Abstract

This paper presents the analysis and experimental results of the application of a composite material (CFRP) sleeve to the rotor for enhancing motor efficiency measurements in the highspeed motor of an oil-free air compressor for fuel-cell electric vehicles (FCEVs). Carbon Fiber Reinforced Plastic (CFRP) applies two or more types of materials for better properties: high strength and lower density. The predicted motor loss at the maximum speed of the oil-free air compressor compared the sleeve performance of each sleeve between Inconel718 and CFRP. The eddy current loss of the CFRP sleeve rotor decreased by 90% compared with that of the previously developed rotor. Rotordynamics model predictions of the two types of sleeves manufactured benchmark the test data. The 1st bending natural frequencies of the CFRP sleeve rotor decreased by 15% against the Inconel718 sleeve rotor. In addition, this study compares the analyses of 2D and 3D models. The results show that the CFRP has low isotropy compared Inconel718 sleeve rotor. This trend is the same as that observed in the experiments. The CFRP sleeve was made by the prepreg of T300-class carbon yarn and epoxy resin, which are commonly used, and was molded using autoclave equipment. It satisfies a 1.5 mm thickness through 8Ply rolling. A series of rotor impact tests were conducted to compare the 1st bending natural frequencies of the previously developed sleeve rotors; Inconel718 and CFRP sleeves. The impact test showed that the CFRP sleeve rotor exhibited different 1st bending natural frequencies depending on the high-temperature and room-temperature conditions, and the range of change was larger than the Inconel718 sleeve rotor. The impact test results at room temperature showed a 25% decrease compared to the Inconel718 sleeve rotor. A previously mass-produced compressor was used in this experiment. Our performance evaluation equipment measured the performance and efficiency of the test compressor. A series of compressor performance and saturation tests at 80k and 90k RPM indicate that the CFRP sleeve results in an efficiency increase of 2% and an 8% decrease in the operating temperature. However, the CFRP sleeve rotor needs to be further improved to increase the operation speed (up to 90kRPM) of the high-speed motor of the oil-free air compressor.

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