表贴式永磁同步电机直接转矩控制变幅值预测控制研究

基于以电压矢量幅值为变量的表贴式永磁同步电机(SPMSM)磁链和转矩方程,采用预测控制计算得出施加不同电压矢量幅值的下一时刻磁链和转矩值,选择使磁链和转矩误差目标函数最小的电压矢量幅值作为最优值,从而确定下一时刻施加的电压矢量。仿真结果表明:在电压矢量变幅值预测下,SPMSM直接转矩控制(DTC)系统运行良好,定子磁链轨迹为理想圆,磁链和转矩均符合控制要求,转速跟踪良好,定子电流波形正弦。预测控制需要从备选电压矢量幅值集合中选择最优幅值。理论上,备选电压矢量幅值个数越多,系统优化效果越好,但也带来更大的计算负担。研究了9种等分电压矢量情况下变幅值预测控制系统的控制效果。根据控制效果和计算负担,提出变幅值预测控制将电压矢量幅值三等分较为理想。     

高空发动机试车台矢量推力现场动态校准技术

根据发动机试车台矢量推力现场动态校准需求，通过系统化论证，针对试车台的技术要求及校准需求，解决发动机试车台现场实际使用和实验室校准条件不同造成的附加测量误差、试验台推力无法整体校准等问题。文中提出了利用摆锤式动态力加载装置实现标准矢量力加载的方案，为了验证设计方案的可行性，利用现有的设备研究验证校准方案，通过试验和分析给出了校准不确定度。结果表明：该方案动态性能优异，响应迅速，动态校准不确定度为2.2%，能满足高空发动机试车台矢量推力测试的需求，为后续进一步准确测试矢量推力提供了依据。     

基于定子电阻自适应辨识的感应电机死区补偿

电压源型逆变器由于死区效应,导致输出发生非标准化、畸变化,影响感应电机的控制精确度,特别是无速度传感器矢量控制,同时造成电网侧能量的流失。为了减小死区效应产生的影响,列出误差计算公式,求得总延时时间。另外,对定子电阻进行自适应辨识,增加所求延时时间精确度的同时可以运用到电机矢量控制中。经过补偿误差电压,提高了控制性能,降低了对控制系统的影响。结果表明所提补偿策略对电流波形、总谐波失真具有改善作用。     

模块化永磁直线游标电机等效磁网络及漏磁分析

在模块化永磁直线游标电机的初始设计及优化设计中,使用有限元方法(FEM)计算漏磁系数时需要耗费大量的建模和计算时间。针对这一问题,建立该种电机的等效磁网络模型,在建模期间,考虑气隙中的边缘效应,并计算永磁体组与定子齿在不同相对位置时的等效磁导,得到该种电机在一个周期内不同相对位置时的漏磁磁导和漏磁系数的数学解析表达式。采用FEM验证了该数学解析表达式的准确性。研究结果为模块化永磁直线游标电机的设计提供了理论依据。     

某飞行器推力矢量试验测力装置研制

为满足某飞行器推力矢量试验的测试要求,采用两台六分量应变天平和一个空气桥组成测力装置来实现飞机全机气动力和喷管推进特性同时分别测量。基于有限元软件,对天平的应变及空气桥对天平的干扰进行了分析。结果表明:空气桥对天平力分量的干扰值优于5%,对力矩(滚转力矩除外)分量的干扰值优于15%,达到了设计指标。通过校准获得了单独天平、天平带空气桥(充压、不充压)状态下的校准公式,校准结果表明:两台天平各分量的综合加载误差均优于0.3%,天平带空气桥(充压、不充压)状态下各分量的综合加载误差优于0.5%,空气桥对天平的干扰量值与有限元分析结果一致。理论分析与实测结果证明:研制的天平及空气桥达到了预定目标,它的测量精准度高,满足推力矢量风洞试验需求。     

Robust model predictive control for satellite formation keeping with eccentricity/inclination vector separation

This study presents model predictive formation control based on an eccentricity/inclination vector separation strategy. Alternative collision avoidance can be accomplished by using eccentricity/inclination vectors and adding a simple goal function term for optimization process. Real-time control is also achievable with model predictive controller based on convex formulation. Constraint-tightening approach is address as well improve robustness of the controller, and simulation results are presented to verify performance enhancement for the proposed approach.     

Thrusting maneuver control of a small spacecraft via only gimbaled-thruster scheme

The thrust vector control (TVC) scheme is a powerful method in spacecraft attitude control. Since the control of a small spacecraft is being studied here, a solid rocket motor (SRM) should be used instead of a liquid propellant motor. Among the TVC methods, gimbaled-TVC as an efficient method is employed in this paper. The spacecraft structure is composed of a body and a gimbaled-SRM where common attitude control systems such as reaction control system (RCS) and spin-stabilization are not presented. A nonlinear two-body model is considered for the characterization of the gimbaled-thruster spacecraft where, the only control input is provided by a gimbal actuator. The attitude of the spacecraft is affected by a large exogenous disturbance torque which is generated by a thrust vector misalignment from the center of mass (C.M). A linear control law is designed to stabilize the spacecraft attitude while rejecting the mentioned disturbance torque. A semi-analytical formulation of the region of attraction (RoA) is developed to ensure the local stability and fast convergence of the nonlinear closed-loop system. Simulation results of the 3D maneuvers are included to show the applicability of this method for use in a small spacecraft.     

A boundary vector cell model of place field repetition

Hippocampal place cells are thought to form the neural substrate of a global cognitive map. However, in multicompartment mazes, these cells exhibit locally repeating representations, undermining the global cognitive map view of place cells. This phenomenon appears to be related to the repetitive layout of these mazes, but still no hypothesis adequately explains it. Here, we use a boundary vector cell (BVC) model of place cell firing to model the activity of place cells in numerous multicompartment environments. The activity of modeled place cells bears a striking resemblance to experimental data, replicating virtually every major experimental result. Our results support the BVC model and indicate that locally repeating place cell firing could result purely from local geometry.     

基于混合深度特征的红外目标抗干扰识别算法

复杂干扰条件下的红外空中目标识别技术是空战对抗领域的热点研究课题,复杂人工干扰严重遮蔽目标,导致目标特征的连续性与显著性遭到破坏,无法全面描述识别对象的特性,造成空中目标识别准确率下降。针对此问题,提出一种基于图像混合深度特征的空中目标抗干扰识别算法。首先,基于卷积神经网络进行图像深度特征的提取,将深度特征与梯度直方图(Histogram of Gradient, HOG)特征进行有效融合,构建混合深度特征。针对作战场景中的目标与干扰的对抗态势多样性,将支持向量机的二分类模型改进为三分类模型,对目标、干扰以及目标干扰粘连三种状态进行精确分类。实验结果表明：在复杂干扰环境下,基于混合深度特征的空中目标抗干扰识别算法正确率为92.29%,该算法可以有效地解决目标被干扰遮蔽、形成目标干扰粘连状态时的抗干扰识别问题。     

带非线性支撑的转子有限元模型求解方法

用数值方法研究了非线性支撑的柔性转子系统的动学行为,提出了一种将有限元与非线性支撑结合的模型和求解方法。利用有限元法(FEM)构建转轴和转盘部分的模型,通过矩阵进行组合;利用离散元方法对包含滚动轴承和挤压油膜阻尼器(SFD)的支撑部分进行建模,此部分包含4个单元,分别为轴承内圈、外圈、SFD内圈和支撑鼠笼。有限元部分和离散元部分通过轴端节点相连,仿真过程中轴端位移传递给非线性支撑部分,支撑部分通过位移计算得到的非线性力反过来作用于有限元转子轴端部分。为了耦合求解有限元转子和非线性支撑组成的数学模型,提出了一种综合的迭代求解方法,克服传统的有限元求解方法对轴端隐性非线性支撑的求解局限性。由于转轴部分采用了Timoshenko梁单元建模,对比与简单转子模型,可以考虑陀螺力矩和轴的柔性特征,更能体现非线性支撑对振动真实影响。在建立的20个轴单元的有限元转子模型中,非线性响应更多体现在靠近非线性支撑的节点1和节点21处,响应频谱中靠近轴端的节点能体现出滚动轴承的2倍和3倍变柔振动频率。