Evaluation of the measurement uncertainties in the conducted emissions from adjustable speed electrical power drive systems

This paper deals with the evaluation of the uncertainties involved in the measurement of conducted emissions from adjustable speed drives. Besides the measurement uncertainty due to all the components of the measurement chain, the uncertainties arising from nonrepeatability and from both the configuration setup and the operating conditions were investigated. Following the test arrangements suggested by the electromagnetic compatibility standards, a detailed analysis and quantification of the effects of the reciprocal position of the power and of the motor cables, of the motor cable lengths, and of the pulse width modulation switching frequency used in the test were carried out.     

大力矩径向驻波型超声波电机有限元分析与实验研究

提出了一种大力矩径向驻波型超声波电机,在实现电机大力矩输出的同时保持结构紧凑的特点。首先设计并分析了电机的结构和工作原理,采用有限元法分析了电机定子的振动特性。接着制作了超声波电机样机,样机直径为32 mm。采用激光测振仪测量了定子的共振频率及径向振动的振幅,测量结果与理论分析结果相吻合。最后,搭建了电机输出特性测试平台,测量了电机在不同电压下的转矩-转速特性。实验测试结果显示,定子工作模态的共振频率为73.3 kHz,当施加的电压幅值为100 V、频率为74 kHz时,电机的空载转速为45 r/min,堵转力矩达到0.41 N·m。与其他同尺寸的超声波电机相比,所提出的径向驻波型超声波电机具有更大的堵转力矩。     

Improved direct torque control of induction motor with dither injection

In this paper, a three-level inverter-fed induction motor drive operating under Direct Torque Control (DTC) is presented. A triangular wave is used as dither signal of minute amplitude (for torque hysteresis band and flux hysteresis band respectively) in the error block. This method minimizes flux and torque ripple in a three-level inverter fed induction motor drive while the dynamic performance is not affected. The optimal value of dither frequency and magnitude is found out under free running condition. The proposed technique reduces torque ripple by 60% (peak to peak) compared to the case without dither injection, results in low acoustic noise and increases the switching frequency of the inverter. A laboratory prototype of the drive system has been developed and the simulation and experimental results are reported.     

Measurement system for end face mechanical seal performance

Improving the performance of mechanical seals requires the investigation of their behaviour. In order to improve the characteristics of long service life and low leakage, operating cost, and (presumably stable) operating torque, seals must be thoroughly evaluated under service conditions. However, the measurement of operating parameters in the field is hindered by the inaccessibility of seal components and by inadequate instrumentation. Therefore, a well calibrated and fully instrumented system is required to measure the performance characteristics of seals in the laboratory. A test stand has been developed to achieve this.     

单相串励电动机扭转振动检测与特性分析

阐述了单相串励电动机的工作原理,建立了对应的数学模型,推导了电磁转矩表达式。对单相串激电动机在多种工况运行下的扭转振动进行了检测,得到了电动机的负载-扭转振动特性,以及电压-扭转振动特性。对相关特性的产生机理进行了分析,根据单相串励电动机的转矩表达式和转矩平衡方程得到了相应的结论,为单相串励电动机扭转振动的抑制提供了技术支撑。     

Modulation Tests on Bluetooth Transmitters Through Time–Frequency Representations

A new digital-signal-processing method for performing modulation tests on Bluetooth transmitters is presented and validated. No preliminary demodulation of the radio frequency transmitted signal is needed to gain the instantaneous frequency trace, on which standard measurement procedures have to be applied. The aforementioned task is, in fact, fulfilled through the application of the short-time Fourier transform (STFT), a typical time-frequency representation, to the acquired samples of the aforementioned signal. Moreover, no specific information concerning the operating conditions of the transmitter under test, such as carrier frequency and hopping sequence, is needed, thus facilitating measurement automation. The optimal tuning of STFT parameters, which are capable of providing the best reconstruction of the instantaneous frequency trajectory as well as the most accurate measurement outcomes, is established as the result of an exhaustive experimental activity.     

Steps for developing a fugitive emission packing for valves

Over the past 15 years, the elimination of traditional sealing materials and clean air legislation have created the need for a fugitive emissions packing for valves. This article describes various criteria that affect sealing performance as it relates to service conditions, the quality of the valve stem packing, and documentation by testing. Test results are presented on torque retention, sealability versus applied torque, effects of live loading, effects of stem finish on sealability, and the effects of travel speed on sealability. These are some of the test factors required for developing fugitive emission packing.     

Mitigation of Torque Ripple in Interior Permanent Magnet Motors by Optimal Shape Design

Optimal shape design of an interior permanent-magnet (IPM) synchronous motor can substantially reduce its torque pulsation. However, the shape design variations should be feasible and practical. We report on an optimal shape design obtained by drilling small circular holes in the rotor. We found that an optimal location and radius of the holes effectively suppresses the torque pulsation of the IPM drive for various loads under steady-state conditions. The optimal design at rated load is considered as the final design. We use a transient finite-element analysis that is coupled with motion and adequate electric excitation for optimization purposes. An evaluation of the optimal design at various operating conditions showed torque ripple reduction and average torque improvement under all load conditions. The optimal design also shows improvement in the field-weakening region for high-speed operation     

基于单片机的改进型五相混合式步进电机驱动器设计

在高性能纺织机械尤其是电脑绣花机中,步进电机是广泛应用的执行部件.电脑绣花机系统中现有五相混
合式步进电机驱动器存在诸多不足之处低频转矩振荡、高频输出转矩不足和多电源供电等.在分析现有步进电机
驱动器的基础上,结合理论分析,设计出一种基于单片机的改进型五相混合式步进电机W动器.该驱动器使用单一
电源供电,采用三相励磁PWM输出方式,改善了驱动的矩频特性,在电脑绣花机系统中投人应用取得良好效果.     

Magnetically induced vibration in a permanent-magnet brushless DC motor with symmetric pole-slot configuration

The paper reports a numerical and experimental study of magnetically induced vibration associated with rotor/stator eccentricity and imperfect magnetization for 8-pole 6-slot symmetric brushless dc (BLDC) motors. Magnetic forces and cogging torque are calculated for various slot angles by using the finite-element method (FEM). The results show that there is an optimal slot angle for minimum cogging torque, but this slot angle is not optimal for reducing magnetic forces. In the idle acoustics test, the motors with reduced magnetic forces show clear reduction at the expected frequencies while the motors with minimum cogging torque show no change at the cogging torque frequency, which implies unbalanced magnetic forces have greater effect on actual vibration of the spindle motor than cogging torque. The results show that the proper direction in motor design is to reduce unbalanced magnetic forces when both cogging torque and unbalanced magnetic forces are not achievable simultaneously.     

H. F.-Bias gesputterte TiN-Schichten zur Verschleißminderung an Grauguß-Kolbenringen

RF-Bias Sputtered TiN-Coatings to Reduce Wear of Cast-Iron Piston Rings By means of the reactive r.f. magnetron sputtering process TiN coatings with a thickness of 2.5 m?m and 6 m?m respectively, have been deposited onto piston rings made of cast iron. The coated piston rings have been tribologically tested using a model wear test, the so called short stroke test, which allows simultaneous testing of eight rings. This test method involves the most important stress features of the fired motor so that a good simulation of the stress conditions under which the piston rings and cylinder linings are working, is achieved. The results found with the short stroke test are compareable to those found with a fired test motor. The test was performed using TiN coated, uncoated and hardchromium electroplated cast iron rings. The reduction of the total wear of the rings and cylinder linings using a 6 m?m thick TiN coating was 85° compared to the uncoated rings and 50° compared to the chromium coated rings. The adhesion of the TiN coatings is excellent and even the graphite inclusions on the cast iron surface did not lead to any adhesion failure of the coatings under the present stress conditions.     

脉冲管整机条件下回热器交变特性实验研究

搭建脉冲管制冷机动态参数测试实验台,在脉冲管制冷机整机运行条件下对处于实际温度梯度的回热器进行了动态速度以及动态压力测试。为了测量回热器冷端的动态速度,研究针对低温侧的热线探针进行了低温条件下的标定。实验测量了充气压力3 MPa、运行频率40—60 Hz、冷端温度100 K工况下回热器的相位特性以及阻力特性,并得到了整机运行条件下回热器阻力系数经验公式。研究结果表明,随着频率的提升,回热器冷热端速度-压力相位差增大,相同雷诺数下的阻力系数增大;随着温度降低,相同雷诺数下的阻力系数增大,并且在低雷诺数下变化更加明显。该研究结果是在回热器实际工作条件下测量得到,能够为脉冲管制冷机中的回热器模拟计算以及回热器热力学分析提供必要的数据支持。     

An indirect test method for the characterization of variablereluctance motors

The determination of the characteristics of the variable reluctance motors (both in static and dynamic conditions) represents a quite critical point, due to the heavy nonlinearity of the motor magnetic paths, to the high distortion of the supply voltage from the converter, and to the high level of saturation of the magnetic paths in normal working conditions. This creates a great difficulty in the accurate measurement of the motor magnetic characteristics (saturation curves or flux linkage versus current curves) and consequently in the determination of the mechanical characteristics (static torque versus current and static torque versus rotor position) which are directly related to the saturation curves. The paper proposes an original digital method that, starting from the measurement of the flux linkage in the motor magnetic paths, determines the saturation curves, evaluates the coenergy versus current curves and then the motor torque characteristics in static conditions. It is then shown how the availability of a fast and accurate method for the measurement of the flux linkage allows the determination of the electromagnetic torque in dynamic conditions, too     

新型旋转式压电惯性电机振子的冲击振动分析

新型旋转式压电惯性电机,是一种利用压电双晶片振子作为驱动元件,利用锯齿波作为激励电信号产生惯性冲击力的旋转电机。本文研究压电惯性电机振子在pzt元件激励下的冲击受迫响应。推导出了压电陶瓷片两端电压响应方程,以及压电振子梁的冲击受迫响应方程。分析了激励信号频率对振子梁端部响应的影响规律。同时,分析了不同激励信号占空比情况下振子梁端部响应变化规律,以及结构参数对电机驱动力矩的影响规律。分析了提高电机驱动力矩的有效途径。     

永磁无刷直流电动机换相脉动转矩及抑制方法

通过分析永磁无刷直流电动机的换相过程,得到了电动机绕组电流换相产生的脉动转矩表达式。为了验证理论分析的正确性,首先对电流换相产生的脉动转矩及相关特性进行了仿真,然后采用永磁旋转角加速度传感器对电动机轴上的脉动转矩进行了实际测量,验证了电机输出转矩中的脉动转矩分量的客观存在性及相关特性。针对脉动转矩,提出了一种基于峰谷互补的抑制方法,并建立了对应的实验平台开展了实验研究,理论分析和实验测量取得了一致的结果,从而证明了该抑制方法的正确性。     

高效节能的永磁同步电机混合控制算法

目的 保证永磁同步电机在变速变载时能够快速响应的同时,降低其在稳态时的转矩脉动和开关频率,使永磁同步电机在整个包装过程更加高效节能.方法 分析永磁同步电机的2种控制策略DTC和PIPC的优缺点和共同点,提出在启动、变速和变载过程采用DTC控制策略保证电机的动态响应速度,在稳态时切换到PIPC控制策略,降低电机的转矩脉动和开关损耗.结果 仿真结果表明,2种控制策略能够实现平滑切换,电机动态响应快,抗干扰能力强,稳态时转矩脉动小、开关频率低;相比DTC,在空载、轻载和重载时转矩脉动分别减小了30％,12.5％和2.4％,开关频率降低了约45％;相比PIPC,响应速度提高了约7％.结论 相比单一的控制策略,DTC_PIPC混合控制算法融合了2种控制策略的优点,使电机在整个运行过程既能快速应对各种突变情况,又能降低其在稳态运行时的转矩脉动和开关频率.     

永磁无刷直流电动机低脉动转矩研究

针对永磁无刷直流电动机在运行过程中存在明显脉动转矩的问题,研究了一种新结构低脉动转矩永磁无刷直流电动机。首先对普通永磁无刷直流电动机在电流换相、极弧系数小于1和电枢反应等3种因素下的脉动转矩进行了物理解析;然后以脉动转矩的变化规律为切入点,提出一种通过电机本体产生2个幅值相同、频率相同、相位互差180°电角度的脉动转矩,实现脉动转矩峰谷互补的抑制策略,并通过理论分析找到了脉动转矩峰谷互补的实现方法;最后研制了低脉动永磁无刷直流电动机及控制器,通过实验验证了脉动转矩抑制的有效性,与普通永磁无刷直流电动机相比,实验结果表明可以减少约70%的脉动转矩。     

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.     

Improved Test Methodology for Production Testing of RF Switches Using a New Relative Measurement Technique

High-volume production testing using automatic test equipment (ATE) is an important part of the integrated circuit manufacturing industry, where it allows products to be rigorously characterized to ensure conformity with their data-sheet specifications. When used in production, the accuracy and repeatability of the ATE must itself be understood so that the final measurements are a true reflection of the underlying product performance and are not adversely influenced by variations or inaccuracies in the ATE setup. This paper reports on the application of the ATE to production testing of CMOS solid-state RF switches operating at 1 GHz and the steps that have been taken to remove sources of variation from the measurement setup. In particular, a calibration path based on the solid-state GaAs switches, which shares most of the RF signal path with the device under test (DUT), is described. The introduction of the calibration path reduces the variability of the measurement system by up to 60%, thus ensuring the suitability of the new setup for an ongoing high-volume production test.     

Signal analysis applied to vortex flowmeters

The signal taken directly from the sensor used in an industrial vortex flowmeter is processed so as to discern the effects of various process conditions on the measurement signal. A mathematical model of how the signal is generated in the vortex flowmeter is derived on the basis of these observations. The model has been used to predict the form of the signal from the flowmeter operating under various flow conditions. The spectrum of the predicted data has been analyzed and the results compared to corresponding results obtained using practical data from an actual flowmeter installed in a flow loop. The implication of this study is that signal processing and system identification techniques can be applied to enhance the quality of the measurement information provided to a supervisory control system