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Standstill Frequency Response (SSFR) testing and modeling of salient-pole synchronous machines are presented for two machines with integral and non-integral number of stator slots per pole per phase. Frequency responses at different rotor positions have been investigated to explore the effects of rotor position in a machine with fractional slot winding, as the electromagnetic fields and the armature magnetomotive forces do not precisely repeat every pole. The test results do not show any significant differences for various direct and quadrature axes rotor positions. The authors obtained a negative value of differential leakage inductance as theoretically postulated in the literature. The pertinent features of testing and modeling of salient-pole synchronous machines are described to point out the differences with SSFR testing of round rotor turbogenerators extensively published in the literature. Keywords: salient-pole synchronous machine, transfer functions, SSFR testing, equivalent circuit modeling, differential leakage inductance

The Magnetic Equivalent Circuit (MEC) method has been used to model the nonlinear magnetic field in electromagnetic devices for steady-state and dynamic conditions. However for highly saturated electromagnetic device, the conventional MEC method is inaccurate in predicting device characteristics. With experience gained from the Finite Element (FE) method, the MEC method can be modified to provide significant accuracy improvement in the field solution results. The main modification is done in the modeling of the highly saturated regions. The Improved Magnetic Equivalent Circuit (IMEC) is used to predict the characteristics of a Switched Reluctance Motor (SRM). The results from IMEC are compared with those obtained by conventional MEC, FE methods, and measurement. Index terms - Magnetic circuits, electromagnetic devices, nonlinear analysis.

In this paper, we report a way to condition the global stiffness matrix resulting from the Galerkin edge element formulation, in order to make the BICG solver converge for high Peclet number situations. The concept of artificial diffusion is introduced and extended to edge element cases. A general expression of the artificial diffusion scheme for 3D edge elements is derived and a numerical validation in 2D case is presented. It was observed that although nearly identical results were achieved both with or without introducing artificial parameters for a 2D test problem, the former provided a better conditioned global stiffness matrix to ensure the BICG's convergence.

This paper presents a 2-D electromagnetic field analysis of the single-sided linear induction motor (LIM), taking into account saturation in both primary and secondary cores. An analytical layer model has been developed in which the primary core is modeled by two different layers representing the yoke and teeth-slot regions. Such representation facilitates the evaluation of the magnetic state of the primary yoke and teeth separately. A new generalized mathematical formulation of a multilayer model is presented. The analytical computation results from a seven layer model correlate very well with experimental results obtained from an intermediate- capacity transit system LIM. The developed model is well-suited for sensitivity analysis and design studies.

Examines evidence for a seventh signature of a document by William Shakespeare. How William Lambarde's `Arxaionomia,' came into the possession of the Folger Library; Comparisons of the secretary and italic forms of handwriting used in Shakespeare's time.

Eddy currents are an electromagnetic phenomenon that represent an inexhaustible source of inspiration for technological innovations in the 21st century. Throughout history, these currents have been a subject of research and technological development in multiple fields. This article delves into the fascinating world of eddy currents, revealing their physical foundations and highlighting their impact on a wide range of applications, ranging from non-destructive evaluation of materials to levitation phenomena, as well as their influence on fields as diverse as medicine, the automotive industry, and aerospace. The nature of eddy currents has stimulated the imaginations of scientists and engineers, driving the creation of revolutionary technologies that are transforming our society. As we progress through this article, we will cover the main aspects of eddy currents, their practical applications, and challenges for future works. [ABSTRACT FROM AUTHOR]

Electrical machines are prone to various faults and require constant monitoring to ensure safe and dependable functioning. A potential fault in electrical machinery results in unscheduled downtime, necessitating the prompt assessment of any abnormal circumstances in rotating electrical machines. This paper provides an in-depth analysis as well as the most recent trends in the application of condition monitoring and fault detection techniques in the disciplines of electrical machinery. It first investigates the evolution of traditional monitoring techniques, followed by signal-based techniques such as spectrum, vibration, and temperature analysis, and the most recent trends in its signal processing techniques for assessing faults. Then, it investigates and details the implementation and evolution of modern approaches that employ intelligence-based techniques such as neural networks and support vector machines. All these applicable and state-of-art techniques in condition monitoring and fault diagnosis aid in predictive maintenance and identification and have the highly reliable operation of a motor drive system. Furthermore, this paper focuses on the possible transformational impact of electrical machine condition monitoring by thoroughly analyzing each of the monitoring techniques, their corresponding pros and cons, their approaches, and their applicability. It offers strong and useful insights into proactive maintenance measures, improved operating efficiency, and specific recommendations for future applications in the field of diagnostics. [ABSTRACT FROM AUTHOR]

The aim of this study is to determine the electromagnetic field spatial distribution and longitudinal end effect characteristics of short primary linear induction motor (SPLIM) in the field of electromagnetic launch. First, in accordance to the electromagnetic model assumption of SPLIM and one‐dimensional electromagnetic field theory, the analytical expression of the whole‐region magnetic flux density of air‐gap is derived using electromagnetic field boundary conditions in line with the actual physical meaning. Second, the finite element method used in comparing the analytical calculation values of key physical quantities, such as air‐gap flux density and secondary eddy current in a multidimensional manner under various static and dynamic working conditions and verifying the correctness of the analytical calculation of the electromagnetic field. On this basis, the air‐gap flux density of SPLIM is decomposed according to the different generation mechanisms, and the spatial distribution of each part of the flux density is studied. Spatial Fourier analysis of flux density is conducted, the end effect coefficient is defined, and the change rule of the end effect coefficient with the design parameters of the motor is studied. Finally, a megawatt‐class high thrust prototype test platform was built, and the measured electromagnetic force was compared with the electromagnetic force calculated by air gap magnetic field and secondary eddy current. The steady‐state error of the two was less than 2%, which verified the accuracy of the analysis and calculation. [ABSTRACT FROM AUTHOR]

Single-sided linear induction motors usually appear in magnetic levitation systems of transportation. Since the beginning of such developments, edge effects represent one of the great challenges to overcome in analytical modelling. For almost four decades, in order to simplify the mathematical treatment of border effects, most analytical models have not considered the secondary leakage flux properly. Although concise and accurate in most cases, such approaches have deficiencies in slotted secondaries. This paper presents an analytical equivalent circuit that considers the secondary reactance for both edge effects, i.e., entry and exit sides. The proposed approach uses an analogical RLC circuit which describes the behavior of magnetizing (exit) and demagnetizing (entry) waves, as well as adapted correction factors for transverse effects. By means of an 8 pole/120–175 N prototype, the measured thrust and vertical forces remarkably validate the model for frequencies equal or higher than 60 Hz. The relevance of secondary reactance in such cases can be explained by accounting its influence, specially, in the rise of the demagnetizing entry wave. [ABSTRACT FROM AUTHOR]

The most often used motor in commercial drives is the induction motor. While the induction motor is operating, electrical, thermal, mechanical, magnetic, and environmental stresses can result in defects. Therefore, many researchers who are involved in condition monitoring have been interested in the development of reliable and efficient fault diagnostic technologies. This paper's goal is to provide an overview of available fault detection methods for the broken rotor bar problem, one of several defects associated to induction motors. Despite the fact that it is less common than bearing or insulator failure, this fault may cause electrical machines to fail catastrophically. It can be quite harmful, especially in large motors, and it can develop as a result of manufacturing faults, repeated starting of the machine, mechanical stress, and thermal stress. Hence, a review on rotor defect diagnosis was conducted. In order to confirm rotor bar fracture, this research provides probable defect signatures that can be extracted from the current signal. Each defect signature is reported according to (a) loading level, (b) the number of BRBs, (c) validation, and (d) methodologies. [ABSTRACT FROM AUTHOR]

Performance analysis of a linear permanent magnet Vernier machine (LPMVM), which has a complex structure, is mostly based on the finite element methods, while for its optimisation or sensitivity analysis a quick mathematical technique is desirable. This paper introduces an LPMVM and its principles of operation. Then, a mixed subdomain and magnetic equivalent circuit are applied to extract magnetic field equations in various parts of the machine, in which the end‐effect in included. Besides, the electromotive force, thrust force, normal force and electric equivalent circuit are determined. An LPMVM was prototyped and tested to verify the accuracy of the proposed method. [ABSTRACT FROM AUTHOR]

This study deals with the characteristic analysis of a permanent magnet synchronous generator (PMSG) with a bolting and an overhang structure. Bolting is applied to a PMSG to prevent the defects caused by scattering. To compensate the flux reduction caused by the end effect and bolting material, an overhang structure is used for the permanent magnet machine. Therefore, an overhang structure must be considered in the three-dimensional (3D) analysis of a PMSG; however, such an analysis is time-intensive. To reduce the initial analysis time, we performed a semi-3D analysis of a PMSG considering a bolting and an overhang structure. Subsequently, we compared the output results of the characteristic analysis with a 3D finite element method and experimental results under loading. [ABSTRACT FROM AUTHOR]

This study demonstrates the application of layer model theory to the analysis of synchronous machines. The derivation of the model from Maxwell's equations is briefly described. With the use of steady‐state equations and terminal operation information, a methodology is established, and the synchronous machine operation is modelled. Two case examples are then analysed. It is shown that the layer model methodology can be applied to synchronous machines with promising results. [ABSTRACT FROM AUTHOR]

Electromagnetic variations of the single‐sided linear induction motor (SLIM) are calculated by three‐dimensional (3D) finite‐element method (FEM) when the primary is displaced sideways from a symmetrical position. For geometrical and electrical asymmetry, a full 3D model, which considering the longitudinal and transverse end effects, overhangs of the primary windings and secondary, as well as lateral displacement, is developed. Apart from the thrust and vertical force, lateral force is produced when the transverse asymmetry occurred. Hence, the calculation equation of thrust, vertical and lateral forces in each element of the 3D FEM model and boundary conditions are presented. Air‐gap flux densities along the longitudinal and transverse directions with different lateral displacements are obtained, as well as the distortion coefficients of the air‐gap flux density is proposed. Corresponding induced currents in the secondary are predicted. Finally, the variations of the thrust, vertical and lateral forces are experimentally validated by measurements on reciprocal power‐fed test rig. It shows that the flux in between overhangs of the primary winding and secondary has great effect on the lateral force, the thrust and vertical force decrease with the increase of the lateral displacement. [ABSTRACT FROM AUTHOR]

This paper presents an algorithm that enables estimation of the speed of a single induction motor in an aggregate current signal supplying several motors from a common utility feed. This algorithm maintains accuracy of speed estimation while using shorter lengths of data, and can distinguish the activation of individual motors in the aggregate signal. The ability to separate and track distinct motor harmonics in an aggregate current signal opens the door to non‐intrusive energy scorekeeping and diagnostics for systems like air conditioning that operate under closed‐loop control. New experimental results demonstrate the approach for these air‐conditioning components in real buildings. [ABSTRACT FROM AUTHOR]