New P3D Hydraulic Fracturing Model Based on the Radial Flow

Pseudo three-dimension (P3D) hydraulic fracturing models often overpredict the fracture height for a poorly contained fracture. To solve this problem, a new method is presented in shaping the P3D fracture geometry on the basis of the fundamental theory and the original 1D fluid flow is replaced with a more representatively radial flow. The distribution of the fluid in the modified fluid field is analyzed and a sound explanation to the problem is given. Due to the consideration of the fluid flow in the vertical direction, the modified model can predict the fracture height much better. To validate the rationality of the radial fluid flow assumption, the distribution of the fluid in the modified fluid field is simulated with the plane potential flow by using finite element method. And the results agree effectively with those from the assumption. Through comparing with the full 3D model, the results show that this new P3D model can be used to aid the fracturing design and predict the fracture height under poorly contained situation.     

电动汽车电池组连接方式研究

为了了解电动汽车电池组连接方式对电池组使用性能的影响,通过大量的电动汽车运行试验,对电动汽车电池组的连接方式进行了研究。建立了电池组连接模型,并重点分析讨论了不同连接模型对电池组连接可靠性和电池不一致性的影响,提出了合理的连接方式选择原则。     

约束系统特性对乘员碰撞响应影响的仿真研究

　Aim　To study the influence of restraint system performance upon the occupant's response during impact, and provide a scientific base for occupant restraint system design. Methods In the light of basic theory of multibody system dynamics and impact dynamics on the basis of classical theory of impact, R-W method is adopted to construct the vehicle-occupant system model consisting of fourteen rigid bodies, thirty seven DOFs and slip joints for the simulation. A software named SVC3D(3-dimensional simulation of vehicle crash) is developed in the FORTRAN language. Results The results of simulation have a good coincidence with those of tests and the restraint system with low elongation webbing and equipped with pretensioner provides better restraint effect for the occupant. Conclusion The model of vehicle-occupant multibody system and SVC3D are suitable for use. Occupant should be belted with low elongation webbing to a certain degree and occupant restraint system should be equipped with pretensioner.     

串联混合电动汽车辅助功率单元输出控制

为使串联混合电动汽车的辅助功率单元和动力蓄电池的功率混合可控,由等效电路分析辅助功率单元的的电压、电流和功率三种输出控制方法,并同时提出了一种速度分级式功率控制算法。通过dSPACE原型控制器,调节电控柴油发动机的转速和无刷交流同步发电机的励磁电流,实现了辅助功率单元的三种输出控制方法。实验结果验证了三种控制方法分析的正确性,其中电压控制法最不易实现辅助功率单元和动力蓄电池的输出功率混合。速度分级式功率控制有效解决了发动机转速和发电机转矩控制的耦合问题,使辅助功率单元和动力蓄电池各自独立或联合为负载提供功率。     

Fuzzy Model for Estimation of the State-of-Charge of Lithium-Ion Batteries for Electric Vehicles

A fuzzy model was established to estimate the state of charge (SOC) of a lithium-ion battery for electric vehicles. The robust Gustafson-Kessel (GK) clustering algorithm based on clustering validity indices was applied to identify the structure and antecedent parameters of the model. The least squares algorithm was utilized to determine the consequent parameters. Validation results show that this model can provide accurate SOC estimation for the lithium-ion battery and satisfy the requirement for practical electric vehicle applications.     

混合电动汽车的技术现状

指出了混合电动汽车发展的必要性 ,介绍了混合电动汽车的部件组成 ,以及多样的驱动布置形式 ,分析了对混合电动汽车设计起决定性因素的控制策略 ,最后着重指出了混合电动汽车设计中的几项关键技术     

电动大客车DC／DC电源的研究与仿真

本文介绍了一种电动大客车用DC／DC电源设计的基本思路和实际电路,并对其中脉冲变压器参数的确定进行了详细的计算,然后报据此电路用PSPICE进行了仿真,从仿真电路的输出电压波形和IGBT两端波形看,取得了比较好的效果。实验表明,仿真电路和实际电路是一致的。     

电动汽车电池管理系统和剩余容量计研究

目的研究和开发电动汽车电池管理系统,实现铅酸储能蓄电池的剩余容量计量技术。方法通过对电动汽车铅酸储能电池基本电化学特性分析,采用了以安时法－Ｐｅｕｋｅｒｔ公式－开路电压法为基本算法,进行电池管理系统的开发,同时考虑了温度、自放电、使用循环寿命等因素对铅酸电池剩余容量预测的影响。结果所开发的管理系统铅酸电池剩余容量静态充放电实验计量误差小于５％,提供给驾驶员一个较准确的剩余容量,并对电池组中每声池进行监测,对铅酸电池的过放电和过充电等非正常工作情况及时报警,实用性强。结论电动汽车电池管理系统可以有效延长电池的使用寿命,优化电池能量的利用,提高电动汽车的性能。     

电动车辆感应牵引电机DTC驱动系统的设计和开发

研究和开发电动汽车三相感应电机驱动装置的直接转矩 (DTC)驱动控制系统 .采用低成本数字信号处理器 ,通过软硬件模块化结构 ,运用程序测试实现感应电机无速度传感器直接转矩全数字实时控制方案的可行性 .通过测试程序实验证明整个控制系统的硬件接口功能正常和软件的可实现性 .测试电机时 ,采用基于空间矢量脉宽调制的变频控制技术 ,电机能够正常运行 ,但以18r/min运行时 ,转矩脉动大 .在已建立的感应电机无速度传感器直接转矩控制理论基础上 ,展开其在电动汽车上的应用研究 ,侧重在转矩响应的快速性、平滑性和稳定性 ,这有利于提高电动车辆的动力性和经济性 .     

基于CAN总线的混合动力汽车监控系统开发

以周立功CAN卡为下位机,在PC机上采用VC++开发监控和标定上位机软件,组成混合动力汽车CAN总线监控系统,实现混合动力汽车CAN总线数据监控和整车控制器(VCU,Vehicle Control Unit)标定;系统具有CAN总线数据采集、显示、存储和回放等功能,同时可实现VCU标定和代替VCU发送控制指令,在台架试验和驻车情况下调试整车基本控制指令,方便和安全地进行整车控制指令发送和响应性能;实验结果表明,所开发的混合动力汽车CAN总线监控系统能够满足整车参数采集和基本控制调试需要。