基于果蝇-蛙跳模糊神经网络PID 的永磁直线同步电机控制

针对永磁直线同步电机(PMLSM)伺服系统存在的非线性、时变性及强耦合性,设计一种基于模糊神经网络PID的速度控制策略,通过融合果蝇优化算法和蛙跳算法形成果蝇-蛙跳算法,实时调整优化模糊神经网络的结构参数,输出适用于PID控制器的最佳参数kp、ki、kd,实现PMLSM速度控制的自适应和智能化。仿真分析与试验结果表明,采用基于果蝇-蛙跳算法优化的模糊神经网络PID速度控制器,能使PMLSM控制系统取得更加优良的控制效果。     

电动公交车匀速下长坡再生制动控制策略优化

针对电动公交车下长坡再生制动过程中被控对象存在汽车质量、汽车旋转质量换算系数不确定性以及电机参数摄动的问题,构建了电动公交车再生制动系统模型。基于线性矩阵不等式(LMI)设计了H∞鲁棒最优控制器,并在MATLAB/Simulink中进行了仿真。结果表明:采用H∞鲁棒最优控制比传统的车速电流双闭环PI控制具有更好的鲁棒稳定性,且回馈的能量提高了2%~3%。     

基于新型滑模算法的永磁同步电机转速控制研究

针对永磁同步电机调速系统中PI控制器无法满足高精度控制要求的问题,提出了一种基于新型趋近律的滑模变结构控制方法。该趋近律在指数趋近律和幂次趋近律的基础上,加入了系统状态变量,有效地抑制滑模控制器在滑动阶段的抖振;等速趋近项与滑模面切换函数关联,保证其在s=0附近有效地稳定趋近,削弱抖振;指数趋近项与系统状态变量x1关联,提高趋近速度。采用李雅普诺夫函数对其进行稳定性分析。经过与PI速度控制器以及传统的滑模控制器进行仿真比较,分析了空载起动、突加负载和变速运动3种情况下的控制效果,结果表明:采用新型滑模控制器可实现快速稳定趋近,并具有稳定性高、抗负载扰动能力强的优点。     

基于电机二惯性特征的PID参数整定研究

基于永磁同步电机的二惯性特征对电机速度环PID控制参数的整定进行了研究,得到了固有频率为100 rad/s的系统在达到设定评价指标时的PID参数整定规律。为了简化过程,将多个变量归结为3个变量,分别是质量比x1、频率比x2和阻尼比x3,并给出了基于仿真数据点的拟合公式。最后通过MATLAB验证了拟合公式在缩短参数调节时间方面的有效性。     

永磁同步曳引机变频调速系统的内模控制

永磁同步曳引机是典型的非线性多变量强耦合系统,在同步旋转坐标系下dq轴电流存在耦合,传统的PI控制器无法实现解耦,提出一种基于内模控制原理和空间矢量算法相结合的高性能永磁同步曳引机解耦控制方法,用内模控制策略控制理想电机模型,对定子电流交叉耦合电势动态解耦,提高系统的动态响应性能,同时在整个电流闭环过程中对参数摄动和外扰动具有良好的鲁棒性,这种方法不需要额外的电机参数和检测硬件,试验结果验证了这种方法有效可行。     

航空发动机H∞PI输出反馈控制——非严格正则LMI方法

基于传递函数矩阵H∞范数的等价原则思想,将非严格正则模型转化为严格正则模型。通过LMI求解方法,在考虑控制能量约束的条件下,对严格正则模型进行静态输出反馈PI控制器设计。提出了一种非严格正则模型静态输出反馈PI控制器求解的算法。以某型双转子涡喷发动机为被控对象,进行静态输出反馈PI控制器的LMI设计,并分区域在飞行包线进行了动静态性能和鲁棒性能仿真验证。     

航空发动机多变量三层神经网络控制

提出了一种发动机多变量神经网络控制方法。采用三层前向神经网络对非线性项进行补偿,神经网络权重自适应律采用在线学习算法。控制系统的设计不需要知道精确模型,适应于全飞行包线。仿真研究表明发动机多变量神经网络控制具有良好的动、静态性能。      

电动舵机模糊自整定PID控制仿真研究

针对传统PID控制器参数不易整定的缺点,将模糊控制和PID控制结合在一起,构造了模糊自整定PID控制器,并将其应用于电动舵机伺服控制系统,仿真和实验结果表明:此方法稳态精度高,动静态性能好,提高了系统的控制性能,具有较好的控制效果。     

单磁极加长降低表贴式永磁电机齿槽转矩

针对表贴式永磁电机存在的齿槽转矩问题,提出运用单磁极加长的方法来降低电机齿槽转矩。运用解析法推导出电机单磁极加长后齿槽转矩解析表达式,通过傅里叶分析,得到对电机齿槽转矩具有重要影响的变量Br(vz)。引入磁极加长系数η,研究如何选取η的数值削弱齿槽转矩。通过有限元仿真验证了所提方法的有效性。结果表明:通过合理选取磁极加长系数,将与齿槽转矩关键谐波分量有关的Br(vz)削减为零可有效降低电机齿槽转矩。     

基于模型参考自适应参数辨识的永磁同步电机电流预测控制

在永磁同步电机运行过程中,电机参数时变使得电流预测控制器的模型参数和实际电机参数不匹配,导致其控制性能下降。提出了基于模型参考自适应系统(MRAS)的改进电流预测控制方法,利用旋转坐标系下d、q轴电流方程作为参考模型,基于Popov超稳定理论构建永磁同步电机的电感和磁链在线辨识系统,将得到的辨识参数应用于电流预测控制模型中,实现控制模型参数的在线更新。分析与仿真结果表明该方法能够有效地提升在电机参数变化下的电流预测控制性能。     

The effect of inlet conditions on the flow and heat transfer in multiple rotating cavity with axial throughflow

This paper discusses experimental results from two different build configurations of a heated multiple rotating cavity test rig.Measurements of heat transfer from the discs and tangential velocities are presented.The test rig is a 70% full scale version of a high pressure compressor stack of an axial gas turbine engine.Of particular interest are the internal cylindrical cavities formed by adjacent discs and the interaction of these with a central axial throughflow of cooling air.Tests were carried out for a range of non-dimensional parameters representative of high pressure compressor internal air system flows(Re up to 5×106 and Rez up to 2×105).Two different builds have been tested.The most significant difference between these two build configurations is the size of the annular gap between the(non-rotating) drive shaft and the bores of the discs.The heat transfer data were obtained from thermocouple measurements of surface temperature and a conduction solution method.The velocity measurements were made using a two component,LDA system.The heat transfer results from the discs show differences between the two builds.This is attributed to the wider annular gap allowing more of the throughflow to penetrate into the cavity.There are also significant differences between the radial distributions of tangential velocity in the two builds of the test rig.For the narrow annular gap,there is an increase of non-dimensional tangential velocity V/Ωr with radial location to solid body rotation V/Ωr=1.For the wider annular gap,the non-dimensional velocities show a decrease with radial location to solid body rotation.      

Research on Auto-detection for Remainder Particles of Aerospace Relay Based on Wavelet Analysis

Aerospace relay is one kind of electronic components which is used widely in national defense system and aerospace system. The existence of remainder particles induces the reliability declining, which has become a severe problem in the development of aerospace relay. Traditional particle impact noise detection (PIND) method for remainder detection is ineffective for small particles, due to its low precision and involvement of subjective factors. An auto-detection method for PIND output signals is proposed in this paper, which is based on direct wavelet de-noising (DWD), cross-correlation analysis (CCA) and homo-filtering (HF), the method enhances the affectiv-ity of PIND test about the small particles. In the end, some practical PIND output signals are analysed, and the validity of this new method is proved.     

Preparation of Highly Dispersed Antimony-doped Tin Oxide Nano-powder via Ion-exchange Hydrolysis of SnCl4 and SbCl3 and Azeotropic Drying

Antimony-doped tin hydroxide colloid precipitates have been synthesized by hydrolysis of SnCl4 and SbCl3 using: (1) an ion-exchange hydrolysis to remove chlorine ions, and (2) isoamyl acetate as an azeotropic solvent to obviate water. The obtained dried powder is of high dispersivity without any need for further grinding. The size and dispersivity of the final particles are investigated with the aid of TG-DTA, BET, XRD and TEM. After having calcined, the antimony-doped tin oxide nanopowder possesses a tetragonal rutile structure with high dispersivity, uniform particles and low hard agglomeration.     

Effects of Mo on the Microstructure and Hydrogen Sorption Properties of Ti-Mo Getters

The effects of Mo on the microstructure evolution, porosity and hydrogen sorption properties of Ti-Mo getters are investigated in this work. The results show that the addition of Mo prolongs the densification process of Ti-Mo getters and results in a significant amount of sintered pores. With the Mo content increasing, the porosity of getters firstly increases reaching the maximum value as it at- tains about 7.5wt.%, and then drops. At the room temperature, the hydrogen sorption property of getters increases progressively with the Mo content increasing, but the tendency is not very clear before its content lies below 2.5wt.%. When the Mo content achieves about 7.5wt.%, the hydrogen sorption property proves to be the best. The discussion is made about the above mentioned phenomena inclusive of hydrogen sorption properties of getters under different activation conditions (from 500-750 ℃).     

超声速燃烧数值模拟中的湍流与化学反应相互作用模型

高精度数值模拟有助于理解超声速湍流燃烧中湍流与化学反应的相互作用,可为发动机燃烧室等工程应用设计提供可靠的预测模型。除直接数值模拟外,目前在湍流燃烧应用中使用的大涡模拟和雷诺平均Navier-Stokes模拟均需要借助模型模化发生在湍流小尺度上的流动与化学反应过程对湍流大尺度运动的影响。现有的湍流与化学反应相互作用模型大致可分为:火焰面类模型和概率密度函数类模型,2类模型在不同的应用中各自具有优势和局限性。此外,现有模型大都基于低马赫数燃烧,而超声速燃烧中通常会伴随快速混合、局部熄火和再着火以及激波等复杂过程,这为发展其中的湍流与化学反应相互作用模型提出了更多的挑战。     

适于低轨卫星IP网络的单核共享树组播算法(英文)

为了解决低轨卫星IP网络中现有典型源组播算法的信道资源浪费问题,本文提出了一套单核共享树组播算法,即核心群合并共享树(CCST)和加权核心群合并共享树(w-CCST)算法。CCST 算法包括动态近似中心(DAC)选核方法和核心群合并组播路径构建方法。DAC方法专为周期、规律运动的低轨卫星网络提出,不需要复杂的星上计算。在核心群合并方法中,以核节点作为初始核心群,通过核心群和剩余组成员的最短路径方法逐步扩展直至整棵组播树构建完成,从而使得组播树的树代价最小,大大提高了网络的带宽利用率和组播传输效率。w-CCST 算法中所提出的加权因子可以调整树代价和端到端传播时延之间的折衷程度,因此,可以通过调整加权因子来适度增大树代价、降低端到端传播时延以支持某些端到端时延要求苛刻的实时组播业务。最后,与低轨卫星 IP 网络中典型算法进行了性能比较,仿真结果说明,CCST 算法的平均树代价比其它算法显著降低,w-CCST 算法的平均端到端传播时延小于 CCST 算法。     

Jet Vectoring Control Using a Novel Synthetic Jet Actuator

A primary air jet vectoring control system with a novel synthetic jet actuator (SJA) is presented and simulated numerically. The results show that, in comparison with an existing traditional synthetic jet actuator, which is able to perform the duty of either “push” or “pull”, one novel synthetic jet actuator can fulfill both “push” and “pull” functions to vector the primary jet by shifting a slide block inside it. Therefore, because the new actuator possesses greater efficiency, it has potentiality to replace the existing one in various appli- cations, such as thrust vectoring and the reduction of thermal signature. Moreover, as the novel actuator can fulfill those functions that the existing one can not, it may well be expected to popularize it into more flow control systems.     

Nonlinear Adaptive Slewing Motion Control of Spacecraft Truss Driven by Synchronous V-gimbaled CMG Precession

The slewing motion control of a truss arm driven by a V-gimbaled control-moment-gyro (CMG) is a nonlinear control problem. The V-gimbaled CMG consists of a pair of gyros that must precess synchronously. The moment of inertia of the system, the angular momentum of the gyros and the external disturbances are not exactly known. With the help of feedback linearization and recursive Lyapunov design method, an adaptive nonlinear controller is designed to deal with the unknown items. Performance of the proposed controller is verified by simulation.     

An SOR Implicit Time-accurate Scheme in Calculating Unsteady Flows

A new time-accurate marching scheme for unsteady flow calculations is proposed in the present work. This method is the combination of classical Successive Over-Relaxation (SOR) iteration method and Jacobian matrix diagonally dominant splitting method of LUSGS. One advantage of this algorithm is the second-order accuracy because of no factorization error. Another advantage is the low computational cost because the Jacobian matrices and fluxes are only calculated once in each physical time step. And, the SOR algorithm has better convergence property than Gauss-Seidel. To investigate its accuracy and convergency, several unsteady flow computa- tional tests are carried out by using the proposed SOR algorithm. Roe’s FDS scheme is used to discritize the inviscid flux terms. Un- steady computational results of SOR are compared with the experiment results and those of Gauss-Seidel. Results reveal that the numerical results agree well with the experimental data and the second-order accuracy can be obtained as the Gauss-Seidel for unsteady flow computations. The impact of SOR factor is investigated for unsteady computations by using different SOR factors in this algorithm to simulate each computational test. Different numbers of inner iterations are needed to converge to the same criterion for different SOR factors and optimal choice of SOR factor can improve the computational efficiency greatly.