【作者】 张宇；

【导师】 李波；

【作者基本信息】 山东理工大学 ， 工程硕士（专业学位）， 2022， 硕士

【摘要】 随着纯电动车技术的出现和进步,具有多级速比的纯电动汽车成为当前研究的热点,变速系统对提高电动汽车动力性、延长电动汽车续驶里程具有重要意义,因此研究并掌握高效变速器的核心技术,是电动汽车动力传动技术发展的主要趋势,对电动汽车的技术进步具有重要战略意义。为了进一步缩短换挡力传递路线,提高变速器换挡效率,课题组研究了一种采用电磁直线执行器作为换挡执行机构的电磁直驱变速器(DirectDriving Automated Mechanical Transmission,DAMT)。为了缩短电磁直驱变速器换挡动力中断时间,提升换挡控制精度,对换挡执行器的非线性驱动力、永磁体温度特性,以及变速器同步环摩擦系数温度特性进行了研究分析,得到了各部件工作特性对变速器换挡力的影响规律,为电磁直驱变速器散热结构设计提供了借鉴意义;研究了基于电磁直驱变速器不同工作特性的跟随补偿控制策略,缩短了电磁直驱变速器的换挡中断时间、提升了换挡控制精度,为电磁直驱变速器在纯电动汽车上的应用奠定了基础,具体工作包含以下几个方面的内容:(1)电磁直驱变速系统分析及动力传动系统参数匹配。首先对电磁直驱变速器的结构及工作原理进行了分析,将换挡过程划分为六阶段,根据换挡各阶段工作原理建立了各阶段的数学模型;其次针对汽车动力性能要求完成驱动电机参数匹配,以及对DAMT两档传动比取值进行了计算;最后分析了换挡执行器的结构及工作原理,设计换挡执行器永磁体阵列方式并对磁路进行了分析,建立了换挡执行器的数学模型。(2)换挡执行器非线性驱动力和温升-驱动力工作特性分析。借助电磁场有限元分析软件JMAG对执行器工作气隙磁通密度的分布进行了分析,探究了驱动力动子位置及激励电流对气隙磁通密度的影响;对换挡执行器动态推力及损耗分析,得到了换挡执行器非线性驱动力变化规律,仿真结果表明换挡执行器在换挡行程内驱动力波动率达到35%,采用数据拟合方式建立了换挡执行器的非线性驱动力数学模型;以换挡执行器各部件损耗作为执行器的发热源,基于等效热网络法建立了执行器四热源热网络模型,得到了执行器各部件工作时温升变化,在此基础上对永磁体进行了热特性分析,永磁体在温度升高至70℃时剩磁和矫顽力分别下降了9.4%和8.6%,最后结合温升变化规律,得到了换挡执行器的温升-驱动力工作特性。(3)电磁直驱变速器传动系统热分析及摩擦系数测定试验。确定了电磁直驱变速器动力传动系统的发热热源为同步器、齿轮副和轴承,针对其工作原理的不同分别对其进行了热功率损失计算;根据DAMT各部件结构及传热形式的不同,对各部件进行导热热阻及对流换热热阻分析计算;选取关键位置进行温度节点划分,搭建了变速器传热系统39节点热网络图,建立了热网络模型的迭代求解模型;最后搭建变速器温度测试平台验证理论分析的有效性,通过试验方式得出同步器摩擦副的温度-摩擦系数对应关系。(4)电磁直驱变速器工作特性跟随补偿控制策略研究。前文分析得到的换挡执行器非线性驱动力、永磁体热特性引起的磁性能衰退以及同步环摩擦副接触表面温度摩擦系数随温度发生变化,这三类工作特性的共同作用会直接影响到换挡执行器的输出换挡力,进而影响电磁直驱变速器的换挡时间。在此基础上设计了换挡执行器的双闭环反馈控制系统并引入前馈控制回路来补偿工作特性引起的驱动力损失;针对换挡各阶段控制目标的不同,并基于非线性驱动力和温升-驱动力工作特性设计了换挡位移阶段和换挡同步阶段补偿控制策略。仿真结果表明在执行器控制系统的基础上加入温度补偿控制策略后,当永磁体温度为20℃和60℃下,执行器换挡动力中断时间分别减少了26%和37%,同步器摩擦副温度在20℃和90℃时,在引入温度系数控制策略后,换挡同步阶段的动力中断时间分别减少了0.01s和0.036s,最后搭建相应的试验平台对补偿控制策略的有效性进行验证。更多还原

【Abstract】 With the emergence and progress of pure electric vehicle technology,pure electric vehicle with multi-level speed ratio has become the current research hotspot.The research group has studied a direct driving automated mechanical transmission(DAMT)using electromagnetic linear actuator as shift actuator.In order to shorten the shift power interruption time of the electromagnetic direct drive transmission and improve the shift control accuracy,this paper takes the electromagnetic direct drive transmission as the research object.Aiming at the reduction of the shift force caused by its working characteristics,through the combination of theoretical analysis,mathematical modeling,simulation analysis and experimental verification,the influence law of the working characteristics of each component on the shift force of the transmission is obtained A follow-up compensation control method based on the working characteristics of the electromagnetic direct drive transmission is studied,which eliminates the adverse effect of the working characteristics on the shift performance,shortens the shift interruption time of the electromagnetic direct drive transmission,and improves the shift control accuracy.The specific work includes the following aspects:(1)Analysis of electromagnetic direct drive transmission system and parameter matching of power transmission system.Firstly,the structure and working principle of electromagnetic direct drive transmission are analyzed.The shift process is divided into six stages.According to the working principle of each stage,the mathematical model of each stage is established;Secondly,according to the requirements of vehicle power performance,the parameter matching of driving motor is completed,and the value of two gear transmission ratio of damt is calculated;Finally,the structure and working principle of the shift actuator are analyzed,the permanent magnet array mode of the shift actuator is designed,the magnetic circuit is analyzed,and the mathematical model of the shift actuator is established.(2)Analysis of nonlinear driving force and temperature rise driving force working characteristics of shift actuator.With the help of the electromagnetic field finite element analysis software jmag,the distribution of the working air gap flux density of the actuator is analyzed,and the effects of the driving force mover position and excitation current on the air gap flux density are explored;The dynamic thrust and loss of the shift actuator are analyzed,and the corresponding relationship between displacement and driving force at different positions of the shift actuator is obtained.The simulation results show that the driving force fluctuation rate of the shift actuator reaches 35% in the shift stroke.The nonlinear driving force mathematical model of the shift actuator is established by data fitting;Taking the loss of each part of the shift actuator as the heat source of the actuator,the four heat source thermal network model of the actuator is established based on the equivalent thermal network method,and the temperature rise change of each part of the actuator is obtained.On this basis,the thermal characteristics of the permanent magnet are analyzed.When the temperature rises to 70 ℃,the remanence and coercivity of the permanent magnet are reduced by 9.4% and 8.6% respectively.Finally,combined with the change law of temperature rise,The working characteristics of temperature rise driving force of shift actuator are obtained.(3)Thermal analysis and friction coefficient measurement test of transmission system of electromagnetic direct drive transmission.It is determined that the heat sources of the power transmission system of electromagnetic direct drive transmission are synchronizer,gear pair and bearing.According to their different working principles,the thermal power loss is calculated respectively;According to the different structures and heat transfer forms of damt components,the thermal resistance of heat conduction and convection heat transfer are analyzed and calculated;The key positions are selected to divide the temperature nodes,the 39 node thermal network diagram of the transmission heat transfer system is built,and the iterative solution model of the thermal network model is established;Finally,the transmission temperature test platform is built to verify the effectiveness of the theoretical analysis,and the corresponding relationship between the temperature and friction coefficient of the synchronizer friction pair is obtained through the test.(4)Research on the control strategy of follow-up compensation for the working characteristics of electromagnetic direct drive transmission.The nonlinear driving force of the shift actuator,the decline of magnetic properties caused by the thermal characteristics of the permanent magnet and the temperature friction coefficient of the contact surface of the synchronous ring friction pair change with temperature.The combined action of these three working characteristics will directly affect the output shift force of the shift actuator,and then affect the shift time of the electromagnetic direct drive transmission.On this basis,the double closed-loop feedback control system of the shift actuator is designed,and the feedforward control loop is introduced to compensate the driving force loss caused by the working characteristics;According to the different control objectives of each shift stage,and based on the nonlinear driving force and the temperature rise driving force working characteristics,the compensation control strategy of shift displacement stage and shift synchronization stage is designed.The simulation results show that after adding the temperature compensation control strategy to the actuator control system,when the permanent magnet temperature is 20 ℃ and60 ℃,the actuator shift power interruption time is reduced by 26% and 37% respectively,and when the synchronizer friction pair temperature is 20 ℃ and 90 ℃,after introducing the temperature coefficient control strategy,the power interruption time in the shift synchronization phase is reduced by 0.01 s and 0.036 s respectively,Finally,the corresponding test platform is built to verify the effectiveness of the compensation control strategy.更多还原