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Axial flux permanent magnet (AFPM) machines are being increasingly used in several applications owing to their outstanding features. Most importantly, they are characterized by a high power-to-weight ratio, compactness, and high efficiency. Designers of AFPM generators seek to achieve the required performance and ensure the proper operation of the machine for the targeted application. Among many other parameters, the performance of the machine is highly dependent on the air gap magnetic flux density and no-load induced voltage. Accurate computation of such parameters helps minimize the overall design process. Therefore, the estimation of flux density plays a vital role in determining many other dependent parameters in AFPM machines. This manuscript provides a robust Correlated Analytical Method (CAM) for calculating the air gap magnetic flux density and no-load induced voltage of Coreless Axial Flux Permanent Magnet Generators (CAFPMG). CAM is an extended version of the Simplified Analytical Method (SAM) that is adjusted using correlated coefficients derived from an experimentally validated Three-Dimensional (3D) Finite Element Model (FEM). A complete procedure for the calculations is provided. The results showed the integrity of the CAM compared to the results obtained from the validated FEM. Such a technique will help designers of CAFPM machines perform parametric analysis and optimization in a fast and reliable manner. [ABSTRACT FROM AUTHOR]

This paper introduces a novel index for static eccentricity (SE) fault diagnosis in synchronous reluctance motors (SynRMs). Although SynRMs with rotor barriers under SE have been modeled in a few papers, any indices for the fault detection have not yet been reported. The proposed index is a specific frequency pattern in the motor current, which can also determine the fault severity. A novel analytical magnetic field investigation is applied to ascertain the proposed index. An accurate nonlinear numerical method is proposed for the motor inductances calculation. The model considers the rotor flux barriers, magnetic saturation, and the stator slots effect. The air gap flux density and the motor current are then achieved. The fast Fourier transform is exploited as a signal-processing tool to calculate motor current spectra. Then, a two-dimension time-stepping finite element method is used to attest of the proposed numerical model. Effectiveness of the proposed index is verified by simulation and experimental tests. [ABSTRACT FROM AUTHOR]

In this paper, a novel mechanical flux-adjusting interior permanent magnet (MFA-IPM) motor is proposed. The key is to employ an additional mechanical flux-adjusting (MFA) device attached to one side of the rotor, which can achieve flexible adjustment of the air-gap flux and obtain a wide speed range. This system with appropriate gears uses centrifugal force to set the cylindrical PMs in a required position. The topology and working principle of the MFA-IPM motor are introduced. Then, the dynamic performance prediction between the deformation length of spring and the rotation angles of PMs is obtained by the dynamic simulation. Moreover, the electromagnetic characteristics of the proposed MFA-IPM motor and a conventional IPM motor are analysed and compared based on finite element analysis, including no-load performances, inductances, electromagnetic torque, flux-weakening ability and speed range, as well as demagnetization evaluation. Finally, a prototype MFA-IPM motor is fabricated and tested. Both the simulation and experimental results indicate the validity and feasibility of the MFA-IPM motor. [ABSTRACT FROM AUTHOR]

Vernier permanent magnet (VPM) machines have been widely used in the last two decades due to their high torque density resulting from their magnetic gearing effect. In this paper, we present a new design of VPM machine with higher efficiency and power/weight ratio than their conventional counterparts. The proposed design is a combination of discrete-pole and hybrid-pole VPM machines, which incorporates the attractive characteristics of both types to improve the distribution of air-gap flux density and reduce construction costs. The arrangement of the magnets in the stator is spoke type, and their magnetization is peripheral. In order to determine the performance characteristics of the proposed machine, an analytical model based on the subdomain method is presented. The proposed method employs a quasi-Cartesian coordinates system to express the Laplace's and Poisson's equations, as well as to determine the solution for each region. Then, the solution of the equations is written in the form of hyperbolic functions and the mathematical expression of the coefficients of the equations will be simpler. To validate the proposed analytical model, a Vernier machine is designed and fabricated and the results of the experimental experiments are compared with numerical (machine simulation in finite element analysis software) and analytical results. The comparison of these results shows that the proposed model is highly accurate. [ABSTRACT FROM AUTHOR]

In surface-mounted PM machines, the cogging torque and the low-order harmonics of the air gap magnetic flux density are the main sources of the torque pulsation. These variables are strongly influenced by the distribution of the PMs on the surface of the rotor as well as the PMs' magnetization. In the presented work, the impact of the arrangement of the PMs and the PMs' magnetization pattern is studied. The PMs are arranged by some techniques such as PM arc optimization, PM shifting, PM segmentation and applying mixed material PMs. In addition, the parallel and radial magnetizations are investigated. For this purpose, the air gap flux density and cogging torque in the slotted SPM machines are predicted analytically. Using the analytical model and applying a direct search algorithm, the optimum arrangement for each technique is found. Moreover, to perform a multi-objective optimization, a weighted normalization method is applied. Finally, the proposed model and the obtained results are validated by finite element analysis. [ABSTRACT FROM AUTHOR]

In this work, an analytical model is developed for the modulated flux density in the surface-mounted PM Vernier machines. The model is valid for on-load and no-load conditions. In the modeling process some conformal transformations, including a Schwarz–Christoffel and a few bilinear transformations, as well the Laplace' solution are applied to obtain the air gap flux density of the PMs and the armature reaction. The limitation of existing conformal transformation-based methods in the modeling of the modulated fields is discussed. To remove these limitations, the concept of the equivalent magnetization current and the uniqueness theorem are adopted. In the modeling process, the machine cogging torque and the electromagnetic torque are obtained analytically. Finally, the obtained results are compared with the results of finite element analysis and the results of the complex permeance model. [ABSTRACT FROM AUTHOR]