Rotor-Bearing System Design of a High Speed Electric Motor Supported on Ball Bearings and Squeeze Film Dampers

Abstract

This study presents a prediction of the electromagnetic and rotordynamic characteristics of a high-speed electric motor system consisting of an electric motor, inverter, and oil pump [1, 2]. The shaft (made of Inconel 718) is supported on four angular contact ball bearings and squeeze film dampers. The shaft sleeve (made of Inconel 718) features a shrink-fitted permanent magnet (made of Sm2Co17). Electromagnetic analysis results indicate a magnetic density below 1.5 T in the current electric motor 2D FEA model, a crucial factor in reducing losses during ultra-high-speed operation [3-6]. The rotordynamic analysis results reveal imbalance responses, natural frequencies, and mode shapes of the rotor, with no shaft bending modes present in the operating area. The results also demonstrate that imbalance mass response decreases and damping ratio increases as the radial clearance of the squeeze film damper increases. All results of the squeeze film damper journal displacement divided by the squeeze film damper clearance were below 0.1