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Acoustic noise modeling, analysis, and reduction are critical in the design of switched reluctance machines for noise-sensitive applications. Although the analytical method can provide a fast simulation of the acoustic noise, it is generally less accurate compared to the numerical method. In order to improve the simulation accuracy, a novel analytical method is presented in this paper. The proposed method considers the excitation of the high-axial-order vibration modes to simulate the vibration behavior and the acoustic noise in the three-dimensional (3D) domain. Methods of obtaining the input data for the 3D analytical simulations are presented. The acoustic noise results obtained from the numerical simulations and experiments from an 8/6 switched reluctance motor drive are used to validate the analytical method presented in this paper. [ABSTRACT FROM AUTHOR]

In most multiobjective optimization problems of electrical machines, the weighted function method is used to convert them into single-objective optimization problems. This paper applies a kind of new multiobjective evolutionary algorithms (MOEAs), called adaptive multiobjective black hole (AMOBH) algorithms, to achieve effective multiobjective optimization of a tubular coreless linear permanent magnet synchronous motor (LPMSM). To reduce the computation cost of the MOEAs, a one-layer analytical model (AM) is presented for the tubular coreless LPMSM in this paper. The accuracy of the simplified one-layer AM is verified by comparisons with multilayer AM and finite element analysis (FEA) under different structure parameters. It is found that the simplified AM has good accuracy and can decrease the computation cost significantly. AMOBH algorithm is subsequently introduced. The optimal Pareto front with regard to thrust, copper loss, and permanent magnet volume are analyzed, and more diversified optimization results are provided. The final Pareto solution can be selected directly by practical physical values according to the application requirements. Finally, a prototype is fabricated for the selected design; its experimental results are provided and compared with those of the FEA results. [ABSTRACT FROM AUTHOR]

Analytical method for vibration and noise prediction in electrical machines is computationally efficient and widely used. In conventional analytical approaches, the slotted stator is simplified as a cylinder, and it is generally believed that the vibration is more sensitive to the air-gap forces with low spatial orders, hence, those high-order air-gap forces are usually neglected. In this paper, the force distribution on the slotted stator is analyzed using a force transformation model and a new phenomenon, i.e., the modulation effect, is found, which indicates that a high-order air-gap force could also induce a low-mode stator vibration with a large amplitude. As a result, the conventional analytical methods are not so accurate for machines with a strong modulation effect, such as fractional-slot concentrated-winding machines. The existence condition for the modulation effect is also discussed in this paper. Finite-element analysis and experiments have been done to verify the analysis results. [ABSTRACT FROM AUTHOR]

Load characteristics have substantial influence on the voltage stability of power systems. The self-restorative characteristic and stalling of induction motor loads can deteriorate the voltage stability, so it is necessary to develop accurate and efficient dynamic analysis methods for voltage stability analysis of systems with induction motor loads. In this paper, a set of methods based on holomorphic embedding is proposed, which is able to solve steady states and dynamics of a power system with induction motors. The paper is the first work that applies holomorphic embedding to dynamic problems of power systems. The test cases on the IEEE 14-bus system, the NPCC 140-bus system, and the Polish 2383-bus system verify both accuracy and efficiency of the proposed methods. [ABSTRACT FROM AUTHOR]

This paper focuses on the analysis and design of a triple-rotor axial-flux spoke-array vernier permanent magnet (TR-AFSAVPM) machine. By cooperating with spoke-array rotor and coil-wounded winding, power factor and torque density of the proposed machine are much improved and its copper utilization is reduced comparing with conventional vernier machines. First, the machine structure and its operation principles are reviewed. After that, analytical equations of its back-electromotive force and torque are derived to reveal the machine characteristics. Based on both quasi-3-D finite element analysis (FEA) and 3-D FEA, its high torque density performance is verified and a set of optimized machine sizing specifications is ultimately settled. A fractional slot axial-flux permanent magnet (VPM) machine and an axial-flux surface VPM machine are designed to compare with the proposed configuration. Analysis results show that the TR-AFSAVPM machine has high power factor viz., 0.96 and high torque density viz., 24.2 kNm/m3. A prototype has been designed and tested to validate the results. No-load test result is illustrated in this paper and the rated load experiment will be added in the future. [ABSTRACT FROM AUTHOR]

This paper proposes a novel spoke-type permanent-magnet (PM) motor with auxiliary salient poles (ASPs). With these ASPs, unequal ASPs and shifted ASPs in the circumferential direction can be realized and combined to reduce the torque pulsation, while their functions are different. Unequal ASPs are employed to eliminate the second-order torque pulsation. Nevertheless, the shifted ASPs are selected to reduce the first-order torque pulsation. Additionally, the relationship between the unequal angle or shifted angle of the ASPs and the order of the torque pulsation is revealed. Furthermore, the revealed principle of the torque pulsation reduction can be extended to other slot–pole combinations. Finally, a prototype is manufactured for experiments to evaluate the low torque pulsation spoke-type PM motor. Through theoretical analysis and experimental testing, it is verified that the proposed motor offers low torque pulsation and that the revealed principle for torque pulsation reduction of different orders is feasible and effective. [ABSTRACT FROM AUTHOR]

This paper proposes an electromagnetic analysis using an analytical method for a permanent magnet synchronous generator (PMSG) in a wave energy converter. To prevent the scattering of the rotor magnet of the PMSG with a wide operating range, bolting to the permanent magnet is required, and the analytical solution is calculated by simplifying it to two analytical models. Based on the electromagnetic theory, the analytical solution of each analytical domain is derived. The electromagnetic parameters are derived from the analytical solution and are calculated using the principle of superposition. The validity of the proposed analytical results is verified by comparing nonlinear 2-D and 3-D finite-element analysis with experimental results. [ABSTRACT FROM AUTHOR]

This paper analyzes the torque characteristics of a magnetic rack-and-pinion gear using an analytical method based on the spatial harmonic method. We obtain the magnetic field distribution due to the permanent magnets and derive the magnetic torque from the magnetic field using the Maxwell stress tensor. The analytical results are extensively validated by comparing with finite element analysis results. Finally, we obtain an accurate analytical solution to reduce the analysis time and experimentally verify this solution by applying it to a newly manufactured rack–pinion gear model. [ABSTRACT FROM AUTHOR]

This paper proposes a new torque analytical method (AM) for five-phase interior permanent magnet synchronous machine (IPMSM) with shifted asymmetrical rotor pole. The key of this method is to consider the permanent magnet (PM) torque and the reluctance torque simultaneously, by using the Lorenz force law. The analytical expressions, including stator magnetomotive force (MMF), rotor MMF generated by PMs and rotor MMF generated by stator MMF, are first derived. Then, Lorentz force law is used to calculate PM torque and reluctance torque, respectively. In order to improve the precision of electromagnetic torque calculation, stator slotting effect under shifted asymmetrical rotor pole is taken into consideration. Finally, the AM is verified by finite element method and experiment. The results show that proposed AM is good enough to predict the torque performance of IPMSM with shifted asymmetrical rotor pole. [ABSTRACT FROM AUTHOR]

Overhang is a useful structure for increasing the torque and power densities of permanent-magnet (PM) machines without expansion of the machine space. A 3-D finite-element method (FEM) is needed to evaluate the performances of PM machines with an overhang structure because the overhang structure results in non-uniform magnetic flux distributions in the axial direction. However, it is computationally expensive, especially in the early design stage. In this paper, we propose a magnetic equivalent circuit (MEC) model considering the overhang effects of interior PM (IPM) machines. With the proposed MEC, the performances of IPM machines with an overhang structure were precisely calculated and the computational time was significantly reduced. The proposed MEC was verified by the 3-D FEM. [ABSTRACT FROM AUTHOR]

Current research on gas discharge theory has made significant development in terms of numerical simulation, but its analytical description of streamer mechanism remains overly simplified, as it is still based on the electron avalanche model characterized with the exponential growth and infinite breakdown current. This paper presents a simple analytical method of gas discharge based on the classic logistic model and covers four aspects. First, it gives the exact definition of generation and mortality rate of electron number, establishes a logistic differential equation and a logistic iteration model for streamer mechanism, and derives deterministic analytical and iterative solution. Second, we also extend the mortality rate to include negative value, thus allowing the logistic model to describe both exponential growth and S shape growth scenarios, and provide criteria for categorizing spark breakdown, Townsend discharge, and stable discharge (glow, arc, aka saturated streamer). Third, the logistic differential model can be transformed into an iterative model. From that we derive the criteria for evaluating discharge instability. Last, although our model is 1-D, but it is still practical and easy to use given its clear analytical expression of underlying physical mechanism. [ABSTRACT FROM AUTHOR]

In this paper, the electromagnetic performance and operating characteristics of magnetic-geared permanent-magnet machines (MGPMMs) are evaluated using the subdomain analytical method. We derive the governing equations for each region based on the electromagnetic theory and some assumptions. The undetermined coefficients of the governing equations are calculated using boundary conditions. Based on the analytical solutions, the electromagnetic performance is analyzed. The proposed analytical method is validated through the nonlinear finite-element method and an experiment. In particular, an analysis of the performance analysis of the slot combination, which is one of the design variables, suggests the increased power factor and operating range. The analytical method can be useful for the initial and optimal designs of MGPMMs. [ABSTRACT FROM AUTHOR]

In this paper, an analytical method for predicting the rotor overhang (OH) effect is presented using two types of conformal mappings (CMs), which are the ${r}$ – ${\theta }$ and zr plane CMs. First, the no-load air-gap flux density (AFD) of a slotted air gap without OH is determined using the ${r} {\theta }$ plane CM. Second, the complex relative air-gap permeance (CRAP) in the zr plane is obtained by the zr plane CM. This helps in taking the OH effect into account. Finally, the no-load AFD of the slotted and OH air gaps in cylindrical coordinates is derived from the no-load AFD in the ${r} {\theta }$ plane with CRAP along the ${z}$ -axis. The accuracy of the presented method is verified by comparing the results of no-load analysis with those of 3-D finite-element analysis. [ABSTRACT FROM AUTHOR]

This paper presents a method to quickly and accurately deduce the optimal pole-arc coefficient for achieving the maximum suppression of intrinsic shaft voltage in fractional-slot permanent-magnet synchronous machines (FSPMSMs). First, with the aid of the analytical method, not only the pole and slot number combinations which can yield the intrinsic shaft voltage in FSPMSMs but the analytical expression of the intrinsic shaft voltage are derived. Then, the effect of pole-arc coefficient on the intrinsic shaft voltage is investigated, and an optimal pole-arc coefficient which can minimize the intrinsic shaft voltage is calculated. Furthermore, the analytical results are validated by finite element method (FEM) well in 6-pole/9-slot, 8-pole/9-slot, and 8-pole/12-slot FSPMSMs, which indicates that the differences obtained between the optimal pole-arc coefficients by two methods are all less than 10%. In conclusion, considering the rapidity of the analytical method and the precision of the FEM, the analytical method should be used first to deduce an initial value to compress the interval of optimization, then run the calculation iteratively by the FEM to get the exact optimal pole-arc coefficient. [ABSTRACT FROM AUTHOR]

This paper presents the characteristic analysis and experiment of pitching moment in a high-precision permanent-magnet linear synchronous motor. The pitching moment is analyzed according to suggested strategy; therefore, analytical solutions for magnetic fields generated by PMs are derived based on the analytical magnetic field calculation in terms of a 2-D polar coordinate system. The analytical solution of each subdomain (PM, air gap, slot, slot opening, and end region) is derived, and the field solution is obtained by applying the boundary and interface conditions between the subdomains. The magnetic force is determined based on the magnetic field analysis results. Finally, the predictions are compared with the measured data to confirm the validity of the analysis methods presented in this paper. [ABSTRACT FROM PUBLISHER]

This paper presents an analytical method for estimating the maximum angular operation range (MAOR) in a permanent-magnet slotted limited-angle torque motor (LATM). The operating principle of three topologies is analyzed and discussed, including a toroidal LATM, a slotted LATM with common pole/slot combination, and a slotted LATM with special pole/slot combination. The analysis indicates that no effective methods have been proposed to estimate the MAOR for a slotted LATM with special pole/slot combination. Hence, this paper is focused on solving this problem. The results obtained from the analytical method are validated by a finite-element (FE) method. The average time of the proposed method takes far less than that of an FE method, so that the design cycle of LATMs can be shortened. Finally, two prototype machines are manufactured, and their experimental results are presented and discussed. The FE and experimental results validate the accuracy of an analytical method. [ABSTRACT FROM AUTHOR]

Compensated pulsed alternator (compulsator) is one of the most popular choices of pulsed power supplies for fusion reactors, high-power pulsed lasers, and hypervelocity electromagnetic launchers because of its high energy density and power density. In general, external excitation in the form of self-excitation or pulse-excitation is adopted in compulsators together with iron core or air core. This results in heavy, bulky components and a system that is more complicated and less reliable. In this paper, a novel compulsator that is excited using a permanent magnet (PM) and is equipped with an iron-core or air-core stator is proposed. An excitation converter or brush-slip ring system is not needed in the novel system, which consequently makes it more reliable, less massive, and less voluminous than the external excitation machines. In addition, the novel PM compulsator acts not only as a pulsed alternator capable of delivering high-power pulses but also as a brushless PM dc motor that can be employed to charge the energy storage rotor. Thus, no external driving motor or gearbox is needed in the pulsed power system, which makes the system integrated and compact. In this paper, analytical models for the air-gap magnetic distribution, the back electromotive force, and the pulsed current waveform of the machine are deduced. A PM compulsator is designed and analyzed, and a scaled prototype of the PM compensated pulsed alternator is fabricated and tested. The actual output voltage waveforms and pulsed-current waveforms are sampled and compared with the predicted ones, which clearly demonstrate that the design of the PM compulsator is feasible. [ABSTRACT FROM AUTHOR]

This paper presents torque analysis and testing of an eddy current brake with permanent magnets using semi-threedimensional (3-D) analytical magnetic field calculations. The magnetic field solutions are obtained by considering the eddy current reaction using a 2-D magnetic vector potential and 3-D case by a simple and effective axial dependence modeling. The magnetic torque is also determined from these solutions. A finite-element method (FEM) is employed to validate the analytical magnetic calculations. The braking torque measurement is experimentally verified to validate the analytical study. From the experimental study, we obtain analytical and 3-D FEM results of braking torque with thermal behavior, and these are in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

This paper describes the rotor design of high-speed permanent magnet (PM) synchronous motors considering rotor magnet and sleeve materials. The influence of four different sleeve materials with two differentPMmaterials on the mechanical stress of a high-speedPMrotor is presented, and the relationship between sleeve thickness and shrink fit is examined. Rotor design criteria according to rotormaterials are described by an analyticalmethod. The proposed method is validated by an actual operational test at 400000 rpm using a fabricated prototype rotor. [ABSTRACT FROM AUTHOR]

This paper presents the torque characteristics analysis and torque measurement of a magnetic spur gear with a three-segment Halbach array based on theQuasi Three-Dimension (3-D)AnalyticalMethod. It analyzes amagnetic spur gear that uses a Halbach array by employing an analytical method for torque calculation. In the analytical method, from the magnetic vector potential and a coordinate system conversion, analytical solutions are obtained for magnetic fields produced by source magnets. By using the derived magnetic field solutions, an analytical solution is obtained for the external magnetic flux density. The drive magnet is next reduced to the equivalent current densities, and the torque is computed from these currents in the external magnetic field, which is obtained from the second process. Finally, the leakage flux in the z-direction occurring in the magnetic gear is considered using the 3-D analytical method. Thus, an analytical result can be obtained. These results are validated by comparison with the finite element method. [ABSTRACT FROM AUTHOR]

For special types of electric machines, it is essential and of utmost interest to develop a mathematical model, characterize a machine for performance evaluation, and test the machine for study and applications. A 2-D analytical method for the performance evaluation of axial flux permanent magnet (AFPM) machine has been presented in this paper. The method computes the electromagnetic torque, magnetic field distribution, cogging torque, and back-electromotive force of the machine using quasi-3-D modeling. Fourier Transform is used for the solution of Maxwell's equations in different regions of the AFPM machine. A surface mounted AFPM motor is designed and developed and tested. Experimental results are demonstrated and compared with the results computed from the analytical model to validate the effectiveness and accuracy of the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, the torque production mechanism of variable flux reluctance machines (VFRMs) is investigated. Initially, based on an analytical instantaneous torque model developed from the Lorentz force law and airgap field harmonic analysis, the magnetic gearing effect is revealed in the torque production of VFRMs. Then, by using a 6-stator-pole/4-rotor pole (6s/4r) VFRM as an example, all its torque components, including synchronous torque, reluctance torque, and cogging torque, are analyzed separately under linear condition. Their average torque and torque ripple characteristics are comprehensively illustrated. Finally, the influence of saturation effect is also accounted for with the help of finite element and frozen permeability methods. The analysis results are verified experimentally. [ABSTRACT FROM AUTHOR]

The rotary type electromagnetic actuator is often used in the electromagnetic mechanical components design, such as high-sensibility switch, signal electromagnetic relay, and so on. This type of actuator is required to have high conversion speed and action frequency, high signal reliability, and low power consumption per volume. In this paper, a new type of rotary electromagnetic actuator with permanent magnet (PM) is designed. Based on the polarity characteristics of PM, a couple of coils are designed in diagonal direction. A flux guide path is designed to optimize the magnetic circuit. PM is applied as the armature, and the electromagnetic system and the contact system are designed individually, which can achieve a high level maximum space utilization. In order to study the characteristic of PM, the PM is divided into several subsections. The migration analysis of the working point based on analytic model is carried on for the selection of PM, and the precise static characteristics of the actuator are analyzed by the finite-element model. The prototype actuator is assembled and tested, and the advantages of fast conversion speed and high reliability is verified by the test. [ABSTRACT FROM AUTHOR]

This paper describes the analysis of the eddy current loss of a double-sided cored slotless-type permanent magnet linear synchronous generator considering tapped holes in mover magnets using the space harmonic method. To calculate the eddy current, an analytical solution was derived by applying the Maxwell’s equation, magnetic vector potential, and Faraday’s law in a 2-D Cartesian coordinate system. Based on the armature reaction field distribution produced by the armature winding current, we obtained an analytical solution for the eddy current density distribution. Then, an analytical solution for eddy current loss induced in a permanent magnet (PM) was derived using the equivalent electrical resistance calculated from the PM’s volume and eddy current density distribution solution. Finally, the resulting current was determined based on the analysis of eddy current loss. The analytical results produced by using this application of the space harmonic method were validated extensively through comparisons with finite-element method results. [ABSTRACT FROM AUTHOR]

Electromagnetic transients resulting from voltage dips not only present challenges for low-voltage ride-through (LVRT) of doubly fed induction generators (DFIGs) in wind turbines (WTs) but also introduce complications for protective relays in power systems. Analysis of the voltage-dip response is a fundamental requirement for methodologies targeting LVRT performance and is also useful for power system development. To date, it has not been feasible to take into account the interval between voltage dip and crowbar triggering, and, consequently, the accuracy of the analytical results has been compromised. In this paper, a concept of equivalent fault source is presented with which the transient process during voltage dips is decomposed into one response to the equivalent stator fault source and the other response to the equivalent rotor fault source. The former results from dips in the supply voltage, while the latter arises from variations in both the rotor resistance and the control voltage produced by crowbar activation. This makes it feasible to incorporate the interval, i.e., the triggering delay, into the analytical solution. Additionally, this decomposition approach allows for the physical mechanisms behind the individual transient components to be more clearly understood. With the explicit analytical formulas, some intrinsic characteristics of the transients are identified. The comparative accuracy and advantages of this analytical method over the conventional approaches is demonstrated through simulations using a 2-MW DFIG for commercial WTs and further verified experimentally on a laboratory-scale test rig. [ABSTRACT FROM PUBLISHER]

In this paper, an exact analytical solution based on Fourier analysis is proposed to compute the cogging torque in a surface-mounted permanent magnet synchronous machine. The analytical solutions are derived by solving the field-governing equations in each simple and regular subdomain, i.e., permanent magnet (PM), air, slot opening, and slot, and then by applying the boundary conditions to the interfaces between these subdomains. Based on these solutions, the cogging torque is also determined analytically. In order to verify the analytical results of the proposed method, an experimental system was implemented on a servomotor and a torque sensor. All analytical results were extensively validated using nonlinear 2-D finite-element analysis and experimental results. Using the proposed method, we investigated the influence on the cogging torque, according to the machine parameters. Therefore, the proposed method should be very useful in the initial design and cogging torque optimization of PM machines. [ABSTRACT FROM AUTHOR]

This paper presents electromagnetic modeling and analysis of the detent force in a permanent magnet linear synchronous machine (PMLSM) according to auxiliary teeth configuration. Analytical solutions for magnetic fields generated by PMs are derived based on the Maxwell equation in terms of a 2-D Cartesian coordinate system. The magnetic vector potential of each subdomain (PM, air-gap, slot, and end region) is derived, and the field solution is obtained by applying the boundary and interface conditions between the subdomains. Based on the analytical solution, the magnetic force is derived by using the Maxwell stress tensor. All the analytical results were extensively validated using nonlinear finite-element analysis and experimental results. Using the proposed method, we investigated the influence of the machine parameters on the detent force. Therefore, the proposed method can be very useful in the initial design and optimization process of PMLSM for detent force analysis. [ABSTRACT FROM AUTHOR]

Permeance variation in the air gap of the permanent-magnet synchronous machine induces eddy-current losses in its permanent magnets even in the absence of stator currents. This paper proposes a new analytical approach to analyze these losses using the permeance-variation vector function introduced for the air-gap magnetic-flux density distribution to take into account the stator teeth. The Laplace equation is employed to derive the radial dependency of the stator slotting effect on the magnetic-flux density distribution. The induced eddy currents are further calculated by using Faraday's law. The analytical results are compared with the numerical ones based on the finite-element analysis. The paper offers a faster alternative to the numerically intensive calculations of eddy-current losses, and the method is especially useful in initial design optimization of the electric machine. [ABSTRACT FROM AUTHOR]

In this paper, numerical and analytical approaches for the study of busbar systems are analyzed and compared. In the first part of this paper, the multiconductor model (MC) is presented for studying a general busbar system and the equation are formalized for "current-driven" and "voltage-driven" problems. Afterward, the "MC method" has been applied for solving a "current-driven" problem related to an industrial busbar system. The evaluation of current distribution and electrodynamic forces of the. system has been compared with the one obtained by using a classical finite-element method. Finally, the total current in the massive conductors of the system has been compared with the measurement. In the second part, an analytical approach for evaluating the electrodynamic forces is presented. The "adjacent massive conductors" configuration considered in the IEC standard 865/93 is fully detailed and the "nonadjacent massive conductors" configuration, not considered in the standard, has been developed. [ABSTRACT FROM AUTHOR]

The basic concept of superconductive magnetic gears (SMGs) is to maximize the benefits and impact of the magnetic gearing technology by highlighting the future perspective of SMGs to produce a more efficient and compact system. This paper deals with a new analytical method (AM) for the calculation of magnetic field distribution in an SMG. A 2-D AM based on Laplace's partial differential equations of magnetic scalar potential in the different subdomains of a magnetic gear is introduced and solved by considering the corresponding boundary conditions. The proposed method shows a significant reduction in the consumed calculation time compared with the finite-element method (FEM) and can be used as a basis for design optimizations. Two-dimensional AM results are compared against those obtained from 2-D FEM simulations, using an accurate, yet efficient, high-temperature superconductor (HTS) modeling, yielded by a detailed localized E-J power law approach combining the different aspects of HTS in a numerical method, so as to find out the benefits and validity of the presented AM. Finally, the effects of PMs and pole pieces' dimensions on torque density are realized. [ABSTRACT FROM AUTHOR]

This paper describes an analytical model for computing the rotor eddy-current losses in the case of permanent magnet synchronous machines, based on a formal resolution of Maxwell’s equations. We focus on the computation of the eddy currents in the machine magnets, in which the diffusion equation is analytically solved, using an accurate electromagnetic model of the stator slotting. The model originality lies in its capacity of taking into account both the diffusion phenomenon and the magnet’s finite length over the pole pitch, imposing that the total current over the magnet’s surface should be zero at each instant. This important problem is studied by solving a Fredholm integral equation. A validation using a 2-D time-stepping finite-element model is also performed, and the obtained losses are shown to be in good agreement with those given by the analytical method, for a shorter computation time. [ABSTRACT FROM AUTHOR]

In this paper, an analytical method is presented to compute the frequency-dependent magnetization inductance and iron losses resistance of the conventional equivalent circuit of current instrument transformers (CTs). This model considers the effect of eddy currents, which are more pronounced at higher frequencies. Furthermore, this model considers the characteristics of the commonly used toroidal laminated cores, which occur due to the spiraled windings of the lamination. Magnetic flux in the core is computed based on Maxwell’s equations. To get a more simple and numerically stable equation for the flux, the occurring Bessel functions are approximated. Finally, the parameters of the equivalent circuit are computed using the derived equation of the magnetic flux. The results of the proposed model are presented using the parameters of a CT. [ABSTRACT FROM AUTHOR]

In electromagnetic launch (EML) applications, a compensated pulsed alternator is an effective form of pulsed power supply because of its high energy density and power density. The basic advantages of compensated pulsed alternators for EML applications are their higher energy density than capacitors and their export ac output that is suitable for transmission and transformation. In general, external excitation is adopted as a form of self-excitation or pulse excitation in compensated pulsed alternators with an iron core or air core. Using this form not only results in heavy and bulky components but also complicates and reduces the reliability of the system. This paper proposes a novel compensated pulsed alternator that is excited by permanent magnets (PMs) and equipped with an iron core or air-core stator. This system does not require any excitation converter or brush–slip ring, thereby making it more reliable, less massive, and less voluminous than the system with self-excitation or pulse excitation. In addition, analytical models are introduced to simulate the air-gap magnetic distribution, back-electromotive force, pulsed current wave, discharge torque, and energy exchange of this machine. A scale-model prototype of the PM-compensated pulsed alternator is designed, fabricated, and tested. The actual output voltage waveform and pulsed current waveform are sampled and compared with the predicted ones. The results show that the design of the PM compulsator is feasible and reliable. [ABSTRACT FROM PUBLISHER]

The leader progression model (LPM) is a tool for estimating the lightning performance of transmission lines. However, the large computation time remains a problem for the engineering application of this model. An analytical method is proposed in this paper to mitigate the aforementioned problem. First, nonlinear trajectory equations describing the movement of upward and downward leaders are obtained, starting with differential equations. Based on the trajectory equations, the average electric field between the upward and downward leader tips is represented with a comprehensive nonlinear equation. The final strike point is determined by solving the equations. Results show that the proposed method effectively mitigates the large computation time problem of traditional (numerical) LPM. [ABSTRACT FROM AUTHOR]

This paper investigates the static characteristics of a novel air-cored linear and rotary permanent magnet actuator (LRPMA) with a Halbach permanent magnet array. By the given magnetization distributions and boundary conditions in the cylindrical coordinate system, the magnetic field distributions of the actuator are analytically analyzed using the magnetic scalar potential and the modified BESSEL functions. A 3-D finite-element (FE) model is established to validate the correctness of the analytical results. Analytical linear electromagnetic force and rotary electromagnetic torque, respectively, are derived and verified using the FE method for the characterization and optimization design of the air-cored Halbach LRPMA. [ABSTRACT FROM AUTHOR]

This paper presents an analytical methodology based on subdomain field model to calculate eddy current loss in vertical conductor windings (VCWs) of surface mounted, radial flux, permanent magnet (PM) machines considering the current penetration effect. The proposed model can be used with any slot–pole combination including fractional slot machines having VCW. Initially, the model solves the two-dimensional problem based on the Laplace's and Poisson's equations using the separation of variables technique for each of the subdomains: PM, airgap, slot opening, and slot. Then, based on that obtained solution, the eddy current reaction field in the slot is calculated by solving complex Helmholtz's equation. The validity and accuracy of the model is verified using finite-element (FE) analysis. The limitations of analytical method are discussed. [ABSTRACT FROM AUTHOR]

This paper presents a method for the calculation of eddy current losses in the permanent magnets, which takes into account the reaction of induced eddy currents. The developed quasi–3-D analytical method considers the effects of axial and circumferential segmentation of magnets. The 2-D time-stepping finite element method and 3-D time harmonic finite element method are used to evaluate the accuracy of the analytical method. A high speed surface-mounted permanent magnet motor with Samarium Cobalt magnets is used for detailed simulations. High-frequency time harmonics of the inverter are considered for analysis of magnet eddy current losses. The novelty of the proposed analytical method is the direct consideration of the reaction of induced eddy currents in the magnets due to travelling and pulsating field waves. [ABSTRACT FROM AUTHOR]

While axial flux permanent magnet (AFPM) machines are manufactured, their wrong assembly can be possible, such as misaligned PM rotor position of double-sided machine. Once the machines are assembled, detecting the misaligned rotor is hard, so the designers are required to have deep insight in its related and unexpected characteristics to prevent them focusing on other possible errors. Therefore, this paper deals with the characteristic analysis on the influence of the misaligned rotor position of double-sided AFPM machine and its experimental verification. In general, the AFPM machines have been analyzed by 3-D finite-element method (3-D FEM) due to their structural features, but it requires very long analysis time to consider various factors. For this reason, analytical approach is presented in order to consider all the cases of the misaligned rotor positions, and it is confirmed to be practical to detect the positions and to reduce analysis time with high reliability. With the analytical approach, the misaligned rotor position characteristics, such as back-emf and its total harmonic distortion are analyzed. Furthermore, all the analysis results are validated by 3-D FEM results and experimental verification. [ABSTRACT FROM PUBLISHER]

In this paper, a 3-D methodology for the overheating hazard assessment on transformer covers based on electromagnetic analytical formulation linked with thermal finite element method is presented. The objective is to offer a practical tool to compute the temperature distribution and to localize the hot spots on transformer covers due to electromagnetic induction. The proposed methodology is carefully focused on those cases where the electromagnetic wave penetration depth compared to the big machine dimensions is a key issue. The accuracy of obtained results is ensured by means of the identification of proper electromagnetic and thermal parameters involved in the computation. An experimental work is presented, and measurements are compared with simulation results using different finite element models. [ABSTRACT FROM PUBLISHER]

The analysis of propagation of bound and leaky modes in single and multiple coupled microstrip lines in planarly layered media by means of Galerkin's method applied to an electric field integral-equation formulation in the spectral domain with Chebyshev polynomials basis functions weighted with the edge behavior of the unknown surface current densities on the metallic strips leads to the evaluation of improper integrals of oscillating functions with a slow asymptotic decay. In this paper, a new analytical technique for drastically speeding up the computation of such integrals is presented. First, suitable half-space contributions are pulled out of the kernels, which makes the integrands exponentially decaying functions. The integrals of the extracted contributions are then expressed as combinations of proper integrals and fast converging improper integrals by means of appropriate integration procedures in the complex plane. [ABSTRACT FROM AUTHOR]

This paper focuses on the intrinsic aspects of power management for hybrid electric vehicles (HEVs) and plug-in HEVs (PHEV). A vehicle power distribution density function is used to describe the drive cycle characteristics. An electric driveline loss is introduced to describe the minimum system loss for a given mechanical power output, and a piecewise linear fuel consumption model is used to capture essential characteristics such as idle fuel consumption rate, peak efficiency, and the minimum power to reach peak efficiency. Models are based on the assumption that both machines operate at the optimal speed and torque for a given mechanical power as if they are coupled with an ideal continuous variable transmission (CVT). The power management strategy is represented with a pair of power parameters that describe the power threshold for turning on the engine and the optimum battery power in engine-on operations. The model of a parallel hybrid electric powertrain is constructed to obtain optimal solutions that maximize the fuel economy for a given battery energy depletion and for a general vehicle power distribution density function. One-dimensional loss models of two power sources as approximations to real machines coupled with hypothetic CVTs are introduced to solve the optimization problem analytically. It is found that the optimal minimum engine power is the controlling factor in minimizing the total fuel consumption for the given battery energy depletion targets and that the optimal power is solely determined by powertrain characteristics. Numerical simulations validated the properties of the optimal power solutions obtained through analytic approaches. The significance of the results to real-world HEV and PHEV applications are also discussed. [ABSTRACT FROM PUBLISHER]

In this paper, harmonic analysis and comparison of permanent magnet vernier (PMV) and magnetic-geared (MGd) machines are presented. The key is to analytically solve the governing Laplacian/quasi-Poissonian field equations in the air-gap regions. By using the time-stepping finite-element method, the analytical method is verified. Hence, the performances of the PMV machine are quantitatively compared with that of the MGd machine. The results show that the PMV machine can offer higher no-load EMF and higher torque-handling capability than its counterpart. Finally, the experimental result is given to further verify the validity of the analysis. [ABSTRACT FROM AUTHOR]

This paper describes the design and analysis of a high-speed and high-power density BLDC motor for a 50-kW, 70000-rpm class centrifugal compressor. Design criteria and power loss analysis of the high-speed machine structure are described by analytical method, and the results are validated by finite element method. And then, the prototype machine has been fabricated and tested. The experimental results confirmed the validity of the proposed design and analysis scheme of the high-speed BLDC motor. [ABSTRACT FROM AUTHOR]

An analytical method for calculating the incremental line inductance of a permanent-magnet synchronous motor is pro posed in this paper. First, the incremental inductance is simplified as a linear combination of the slot inductance and the air-gap inductance, which are both estimated, by the equivalent magnetic circuits. The reluctance of the rotor back irons and the stator back irons are ignored when the slot inductance is calculated However, for the calculation of the air-gap inductance, the iron saturations and the perturbations of the permanent magnet are considered. The proposed method is verified by a finite-element method. [ABSTRACT FROM AUTHOR]

Superconducting Magnetic Energy Storage can be used to produce very high pulsed power peak. A superconducting coil is magnetically coupled with another coil linked to the load. During the storage phase, the current is constant. In order to transfer the energy to the load, we cause the quench of the superconducting coil. It is very important to know the efficiency of the transfer and how much energy is discharged in the Helium vessel. In this paper, we propose an analytical method which enables us to calculate very quickly the electrical parameters of such a device. [ABSTRACT FROM PUBLISHER]