Conventional surface mounted permanent magnet synchronous motor (SPMSM) at high speed has large iron loss in the stator and eddy current loss in the rotor. The higher the eddy current loss, the higher the rotor temperature. Therefore, a plan to reduce the loss must be devised. Also, weight at high speed is related to mechanical stiffness and electromagnetic vibration noise. Therefore, a plan to reduce the weight must be devised. In this paper, we propose to change the shape of the conventional 15 kW 110 000 rpm class into a slotless shape. A process of protocol change was proposed, and the sizing design of the rotor and stator was devised. The advantages of the proposed shape were verified through performance comparison through finite element analysis (FEA) and mechanical stiffness analysis.

A ring magnet attached under the safety window motor is used for detecting the position of the window with a hall sensor. A dead zone that the magnetic flux is weak appears between the poles of the ring bonded magnet and the larger the angle of the dead zone, the more difficult it is to detect the precise position of window. In this study, the shape of polar anisotropic magnetizing yoke with a magnetic flux concentration structure is proposed to reduce the range of the dead zone. A magnetic equivalent circuit (MEC) was presented to prove the theoretical validity. With the design variables as the inner width, outer width, and magnetic flux angle of the teeth of the yoke, the response value for the dead zone minimization was obtained using the response surface method, which is an optimization technique. And to examine this result as the tendency of flux line change in the model, finite element analysis was performed, and the final model was obtained. The prototype of the final model was manufactured, and the validity of the analysis result was verified.

Demand for high-speed motors is increasing. Surface-mounted permanent magnet synchronous motors (SPMSM) used in high-speed applications have magnets attached to the rotor, so there is a risk of damage and scattering due to centrifugal force as the speed increases. For this reason, applying the retaining sleeve to the rotor is essential. However, when using sleeves, there is a problem of reducing efficiency due to eddy current loss. In this paper, a study was conducted on a motor for a 100 kW building air conditioning system operating at a speed of 20,000 rpm. The purpose of the study is to reduce eddy current loss by optimizing the sleeve geometry. To this end, 3D finite element analysis (FEA) using JMAG 22.1 was conducted to analyze eddy current loss, the minimum safety factor was analyzed through mechanical stiffness analysis using ANSYS Workbench, and the validity of sleeve shape was proved through cause analysis. Through the research results, it is expected that the shape change of the sleeve will have the effect of reducing eddy current loss.