Dynamic electromagnetic torque model and parameter estimation for a deep-bar induction machine

A dynamic analytical electromagnetic torque model for a deep-bar induction machine is presented. The model is based on the space-vector theory of electrical machines. The parameters are estimated using the data provided by the numerical impulse response test performed within the two-dimensional time-stepping finite element analysis. Two different impulse tests are studied. The impulse excitation is applied to the stator voltage and rotor position angle, and the parameter estimates are compared. The applicability of the impulse test is based on the assumption of linear behaviour in the neighbourhood of an operation point. Hence, one of the main objectives is to study the validity of the impulse test. From the results of the angle impulse test, a frequency range of negative damping is detected. The phenomenon is also studied by measurements.     

高速列车谐波转矩振动分析及自抗扰控制

高速列车在实际运行过程中,当路面不平顺、车轮磨耗或者列车由明线运行到突然进入隧道均可能会引起转矩脉动,引起齿轮箱振动加剧。为研究谐波转矩波动幅值对高速列车牵引齿轮箱振动加速度的影响,建立考虑时变啮合刚度、啮合阻尼、啮合误差、齿侧间隙的齿轮传动系统与三相异步动态电机耦合的机电传动系统模型,在Simulink平台上分析牵引传动系统在谐波转矩幅值变化的工况下齿轮箱输入端振动加速度特性。结果表明,谐波转矩增大使齿轮箱振动加速度加大,且横向振动加速度增加最明显。耦合系统叠加混合型自抗扰控制器(ADRC)后,对谐波转矩引起的齿轮箱横向振动具有较好的抑制作用。     

高速列车“通过噪声”的测试分析

为了评估高速列车运行时对轨道周围环境的噪声污染程度,对高速列车以不同速度工况通过时的车外辐射噪声(称为"通过噪声")进行了测试,得到了以最大A声级和1/3倍频程A声级标志的列车通过噪声的测量数据。分析了通过噪声的频谱特性、及其与列车速度的关系。测试数据表明高速列车通过噪声是宽频噪声,最大A声级在标准规定测试点上的值达到约90 dB,对铁路附近的噪声污染比较大;通过噪声随着列车速度增大而增大,在时速370 km以上增幅变大。     

高速轧辊磨床微进给机构动力学分析

以高速轧辊磨床微进给机构为研究对象,利用HYPERMESH建立各零部件的有限元模型,并在ANSYS中采用弹簧阻尼器单元COMBIN14建立各结合部的动力学模型,从而建立微进给机构整体有限元模型,进行了模态分析和谐响应分析,得到微进给机构前10阶模态,识别了微进给机构的薄弱环节,从而为微进给机构的设计改进提供依据。     

Comparative thermal analysis of different rotor types for a high-speed permanent-magnet electrical machine

A thermal analysis of three different rotor constructions for a high-speed permanent-magnet electrical machine is performed. The first type of rotor has a carbon-fibre sleeve for retaining the magnets against the centrifugal forces and an aluminium shield for eddy currents. The other two rotors have retaining sleeves made of different titanium alloys and do not have additional eddy-current shields. The thermal analysis of the rotor types is performed using two completely different approaches. The first implemented method is a numerical-multiphysics one that couples computational fluid dynamics equations with heat-transfer equations. For better reliability of the analysis, a traditional thermal-network method is also implemented for estimation of the temperature distribution in the examined rotors. The accuracy of the aforementioned methods is verified using experimental results for the average temperature rise of the permanent magnets. The results obtained from the implemented methods show that although the rotor with a retaining sleeve made of titanium alloy Ti?6%Al?6%V?2%Sn does not have any eddy-current shield, it fulfils the thermal constraints and can be implemented for high-speed applications.     

Optimisation techniques for a hysteresis current controller to minimise torque ripple in switched reluctance motors

The switched reluctance (SR) motor has many benefits owing to its low cost, simple design, rugged construction and comparatively high torque-to-mass ratio. Unlike DC and induction motors, the SR motor is intended to operate in deep magnetic saturation to increase the output power density. Because of the saturation effect and the variation of magnetic reluctance with respect to rotor position, all the relevant characteristics of the machine are highly non-linear functions of both rotor position and phase current. The ultimate outcome of all these non-linearities is that the generated torque contains significant ripples. The non-linearities in the SR motor have been extensively studied and many control strategies to reduce the generated torque ripples have been proposed in the literature. Modulation of phase current profile for generating torque in the SR motor with minimum ripples was the focus of most of the research. However, the main challenge to minimise the torque ripple is to design a current controller that is able to track the modulated phase current. In this work, new techniques to optimise the widely used hysteresis current controller are studied, and experimental verifications under closed-loop speed control with the modulated reference current data are presented. The experimental results indicate that the torque ripple is reduced to lie within 5% of the desired steady torque using the proposed optimisation techniques.     

加载装置对扭矩扳手标准检定装置测量误差的影响

扭矩扳手标准检定装置中的不少加载装置产生的测量误差远远大于仪器和传感器产生的系统误差。本文以工程力学定性剖析扭矩传感器配套的加载装置是引起扭矩扳手标准检定装置测量误差的主要因素,认为结构不良的扭矩加载装置是最大的测量误差源。     

Torque ripple reduction in direct torque controlled five-phase induction motor using modified five-level torque comparator

The five-phase induction motor inherently has the minimal torque ripple. However, when it is controlled by direct torque control (DTC) technique, the torque ripple increases due to the presence of a hysteresis torque comparator. The classical five-level torque comparator is presented in the previous literatures to control the torque ripple. However, this comparator has the drawback of wrong selection of zero voltage vectors inside the inner band on the positive side of the comparator, which enables the torque ripple to increase and dc-link utilization to decrease. In this paper, in order to reduce the torque ripple and to increase the dc-link utilization, a modified five-level torque comparator is proposed, which selects either medium or small voltage vectors instead of zero voltage vectors inside the inner band on the positive side of the comparator. In addition to torque ripple reduction and improvement in dc-link utilization, the proposed comparator significantly improves the quality of phase current. All the available 32 voltage vectors are selected through the proposed five-level torque comparator based on the location of x–y stator flux in order to eliminate the x–y stator flux so as to obtain reduced distortion in the phase current. By employing all the available voltage vectors, the freedom of utilization of all voltage vectors in the five-phase induction motor DTC drive is availed. The proposed five-level torque comparator is compared to its classical five-level counterpart through simulation and experimental results in order to validate the proposed DTC strategy.     

Control of rotor torque and rotor electric power of a shaft-mounted electrical load in a mixed pole machine

A new operational mode for mixed-pole machines is presented. The proposed wound reluctance rotor machine can produce an n-phase rotor electric power from the rotor windings to a resistive or inductive load, independent of rotor torque, at any desired synchronous speed. The two-stator windings, with a different number of poles, are fed from two voltage source inverters on a common dc link. This type of machine can be used in applications that require control of both rotor torque and rotor electric power, such as contactless rotational antennas and turret systems. The machine mathematical model is presented, with open- and closed-loop control systems, simulated and experimentally validated.     

高速导带式数码印花机故障模式、影响及危害度分析

导带式数码印花机发生故障，一方面影响企业生产进度，另一方面导致坯布打印失败而产生浪费，致使企业财产损失。为了降低机器故障率、减少财产损失，针对高速导带式数码印花机所有可能的故障，应用故障模式、影响及危害度分析（failure mode ，effects and criticality analysis ，FMECA）方法对其进行可靠性分析，找出了其薄弱环节为导带传送装置、喷墨打印装置、喷头清洗装置，得到了故障模式、影响及危害度分析表（FM ECA表）。并以此为基础，对危害度较大的故障模式给出了检修与日常维护建议，为企业制定高速导带式数码印花机的检修、保养策略提供依据，也为高速导带式数码印花机的可靠性设计提供基础，有利于提高其可靠性。     

Improving the performance of hysteresis direct torque control of IPMSM using active filter topology

This paper describes an active filter topology to improve the performance of hysteresis direct torque control (HDTC) of interior permanent magnet synchronous motor (IPMSM). The filter topology consists of an active filter and two RLC filters, and is connected to the main power circuit through a 1:1 transformer. The active filter is characterized by detecting the harmonics in the motor phase voltages and injecting equivalent harmonic voltages to produce almost sinusoidal voltage waveform to the motor terminals. The active filter uses hysteresis voltage controller while the motor main circuit uses hysteresis direct torque control. The simulation results of this combined control structure show considerable torque ripple reduction in the steady state range and adequate dynamic torque performance as well as considerable harmonic voltage and EMI noise reduction.     

Failure analysis of a high-speed pinion shaft

The failure of a high-speed pinion shaft from a marine diesel engine was investigated. The shaft, which had been in service for more than 30 years, failed shortly after a service operation in which the bearings were replaced. Examination of the shaft revealed cyclic fatigue as the failure mechanism, with a substantial distribution of nonmetallic inclusions near the fracture initiation site. Fracture mechanics analysis indicated that the inclusions would be unlikely to have served as failure initiation sites if only stresses acting on the shaft were induced by normal service loads. Further examination of the bearing elements revealed an abnormal wear pattern, consistent with the application of elevated bending loads to the shaft after bearing replacement. The root cause of failure was determined to be an increase in service stresses after bearing replacement along with the presence of significant nonmetallic inclusions in the pinion shaft.     

Evolution of local to global minimum torque ripples of direct torque control for induction motor drives

This study discusses the evolution of the local minimum to global minimum torque ripples of the direct torque control of induction motor drives. This study will show that the previous minimum torque ripple design is not the global minimum but a local minimum root-mean-square (RMS) torque ripple. To show this, the study finds the optimal initial torque error, which makes the global minimum torque ripple, and then the related global minimum RMS torque ripple. Moreover, after finding the optimal initial torque error and its related global minimum RMS torque ripple, this study derives the evolution of the initial torque ripple error, under the local minimum RMS torque ripple control strategy. Furthermore, this study also proves that under the local minimum RMS torque ripple control strategy, the local minimum torque ripple will converge to the global minimum value.     

径向驱动式啮合电机结构设计与静态转矩分析

针对机器人系统对驱动电机的启动性能和空间适应性的要求,设计了一种径向驱动式啮合电机结构.该电机利用3个定子和1个转子间磁阻的变化将电能转化为机械能,驱动转子在十字滑块机构约束下绕定子轴线做圆周平动,进而直接带动摆线机构输出低速大扭矩.设计制作了一台物理样机,给出了该电机的控制方法,运用有限元方法分析了在不同转子位置角的...     

分布式驱动用永磁同步电机电磁转矩的解析计算

针对分布式驱动电动汽车车身阶次振动和车内噪声的主要振源—外转子表贴式永磁同步电机6k阶（ ）转矩波动,提出了一种分布式驱动用永磁同步电机电磁转矩的解析计算方法。基于永磁同步电机磁场畸变,对永磁磁极在均匀气隙中的径向分量进行了傅里叶级数分解,通过磁链、电压的计算,最终得到电磁转矩的解析解,为永磁同步电机的阶次振动与振源识别提供了理论基础。当不考虑电流谐波的影响时,对电磁转矩做了阶次分析,论证了由永磁体磁场谐波引起的电磁转矩波动频率是电源频率的6k倍频。最后,通过有限元计算验证了该解析计算结果。