Selection of Rotor Retaining Sleeve Considering Loss Density and Prototype Machine Operating Characteristics in 2-pole Ultra-High-Speed Motors

Abstract

In recent years, the demand for miniaturized electric motors with high output power density has significantly increased. High power density can be achieved by increasing the rotation speed thus, research on ultra-high-speed motors is being actively conducted. Ultra-high-speed motors have a high operating frequency and large losses inside the motors therefore, it is difficult to cool the rotor for continuous operation. If a concentrated winding structure is used to enhance the output power density, the rotor loss further increases. Therefore, in this study, we focused on the material of the rotor retaining sleeve and designed an ultra-high-speed motor considering the loss density. We developed a prototype machine with separate magnetic bearings from the motors and clarified the precise operating characteristics of the ultra-high-speed motor through experiments. We also report some detailed operating characteristic of the motor under different load conditions.