This paper presents torque analysis and testing of an eddy current brake (ECB) with permanent magnets (PMs) using semi-three-dimensional (3D) analytical magnetic field calculations. The magnetic field solutions are obtained by considering the eddy current reaction using a 2D magnetic vector potential and 3D 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 3D FEM results of braking torque with thermal behavior, and these are in good agreement with the experimental results.

This study deals with the analysis of electro-mechanical characteristic analysis on permanent magnet synchronous machines (PMSMs) for electrically driven tools primarily used in industrial applications. This study compares the noise, vibration, and harshness (NVH) characteristic results generated by fractional pole/slot combinations. The electromagnetic (EM) analysis results of the PMSMs are derived using the finite element method (FEM), and the NVH analysis is performed by applying the EM analysis results. The analysis results and the effects of EM characteristics on the vibration of the PMSMs were analyzed. The effects of EM excitation characteristics on the rotor vibrations in the PMSM were compared and analyzed.

This paper presents a characteristic analysis and experimental verification for predicting the electromagnetic losses in high-speed permanent magnet synchronous motors. To predict the operating characteristics (such as speed and input current), dynamic modeling is conducted that combines models for the space vector pulse width modulation (SVPWM) inverter and high-speed permanent magnet synchronous motor (HPMSM). By applying the predicted harmonic currents to the electromagnetic analysis, DC and AC copper losses of the stator winding, and eddy current loss of the rotor sleeve and rotor permanent magnet, are comprehensively analyzed using the finite element (FE) method. In particular, by analyzing the magnetic field behavior of magnetic flux density according to harmonics, a core loss analysis technique was presented. The validity of the hybrid analysis, which combines the stator copper loss and rotor eddy current loss derived from the FE analysis and the proposed core loss analysis, was verified through comparison with the experimental results under various operating conditions. Compared with the experimental results, the error of total losses using the hybrid analysis with a sinusoidal current was about 47.39%, and total losses using the hybrid analysis with a harmonic current was significantly improved to within 3.7%.

In high-speed permanent magnet synchronous generator (PMSG), the rotor design should not only ensure mechanical stability at high speeds but also ensure the required electromagnetic (EM) performance. This paper deals with the EM analysis and design of high-speed PMSGs considering the rotor structure. In particular, the effects of active power and output voltage due to internal impedance from leakage flux are presented. The relationship between design variables of rotor and performance is analyzed using three-dimensional static finite element analysis and simplified equivalent circuit method. Based on the analysis results, a model with improved EM performance using a nonmagnetic pad is presented according to design parameters of rotor structure. The EM performance and the mechanical reliability of the designed model are validated by comparing the FE results with experimental results.

This paper presents the analytical modeling and experimental study for electromagnetic analysis of tubular linear synchronous machines with axially magnetized permanent magnets, accounting for the flux-passing iron pole. The field domains are divided into five regions: air gap (I, III), coreless winding (II), outer magnet mover (i), and nonmagnetic material (IV). The governing equation in all subdomains can be solved, and the field distribution can be obtained by applying the boundary conditions to the interfaces between the subdomains. The analytical solutions allow for the prediction of the back electromotive force, inductance, and generating characteristics in closed forms. The magnetic field and electromagnetic performance obtained by the analytical method were compared with those obtained by the finite element method and experimental test. In turn, these facilitate the characterization of the machines and provide a basis for comparative studies, design optimization, system dynamic modeling and simulations, and control development.

In a permanent magnet (PM) machine, core losses are caused by the changing flux densities in various parts of the iron structures. As some of these core losses can be significant during high-frequency operations, it is imperative to consider the core losses during the design stage. The purpose of this study is to analytically predict the core loss of the PM machine at the design stage. The stator core loss can be calculated from the loss coefficient calculated by curve fitting of the original core loss data and the magnetic flux density of the stator calculated by the analytical method. The core loss obtained by the analytical method is compared with those obtained using the finite element method and experiments. The core loss results obtained using the proposed method were verified by implementing an experimental system with a commercial PM machine, power analyzer, and the manufactured test PM machine.