PMSM无位置传感器矢量控制的滑模观测器设计

永磁同步电机无传感器控制技术不但能够降低系统成本,而且能够增加系统的可靠性。为实现永磁同步电机无位置传感器的运行,本文提出了一种基于自适应滑模观测器的非线性速度/角度估算方法,基于永磁同步电机的数学模型,根据实测电流与估算电流之间的误差构成滑模面,将反电动势估算值反馈引入电机电流观测中。为简化调速系统的硬件结构,我公司设计了一个截止频率可随转速变化的低通滤波器。     

一种改进的高压大功率有源电力滤波器设计及实现

设计了一套用于高压系统的大容量有源电力滤波器.该APF采用双DSP CPLD为核心的数模混合控制系统.谐波电流检测方法采用离散傅立叶变换,电流跟踪采用三角载波比较方式.并针对直流侧电容电压控制,提出了一种新的基于趋近率的滑模变结构控制方法,该方法跟踪性能好、鲁棒性强,克服了传统PI调节超调量和静态响应误差大、响应速度慢、参数难调节等缺点.挂网运行表明该APF谐波抑制效果显著.     

基于滑模变结构矢量控制的异步电机调速

针对异步电机矢量控制系统因电机参数变化和负载波动等因素使调速性能变差的问题,在转差频率控制的异步电机矢量控制系统的基础上,用两个滑模变结构控制器代替传统的PI控制器分别控制d轴和q轴的电流,并采用电压空间矢量技术来调节电机的输入电压,达到调速的目的.仿真结果说明,文中所提出的控制方式与传统的PI控制方式相比较,具有响应速度快,控制精度高,对负载波动和电机参数变化具有较强的鲁棒性.     

基于旋转坐标系IPMSM的容错控制策略研究

针对内置式永磁同步电机(IPMSM),当以旋转变压器为位置传感器发生严重故障时,提出了一种故障诊断及容错的方案。采用了基于旋转坐标系的改进滑模观测器算法和TypeⅡ型跟踪环路转子位置和角速度提取算法,用于IPMSNM的转子位置和角速度的估算。利用估算数据分析并检测位置传感器是否出现故障,并采用加权算法实现故障情况下系统的平滑切换。通过搭建MATLAB/Simulink仿真模型对设计的方案进行验证,输出的结果显示了此方案具有较好的容错控制效果,说明了提出的这个方案可行性和有效性。     

Critical State of Granular Materials Based on the Sliding-Rolling Theory

By representing the assembly by a simplified column model, a constitutive theory was recently developed for a two-dimensional assembly of rods. This theory, referred to as the sliding-rolling theory, is extended in this paper to represent the triaxial stress-strain behavior of granular materials. The sliding-rolling theory provides a dilatancy rule and an expression for the slope of the line of zero dilatancy in the stress space. These rules are then combined with triaxial observations to provide a microstructural interpretation of the critical state of granular materials. According to the theory, the slope of the critical state line in the stress space depends on the interparticle friction angle and the degree of contact normal anisotropy. To verify the basic ideas of the sliding-rolling theory, numerical experiments are conducted using the discrete-element method on three-dimensional assemblies of spheres.     

滑动径向轴承轴心轨迹的可视化及其应用

讨论了轴承 转子系统的非线性动力分析 ,由此计算轴心轨迹 ,并研制开发了滑动径向轴承轴颈轨迹数值实验软件系统。能指导设计人员预先了解轴承的运行状态 ,从而提高了滑动轴承和机械产品的设计质量和效率 ,在应用中具有很强的实用性。     

任意切换时间下的二维线性混合系统的滑模控制

由于混合系统的复杂性,设计出能保证混合系统在任意切换时间下都能稳定的控制是比较困难的。为了突出滑模控制设计的思想,文章针对一类二维线性混合系统,提出通过确保混合系统实现滑动模的充分条件来保证系统的稳定性,并得到相应的控制律。仿真结果表明了该控制律的有效性。     

基于滑模变结构控制的RBF神经元网络

针对高精度飞行仿真转台,设计一种基于滑模变结构控制的RBF神经元网络控制器。该控制器根据滑模变结构控制器的特点,将控制律分为等效控制律和到达控制律。等效控制律使系统运动于滑模面附近,由RBFN拟合而成,权值用自适应算法在线修正,确保了实时控制的可能性;到达控制律可使处于状态空间内任意初始位置的系统趋近于滑模面,由滑模控制器的可达性条件推出,其中用到了系统的不确定性参数的上下界。计算机仿真结果表明了该方法的鲁棒性和实际应用的可能性。     

Altered age-hardening behavior in the ultrafine-grained surface layer of Mg-Zn-Y-Ce-Zr alloy processed by sliding friction treatment

To gain insight into the ageing behavior of ultrafine grain(UFG)structure,the precipitation phenom-ena and microstructural evolutions of Mg-6Zn-1Y-0.4Ce-0.5 Zr(wt.％)alloy processed by sliding friction treatment(SFT)were systematically studied using hardness texting,transmission electron microscopy(TEM)equipped with high-angle annular dark-field scanning(HADDF-STEM),X-ray diffraction(XRD)and XRD line broadening analysis.The microhardness of the SFT-processed(SFTed)sample initially decreases from 109.6 HV to 104.8 HV at ageing for 8 h,and then increases to the peak-ageing point of 115.4 HV at 16 h.Subsequently,it enters the over-aged period.The un-SFTed sample,as the counterpart,follows a regular ageing behavior that increases from 89.9 HV to 99.6 HV when ageing for 12 h,and then drops.A multi-mechanistic model is established to describe the strengthening due to grain refinement,disloca-tion accumulation,precipitation etc.The analysis reveals that the temperature sensitive UFG structure has an obvious grain coarsening effect,which arouses the soft phenomenon in the early ageing stage.But precipitation hardening provides an excellent hardness enhancement for overcoming the negative influ-ence and helping to reach the peak-aged point.In our microstructural observations,a lot of equilibrium ultrafine MgZn2 precipitates precipitate along dislocations because defects can provide the favorable conditions for the migration and segregation of solute atoms.     

RESEARCH OF A HIGH EFFICIENCY SLIDING SCREW DRIVER

A high efficiency sliding screw driver is introduced. It can improve driving efficiency obviously. As the material strength of the nut in this structure is low and the nut is the most dangerous part, so it is important to master the structure's characters of deformation and stress. The deformation and stress of this structure are researched by finite element method(FEM), and the changing law of stress concentration coefficient of the structure is gained. So the exact stress of nut teeth with highest load can be calculated directly based on this result.