The study of eddy current in rotor and circuit coupling analysis for small size and ultra-high speed motor

Recent developments of power electronics technology, low-loss iron core materials and highly efficient permanent magnet, etc have made it possible to realize a small size, high or ultra-high speed, and high performance electrical drive system. We designed and built a trial ultra-high speed drive system of 2 poles, 5 kW, 240,000 rpm and had described our prototype system and showed some experimental results in the previous paper. This kind of motor is supported to development of various technology, such as control technology including DSP, FPGA, etc., power conversion technology and design technology which includes a finite element method. The development as a comprehensive drive system is necessary. We describe the coupled analysis model which is represented for entire drive system. This model was used to evaluate the fundamental motor characteristics at the first of design stage. And the model also has been applied to total systematic approach to enhance the total drive system. Trial for reducing the eddy current in the inconel material for magnetic-scattering-proof was also examined in consideration of transient analysis by using the FEM for this ultra-high speed motor.