基于Si纳米膜的差分结构矢量水听器工艺研究

通过关键工艺步骤,将硅(Si)纳米膜制备在差分结构水听器上作为压敏电阻,利用Si纳米膜的巨压阻效应来提高水听器的灵敏度;利用深Si刻蚀,将Si柱与芯片一体化,减少了差分结构的对准误差,同时抑制海洋洋流带来的振动干扰。设计了相对应的光刻掩模版和整套工艺流程,通过MEMS工艺,成功加工出Si纳米膜作为压敏电阻,实现矢量水听器芯片与Si柱集成化。对制备好的芯片进行观测与测试,使用激光共聚焦显微镜和扫描电子显微镜(SEM)设备观察芯片形貌良好,尺寸与设计基本一致;通过半导体分析仪测量得到压敏电阻器的阻值为15.3×10^(4)Ω,线性度良好,符合矢量水听器功能需求。

基于MEMS的压阻式一体化矢量水听器

随着水下探测技术的发展,为满足水听器更精准的定位和更远距离的探测要求,提出了一种基于微电子机械系统(MEMS)的压阻式一体化矢量水听器。设计了一套能够将硅纤毛与二氧化硅悬臂梁相集成的工艺方案,以期解决长期以来由于纤毛二次集成带来的一致性误差。对水听器的性能进行有限元仿真分析,通过应力仿真得出理论上能够将其灵敏度提高约11.3 dB,模态分析表明其具有更宽的工作频带,证明该方案能够有效优化水听器的性能。介绍了该方案的具体工艺流程及重点工艺步骤,完成了一体化矢量水听器的制备。通过扫描电子显微镜(SEM)进行形貌观测,得到悬臂梁长为247μm、宽为121μm、厚为3.3μm,与设计指标基本一致,验证了工艺设计的合理性。对压敏单元进行电阻测试,得到了线性度很高的I-V特性曲线,说明其欧姆接触良好。分别对4个悬臂梁上的压敏电阻进行电阻测试,阻值均为(7 000±50)Ω,表明电阻的一致性很好,符合矢量水听器的设计需求。

一种微纳跨尺度一体化的MEMS矢量水听器

随着水下消声技术的发展,水下目标探测难度越来越大,单个水听器难以实现有效探测,需组成水听器阵列,而现有微电子机械系统(MEMS)矢量水听器存在粘接纤毛一致性相对较差、阵列应用相对困难等问题。设计了一种微纳跨尺度一体化MEMS矢量水听器。根据理论与有限元仿真分析,确定了在满足水下探测频率20~1 000 Hz使用条件下的MEMS矢量水听器的基本尺寸,并对该水听器进行了微纳跨尺度一体化加工流程设计,通过一体化加工工艺方式,加工出硅纳米线作为敏感压阻单元,使该水听器压阻达到约1.2×104Ω,相比现有水听器压阻的阻值有了明显的提高,并对硅纳米线压阻进行了压阻系数测试,结果表明一体化工艺加工出的硅纳米线比传统体硅压阻系数提高了3~4倍。同时该工艺将硅纤毛与二氧化硅梁集成在一起,减少了粘接过程存在的对准精度与一致性差的问题,为MEMS矢量水听器发展提供了一个新的研究方向。

无离合器机械式自动变速器换挡过程的扭矩控制

电动汽车所采用的无离合器机械式自动变速器的降扭和扭矩恢复会引起传动系统的扭振,降扭调节不当还会对后续的换挡控制产生不利影响.为提高换挡品质,对换挡过程的降扭和扭矩恢复两个阶段的动力学机理和控制方法进行了研究.建立了传动系统扭振模型和同步器齿轮啮合模型,分析了换挡过程扭矩变化对扭振的激励规律,揭示了非充分降扭对摘挡过程车辆动力学性能以及执行机构损伤的影响机理;根据二阶系统特性设计了扭矩控制器,根据系统初始状态假设设计了虚拟系统,实现了对扭矩控制过程的系统扭振抑制和初始状态估计;完成了降扭和扭矩恢复控制效果仿真验证.研究表明,所设计控制器可以通过调节控制率系数来配置系统阻尼比,从而得到不同的扭矩控制特性,在阻尼比系数接近于1时能够有效降低降扭阶段和扭矩恢复阶段产生的扭转振动.

纤毛-硅柱结构MEMS二维矢量水听器设计与制备方法

微机电系统(MEMS)矢量水听器在使用中会受到平台运动、海浪、洋流等冲击的干扰从而影响对目标声源的探测。为实现水听器的精准探测,提出了一种纤毛-硅柱结构的可抑制振动噪声的矢量水听器。设计了一种力矩平衡结构,利用COMSOL软件对矢量水听器的参数构建有限元分析模型,并对其静态分析、模态分析以及谐响应分析仿真。结果表明:矢量水听器灵敏度为-184.35 dB;可在0~100 g n载荷内正常工作;在工作带宽20~1000 Hz内能有效降低振动噪声带来的干扰。随后提出一种基于MEMS技术的可批量制造工艺,可确保硅柱与水听器的一体化集成,可极大提高矢量水听器的一致性。

集成硅纤毛的MEMS矢量水听器的压阻特性

水听器是水下探测的主要仪器,通过对其结构的研究和改进可显著提升其性能。针对现阶段矢量水听器所采用的纤毛二次集成方式所造成的一致性误差较大的问题,以硅纳米膜作为压敏单元,设计了一种新型基于微电子机械系统(MEMS)的压阻式矢量水听器。通过理论及仿真确定最优尺寸,进行一体化工艺流程的设计,将硅纤毛直接集成在二氧化硅梁上,既提高了对准的精度,又缩小了整体尺寸。对制备的水听器芯片进行测试,得到了压敏单元的I-V特性。测试结果表明其阻值达到7 kΩ,同时测得该压敏单元的压阻系数为3.12×10^(-9) Pa^(-1),相比于传统p型[110]体硅压敏单元的压阻系数提高了约4.35倍,压阻系数的提升可以有效提高水听器的灵敏度。此设计能够优化水听器的性能,可为后续水听器的研究和改进提供新的思路。

基于能量法的分布式驱动电动汽车防侧翻控制

分布式驱动电动汽车具有优越的侧倾稳定性控制功能,但基于横向载荷转移率评价进行控制并不能充分发挥其技术优势。为提升该类车型恶劣工况下的防侧翻控制能力,针对当前侧翻评价指标的不足,开展基于能量转化评价的稳定性控制研究。针对该类车型的结构特点,建立车辆系统坐标系,借助欧拉旋转角法推导了整车在侧翻运动过程中动能、势能和耗散能的表达方程;通过计算车辆失稳能量阈值与车辆实时失稳能量,提出综合多因素的车辆稳定性评价指标;基于侧翻动力学模型设计出防侧翻滑模控制器;通过在分布式驱动系统力矩阈值范围内开展基于驱动轮力矩分配的差动驱动,实现了整车的防侧翻控制。研究表明,基于能量法制定的空间失稳评价指标相较于横向载荷转移率而言,更能准确、灵敏地反映整车侧倾运动状态的变化趋势,基于其设计的防侧翻控制方法通过主动分配两侧驱动力矩,削弱了相关能量转化,有效抑制了整车侧倾运动,显著提高了侧倾稳定性。

Parameters optimum matching of pure electric vehicle dual-mode coupling drive system

As an important development direction of pure electric vehicle drive system,the distributed drive system has the advantages of compact structure,high transmission efficiency,and flexible control,but there are some serious problems such as high performance requirements to the drive motors,complex control strategies,and poor reliability.To solve these problems,a two motors dual-mode coupling drive system has been developed at first,which not only has the capacity of two-speed gear shifting,but also can automatically switch between the distributed drive and the centralized drive by means of modes change control.So,the performance requirements to the drive motors can be reduced,the problem of abnormal running caused by the fault of unilateral distributed drive systems also can be resolved by replacing the drive mode with centralized drive.Then,the system parameters primary and the optimum matching under the principle of efficiency optimization have been carried out,which makes the drive system achieve predetermined functions and meet the actual demands of different operating statuses.At last,the economic comparison of a pure electric vehicle installation with a dual-mode coupling drive sytem,a single-motor centralized drive system or a dual-motor distributed drive system in the simulation conditions has been completed.Compared with other systems,the driving range of the electric vehicle driven by the designed system is significantly increased,which proves the better efficiency and application value of the system.

Powertrain design and energy management of a novel coaxial series-parallel plug-in hybrid electric vehicle

For a series plug-in hybrid electric vehicle,higher working efficiency can be achieved by the drive system with two small motors in parallel than that with one big motor alone.However,the overly complex structure will inevitably lead to a substantial increase in the development cost.To improve the system price-performance ratio,a new kind of series-parallel hybrid system evolved from the series plug-in hybrid system is designed.According to the technical parameters of the selected components,the system model is established,and the vehicle dynamic property and pure electric drive economy are evaluated.Based on the dynamic programming,the energy management strategy for the drive system under the city driving cycle is developed,and the superiority validation of the system is completed.For the studied vehicle driven by the designed series-parallel plug-in hybrid system,compared with the one driven by the described series plug-in hybrid system,the dynamic property is significantly improved because of the multi-power coupling,and the fuel consumption is reduced by 11.4%with 10 city driving cycles.In a word,with the flexible configuration of the designed hybrid system and the optimized control strategy of the energy management,the vehicle performance can be obviously improved.

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, the 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.