Stochastic sampled-data multi-objective control of active suspension systems for in-wheel motor driven electric vehicles

This paper addresses the sampled-data multi-objective active suspension control problem for an in-wheel motor driven electric vehicle subject to stochastic sampling periods and asynchronous premise variables.The focus is placed on the scenario that the dynamical state of the half-vehicle active suspension system is transmitted over an in-vehicle controller area network that only permits the transmission of sampled data packets.For this purpose,a stochastic sampling mechanism is developed such that the sampling periods can randomly switch among different values with certain mathematical probabilities.Then,an asynchronous fuzzy sampled-data controller,featuring distinct premise variables from the active suspension system,is constructed to eliminate the stringent requirement that the sampled-data controller has to share the same grades of membership.Furthermore,novel criteria for both stability analysis and controller design are derived in order to guarantee that the resultant closed-loop active suspension system is stochastically stable with simultaneous𝐻2 and𝐻∞performance requirements.Finally,the effectiveness of the proposed stochastic sampled-data multi-objective control method is verified via several numerical cases studies in both time domain and frequency domain under various road disturbance profiles.

MPC-based Torque Distribution for Planar Motion of Four-wheel Independently Driven Electric Vehicles:Considering Motor Models and Iron Losses

The most critical obstacle for four-wheel independently driven electric vehicles(4WID-EVs)is the driving range.Being the actuators of 4WID-EVs,motors account for its major power consumption.In this sense,by properly distributing torques to minimize the power consumption,the driving range of 4WID-EV can be effectively improved.This paper proposes a model predictive control(MPC)-based torque distribution scheme,which minimizes the power consumption of 4WID-EVs while guaranteeing its tracking performance of planar motions.By incorporating the motor model considering iron losses,the optimal torque distribution can be achieved without an additional torque controller.Also,for this reason,the proposed control scheme is computationally efficient,since the power consumption term to be optimized,which is expressed as the product of the motor voltages and currents,is much simpler than that derived from the efficiency map.With reasonable simplification and linearization,the MPC problem is converted to a quadratic programming problem,which can be solved efficiently.The simulation results in MATLAB and CarSim co-simulation environments demonstrate that the proposed scheme effectively reduces power consumption with guaranteed tracking performance.

Decentralized Dynamic Event-Triggered Communication and Active Suspension Control of In-Wheel Motor Driven Electric Vehicles with Dynamic Damping

This paper addresses the co-design problem of decentralized dynamic event-triggered communication and active suspension control for an in-wheel motor driven electric vehicle equipped with a dynamic damper. The main objective is to simultaneously improve the desired suspension performance caused by various road disturbances and alleviate the network resource utilization for the concerned in-vehicle networked suspension system. First, a T-S fuzzy active suspension model of an electric vehicle under dynamic damping is established. Second,a novel decentralized dynamic event-triggered communication mechanism is developed to regulate each sensor's data transmissions such that sampled data packets on each sensor are scheduled in an independent manner. In contrast to the traditional static triggering mechanisms, a key feature of the proposed mechanism is that the threshold parameter in the event trigger is adjusted adaptively over time to reduce the network resources occupancy. Third, co-design criteria for the desired event-triggered fuzzy controller and dynamic triggering mechanisms are derived. Finally, comprehensive comparative simulation studies of a 3-degrees-of-freedom quarter suspension model are provided under both bump road disturbance and ISO-2631 classified random road disturbance to validate the effectiveness of the proposed co-design approach. It is shown that ride comfort can be greatly improved in either road disturbance case and the suspension deflection, dynamic tyre load and actuator control input are all kept below the prescribed maximum allowable limits, while simultaneously maintaining desirable communication efficiency.

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.

Electromagnetic analysis and design of in-wheel motor of micro-electric vehicle based on Maxwell

To obtain a good drivability and high efficiency of the micro-electric vehicle, a new driving in-wheel motor design was analyzed and optimized. Maxwell software was used to build finite element simulation model of the driving in-wheel motor. The basic features and starting process were analyzed by field-circuit coupled finite element method. The internal complicated magnetic field distribution and dynamic performance simulation were obtained in different positions. No-load and load characteristics of the driving in-wheel motor was simulated, and the power consumption of materials was computed. The conformity of the final simulation results with the experimental data indicates that this method can be used to provide a theoretical basis to make further optimal design of this new driving in-wheel motor and its control system, so as to improve the starting torque and reduce torque ripple of the motor. This method can shorten the development cycle of in-wheel motors and save development costs, which has a wide range of engineering application value.

基于路面影响因子的轮毂电机驱动车辆自适应转矩控制

为实现轮毂电机驱动越野车辆在附着条件多变、路面起伏不定的复杂环境中动力性和稳定性的多目标优化,提出一种基于路面影响因子的自适应转矩控制策略。以滚动阻力差异、空气阻力归一化比例、坡度阻力归一化比例、路面附着差异方差以及最小路面附着系数5个特征参数作为输入,并基于模糊理论方法搭建路面影响因子五参数辨识模型。基于辨识出的路面影响因子,开发整车动力性和稳定性多目标优化自适应转矩控制策略,构建了三层式控制架构:顶层引入路面影响因子对加速度紧迫程度进行判定,采用模型预测控制算法得到期望总驱动力;中层为目标决策层,以最优滑转率为目标决策驱动防滑力矩,并基于路面行驶阻力,决策期望前馈补偿力矩;下层为转矩分配层,以需求总驱动力及轮胎利用率作为控制目标,引入路面影响因子优化两者权重系数,以多约束条件的混合优化算法对转矩进行自适应控制。利用Matlab/Simulink-CarSim联合仿真平台进行仿真,基于实车进行验证。结果表明,在低附着路面,在0.2s内快速完成滑转率抑制;在对开路面,侧向位移接近0;在大扭曲路面,避免腾空车轮出现大滑转率,滑转率最高0.2。

Simulation and verification analysis of the ride comfort of an in-wheel motor-driven electric vehicle based on a combination of ADAMS and MATLAB

To study the ride comfort of wheel-hub-driven electric vehicles,a simulation and verifi-cation method based on a combination of ADAMS and MATLAB modeling is proposed.First,a multibody dynamic simulation model of an in-wheel motor-driven electric vehi-cle is established using ADAMS/Car.Then,the pavement excitation and electromag-netic force analytical equations are provided based on the specific operating conditions of the vehicle and the in-wheel motor to analyze the impact of the electromagnetic force fluctuation from an unsprung mass increase and motor air gap unevenness on vehicle ride comfort after the introduction of an in-wheel motor.Next,the vibration model and the motion differential equation of the body–wheel dual-mass system of an in-wheel motor-driven electric vehicle are established.The influence of the in-wheel motor on the vibration response index of the dual-mass system is analyzed by using MATLAB/Simulink software.The variation in the vehicle vibration performance index with/without the motor electromagnetic force excitation factor is analyzed and com-pared with the ADAMS multibody dynamics analysis results.The results show that the method based on a combination of ADAMS and MATLAB modeling can forecast the ride comfort of an in-wheel motor-driven electric vehicle,reducing the cost of physical prototype experiments.

轮毂电机驱动电动汽车4WS和DYC协调控制

为了提高轮毂电机驱动电动汽车的路径跟踪能力和操纵稳定性,本文针对主动四轮转向系统(4WS)和直接横摆力矩控制系统(DYC)提出一种新型的协调控制策略。首先,综合考虑车辆的路径跟踪性能和操纵稳定性,建立一种共享转向控制模型,并在此基础上提出基于非合作Nash博弈的4WS控制策略。其次,为了提高危险行驶工况下的车辆侧向稳定性,基于质心侧偏角相平面将车辆状态划分为稳定区域、过渡区域和失稳区域,并分区域建立DYC控制器。再次,为了实现后轮转向与直接横摆力矩的协同控制,建立基于模糊神经网络的ARS/DYC协调控制器。最后,利用CarSim/Simulink联合仿真平台和硬件在环平台,分别进行双移线工况下的试验验证。研究结果表明,所提出的控制策略能够有效地提高车辆在极端行驶工况下的路径跟踪精度和操纵稳定性能。

Rollover prevention control for a four in-wheel motors drive electric vehicle on an uneven road

When a four in-wheel motors drive electric vehicle with a specific wheels mass is running on an uneven road and transient steering occurs in the meantime, the joint action of the large unsprung dynamic load and the centrifugal force may cause the vehicle to rollover. To avoid the above accident, a rollover prevention control method based on active distribution of the in-wheel motors driving torques is investigated. First, tile rollover evolution process of the four in-wheel motors drive electric vehicle under the described operating condition is analyzed. Next, a multiple degrees of freedom vehicle dynamics model including an uneven road tyre model is established, and the rollover warning threshold is determined according to the load transfer ratio. Then, the hypothesis of the effects of unsprung mass on the vehicle roll stability on a plat road and on an uneven road is verified respectively. Finally, a rollover prevention controller is designed based on the distribution of the four wheels driving torques with sliding mode control, and the control effect is verified by simulations. The conclusion shows that, once the wheels mass does not match road conditions, the large unsprung mass may play a detrimental role on the vehicle roll stability on an uneven road, which is different from the beneficial role of large unsprung mass on the vehicle roll stability on a plat road. With the aforementioned rollover prevention controller, the vehicle rollover, which is caused by the coupling effect between large unsprung dynamic load and suspension potential energy on an uneven road, can be avoided effectively.

基于温度失效工况的分布式轮毂电动机驱动车辆容错控制

轮毂电动机驱动车辆各轮转矩独立可控,动力响应迅速,驱动系统冗余配置,在车辆动力学集成控制方面有显著优势,但其复杂的行驶工况和较高的功率需求容易使电动机发生温升故障,最终影响驱动效率.为了研究轮毂电动机温度故障诊断以及温度失效情况下的各轮转矩分配策略,保证整车稳定性及动力性,设计了模糊逻辑检测算法用于诊断电动机温度故障,提出温度失效因子量化表征轮毂电动机失效状态,根据期望速度和前轮转角计算纵、横向力需求,设计容错控制策略实现转矩重构优化分配.对所设计的算法进行实车试验验证.结果表明:故障诊断和处理策略能及时判断电动机失效状态并进行转矩重构分配,提高了行驶安全性,实现了整车动力性与稳定性的协调控制.

基于深度强化学习的轮毂电机驱动电动汽车垂向振动控制

轮毂电机驱动电动车作为分布式驱动的一种理想的解决方案,对于缓解能源问题具有重要意义,然而当轮毂电机引入轮毂时,其平顺性会恶化。为解决轮毂电机电动汽车平顺性问题,建立了考虑座椅、车身和簧下质量振动特性以及主动与半主动悬架时间迟滞因素的三自由度轮毂电机电动汽车的1/4车模型,并基于深度强化学习算法对轮毂电机驱动电动汽车通过主动悬架进行垂向振动控制。在此基础上,对轮毂电机驱动电动车在随机路面与减速带路面下行驶的情况进行训练,进而对其训练案例的控制效果进行测试,并将之与被动悬架和天棚阻尼控制策略的控制效果进行对比,最后对轮毂电机驱动电动车在随机路面的基于深度强化学习主动悬架控制策略进行泛化能力测试。结果表明,对于训练与泛化测试案例,针对轮毂电机驱动电动车的垂向振动控制,基于深度强化学习的主动悬架控制策略所产生的控制效果均优于被动悬架与天棚阻尼控制策略。

四驱电动车经济性改善的最优转矩分配控制

阐述了转矩分配控制实现四轮驱动电动车经济性改善的思路,采用效率最大化方法优化确定了转矩分配系数矩阵作为最优转矩分配控制策略核心.针对各种驾驶循环进行了能量消耗的仿真分析.仿真分析表明,最优转矩分配控制方法能够明显减少驱动能量消耗,增加反馈制动能量回收,总体能效提高约3%.同时能够大大降低轮毂电机的发热功率,延长其使用寿命.转矩分配最优化的控制方法能够应用于采用轮毂电机的纯电动车、前轴机械驱动,以及后轴电驱动的混合动力四轮驱动汽车的能量消耗经济性改善控制.

我国城市交通发展特征分析

以详实的数据从交通工具、道路交通基础设施、居民出行等3个角度对我国城市交通发展特征进行了分析．研究结果显示，我国城市机动车保有量保持快速增长，车型结构向客运方向发展，特别是小客车比例越来越大；而自行车经过快速发展以后，20世纪90年代中期以后呈现下降的趋势；公共交通逐渐得到重视，客运量得到稳步发展；而道路交通基础设施按照新建和扩建并举的模式发展，但增长速度比较缓慢；城市居民出行次数随城市规模增大而减小，但随社会经济发展而呈现增长趋势，出行结构则越来越向个体快速交通方式转变．

四轮轮毂电机电动汽车电子差速控制研究（英文）

针对四轮轮毂电机电动汽车转向时四轮差速问题,进行了电子差速控制研究。设计了电子差速控制策略,建立差速运动参考模型,根据四轮轮毂电机电动汽车四轮驱动力矩独立可控的优势,通过驱动力矩分配器对四轮驱动力矩进行合理分配,实现了实际轮速跟踪参考轮速,并在Matlab/Simulink里搭建了四轮轮毂电机电动汽车电子差速系统模型,通过CarSim与Matlab/Simulink联合仿真进行了验证。结果表明:电子差速差速控制策略能够有效实现转向时四轮差速控制,提高电动汽车的操纵稳定性。

电动车用永磁同步电机非线性扭转振动模型

针对电动车车身阶次振动和车内噪声的主要振源—永磁同步电机的扭转振动问题,首先,利用集中参数法建立了永磁同步电机扭转振动的非线性动力学模型,解析求解了考虑非正弦分布的永磁磁场、定子开槽、时间谐波电流的永磁同步电机电磁转矩,获取了定子铁芯、机壳的刚度和阻尼参数,指出了电磁转矩波动是引起永磁同步电机非线性振动的主要原因。然后,采用状态变量法求得了非线性方程组的解。最后,通过永磁同步电机扭转振动实验验证了本模型的有效性。

基于MOBILE6.2的北京市出租车排放污染物分析

利用MOBILE6.2模型计算了2000年、2005年及2008年北京市出租车的排放因子,同时,计算了北京市出租车2005年更换部分旧车以及2008年更换全部旧车以后,相对于2000年污染物的降低总量。结果表明,排放污染物随更换车型大大下降。HC排放物的总量下降了1779.4T,CO排放物的总量下降了13304.3T,NOx排放物的总量下降了684.4T。2008年完成出租车全部更换后,相对于2000年,HC排放物的总量下降3097.9T,CO排放物的总量下降17483.5T,NOx排放物的总量下降了1211.8T。同时,还估算了2000年和2008年其他类型机动车的排放因子及污染物的排放总量,并计算了各车型对排放的贡献率。

集中电机驱动车辆动力传动系统NVH性能研究现状与展望

阐述了电动汽车振动与噪声问题的近期研究成果。针对集中驱动式电动车动力传动系统的特点,从5个方面分别进行介绍,即动力传动系统扭转振动的研究、动力总成磁固耦合振动的研究、驱动电机转矩波动的研究、动力总成悬置系统的研究、动力传动系统机电一体化研究。最后,对此领域的研究工作进行了展望。

基于吸振原理的轮边驱动电动车垂向振动负效应的抑制

针对轮边驱动电动车非簧载质量引起车辆垂向振动负效应,提出了一种在车轮转向节上加装动力吸振器的方案,并建立了数学模型;根据某轮边驱动电动车参数,对吸振器参数进行了优化设计。结果表明,优化后的悬架性能较优化前有明显提高。

轮毂电机驱动电动汽车双横臂前悬架运动学优化

基于传统汽车底盘平台进行电动轮驱动改型时,轮毂电机的布置将导致悬架硬点坐标的改变,从而严重影响悬架运动学特性,为此须对电动轮驱动改型车悬架系统进行优化设计。以某传统车底盘平台的双横臂前悬架运动学特性为优化目标,根据参数灵敏度分析结果,提出两步优化方案,即首先进行主销定位参数的优化,而后再进行前轮外倾角和前轮前束角的优化。利用ISIGHT软件和全局非归一化的多目标遗传优化算法NSGA-II得到的悬架参数优化解集在ADAMS/Car平台下进行了验证。结果表明,悬架运动学特性得到较大幅度的改善,特性曲线与原型车悬架K特性实验结果基本一致。证明了该优化方法的可行性,确保了改型后电动汽车的操纵稳定性受安放轮毂电机的影响较小。

AFPM型轮毂驱动电机研究综述

新能源汽车产业化是推动汽车产业可持续发展的重要途径,是解决当前能源短缺与环境问题的关键举措。电动汽车作为新能源汽车的重要发展方向,将在未来汽车产业竞争中起到至关重要的作用,其中尤以轮毂驱动方式的电动汽车最为突出。轴向磁通永磁无刷电机以其结构紧凑、功率密度高、工作噪声低以及散热性能好等优点逐渐成为轮毂驱动装置的优选对象。在对AFPM电机技术研究现状进行阐述的基础上,着重分析了AFPM电机在轮毂驱动方面的工程应用及存在的技术问题,尤其是AFPM电机与其他系统的匹配和在高负荷工况下的散热技术问题,并对其在未来汽车行业发展中将起到的关键作用进行了展望。研究结果对AFPM电机在新能源汽车领域的技术应用具有一定的参考价值。