关键词: 永磁同步电机, 气动噪声, 计算流体力学, Lighthill声类比

Abstract: To accurately predict and optimize the aerodynamic noise of the self-ventilated permanent magnet synchronous motors(SVPMSM) at high speed, a method combined with CFD approach and Lighthill acoustic analogy was applied to simulate the aerodynamic noise of the motors. RNG k-ε model and large eddy simulation were used to simulate the flow field in the motors. Then, Lighthill acoustic analogy method was used to solve the acoustic problems, which were verified by experiments. A simplified model without air duct was established to study the effects of different fan structures on aerodynamic noise. The effects of duct expansion chamber structures on aerodynamic noise was studied by the motor simulation model. The results show that the difference between the sound power levels calculated by the motor simulation and the test at 4250 r/min is as 0.6 dB(A), which prove that the aerodynamic noise simulation model may effectively predict the aerodynamic noise of the motors. Through motor optimization, it is found that the changes of fan inner radius and blade curvature have little effect on the flow field, so there is little difference in aerodynamic noise. More blades and equidistant arrangement have better acoustic characteristics than less blades and non-equidistant arrangement. The expansion cavities added to the air ducts of the motors have a better noise reduction effectiveness at the low frequencies. The sound power level of the motors with the expansion chamber length of 94.4 mm is lower than that with the expansion cavity length of 134.4 mm. Setting two expansion cavities in the air ducts have a better noise reduction effectiveness than that only setting one expansion cavity.

Key words: permanent magnet synchronous motor, aerodynamic noise, computational fluid dynamics （CFD）, Lighthill acoustic analogy