Vector Magnetic Characteristics of Ultra-Thin Electrical Steel Sheet for Development of High-Efficiency High-Speed Motor

This paper presents measured results of the 2-D vector magnetic characteristics of ultra-thin electrical steel sheets for high-efficiency high-speed motors. Generally, Non-oriented electrical steel sheets with 0.2-0.5 mm of thickness are used for motor cores. However, their thicknesses are not appropriate to use for cores of high-speed motors. We newly developed “Ultra-thin electrical steel sheet” with 0.08 mm of thickness to reduce the core loss of high-speed motors. The magnetic characteristics of the Ultra-thin electrical steel sheets are almost equal to NO (35A300) under exciting frequency of 50 Hz. Since the thickness of the steel sheet is very thin as 0.08 mm, eddy currents are hardly generated under high frequency. As the result, it was confirmed that the iron loss was decreased by 53% when we compare the iron loss of the motor used ultra-thin electrical steel sheets (0.08 mm) to that of the motor used conventional electrical steel sheets (0.35 mm) under the condition of 10 000 rpm.