Abstract
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.
Highlights
Electric motor is one of the essential and important components to realize the reciprocal transformation of electrical energy and mechanical energy
In order to investigate the dynamic characteristics of the motor rotor system under a multifield coupling condition, an experimental platform is employed, as shown in Figure 1. e motor whose rotating speed is controlled by SPWM variable frequency drive (VFD) or inverter (MicroMaster 440) is mounted on the rigid base. e laser displacement sensor (M7L-4) with a resolution of 0.001 mm is placed vertically at the end of the shaft. e motor rotor is supported by two ball bearings at the two ends of the shaft
A motor test platform controlled by a variable frequency converter is established, and the experiments under multiworking conditions are carried out for analyzing the rotordynamic characteristics of the motor system
Summary
Electric motor is one of the essential and important components to realize the reciprocal transformation of electrical energy and mechanical energy. Only a few of published articles had studied the nonlinear dynamic behavior under one or two of these factors It is noted by Harris [13] that the friction in ball bearing could lead to the temperature rise, which could have an important impact on the rotor-bearing system. Numerical or/and experimental research studies on the coupling effect of electromagnetic, mechanical, and thermal factors are still scarce, especially the corresponding research studies combined with experiments. Combined with a large number of experimental tests and numerical analysis based on the presented coupling dynamic model, the mechanism of magnetic-solid-thermal interaction and the influence of multifield coupling characteristics of the motor are investigated efficiently in this study
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