Calculation of torque and speed of induction machines under rotor winding faults

Based on the multi-loop method, the rotating torque and speed of theinduction machine are analyzed. The fluctuating components of the torque and speed caused by rotorwinding faults are studied. The models for calculating the fluctuating components are put forward.Simulation and computation results show that the rotor winding faults will cause electromagnetictorque and rotating speed to fluctuate; and fluctuating frequencies are the same and their magnitudewill increase with the rise of the severity of the faults. The load inertia affects the torque andspeed fluctuation, with the increase of inertia, the fluctuation of the torque will rise, while thecorresponding speed fluctuation will obviously decline.

An Observing Method for Flux and Speed with Direct Torque Control

An observing method for stator flux and rotor flux is presented. Based on the proposed flux observing method, a novel speed estimator has been designed. At last, the speed estimator combined with the flux observing is applied in the direct torque control system without speed sensor. The simulation results show that these methods can improve the accuracy of speed observing and the low speed performance of direct torque control system, and strengthen the robustness of system.

Calculating Methods of Inertia Moment of TurboGenerator Rotor Using Load Rejection Test

Calculated results of inertia moment of turbo-generator rotor can be quite different by methods used in load rejection tests. In view of fluctuation features of rotor speed rise curve during load rejection tests, the measurement principle of rotor inertia moment was expounded. Based on the measured data in load rejection tests for an imported type of domestic 300-MW generating unit, the rotor speed rise curve was fitted with three kinds of functions to get initial runup rate, but the obtained results differed a lot from each other. According to analysis on the mechanism of rotor speed rise, m=2 consecutive points averaging or FFT (Fast Fourier Transform) smoothing technology was introduced to process test data, and then the initial runup rate was determined by the method of linear fitting of rotor speed in the range of governing valve closing time. Although the obtained curves had a fluctuating shape, the results of rotor inertia moment for 50% and 100% load rejection tests were of good consistency.

高速磁悬浮电机三段式转子动力学分析研究

为解决高速磁悬浮电机三段式转子的动力学分析问题,基于Workbench有限元仿真平台完成了三段式转子建模、模态振型计算、坎贝尔图求解、不平衡响应分析。总结讨论了关键因素对三段式转子的动力学特性的影响规律,并通过模态试验对转子建模的合理性进行了验证。仿真结果与实验结果误差在5%,证明了建模及分析方法的可靠性,为应用在高速磁悬浮电机上同类转子的进一步优化设计和不平衡响应抑制提供理论参考。

微转速差双转子系统对自动液力变速器车型怠速抽动的影响研究

为分析液力变矩器与曲轴组成的微转速差双转子系统对自动液力变速器(AT)车型怠速抽动的影响,通过对双转子系统动不平衡耦合激励力进行希尔伯特变换(Hilbert Transform),揭示出部件拍振是导致有规律怠速抽动的根本原因,其抽动激励幅值最大值为激励力之和,抽动间隔频率为激励力频率之差。建立包括发动机、变速器、悬置等系统的机械系统动力学自动分析(ADAMS)模型并进行仿真,结果表明,动力总成垂向刚体模态频率与激励频率越接近,液压悬置垂向一阶动刚度越大,振动幅值越大。因此,可通过动力总成Z向模态频率与曲轴动不平衡激励频率间的避频设计、降低液压悬置垂向动刚度、提高悬置系统的隔振性能等方式改善怠速抽动。

机舱式激光雷达应用下风机功率测试研究

在风机周围的环境中存在其他风源、建筑物、地形影响因素,导致准确采集风机风速和风向难度较高,使得风机功率测试结果不准确。为此,该文提出一种机舱式激光雷达应用下风机功率测试方法。利用机舱式激光雷达技术测量风速、风向;采用零均值化方式与滤波器预处理功率信号、计算转矩,并借助频谱分析算法计算同频信号的扭转角;根据磁阻传感器输出的交流电流信号计算风机相位差,最终得出风机功率,完成风机功率测试。实验结果表明,所提方法满足风机测试精度等级要求,且测试精度高,8台风机只用18 ms内即可完成功率测试。

A novel control method for turboshaft engine with variable rotor speed based on the Ngdot estimator through LQG/LTR and rotor predicted torque feedforward

In order to compensate for the disturbance of wide variation in rotor demanded torque on power turbine speed and realize the fast response control of turboshaft engine during variable rotor speed,a cascade PID control method based on the acceleration estimator of gas turbine speed(Ngdot)and rotor predicted torque feedforward is proposed.Firstly,a two-speed Dual Clutch Transmission(DCT)model is applied in the integrated rotor/turboshaft engine system to achieve variable rotor speed.Then,an online estimation method of Ngdot based on the Linear Quadratic Gaussian with Loop Transfer Recovery(LQG/LTR)is proposed for power turbine speed cascade control.Finally,according to the cascade PID controller based on Ngdot estimator,a rotor demanded torque predicted method based on the Min-batch Gradient Descent-Neural Network(MGD-NN)is put forward to compromise the influence of rotor torque interference.The simulation results show that compared with cascade PID controller based on Ngdot estimator and the one combined with collective pitch feedforward control,the novel control method proposed can reduce the overshoot of power turbine speed by more than 20%,which possesses faster response,superior dynamic effect and satisfactory robustness performance.The control method proposed can realize the fast response control of turboshaft engine with variable rotor speed better.

Aerodynamic characteristics of rigid coaxial rotor by wind tunnel test and numerical calculation

Focusing on aerodynamic characteristics of rigid coaxial rotor of a high-speed helicopter in hover and forward flight, a wind tunnel test is conducted in the 8 m ? 6 m low-speed straightflow wind tunnel of China Aerodynamics Research and Development Center. In the experiment,a 4 m diameter composite model rigid coaxial rotor is designed and manufactured, and firstorder flapping frequency ratio of the blade is 1.796 to ensure sufficient stiffness at the blade root.Rotor aerodynamic performance is measured under hovering and high advance ratio conditions.Also, the numerical method is used to calculate aerodynamic characteristics in typical states of the rigid coaxial rotor for analysis purpose. The rotor lift-drag ratio and lateral lift offset in the experiment are emphatically analyzed for the rigid coaxial rotor. The results indicate that in forward flight condition, the rotor lift-drag ratio first increases and then decreases with the increment of advance ratio and lift offset. When advance ratio remains constant, with the increment of lift offset, the lift-drag ratio of rigid coaxial rotor first increases and then decreases.

双馈感应电机无速度传感器直接转矩控制方法

风电机组双馈感应发电机运行中,由于参数变化的不确定性导致其无速度传感器直接转矩控制输出值出现异常波动,为保证双馈感应电机的频率稳定性,提出一种双馈感应电机无速度传感器直接转矩控制方法。计算转子磁链同步转速和转差速度,得到发电机的转速观测值;分析转子绕组电压空间矢量,建立磁链模型并构建电磁矩阵,在矩阵中计算定子绕组和转子绕组的磁势矢量,通过二者的矢量积得到电机的电磁转矩;转速和转矩共同组成直接转矩控制系统,实现对电机的速度调节和控制。仿真分析结果表明:采用所提方法时,在双馈感应电机启动后转速迅速增加,且在1.2 s后转速始终保持为1400 r/min,可保证转子磁链的运行轨迹接近于圆形,直接转矩控制效果平稳。

曲轴摆缸式阀配流水液压马达工作特性研究

为解决盘配流和轴配流低速大扭矩水液压马达配流副存在的磨损和泄漏问题,提出一种新型阀配流结构的低速大扭矩水液压马达,柱塞配流通过配流凸轮控制配流阀的通断实现。研究柱塞运动学规律和马达输出扭矩形成,揭示配流阀推杆位移、阀芯通断、柱塞进回液间的对应关系,分析马达角排量波动随转角、结构设计参数K的变化规律,当结构设计参数K为0.13时,马达输出扭矩波动率为6.59%。在AMESim中建立了配流阀及单柱塞配流过程的仿真模型,分析配流阀的工作特性及单柱塞动态配流性能,工作中配流阀产生最大压降为0.08 MPa,进/回液配流阀无高低压串液。为验证阀配流结构在水液压马达中的工作性能,建立阀配流单柱塞试验台,并研究不同工况下的配流工作特性。试验结果表明,配流阀在马达转速0~60 r/min、压力0~21 MPa的工况下稳定配流,进液阀口压力在柱塞腔进回液转换时存在瞬间小幅压力波动,但对配流过程基本无影响,阀配流结构能够满足曲轴摆缸式马达柱塞的配流需求,为低速大扭矩水液压马达的配流提供了思路。

永磁/磁阻混合转子双定子低速大转矩同步电机冷却及热管理技术研究

低速大转矩同步电机(LSHTSM)在诸多领域有着广泛应用,针对现有低速大转矩永磁电机内部空间未得到充分利用,转矩密度较低且永磁体成本高、易发生高温退磁等问题,研究了一种永磁/磁阻混合转子双定子低速大转矩同步电机。首先,介绍了电机的拓扑结构及机械结构,针对电机结构复杂、温度难以快速准确计算问题,建立了电机精确热网络温度计算模型,详细推导了电机各特殊结构件之间的热阻数学模型,解析计算了电机各部件稳态温度,总结了电机温度分布特点。其次,针对电机结构特殊、散热困难问题,设计了一种双水冷方式的冷却系统,研究分析了冷却系统结构参数对电机冷却效果的影响,总结了特殊结构电机冷却系统设计原则。最后,分别采用有限元仿真与实验方法验证了所建立热网络温度计算模型的准确性以及冷却系统的有效性。

电磁式平衡头动环自锁特性分析与实验研究

针对电磁式平衡头动环结构整体设计过程中存在的自锁磁场与自锁力矩问题,对电磁式平衡头动环自锁特性进行了有限元仿真分析与实验研究。首先,根据磁路自锁原理,建立了由磁性齿盘、永磁体、配重盘3个零件构成的三维模型;然后,利用Ansoft-Maxwell平台,通过控制单一变量的方式,分析了永磁体对数对气隙磁密和自锁力矩大小的影响,研究了气隙对自锁力矩的影响;最后,基于扭矩传感器及LabVIEW软、硬件搭建了实验平台,通过增减垫片数量的方式,进行了自锁力矩气隙实验。研究结果表明:永磁体对数从8对增加到18对时,有效工作区最小磁通密度增加了103%;有限元分析结果与实验结果的差值在15%以内,且实验数值与有限元分析数值整体趋势一致,自锁力矩随气隙的增大逐渐减小;该实验结果证实了仿真结果的可靠性,为电磁平衡装置的整体分析与优化提供了依据。

轴段可调节式双转子结构动力特性模拟试验台设计与优化

为了解航空发动机双转子的动力学特性,搭建了轴段可调节式双转子结构动力特性模拟试验台,其主要包括高速电机、低压转子、高压转子、模拟盘、支架、齿轮箱、基座等。采用有限元法和变换哈默斯利算法相结合的联合仿真方法,对试验台进行了临界转速的计算及优化;计算了双转子系统的稳态不平衡响应,分析了临界转速变化对转子系统振动特性的影响。结果表明:优化后试验台前4阶临界转速与原型机实测临界转速的误差在5%以内,试验台能较好的模拟原型机动力学特性;优化后各轴承处最大响应幅值中的最大值明显减小,试验台具有良好的振动特性。

气隙固定磁通可调型永磁调速器极槽配合分析

为了提升永磁调速器的输出转矩,并简化其调速过程中所需机械操动机构,将开槽导体转子结构和机械调磁方法相结合,提出了一种气隙固定磁通可调型永磁调速器.首先,分析新型永磁调速器的结构特征和运行原理;然后,基于理论模型和有限元法分析影响其基本电磁特性的关键因素,重点研究永磁极数与导体转子槽数之间的配合问题,并获取多种极槽配合情况下输出转矩滑差特性以及转矩脉动情况;最后,以输出转矩最大、转矩脉动最小为目标,获取最优极槽配合方案,并制造原理样机,得到其调速特性、功率、损耗和效率.结果表明:每对极导体转子槽数为奇数时,转矩脉动小;每对极导体转子槽数为偶数时,转矩脉动较大,并且随着每对极导体转子槽数的增加,转矩脉动降低.

无人机系统飞行性能测试及分析系统研究与实现

无人机系统飞行性能是影响产品飞行安全和作业质量的关键,GB/T 38058—2019《民用多旋翼无人机系统试验方法》及行业标准中,已规定平飞/爬升速度、高度/速度保持、定点悬停、航迹精度等飞行性能项目的测试及分析方法。基于现有标准对比分析,文中提出一种地面测试基站获取高精度基准点后与机载测试设备组合解算,测量无人机飞行绝对坐标、姿态角等参量的软硬件实现方法,并将飞行数据的截取、计算、分析、报告等环节嵌入整个测试流程,设计一种可用于旋翼和固定翼无人机系统飞行性能测试及分析的系统。经过实际测试应用,所设计系统满足GB/T 38058—2019标准和行业标准的试验要求,可有效提升飞行性能测试及结果评价的准确性、时效性,缩短测试周期,降低测试成本。

基于无位置传感器BLDCM的新能源汽车电子水泵智能控制系统

传统系统发送和接收水泵控制指令和工况信号时,受通信接口干扰信号影响,使得水泵动态响应调节时间较长,超调量较大。提出基于无位置传感器BLDCM的新能源汽车电子水泵智能控制系统。硬件方面,由无位置传感器BLDCM电机、控制器、对外接口,组成系统框架,利用电解电容,吸收通信接口外部干扰信号,利用控制器防护电路和滤波电路,抑制接口内部干扰信号,发送并接收电机工况信号和水泵控制指令;软件方面,采用矢量控制方式,根据BLDCM电机电压和转矩方程,确定电机运行控制量为转子角速度,比例积分调节转子角速度,改变电机转矩,间接控制水泵转矩和角速度。搭建系统测试平台,实验室内进行水泵冷却水加压循环,设置600、800、1 000 r/min电子水泵转速工况。实验结果表明,设计系统相比常规系统,缩短了水泵到达给定转速的调节时间,减小了超调量,改善了水泵动态加速性能。

空间展开臂关节真空−热−力耦合试验方法研究

针对空间展开臂关节热真空环境下展收性能验证的需求,提出一种适用于展开臂关节的真空−热−力耦合的试验方法,即通过热真空试验系统完成真空、冷黑和太阳辐射环境的模拟,通过外部定量惯量盘施加负载。对该方法开展试验验证的结果表明:试验过程中罐体真空度、温度及控温精度均满足试验要求;高低温环境下展开臂关节工作电流呈随机状波动,波动范围均处于设计安全范围内;试验前后展开臂关节启动力矩、关节最高转速以及指向精度无明显变化,且精度优于0.001°。该方法可为后续展开臂关节真空−热−力耦合试验提供技术保障。

Investigation of pressure wave behaviors in the rotational speed effects on a pressure-exchange wave rotor

A wave rotor is suitable for compact and efficient pressure-exchange between gas flows.This work measured the circumferential pressure distribution of the rotor/stator interfaces and utilized a CFD method to simulate the unsteady pressure waves.The experimental and CFD results showed some slopes in the circumferential pressure distributions,and the slopes indicated the traces of specific unsteady pressure waves.Such traces varied regularly if the rotational speed varied within a range from-11%to+11%off the baseline value,but they were seriously disturbed if the rotational speed varied by-45%from the baseline value.It verified that a pressure wave in a wave rotor tended to keep its pressure ratio and propagation velocity unchanged if the rotational speed varied by a small extent,and that the pressure wave could not keep its propagation patterns if the rotational speed varied by a large extent.Because of the pressure wave behaviors,the wave rotor demonstrated specific regulations of the rotational speed effects on its operational states.

充电式电钻静态堵转力矩测量分析与探讨

《手持式、可移式电动工具和园林工具的安全第2部分:电钻和冲击电钻的专用要求》是电动工具制造商参照并执行的国家推荐性安全标准之一。随着电动工具产品技术的不断更新,充电式电动工具占有的市场份额越来越多,对于充电式电钻的静态堵转力矩,尤其在力臂的界定等环节,业界的理解各不相同。通过对比三种实际应用方案,提出更有针对性的选择及参考依据。

高速转子试验支座振动优化设计与验证

针对燃气发生器转子在动力特性试验过程中出现的转接支座振动加速度过大现象,开展原因分析和转接支座振动优化研究。采用有限元法建立了支座模态计算模型,得到前5阶模态振型和频率,确定支座在转子工作转速范围内存在多阶有害共振频率是振动过大的主要原因;设计了3种结构的试验支座并进行了对比分析,对优选支座分别进行了不带燃气发生器转子和带燃气发生器转子的试验验证。结果表明,优选支座在转子工作转速范围内不存在有害共振频率,高转速下的振动加速度大幅降低;研究成果为航空发动机转子动力学试验提供了保障,可推广至其他转子试验支座设计。