This paper presents a comparison of axial flux permanent magnet machines (AFPMs) with an electrical steel core and that with a soft magnetic composite (SMC) core. SMCs have several advantages such as low core loss and low eddy current loss. However, compared with electrical steel, SMCs have poor magnetic properties such as low flux density saturation and unsaturated relative permeability. The analysis of the electromagnetic characteristics in a wide frequency range revealed that for an AFPM using an electric steel core, the performance was excellent in a low-frequency range; however, for an AFPM using an SMC core, the performance improves with an increase in frequency. Finally, the operation area of an AFPM using an SMC core is proposed.

This paper presents design guidelines for a high-speed permanent magnet synchronous motor (PMSM) for a 110 hp and 12 500 r/min centrifugal pump considering the mechanical and electromagnetic characteristics. We selected the size of the rotor based on the torque per unit rotor volume method. The rotor stress analysis was performed using the analytical method and the finite-element method. Based on these results, appropriate sleeve thickness and material were selected considering mechanical stability and electrical performance. The PMSM design was carried out by using the mechanically stable rotating body, and the model with excellent electromagnetic performance was selected based on the iron loss analysis and the eddy current loss analysis using the finite-element method. In addition, the stability of high-speed operation was confirmed by the critical speed analysis of the finally designed PMSM model. The high-speed PMSM verifies the performance through the manufacturing and test it was confirmed that there is no problem when applied to the actual centrifugal pump systems.

This study considers the reduction of the force ripple of a permanent magnet linear synchronous machine (PMLSM). The PMLSM has a relatively large magnetic air gap. Therefore, a slot-ted type of stator structure is generally employed. Furthermore, the detent force, which is caused by the energy imbalances owing to the interaction between the tooth-slot structures and the permanent magnets (PMs), must be minimized for better start-up performance. Therefore, in this study, the addition of the auxiliary teeth and teeth notching are employed to reduce the detent force. In particular, the influence of the auxiliary teeth and notching on the detent force is analyzed, and an experiment is per-formed to verify the proposed design.

This paper describes the analysis of the eddy current loss of a double-sided cored slotless-type permanent magnet linear synchronous generator (PMLSG) 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 two-dimensional 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 using by this application of the space harmonic method were validated extensively through comparisons with finite element method results.

This paper proposes 2D equivalent analysis techniques for BLDC motors with 3D structures that are permanent magnet (PM) overhang and housing-integrated rotor core. These 3D structures require 3D analysis method for accuracy of analysis. However, being a time consuming process, 3D analysis method is not a suitable choice for initial motor design. In this paper, it is proposed that this limitation can be addressed by replacing 3D structures with 2D equivalent analysis techniques. First, PM overhang is corrected to have same magnetic energy as in 2D analysis model. Second, housing-integrated rotor core is corrected to consider magnetic flux in radial direction. Finally, the 2D equivalent analysis techniques is validated by comparing experimental results of electromagnetic performance with corrected and uncorrected 2D analysis models.