Experimental and Numerical Research Studies on Multifield Coupling Rotordynamic Behaviors of Motor

The magnetic pull, bearing forces, and operating temperature, as important factors affecting motor performance, actually act together on the electric motor. In this study, the magnetic-solid-thermal coupling rotordynamic behaviors of a three-phase asynchronous motor are investigated via experiments and numerical analysis. A motor test platform controlled by a variable frequency converter is offered, and the experiments under multiworking conditions are carried out to explore the rotordynamic characteristics of the motor system. A rotordynamic modeling method of the magnetic-solid-thermal coupling system is presented for analyzing the coupling effect of the unbalanced magnetic pull (UMP), nonlinear ball bearing forces (NBB), and operating temperature on the motor rotordynamic behaviors. All of the predicted results coincide well with the experimental data to validate the presented model. Through experiments and numerical analysis, it is shown that the interaction of magnetic, structural, and thermal fields plays a significant role in the nonlinear vibration of the motor rotor. UMP, even with slight amplitudes at low rotating speeds, can induce a remarkable impact on the dynamic characteristics of the system on account of the nonlinear effect of ball bearing forces. The combined action of UMP and NBB on the thermal effect is more notable than that of single action. The effect of the unbalanced load gradually decreases with the increase of the temperature. The experimental and numerical results indicate that the magnetic-solid-thermal coupling influence is a noticeable issue in the optimum design, failure diagnosis, and operation maintenance of motor systems.