Science and engineering issues in extreme fast charging of electric vehicles powered by lithium-ion battery

“里程焦虑”一直困扰着电动车产业的发展,在电池能量有限的情况下,消费者期望电动车能够在10 min内完成充电,即充电能够像燃油车加油一样的方便快捷。电动车的快速充电一般指充电时间为0.5～2 h,长于2 h为常用的慢速充电,而低于10 min则为极快速充电。本文仅从科学与工程问题出发,从基础设备/设施、电池电源系统、热管理、单体电池设计、电池材料等层面分析了锂离子电池在极快速充电模式面临的一系列挑战,比较了目前技术水平与极快速充电要求之间的差距,对极快速充电需要解决的技术难题进行了凝练,虽然极快速充电目前还没有实现,本文提出了研发方向建议。     

基于RTWT的汽车主动式油门踏板试验台

为了设计开发一套基于RTWT的主动式油门踏板试验台,首先进行了机械执行装置的机械原理设计及传动参数优化设计;然后利用快速控制原型技术,基于MATLAB/RTWT设计开发了电子控制系统硬件及控制程序;最后通过实验测试了试验台的力反馈和刚度反馈功能。结果表明该试验台具有较好的可靠性与有效性。     

Analysis,modeling, identification and control of pancake DC torque motors: Application to automobile air path actuators

This article is focused on the working, modeling and control of pancake DC torque motors, used in automobile engine air path actuators. These motors, with a limited working angle, provide high torque which makes them suitable for use in actuators without any additional gear reduction. The torque is a nonlinear function of the motor angle. This article provides a modeling scheme, suitable for control purposes, which takes into consideration nonlinearities arising from friction and operating temperature. Comparison between simulation and experiments shows the effectiveness of the proposed model. Second order sliding mode control has been applied to the actuators for robust control under the influence of nonlinearities and uncertainties. The effectiveness of the control algorithm has been proven experimentally.     

Reduced order models for diffusion systems using singular perturbations

In this paper, we consider a special case of the one dimensional heat diffusion across a homogeneous wall. This physical system is modeled by a linear partial differential equation, which can be thought of as an infinite dimensional dynamic system. To simulate this physical system, one has to approximate the underlying infinite order system by a finite order approximation. In this paper we first construct a simple and straight forward approximate finite order model for the true system. The proposed approximate models may require large model order to approximate the true system dynamics in the high frequency regions. To avoid the usage of higher order models, we use a scheme similar to singular perturbations to further reduce the model order.     

A comparative analysis of contact algorithms in contact shape optimization problems

This paper presents a comparative analysis of contact algorithms used for solving contact shape optimization problems. Specifically, a nonlinear, feasible direction interior point method (FDIPM) for the frictional contact analysis of hyperelastic materials has been implemented in which the friction is introduced using the return mapping approach. This comparative investigation aims to find the cause of instability in sensitivity of the contact pressure nonuniformity (CPN). The results obtained by the FDIPM are found to be comparable with those by the penalty methods (PM) and the augmented Lagrange multiplier methods (ALMM); however, the FDIPM possesses advantages, including good convergence and convenience in modeling. Furthermore, the basic cause of the unstable sensitivity is revealed to be the discretization of the finite element method, which causes the discontinuous increase of contact area with respect to the continuous increase of contact load. To improve the stability of the CPN, an adaptive post-processing technique is proposed.     

Effects of pulse flow and leading edge sweep on mixed flow turbines for engine exhaust heat recovery

Recovery of heat energy from internal combustion engine exhaust will achieve significant road transportation CO2 reduction. Turbocharging and turbogenerating are most commonly used technologies to recover engine exhaust heat energy.Engine exhaust pulse flow can significantly affect the turbine performance of turbocharging and turbogenerating systems,and it is necessary to consider the pulse flow effects in turbine design and performance analysis.An investigation was carried out by numerical simulation on th...     

线性高速开关阀的设计及验证

受限于成本原因,电控液压制动系统中多使用高速开关阀,但在液压阀开关控制中电磁阀的敲击噪声、液压冲击噪声和压力波动造成制动控制品质和精度劣化,因此通过脉冲宽度调制控制实现高速开关阀线性化调控性能是此类高速开关阀的设计关键.高速开关阀动态运动特性受瞬态液动力、非线性电磁力与机械惯性、弹簧力综合作用,电磁阀动力学特性决定其线...     

Estimation of vehicle sideslip angle based on steering torque

Vehicle sideslip angle is one of the important indicators to determine whether vehicles are stable and is also a significant parameter for vehicle stability control. However, it is almost impossible to be measured directly without complex and expensive sensors or devices. Soft measurements are therefore generally adopted to estimate vehicle sideslip angle on the basis of easily observed physical quantities. This paper proposes an estimation method of sideslip angle based on steering torque instead of steering angle, for the fact that steering torque signal has more rapid and direct response compared with that obtained from steering angle. The frequency is analyzed between steering torque-sideslip angle and steering angle-sideslip angle transfer functions, and the extended Kalman filter (EKF) for vehicle sideslip angle based on steering torque is proposed. Both simulation results and vehicle tests prove the validity of our estimating method, indicating that the proposed method based on steering torque exhibits better accuracy and more rapid response in extreme region than the one based on steering angle.