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 deals with the optimization design process of an interior-type permanent magnet synchronous motor (IPMSM) for electric compressors of air conditioners applied to electric cars and hybrid vehicles. Based on a prototype IPMSM, we identified the current level for efficiency and cogging torque using finite-element analysis (FEA). The IPMSM’s main design variables are optimized to primarily satisfy the target of efficiency and cogging torque. A second optimization design is carried out using the response surface method (RSM) for the main design variables obtained from the Taguchi method analysis. As a result, the optimization design is carried out through a two-step optimization design process using the Taguchi method and RSM. The IPMSMs are analyzed using FEA, and their validity is confirmed by comparing the test results against each step-by-step model. We validate an effective optimization design process using a two-stage design process. We conclude that the proposed approach provides an effective design method for engineers.

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 permanent magnets (PMs) are derived based on the Maxwell equation in terms of a two-dimensional 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.

This paper describes the rotor design of high-speed permanent magnet (PM) synchronous motors (PMSMs) consider-ing rotor magnet and sleeve materials. The influence of four dif-ferent sleeve materials with two different PM materials on the mechanical stress of a high-speed PM rotor is presented, and the relationship between sleeve thickness and shrink fit is examined. Rotor design criteria according to rotor materials are described by an analytical method. The proposed method is validated by an actual opera-tional test at 400,000 rpm using a fabricated proto-type rotor.

This study investigates the correlation between rotor vibration and mechanical stress in ultra-high-speed permanent magnet (PM) synchronous motors; the mechanical stress generated in the PM and the rotational vibration when the PM synchronous motor rotates at high speeds were evaluated. Two PM rotors that have the same performance characteristics but different shrink fits were studied, and the vibration of these two PM rotors was analyzed. Further, to evaluate the correlation between mechanical stress and vibration, the rotor design parameters, such as sleeve thickness and shrink fit, were varied. Based on the analysis results, a real-world model was developed and an experiment was conducted to test the vibration of these two rotors; the validity of our results was verified by performing experiments.

This paper proposes an analytical technique for calculating the armature reaction field and inductance of permanent magnet linear synchronous machines based on a subdomain analytical model. The analytical solutions based on the subdomain model in terms of a two-dimensional Cartesian coordinate system are obtained using continuous and Neumann boundary conditions. The analytical results of the magnetic field are validated extensively with finite element method (FEM). Based on these solutions, the inductance is also determined analytically. In addition, we improve the accuracy of the analysis by using a simplified method of calculating the end inductance. Finally, the predictions are compared with a three-dimensional FEM and measured data to confirm the validity of the analysis methods presented in this paper.