In general, permanent magnet (PM) motors are driven by a pulse width modulation (PWM) voltage source inverter for vector control. The generated PWM signals cause high-frequency voltage components at the carrier frequency. Such components can increase the electromagnetic losses, thereby necessitating the consideration of the phase current corresponding to the carrier harmonics. This study aims to examine the feasibility of high-speed permanent magnet (PM) motors in which rare-earth magnets are replaced by ferrite magnets, by considering the current harmonics. The electromagnetic characteristics of a high-speed motor with rare-earth and ferrite PMs were analyzed considering the current harmonics. Based on the existing rare-earth magnet model, a ferrite magnet model with the same performance was developed to perform a comparative analysis. The findings were validated via comparison with the experimental results of the manufactured models.

In this article, an exact analytical model for predicting irreversible demagnetization in Permanent Magnet Synchronous Machines (PMSMs) under overload and high-temperature conditions is presented. The proposed model includes a nonlinear model combined with a process for determining demagnetization. First, the nonlinear model considers non-uniform magnetization by dividing each permanent magnet (PM) into numerous small segments with separated remanence flux densities (RFDs). Harmonic modeling (HM), combined with an iterative loop, is employed to obtain nonlinear solutions, accurately capturing saturation effects that lead to high demagnetizing fields. The RFDs are iteratively updated until convergence is achieved. The proposed model can accurately predict machine behavior, capturing both demagnetization and saturation effects. Validation using a PMSM shows excellent agreement with both Finite Element Analysis (FEA) and experimental results, significantly reducing computation time compared to FEA simulations. This approach provides a robust tool for engineers to design and evaluate PMSMs, ensuring machine reliability under adverse conditions.

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.

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 torque characteristics analysis and torque measurement of a magnetic spur gear with a three-segment Halbach array based on the Quasi Three-Dimension (3-D) Analytical Method. It analyzes a magnetic 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 (FEM).

In this study, a 10 MW-class superconducting generator that can be applied to electric propulsion aircraft and large-capacity wind turbines is proposed. An active shielding air-core rotating armature-type superconducting generator was designed to minimize the weight and maximize the power density. A 10 MW 3000 rpm class (specific power: 13.7 kW/kg) generator for an electric propulsion aircraft and a 10 MW 500 rpm class (specific power: 4.3 kW/kg) generator for a large-capacity wind turbine were designed, respectively. In addition, to experimentally verify the armature rotating partial superconducting air-core-type superconducting generator, small experimental devices were manufactured, and preliminary experiments were performed on the force characteristics of the superconducting coil and the generating characteristics of the rotating armature-type generator to verify the feasibility of the study.