In the 45kW high-speed permanent magnet machine test rig

permanent magnet machine's raising speed experiment was made to research the influence of bearings supply pressure and the raising speed rate on the shaft stability.Bifurcation plot

frequency-domain characteristic and axes locus were analyzed to find sub-synchronous vibration.The result shows that:adjusting the bearing supply pressure can control bifurcation point from 18400r/min to 38900r/min

and eliminate half-speed whirling under 38900r/min.To change the raising speed rate (from 825(r/min ) /s to 660(r/min ) /s) can reduce power frequency vibration amplitude from 95μm to 75μm.