Torque Distribution of Electric Vehicle with Four In-Wheel Motors Based on Road Adhesion Margin

With the worsening of energy crisis and environmental pollution,electric vehicles with four in?wheel motors have been paid more and more attention. The main research subject is how to reasonably distribute the driving torque of each wheel. Considering the longitudinal motion,lateral motion,yaw movement and rotation of the four wheels,the tire model and the seven DOF dynamic model of the vehicle are established in this paper. Then,the torque distribution method is proposed based on road adhesion margin,which can be divided into anti ? slip control layer and torque distribution layer. The anti?slip control layer is built based on sliding mode variable structure control,whose main function is to avoid the excessive slip of wheels caused by road conditions. The torque distribution layer is responsible for selecting the torque distribution method based on road adhesion margin. The simulation results show that the proposed torque distribution method can ensure the vehicle quickly adapt to current road adhesion conditions,and improve the handling stability and dynamic performance of the vehicle in the driving process.

Torque Distribution Strategy for Integrated Starter/ Generator Hybrid Bus Implemented by Fuzzy Algorithm

A torque distribution strategy was designed by using fuzzy logic to realize the optimal control. The vehicle load zones were dynamically divided into several zones by several torque lines to indicate the drivers demand and the high or low efficient operating areas of the diesel engine. The fuzzy logic controller with trapezoid membership function and Mamdani rule reference mechanism was utilized. There are over 100 rules used in this fuzzy-based torque distribution strategy which are sorted into four rule-bases. The fuel economy and acceleration tests were designed to test and validate the integrated starter/generator (ISG) bus perfor-mance using fuzzy-based torque distribution strategy. The fuel economy is improved 7.7% compared with the rule-based strategy. Finally the road test results reveal that there is about 15% improvement of fuel economy. And the 0-50 km/h acceleration time is 9.5% shorter than the original bus.

Fluid-solid interaction analysis of torque converters

In order to extend the service life of torque converters, it is essential to predict the pressure condition and improve its weak areas. According to computational fluid dynamics and structural statics, a model of torque converter is constructed using software ANSYS. Then, a fluid-solid interaction(FSI) analysis method is proposed to obtain its stress distribution, in which the fluid pressure is applied to the coupling surface to calculate the interaction between fluid and solid. The results show that the fluid pressure at the inlet of the impeller is maximum and decreases along the flow direction, the pressure at the inlet of the turbine blade is minimum and the outlet pressure is the largest, increasing along the flow direction gradually;the pressure distribution of the impeller is concentrated mainly at the corner, especially between the inner ring and the impeller blades;the pressure of the turbine is concentrated mainly on the connection between turbine and the outer edge of the blade.

Analysis of Torque Ripple of Permanent Magnet Brushless DC Motor

Torque tripple has significant effect on performance of permanent magnet brushless DC motor. This paper presents a mathematical model built for such a motor, the analysis of torque tripple for a brushless DC motor with sinusoidal flux distribution, which is verified by torque tripple experiments run with a test motor, and equations developed for torque tripple resulting from different sator current errors.

Mode switching torque distribution strategy of timely four-wheel driven high-gap plant protection machine

The high-gap plant protection machine is taken in this paper as the research object to ensure the good driving power and safety of the high-gap plant protection machine,and the control strategy of inter-shaft torque distribution is established under different working conditions to improve vehicle power and lateral stability.The anticipated demand torque is initially determined based on the structural characteristics and operational principles of the plant protection machine.Subsequently,a hierarchical control framework is devised by incorporating a formulated switching control strategy.Finally,a simulation model for torque distribution control strategy between shafts is developed on the Matlab/Simulink platform,followed by simulation and experimental verification.The results are presented as follows:the inter-shaft torque distribution strategy established in this paper increases the average longitudinal acceleration by 0.13 m/s^(2) and 0.14 m/s^(2) under the control of low and high to low adhesion road surfaces,respectively.Under the control of the single-line shifting condition,the yaw velocity can successfully follow the expected value with a maximum value of 0.61 rad/s.The side deflection angle of the center of mass does not exceed 2.8°,which can follow the ideal trajectory and improve power and safety.

一种开关磁阻电机转矩分配优化控制策略

针对开关磁阻电机存在转矩脉动较大的问题,通过对传统余弦型转矩分配函数进行改进,提出一种开关磁阻电机补偿型余弦转矩分配优化控制策略。根据实际总转矩与期望转矩的稳态偏差,引入傅里叶逼近曲线,对分配转矩进行补偿,并采用双关断角的功率变换电路驱动控制,进行零电压续流,提高实际转矩对分配转矩的跟踪能力。为获得更好的控制性能,进一步采用遗传算法,以降低转矩脉动和铜损为目标,对控制参数进行了全局寻优。以1台四相8/6极开关磁阻电机为控制对象进行建模仿真,来验证所提策略的有效性。结果表明:与传统余弦型转矩分配控制相比,所提改进控制策略提升了电机在不同转速下的性能,转矩脉动降低最高达68.89%,均方根电流减小最高达11.74%。

Lateral stability region conservativeness estimation and torque distribution for FWIA electric vehicle steering

Estimation of the lateral stability region and torque distribution on steering is very important to improve stability in lateral handling for all wheel drive electric vehicles.Based on the built-nonlinear vehicle dynamic model,the lateral stability region of the vehicle related to steering is estimated using Lyapunov function.We obtained stable equilibrium points of non-straight driving according to the estimated lateral stability region and also reconstructed the Lyapunov function matrix,which proved that the closed-loop system composed of yaw rate and lateral velocity is satisfied with negative definite property.In addition,the designed controller dynamically allocates the drive torque in terms of the vertical load and slip rate of the four wheels.The simulation results show that the estimated lateral stability region and the designed controller are satisfactory in handling stability performance against different roads and vehicle parameters.

Torque Distribution Strategy of Electric Vehicle with In-wheel Motors Based on the Identification of Driving Intention

A driver’s intention is recognized accurately by employing fuzzy identification and a logic threshold including acceleration intention and steering intention.Different torque distribution control strategies are developed for different intentions and the driver’s torque demand is amended by fuzzy identification so that the response of the vehicle is more consistent with the driver’s intention of operation.Finally,a simulation model is built using MATLAB/Simulink to validate the control strategy.Simulation results show that the system accurately identifies the driver’s intention and improves the acceleration performance and steering stability of the vehicle.

Inductances Estimation in the d-q Axis for an Interior Permanent-Magnet Synchronous Machines with Distributed Windings

The inductances in d-q axis have an important influence on the behavior of PMSM （PM （permanent-magnet） synchronous machines）. Their calculation is fundamental not only to evaluate the performance such as torque and field weakening capability but also to design the control system to maximize performance and power factor. This paper presents a study of inductance in the d-q axis for buried （i.e., IPMSM （interior） PM Synchronous Machines）. This study is achieved using 2-D （two-dimensional） FEM （finite-element method） and Park＇s transformation.

分布驱动式纯电动汽车电子差速控制策略研究

以轮毂电机直接驱动的分布驱动式电动车为研究对象,为解决汽车转向行驶稳定性和主动安全性的问题,对其电子差速控制策略进行研究。将汽车转向时的横摆稳定性和车轮滑动率相结合,基于动力学计算转矩输出,使用模糊控制算法确定变量范围并设计出模糊控制器,采用双移线和方向盘角阶跃两种输入工况,通过CarSim搭建整车仿真联合模型,对两种电子差速控制策略的对比分析及仿真验证。结果表明,采用DYC+S控制策略比采用DYC+T控制策略的性能更加优越,提高了整车的驾驶性能。

分布式驱动电动汽车横向稳定性抗饱和滑模控制

【目的】探讨轮毂电机输出转矩的幅值和响应速度饱和的问题。【方法】以分布式电动驱动汽车为研究对象,结合二阶嵌套饱和函数对滑模控制进行抗饱和设计,并基于轮毂电机的峰值转矩及其在台架试验中的实际响应设计抗饱和滑模控制器的上下限参数。【结果】抗饱和滑模控制器能严格限制直接横摆力矩的幅值和变化速率,能极大地提高极限工况下车辆的横向稳定性。【结论】本文提出的方法有效解决了极限工况下轮毂电机易陷入饱和的问题,避免了因车轮滑移导致车辆失稳。

分布式电动车转向横向稳定性力矩适应性分配策略

为了提高分布式驱动电动汽车转向行驶的横向稳定性,基于Matlab/Simulink和CarSim建立了分布式驱动电动汽车二自由度动力模型,并设计了车辆的横向稳定性控制策略。控制系统由上下两部分组成:上层力矩计算控制器,主要基于PID控制策略计算车辆所需的附加横摆力矩;下层力矩分配控制器,根据车辆转向行驶时所需附加横摆力矩的大小,在差动驱动、差动制动、摩擦制动3种力矩分配方式中选取相适应的分配方式将力矩合理分配到各个轮毂电机上。研究结果表明:所设计的横向稳定性控制系统最大能够使车辆横摆角速度减小58%,并且可以良好地追踪理想质心侧偏角,且波动减少,有效提高了车辆转向行驶时的横向稳定性。在差动驱动分配方式控制下车辆对追踪期望速度具有良好的效果;车辆所需附加横摆力矩较大时,下层力矩分配控制器采用差动制动、摩擦制动分配方式将牺牲对期望速度的追踪。

基于二维动态减载和双层MPC的风储联合调频与功率优化分配

风机可以通过减载控制提供调频备用功率,但存在弃风量大的问题。为此,结合储能装置,设计了考虑风速分区与储能荷电状态(SOC)的二维动态减载策略,在提供充足调频备用功率的同时减小了弃风功率。在此基础上,结合双层模型预测控制(MPC)架构,提出了计及机组转矩波动的风储联合调频控制策略,上层MPC将风电场视作整体,通过协调风储出力提升调频效果;下层MPC通过风电场内的功率优化分配以抑制机组的转矩波动,保证调频性能的同时提高了机组运行稳定性。通过仿真分析验证了所提策略的有效性,结果表明该减载策略具有更高的风能利用率,且在调频过程中通过机组的功率优化分配减小了机组的转矩波动,提高了机组运行稳定性。

双轮毂电机驱动力矩在线分配控制方法研究

针对双轮毂电机驱动汽车的高效低耗能问题,提出一种考虑双轮毂电机驱动力矩在线实时反馈的优化方法。首先,建立轮毂电机能耗模型、动力学模型以及转矩分配控制模型;其次,以轮毂电机驱动效率为目标,以轮毂电机转矩、转速和能耗为不等式约束,建立基于加入异变序列的QPSO-LSTM算法的优化模型;最后,搭建Lab-VIEW软件实验平台,使轮毂电机在716 N·m转矩峰值和1000 r/min转速峰值的约束条件下稳定输出。结果表明,软件平台可实时监测并调整驱动车辆系统数据,在FTP-75工况下,加入异变序列的QPSO-LSTM算法比量子遗传算法和粒子群算法的单循环能耗分别降低了2.98%和4.64%;在CLTC-P工况下,单循环能耗分别降低了3.06%和4.81%。

分布式电动汽车转矩型电子差速控制策略研究

分布式电动汽车在高速工况下整车模型呈非线性,速度型电子差速控制策略依赖Ackermann转弯模型,没有考虑轮胎特性引起的非线性扰动。该文采用转矩型电子差速控制策略,提高了车辆在高速工况下的转向稳定性。建立了三自由度整车模型、二自由度参考模型、Dugoff轮胎模型以及轮毂电机模型。设计了双层结构转矩分配控制器,上层控制器基于GA-BP神经网络算法获得附加横摆力矩,下层控制器基于二次规划算法在线优化分配4个车轮的驱动力矩。基于Carsim/Simulink进行联合仿真,对所提出的控制策略进行验证。结果表明:在高速双移线工况下,相比较仅速度跟随控制策略,该文的控制策略能有效跟踪期望轨迹,更好地控制质心侧偏角与横摆角速度,在实现电子差速的同时能够保证车辆稳定行驶,提高了车辆行驶的安全性,且该控制策略减少了转向行驶阻力和驱动转矩需求,降低了整车能耗。

一种基于EKF的DDEV主动容错控制方法

分布式驱动电动汽车(DDEV)的行驶稳定性和动力性受电机故障的影响会变差,而驱动系统的容错控制则能够有效改善车辆的行驶稳定性和动力性。为此,针对分布式驱动电动汽车驱动电机,提出了一种主动容错控制方法。首先在Simulink中搭建了包含七个自由度的车辆动力学模型,接着搭建了基于扩展卡尔曼滤波(EKF)的故障观测器,为后文建立的主动容错方法提供故障信息。然后基于滑模控制,搭建了主动容错控制模型,根据故障信息对驱动力矩进行重新分配。最后搭建了Carsim/Simulink联合仿真平台,结果表明,提出的主动容错控制方法能够有效改善车辆在故障状态下的行驶稳定性和动力性。

四轮独立电驱动越野车驱动力优化控制

为了充分利用四轮独立电驱动越野车各轮转矩独立可控的优势,提高越野车的牵引力和越野能力,提出了一种驱动转矩协调控制策略.根据越野车前后轴载荷预分配驱动电动机转矩,利用基于车轮滑转率-路面附着系数的极值寻求算法实现路面最优滑转率估计.采用比例-积分-微分(proportional-integral-differential, PID)控制-滑模控制(sliding mode control, SMC)和基于状态的驱动力再分配方法实现各轮驱动转矩的协调分配,抑制越野车在恶劣路面条件下的车轮打滑.通过CarSim/MATLAB联合仿真以及硬件在环(hardware-in-the-loop, HIL)测试,进行了爬陡坡、单一附着路面、对开路面及连续起伏路面工况的试验验证.结果表明:提出的控制策略能根据实际工况分配驱动轮的转矩,降低驱动轮滑转率,实现整车驱动力的优化.

分布式驱动电动汽车执行器失效容错控制研究

为了提高单电机故障状态下分布式驱动电动汽车的稳定性,提出了一种驱动力重构和主动前轮转向(AFS)结合的容错控制方法。首先,设计滑模控制器,控制输入量为横摆角速度和质心侧偏角,进而对所需横摆力矩和前轮附加转角进行控制。其次,建立电机故障状态下的整车驱动力优化分配模型。当车辆电机出现故障时,运用二次规划算法对各电机转矩进行重构分配。同时,当某一电机发生故障且同侧电机出现输出饱和而无法提供足够的横摆力矩时,通过主动前轮转向提供附加横摆力矩。最终搭建CarSim/Simulink联合仿真模型进行验证,结果显示,所采用的容错控制方法可有效提高车辆稳定性和动力性。

基于NSGA-Ⅱ算法的分布式驱动电动汽车制动转矩分配控制策略研究

针对分布式驱动电动汽车制动安全性和制动能量回收兼顾的问题,研究了基于NSGA-Ⅱ多目标优化算法的车辆制动转矩分配控制策略。建立基于模糊控制的优化集筛选模块,根据车速以及需求制动转矩从Pareto前沿优化集中确定最优转矩分配系数。以某款乘用车为研究对象,基于MATLAB/Simulink和VPAT搭建制动转矩分配控制策略模型进行仿真,并搭建硬件在环仿真平台,对算法的实时性和有效性进行了验证。结果表明:WLTC工况下,基于NSGA-Ⅱ的制动转矩分配的控制策略制动转矩分配系数更加接近理想Ⅰ曲线对应的分配系数,电机制动高效区工作点提高了9.51百分点,再生制动能量回收率提升4.71百分点。

双流耦合构型混合动力拖拉机旋耕工况控制策略研究

大功率拖拉机作业时载荷冲击会造成发动机的输出转矩大范围波动,为减小载荷冲击对拖拉机动力单元的影响,提出以发动机和双电机为动力源的拖拉机双流耦合动力系统构型,以减小载荷冲击引起的动力传动系统换挡频次。基于Haar小波分解提出了基于功率预测的转矩分配策略,首先记录拖拉机的作业参数,基于径向基神经网络对拖拉机旋耕作业时的功率需求进行预测,由Haar小波变换确定高频和低频转矩需求值的范围,并分别由电机和发动机提供。最后,通过硬件在环试验对提出的动态转矩分配进行了可行性验证,测试结果表明:提出的基于神经网络功率需求预测模型对行驶端和动力输出端(Power take-off,PTO)的功率进行预测,实际值和预测值均方根误差分别占最大功率的7.6%和7.9%;提出的转矩分配策略能够应对拖拉机旋耕时的载荷波动。发动机转矩波动与传统构型相比减小35.0%,有效地缩小了发动机转矩波动范围,缓解了拖拉机作业时载荷冲击对发动机的影响。