低噪声屏蔽电机定子屏蔽套激振力和受迫振动分析

三相屏蔽电机是屏蔽电泵专属特种电机,该电机的性能优劣对系统振动噪声有很大影响。屏蔽电机气隙内的旋转磁场在定子屏蔽套中感应出涡流,除产生屏蔽套涡流损耗外,该涡流还将与气隙合成磁场相互作用形成径向和切向高频电磁激振力。考虑到定子屏蔽套是薄壁件,与定子齿冠间存在一定的安装间隙,所以在电磁激振力下定子屏蔽套将产生电磁振动和噪声。首先从解析的角度推导得到了径向和切向电磁激振力的数学表达式,进而采用有限元法计算定子屏蔽套典型位置点磁通密度时间谐波和圆周方向上磁通密度空间谐波分布规律及谐波含量,得到了不同屏蔽套材质时的涡流电流密度分布。计算了定子屏蔽套采用哈氏合金时的电磁激振力变化曲线,并与解析计算结果进行了横向对比,验证了解析计算的正确性。最后,计算分析定子屏蔽套的工作模态和在电磁激振力作用下的机械形变,为后续屏蔽电机的减振降噪提供理论依据。

The Exciting Force and Forced Vibration Analysis of the Stator Can for Low Noise Canned Motor

The three phase canned motor is the exclusive special motor for nuclear reactor coolant pump and its performance determines the vibration and noise of the system. The rotation magnetic field in the airgap would induce the stator can eddy current which not only produces the eddy loss but also mutually effect on the airgap magnetic field and produces the high frequency electromagnetic exciting force(EEF). The stator can is the thin-walled parts, there is mounting clearance between the stator can and the stator tooth face. So the stator can would produce the electromagnetic vibration and noise under the electromagnetic exciting force. At first the mathematic expressions of radial and tangential electromagnetic exciting force on the stator can were derived by using mathematical analysis method. Then, finite element method was applied to calculate the flux density time harmonics, the peripheral direction space harmonics distribution regulation, the harmonics content in the typical positions and the eddy current density distributin of multiple materials were received. In this paper, the variable curves of the electromagnetic force and magnetic field force act on stator can with the hastelloy materials was calculated, which has been compared with the mathematic expressions caculated result and the accuracy of the mathematic expressions was verified. Finally, compared the mode constrained to the mechanical deformation under the electromagnetic exciting force, which provides the theoretical foundation to the following research of vibration and noise reduction of canned motor.