material permeability, applied load and driving velocity on the engagement characteristics of the wet clutch were studied. The results show that friction material with high permeability reduces the film thickness rapidly and increases the torque peak; the applied load increases the asperity contact pressure and the friction torque, and reduces the engagement time; the driving velocity mainly increases the engagement time. The theoretical torque and relative velocity curves agree qualitatively with the experimental ones, which verifies the wet clutch engagement model.展开更多
文摘锂电池荷电状态(state of charge,SOC)估计技术是保证电力储能和电动汽车合理应用的核心技术,也是锂电池系统控制运营、监测维护的基础。在锂电池实际应用中,其表现出非线性、时变性、影响因素复杂性和不确定性的问题,造成了荷电状态估计难度大、精度不高和适应能力不足。为此,众多锂电池荷电状态估计算法及改进策略应运而生。与此同时,部分研究人员针对不同估计方法和改进策略的实现方式和优缺点开展了分析与对比,但相关综述对估计方法的技术特点和适用性方面的论述不足且缺乏系统性总结。本文首先分析了锂电池荷电状态估计的影响因素和测试标准;然后从基于实验计算的传统方法、基于电池模型的滤波类算法、基于数据驱动的机器学习技术以及数模混合估计方法四个方面开展对比分析,归纳总结各类方法的技术特点、实现过程、适用条件、难题痛点以及应用优势,系统全面地论述了现有锂电池荷电状态估计技术的研究重点和应用现状;最后,展望了锂电池荷电状态估计算法的未来研究方向。
基金Supported by the National Natural Science Foundation of China(61074162)the Ph.D.Program Foundation of Ministry of Education of China(200802870011)~~
文摘The mathematical model of 4He quantum interferometer gyroscope is presented. The model includes the driven equation, the current equation and the position equation. Therefore, it can sufficiently describe the gyro- scope system. The driven equation shows the thermally driven gyroscope can work for a long time but the pres- sure driven one cannot. From the current equation, the superfluid currents passing through the weak link contain the AC currents which show the rotation flux, and other currents caused by drive. As shown in the position equa- tion, the displacement of diaphragm is the only detectable parameter in the gyroscope system. The model is tested by the simulations based on experimental parameters, and can be used to research performance of the gyroscope and analyse the gyroscope error.
基金Funded by the Innovation Foundation of Beijing University of Aeronautics and Astronautics for PhD Candidates
文摘A mathematical model was developed to analyze the characteristics of the wet clutch during engagement. The lubricant squeeze action was simulated with Patir and Cheng average flow model in which the permeability of friction material is taken into account, and the asperity load is calculated according to the Greenwood and Tripp approach. In this model, effects of friction material permeability, applied load and driving velocity on the engagement characteristics of the wet clutch were studied. The results show that friction material with high permeability reduces the film thickness rapidly and increases the torque peak; the applied load increases the asperity contact pressure and the friction torque, and reduces the engagement time; the driving velocity mainly increases the engagement time. The theoretical torque and relative velocity curves agree qualitatively with the experimental ones, which verifies the wet clutch engagement model.
