Vibration Analysis of Internal Permanent Magnet Synchronous Machines Under Asymmetric Three-Phase Current Condition

The asymmetric three-phase current is always found in the internal permanent magnet synchronous machines (IPMSMs), especially for high load applications such as traction motor. In this paper, the vibration characteristics of IPMSMs under asymmetric three-phase current condition are analyzed considering different rotor eccentricities. Firstly, the Maxwell stress tensor and symmetrical component method are applied to obtain the electromagnetic force harmonics analytically with rotor centricity or eccentricity when the input three-phase current is asymmetric in amplitude and phase. Then, the finite element model of an 8-pole 48-slot IPMSM is built and simulated to validate the analytical results. Moreover, the vibrations caused by asymmetric three-phase current and different rotor eccentricities are also analyzed. Finally, an experiment is conducted to verify the results of mathematical and simulation analysis. It is found that the influence of asymmetric current on the rotor centricity machine vibration is negligible, while the interaction of asymmetric current and rotor static eccentricity would seriously deteriorate the vibration performances, the maximum vibration under this condition is 12 m/s(2), almost 6 times larger than the vibration under symmetric current.