发电机碳刷多点全周摩擦引起的不稳定振动分析

以发电机碳刷与转轴之间发生的摩擦振动为对象,研究这类特殊周向多点全周摩擦振动机理。根据碳刷工作原理,建立多点全周摩擦力计算模型,采用热弹性力学方法建立摩擦截面温度场和转子热弯曲计算模型,将热弯曲模型与转子振动有限元模型耦合求解振动响应。以某发电机为例进行分析,仿真分析和试验研究了碳刷轴全周摩擦振动特征。研究表明,发电机碳刷与转轴之间的多点全周摩擦会引发振动周期性波动和爬升,不稳定现象与不平衡力、碳刷-转轴不同心度和碳刷摩擦因数有关,可以通过精细动平衡、适当增大碳刷-转轴不同心度和减小碳刷摩擦因数来消除。

Unstable Vibration induced by full annular rub between carbon brushes and rotor in a generator

Here, the vibration characteristics induced by full annular rub between carbon brushes and rotor in a generator were analyzed. According to carbon brushes working principle, a rub force model was set up. The rub cross-section temperature field and the rotor's thermal bending model were built based on the theory of thermoelasticity. The rotor thermal bending model was coupled with the rotor FE dynamic model, and the system vibration responses were computed with the coupled model. Vibration characteristics were analyzed with a generator rotor model. Results showed that the rub between carbon brushes and the rotor can cause the systems spiral or divergent unstable vibration. The effects of unbalance force, carbon brushes rotor non-concentricity and brushers friction coeficient on the sytem vibration were studied. It was shown that unstable vibration can be eliminated through using more refined dynamic balance, increasing carbon brushes rotor non-concentricity, or reducing brushers friction coeficient.