Fiber Migration and Distribution of Twist at Different Radial Positions of Rotor Yarn-by Hi-Scope Video Microscope System

This paper describes systematic measurement of fiber migration and distribution pattern of twist at different radial positions of rotor spun yarn mixed tracer fiber by Hi-Scope Video Microscope System. The positions of tracer fibers were measured in three dimensions accurately, and the migration index and the twist distribution at different radial positions of rotor yarn were calculated and analyzed. This research result serves to provide useful references for further study on the structural mechanics of rotor spun yarn.

Improved estimation of rotor position for sensorless control of a PMSM based on a sliding mode observer

This work proposes a new strategy to improve the rotor position estimation of a permanent magnet synchronous motor(PMSM) over wide speed range. Rotor position estimation of a PMSM is performed by using sliding mode observer(SMO). An adaptive observer gain was designed based on Lyapunov function and applied to solve the chattering problem caused by the discontinuous function of the SMO in the wide speed range. The cascade low-pass filter(LPF) with variable cut-off frequency was proposed to reduce the chattering problem and to attenuate the filtering capability of the SMO. In addition, the phase shift caused by the filter was counterbalanced by applying the variable phase delay compensation for the whole speed area. High accuracy estimation result of the rotor position was obtained in the experiment by applying the proposed estimation strategy.

Initial Rotor Position Detection of 12/10 Flux-switching Permanent Magnet Motors

电机转子初始位置检测的精度直接决定其启动运行时的性能。针对12/10极永磁磁通切换型电机,在验证其凸极性的基础上,采用注入脉振高频信号实现转子初始位置估计。通过对传统高频脉振正弦电压信号注入的分析,研究了基于高频方波或三角波的注入方法,再利用电流差值调制或直接信号调制方法得到位置误差信号,同时根据磁路的饱和效应,通过对d轴电流过零点时间差值的累加,实现了磁极方向辨识。分析了位置误差信号的系数与初始位置检测收敛性的关系。通过实验验证了所提方法的正确性和可行性。

Optimization Method of Bearing Support Positions in a High-Speed Flexible Rotor System

Bearing support position is one of main factors affecting vibration characteristics of rotor systems. To optimize the bearing support positions in a high-speed flexible rotor system (HSFRS) based on the vibration characteristics, an optimization method of bearing support positions in the HSFRS is proposed. In this method, a finite element (FE) model of a high-speed flexible rotor (HSFR) was established. The natural frequencies and mode shapes of the HSFRS were used to obtain the initial design scheme of the bearing support positions. A frequency characteristic equation of the HSFRS was established to obtain the critical speeds of the HSFRS. And a dynamic model of the HSFRS was established to analyze the vibration characteristics for different bearing support position cases. The problem of optimizing bearing support positions in the HSFRS was solved by the developed method. The results showed that vibration amplitudes of the HSFRS were more stable when the bearing support positions were optimized. This study can provide a new method for optimizing bearing support positions of rotor systems.

Robust Position Observer for Sensorless Direct Voltage Control of Stand-Alone Ship Shaft Brushless Doubly-Fed Induction Generators

The aim of this paper is to investigate an adaptive sensorless direct voltage control(DVC)strategy for the stand-alone ship shaft brushless doubly-fed induction generators(BDFIGs).The proposed new rotor position observer using the space vector flux relations of BDFIG may achieve the desired voltage control of the power winding(PW)in terms of magnitude and frequency,without any speed/position sensors.The proposed algorithm does not require any additional observers for obtaining the generator speed.The proposed technique can directly achieve the desired DVC based on the estimated rotor position,which may reduce the overall system cost.The stability analysis of the proposed observer is investigated and confirmed with the concept of quadratic Lyapunov function and using the multi-model representation.In addition,the sensitivity analysis of the presented method is confirmed under different issues of parameter uncertainties.Comprehensive results from both simulation and experiments are realized with a prototype wound-rotor BDFIG,which demonstrate the capability and efficacy of the proposed sensorless DVC strategy with good transient behavior under different operating conditions.Furthermore,the analysis confirms the robustness of the proposed observer via the machine parameter changes.

Research on a combinatorial control method for coaxial rotor aircraft based on sliding mode

Aiming at the position and attitude tracking of coaxial rotor aircraft(CRA),this paper proposes a combinatorial control method of sliding mode control(SMC)coupled with proportional-integralderivative control(PIDC).Considering the complete description of flight dynamics,aerodynamics and airflow interference,the dynamical model of CRA is established.The dynamical model is simplified according to the actual flight,then the simplified dynamical model is divided into two subsystems:a fully-actuated subsystem and an under-actuated subsystem.The controller of the fully-actuated subsystem consists of a SMC controller coupled with a rate bounded PIDC controller,while the controller of the under-actuated subsystem is composed of a SMC controller.The sliding manifold is defined by combining the position and velocity tracking errors of the state variables for each subsystem.Lyapunov stability theory is used to verify the stability of the sliding mode controller,which ensures that all state trajectories of the system can reach and stay on the sliding mode surface,the uncertainty and external interference of the model are compensated.Simulation and experiment compared with the conventional PIDC are carried out,the results demonstrate the effectiveness and the robustness of the proposed control method of this paper.

Sizing and performance features of rotary and reciprocating positive displacement pumps

An overview of some popular rotary and reciprocating positive displacement( PD) pump types is given with the objective of presenting and comparing the respective sizing relationships and performance features. Reciprocating pumps discussed are the piston and plunger types. Rotary pumps addressed are gear( external and internal),vane,lobe,screw,and liquid ring pumps. To put the relative pump sizes in perspective,attention is fixed on the rotors or reciprocating elements of PD pumps,just as impellers indicate the sizes of rotodynamic pumps. The size of a PD pump is found from a dimensionless combination of displacement flow rate,rotative speed and diameter. The flow rate,head( or pressure rise) and power are related through the component efficiencies. The cavitation coefficient,often close to unity,connects the rotor tip speed or piston speed with the required NPSH,which can also be affected by the pressure rise of the pump due to leakage across the internal clearances. Operational effects due to cavitation,ingestion of gas or abrasives,and viscous and non-Newtonian fluids are discussed.

一种自适应扩展卡尔曼滤波的永磁同步电机无位置传感器矢量控制

在粗差干扰或噪声统计偏差情况下,扩展卡尔曼滤波(EKF)对永磁同步电机(PMSM)的速度和转子位置估计存在精度下降问题,为此提出一种基于新息序列的自适应扩展卡尔曼滤波算法(AEKF)。首先,将粗差干扰加入系统观测方程中,分析粗差干扰对系统观测精度的影响。其次,为增强算法的抗扰性能,在新息协方差计算中设置加权系数,通过调整临近时刻的新息协方差阵权重,计算出新息协方差值,并更新到卡尔曼增益的计算。最后,建立AEKF数学模型,并对比粗差干扰与噪声统计出现偏差情况下,AEKF与EKF两种策略的观测性能。仿真和实验结果表明,在粗差干扰或噪声统计信息出现偏差情况下,AEKF算法对永磁同步电机转速的观测具备更强的鲁棒性及更高的预测精度。

用于边境巡逻的定点式多旋翼无人机无线充电系统设计

为了解决目前边境巡逻多旋翼无人机续航能力不足、巡航范围受限的问题,研究了一种应用于沿边境巡逻,具有辅助对准功能的无人机无线充电方案,为无人机执行远距离边境巡逻任务提供保障。设计了中继电能补给站供电和辅助降偏矫正系统,无人机降落后自动对准,开启供电系统实施充电;设计了无人机机载电能接收及充电系统,对发射电能实施有效接收,并转换为可控的恒流及恒压能量流输送至机载电池;搭建了微缩化实验样机,测试结果表明辅助对准系统可实现无人机精确对准,无线充电系统实现了71.3 W能量传输,对应整机充电效率84.6%,机载的电能接收机构仅重28 g。

永磁同步电机无位置传感器控制技术综述

无位置传感器电机驱动器具有成本低、可靠性高、硬件电路简单以及维护要求少等优势,在学术界和工业应用中受到了越来越多的关注。对适用于零低速域、中高速域以及全速域三种运行范围的多种无位置传感器技术进行了综述。首先,分别对比分析了零低速域和中高速域下各种无位置传感器控制方法的优缺点。其次,梳理和总结了目前全速域运行的切换控制策略。最后,对永磁同步电机无位置控制技术的未来发展趋势进行了展望,并指出了后续研究的关键问题。

基于励磁机定子直轴电流定点采样的航空多级式起动/发电机低速段转子位置估算方法

航空多级式起动/发电机起动时,需要准确的主电机转子位置,而位置传感器受体积、重量等制约,需要开展转子位置估算研究。该文基于多级式电机结构特征,通过分析转子位置在主励磁机定子电流中的表征,提出一种基于两相励磁机定子直轴电流定点采样的低速段转子位置估算方法。该方法在起动时分三步实施:首先,实时采集主励磁机定子两相电流,并变换到定子磁场同步旋转dq坐标系;其次,对直轴电流定点采样,提取包含转子位置信息的正余弦信号,通过锁相环获得主励磁机转子位置增量;然后,结合主电机与主励磁机同轴安装特征及主电机初始位置,获取主电机实时转子位置,并实现低速段无位置传感器起动。该方法无需高频信号注入和滤波器,不依赖主电机凸极性且锁相环鲁棒性强。最后,实验验证了所提方法的有效性和较高的估算精度。

基于LESO的PMSM转子位置估算误差补偿方法

高速永磁同步电机运行中,转子位置精确与否确定了系统运行性能优劣,对于只补偿一拍滞后和零阶保持器引起的角度误差,以及通过与前馈解耦做差获得误差角进行补偿的方法,在精度和动态性等方面性能欠佳。为此,通过分析转子位置估算误差产生原因,推导出误差角的通用型数学模型,提出一种基于线性扩张状态观测器(LESO)的转子位置估算误差补偿方法。基于推导模型设计出一种可提取转子位置误差角的LESO,并采用获得的转子位置误差角进行补偿。此转子位置误差角估算考虑了不同类型非理想因素的影响,以及动态过程中电感电压项对误差角的影响,精度高、动态性好。最后搭建系统实验平台,实验结果表明所提转子位置估算误差补偿方法在精度和动态性方面具有优势。

基于励磁电压方波调制的三级式同步起动/发电机转子初始位置估算方法

现有基于高频注入的三级式同步起动/发电机转子初始位置估算方法由于高频衰减,面临失效风险。该文基于主电机定转子互感,提出一种“基于励磁电压方波调制的三级式同步起动/发电机转子初始位置估算方法”,将励磁电压作为载波,用低频方波对其进行调制后,提取主电机定子侧低频响应电流用于转子初始位置估算。定子逆变器三相下管导通状态下,该方法分为2步:首先对励磁电压进行低频方波调制,采集主电机定子低频感应电流用于转子初始位置预估算;其次,由预估算初始位置,判断励磁电压断电前后相关电流特征,得到包含磁极信息的最终初始位置。所提方法通过虚拟角度变换和方差对采集低频电流进行处理。实验表明所提方法具有较高估算精度。

开关磁阻电机无位置传感器控制策略研究

针对开关磁阻电机无位置传感器下的转子位置还原,提出一种基于电流上升时间监测的无位置传感器控制策略,该策略包含初始位置检测、电机启动运行、转子位置重构和调速控制几个部分。首先离线测得电机在特殊位置时滞环带宽内的电流上升时间,作为初始阈值用于电机启动;接着分别对各相绕组注入小电流,比较各相电流在滞环带宽内的上升时间进行初始位置分区;然后将转子从电感下降区进入电感最小区起始点作为特征点,利用初始阈值启动电机并在电机运行过程中依据实时工况更新特征点处时间阈值作为下一周期的检测特征;最后通过检测特征点位置信号对转子进行位置重构和转速估算实现换相与调速。仿真与实验结果验证了所提出控制策略的有效性与准确性。

Effect of bristle pack position on the rotordynamic characteristics of brush-labyrinth seals at various operating conditions

Over the last few decades,the research on the effect of bristle pack position on the rotordynamic characteristics of the brush-labyrinth seals is not sufficient.To this end,two kinds of brush-labyrinth seals for the bristle pack element installed upstream of the labyrinth teeth named BSU and installed downstream of the labyrinth teeth called BSD were used to investigate the effect of bristle pack position on the rotordynamic characteristics of the brush-labyrinth seals.Using the numerical model combining the porous medium model and the whirling rotor method,the rotordynamic characteristics of the BSU and BSD at various operating conditions including four kinds of pressure ratios,five kinds of inlet preswirl speeds and four kinds of rotor spinning speeds were conducted.The obtained results show that the effects of operating conditions on rotordynamic coefficients for the different seal configurations are different.The direct stiffness,cross-coupled stiffness and direct damping of the BSU are lower than those of the BSD.The rotordynamic coefficients of the BSU are more insensitive to the operating conditions variation.From the perspective of the seal stability,the BSU is a better brush-labyrinth seal configuration at high pressure ratio,high positive preswirl or high rotor spinning speed conditions.While in the case of low pressure ratio,low positive preswirl or low rotor spinning speed conditions,the BSD is a better choice.

基于非线性建模与拟合的永磁同步电机转子初始位置精确估计方法

针对永磁同步电机转子初始位置估计的精度与收敛速度受限问题,提出一种基于高频信号注入的非线性建模与拟合实现的初始位置估计方法。首先,建立初始位置与高频信号响应的关联模型,表明高频响应可用于直接计算初始位置,但直接计算结果在大部分转子位置易受测量噪声的影响。为此,提出基于多项式模型建立位置估计非线性模型,选取合适的模型参数,利用少量测试点拟合该模型,即可实现初始位置的快速精确估计,有效提高了估计精度与系统抗干扰能力。实验与仿真结果表明,相比现有方法,提出的方法易于实现,无需复杂滤波器与观测器设计,仅需要选取少量测试点即可快速估计精确转子初始位置,在保证估计精度的同时改进了传统估计方法收敛速度慢问题。

抽水蓄能电机转子匝间短路无传感器检测方法

定位筋作为抽水蓄能电机的固有部件,其感应电动势可有效反映转子绕组匝间绝缘健康水平。首先,通过引入衰减系数法推导了杂散磁通与气隙主磁通之间的关系,进而获取了定位筋感应电动势在匝间短路状态下的特征谐波,据此提出了谐波幅值比阈值检测法;其次,根据抽水蓄能电站服役机组运行参数搭建了二维电磁仿真模型,分析了匝间短路故障前后定位筋感应电动势时/频域特征的演变规律,并验证了谐波幅值比阈值检测法的有效性;最后,结合信号调理装置对动模实验机组不同匝间短路程度下的定位筋感应电动势信息进行采集。监测结果表明,故障磁极所对应的定位筋感应电动势时域特征幅值及基频幅值均呈衰减趋势,其频谱分数次谐波幅值呈递增趋势,进一步计算多个周期信号的谐波幅值比,据此构建统计箱线图并设定故障检测阈值,可有效为转子绕组匝间绝缘故障防御提供指导。

基于转子极性判断优化的脉振高频电压注入法

在永磁同步电机零速和低速运行时,采用脉振高频注入法能够准确估计转子位置信息。针对脉振高频注入法无法实现转子极性判断,而传统极性判断方法存在响应时间长、采样和实施过程复杂以及极性误判等问题。文中提出了一种基于正负电压脉冲注入的电机转子极性判断方法。该方法给电机注入正负电压脉冲,并根据对应脉冲的响应电流峰值判断转子极性。脉振高频注入法将转子位置估计值和极性判断结果相结合,可得到准确的转子初始位置。文中通过Simulink仿真验证算法的有效性。仿真结果表明,所提转子极性判断方法能够简化采样方式和算法复杂性,降低判断转子极性的响应时间,使脉振高频注入法能够准确和快速地估计转子初始位置。

基于FFT的高频信号注入法在永磁同步电机中的应用

为解决静止和低速问题,许多学者提出了高频注入的方案,通过注入一个已知的高频信号,再提取电流响应中的高频成分,得到关于转子角度信息的变量,再从中求解转子位置。传统的高频注入存在磁极难以识别的问题。为此,提出一种基于快速傅里叶变换(FFT)的信号提取方法,通过傅里叶变化即可求出转子位置信息,省去大量滤波器的使用。

基于多旋翼无人机视觉惯性里程计的设计与实现

针对GNSS信号受到干扰或在拒止环境下,多旋翼无人机的导航定位问题,设计一种多旋翼无人机视觉惯性里程计系统。介绍系统的总体设计方案、硬件选型与设计、软件系统搭建、通信协议规定以及算法设计思路。实验验证结果表明:该系统可以实际运行在多旋翼无人机上,当GNSS信号不可用时,仍可向飞控实时提供多旋翼无人机当前可用位姿,为多旋翼无人机视觉辅助导航设计提供参考。