The Study on Vibration and Noise Characteristics of Fan Motors Caused by the Electromagnetic Force

C3 - Motors

The fan motors is combined with motor and fan for cooling of the equipments. The fan motors are using many equipments such as Information equipment, OA equipment, electrical household appliances, in-vehicle equipment, and industrial equipments. Commonly the fan motors are required for high efficiency, high air capacity, and low vibration and noise. In particular, recently market focus to lower noise and vibration. Vibration and noise in the fan motors have been studied separately as problems of fluid dynamics, mechanical structural dynamics, or electromagnetic dynamics. Recent trends in many people’s lifestyles brought up reduction of vibration and noise of the fan motors as an important issue. In order to solve these issues, analyses on fluid dynamics, electromagnetic dynamics, and mechanical structural dynamics of the fan motors are needed to be performed not separately but simultaneously. This is because in a fan motor vibration and noise can be caused electromagnetically, mechanically, or fluid-dynamically at the operated speed. In other words, the vibrations and noises caused in three different mechanisms overlap one another. Fluid dynamics, electromagnetic dynamics, and mechanical structural characteristics are important factors for vibration and noise in the fan motor.
In this study, effect on the noise caused by electromagnetic dynamics and fluid dynamics the small fan motor is clarified. The noises of the fan motor caused by the blade-passing force and the electromagnetic force were prominent. Intense peaks were present at frequencies at which both the blade-passing force and the electromagnetic force have their harmonic components. In particular, noise becomes maximum at a frequency that the harmonic frequency of the electromagnetic force and the natural frequency in the fan in the axial direction to match. This noise in the axial direction is highest. Regarding the vibration and noise in the fan motor, radiated noise generated structure vibration cause by the electromagnetic force, and fluid noise characteristics caused by fluid dynamic are clarified.