| Because of the permanent magnet BLDC motor has small torque fluctuation,simple rotor structure, high efficiency, so it is suitable for high speed fan. Whenthe fan is rotating highly, it can make noise loudly; and it running after a period oftime it will be very hot. In order to solve these technical problems, many scholarshave made a thorough research in electric machine design.When the fan rotates at high speed, the frequency of the permanent magnetbrushless dc motor is very high, it can produce very big loss, temperature is too high.It will make fan cooling is not good, even make permanent magnet demagnetization,and lead to the motor operates abnormaly. About motor's loss and torque rippleproblem, this paper designed a permanent magnet brushless dc motor with doublerotors and single stator structure, which is used in high speed fan. This paper mainresearch contents include:(1) Studying the fan's torque fluctuation and loss problem in the permanentmagnet BLDC. Stator core uses no tooth structure, which fundamentally eliminatesthe cogging torque and torque ripple can reduce. The rotor with double rotorstructure can greatly reduce the loss of iron core. Counter rotating torque fluctuation,and calculation of rotor loss are analyzed by finite element method. We study theair-gap length how to influence the rotor eddy current loss.(2) The finite element theory and simulation software was introduced in detail.The concrete operation process of Maxwell is told. Finally in environment of AnsoftMaxwell2D we made a two-dimensional model, and the empty and load simulationanalysis was carried out. The results is concluded that the designed for use in the fanmotor is in conformity with the technical indicators.(3) According to the size of the optimization, we made prototype, and carriedon the test, test results were given by analyzing the prototype production qualified. |
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