An automated system for frequency response analysis with application to an undergraduate laboratory of electrical machines

This paper describes a LabVIEW-based automated system to carry out frequency response tests in electrical machines. The system is being used by undergraduate students in the laboratory of electrical machines, where they can experiment with the application of frequency response analysis and the characterization of mathematical models. An advantage of the system is its friendly user interface to a laboratory experiment. The system avoids the risky utilization of oscilloscopes for data acquisition and shortens the time taken to analyze the measured data. The Automated System for Frequency Analysis (ASFFA) can carry out tests within a bandwidth of 0.001-900 Hz. In addition, the ASFFA can estimate the transfer function parameters based on one- or two-port network theory. Design details of the interface, system structure, frequency response tests, electrical machine modeling, and signal processing are presented. Finally, ASFFA is applied to synchronous, induction, and direct-current machines.     

改进的区域消去法在电机优化设计中的应用

将一种新的全局优化算法－－区域消去法,引入电机优化设计领域。针对电机优化问题的具体特点,提出将混合罚函数法和修正的鲍威尔法进行组合用于其中的局部寻优。典型函数验证和永磁起动机优化设计中的应用该方法适于工程问题的全局优化,且具有收敛速度快的特点。     

Appraisal of the application of the two-reaction theory to unsaturated salient-pole machines

A reassessment is presented of the application of the two-reaction theory to unsaturated salient-pole machines. The study reveals that calculation of the airgap flux or voltage of the salient-pole machine by the two-reaction theory is far from agreement with the test results under unsaturated conditions. A method of representing an unsaturated salient-pole machine by a simple function is described. By the aid of this new method it is shown that the direct- and quadrature-axis magnetizing reactances of an unsaturated salient-pole machine are not the same as the slopes of the airgap lines of the respective magnetization characteristics.     

On the theory of main flux saturation in smooth airgap electrical machines

Contents The physical foundation of the theory of the smooth airgap machine with main flux saturation taken into account is carefully examined with special reference to the justification of the simplifying assumptions commonly used when the transient equations are established. An experiment showing the nature of the magnetic interaction between coils in quadrature is demonstrated. Measured and computed results are compared.

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Über die Theorie der Sättigung des magnetischen Hauptflusses in Zylinderläufermaschinen

Übersicht Die physikalischen Voraussetzungen und die notwendigen Vereinfachungen in der Theorie der Zylinderläufermaschine bei veränderlicher Sättigung des magnetischen Hauptflusses sind genau formuliert und präzisiert. Es wird ein Experiment beschrieben, das die Messung der induktiven Kopplung zwischen zwei Spulen erlaubt, deren Achsen senkrecht zueinander stehen. Die durch Messung genauen Resultate werden mit den numerisch berechneten Ergebnissen verglichen.

     

The improvement of the electrical insulation of high voltage electrical machines

Comparative parameters are presented for the electrical insulation systems of high voltage electric machines. Composite insulation materials produced by different manufacturers are studied. The influence of the structure and composition of electrical insulation materials on the main operation parameters (electric strength, dielectric losses, the mechanical characteristics, and resistance to thermal cycling) of the insulation systems of electric machines is shown.     

Oscillator analysis with respect to higher harmonics

Contents The modified harmonic balance method has been worked out to describe the behaviour of oscillators generating output signal not on the first harmonic, as it is usual, but on the higher one. The main assumptions are: All higher harmonics are considered small compared to the first one and there is only one dominant resistive nonlinearity limiting amplitude of oscillations. The approximate solution of a microwave oscillator with Gunn diode is presented as an example. The results are in accordance with experimentally observed phenomena in the oscillator such as discontinuities and power drops in its characterstics.

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Oszillator-Analyse mit höheren Harmonischen

Übersicht Die Methode der modifizierten Harmonischen-Bilanzierung wurde weiterentwickelt, um das Verhalten von Oszillatoren zu beschreiben, die nicht wie üblich Signalleistung auf der Fundamentalen abgeben, sondern auf höheren Harmonischen. Dabei wird als wesentlich angenommen, daß die Amplituden der höheren Harmonischen klein sind, verglichen mit der ersten, und daß nur eine resitive Nichtlinearität dominierend die Schwingamplitude begrenzt.Als Beispiel wird die Näherungslösung eines Mikrowellenoszillators mit Gunn-Element vorgestellt. Die Lösungsergebnisse stimmen mit experimentelll beobachteten Erscheinungen im Oszillatorbetriebsverhalten überein, wie Kurvensprüngen und Leistungseinbrüchen.

     

Re-inventing the electrical machines curriculum

Undergraduate courses in electromechanical energy conversion are typically oriented toward the steady-state analysis of electrical machines. The advent of low-cost computer power and the availability of numerical software tools provide the opportunity to fundamentally reorient the pedagogical approach to the topic. A new approach is consistent with the developing need to emphasize the study of new machine designs and machines employed for control purposes as well as machines for use in more traditional power applications. This paper presents the results obtained from simulations developed as an integral part of an undergraduate electrical machines course at the University of Dayton, USA. Sample simulation files are presented to demonstrate the ease with which the matrix model of the machine is transferred to the program. The matrix models and simulation results of the following machines are included: the single-phase transformer; the variable-reluctance machine; the cylindrical-rotor dual-winding machine; the symmetrical two-phase induction motor; a PWM-controlled DC machine; and an inverter-driven brushless machine. The selected machines provide a systematic framework for analysis and simulation and present problems of increasing complexity to the student     

电动汽车充电站对电网谐波影响分析

介绍了电动汽车充电站对电网电能质量的影响及充电站GTBC-500200直流充电机采用BMS(电池管理系统)充电方式.分析了充电站充电过程电压、电流谐波变化.提出了充电站治理谐波措施及通过采用APF-100有源滤波装置,可实现降低电压、电流谐波畸变率目的.     

Model reference adaptive control applied to electrical machines

This contribution reports about a discrete-time robust adaptive control strategy for single-input/single-output systems with arbitrary zeros. The adaptive algorithm is mainly based on a direct model reference method. The basic idea presented here is to divide the feedback law into a direct adaptive and a fixed part. By a certain choice of the non-adaptive controller parameters the robustness of the adaptive control loop with respect to unmodelled dynamics of the plant may be increased. The non-adaptive part of the controller can be reformulated as a bypass to the plant and will be denoted as the ‘correction network’ owing to its action on the open-loop zeros of the augmented plant. The new adaptive control strategy removes the major drawbacks of model reference control and is investigated for speed control of a DC motor and voltage control of a synchronous generator.     

低压电器机械开关电接触可靠性分析及应用

电接触可靠性是低压电器机械开关可靠性的一个重要方面,特别对小容量低压电器机械开关(如继电器、断路器),二者的关系更加密切。电触头是低压电器中的关键元件,其性能直接影响到低压电器机械开关电接触可靠性。本文介绍了低压电器产品中常用电触头的特性及其应用领域。给出了低压电器产品选用电触头的建议和应用实例。     

稀土永磁电机的开发与应用(二)

(续上期) 5 稀土永磁电机的开发方向 近年来,随着永磁材料性能的不断提高和完善,特别是钕铁硼磁体的热稳定性和耐腐蚀性的改善以及电力电子元件的进一步发展和改进,加上永磁电机研究和开发经验的逐步成熟,除了大力推广和应用已有研究成果外,稀土永磁电机的应用和开发进入一个新阶段,目前正向大功率化(超高速、高转矩)、高功能化、微型化和环境适应性方向发展[7,11,13].     

Analysis of electrical machines using Symphony

The application of Symphony spreadsheet programs to electrical machine analysis is described. Seven typical examples are presented, namely steady-state performance of a DC shunt generator, speed control of a DC shunt motor, magnetizing current waveform of a transformer, steady-state performance of a three-phase induction machine, frequency control of a three-phase induction motor, induction motor run-up, and swing curves of a synchronous generator. Advantage is taken of the spreadsheet environment for such operations as tabular calculation, table lookup, numerical integration, and what-if analysis. Extensive use is made of the integrated graphics facilities of Symphony for producing good quality screen displays on a personal computer, which proves very convenient and useful for computer-aided instruction. Certain features of Symphony are described in the context of the applications described     

The optimization of spectral analysis for signal harmonics

FFT has been applied to technologies of spectrum analysis widely. However, since the signal sampling is at random, and FFT suffers specific restrictions, some defects inevitably occur, which means that harmonic parameters do not show on the spectrum exactly. These defects result from frequency scales not matching signal characteristics. This paper discusses the optimization of spectrum analysis for signal harmonics. By means of scale fine-tuning, the frequency scales will match the signal characteristics. The method eliminates both of the picket-fence effect and the leakage effect; it makes the harmonic parameters show on the spectrum more accurately. This paper takes reasonable and practical evaluations to verify the theory