针对柔性转子系统的电磁轴承支承刚度阻尼参数识别

Parameter identification for stiffness and damping of active magnetic bearing in flexible rotor system

为了用传统转子动力学的理论和方法分析支承在电磁轴承上的转子系统动力特性,电磁轴承支承的等效刚度和等效阻尼是必须获知的重要参数。已有研究提出的电磁轴承等效刚度和等效阻尼的识别方法大多都是建立在单自由度模型或刚性转子模型上的。针对支承在电磁轴承上的柔性转子系统,提出了其等效刚度和等效阻尼参数的识别方法。首先,设计了静态力和动态力两种自由度凝聚方法,把柔性转子有限元模型凝聚到所需要的自由度,减少了模型中未知数的数量,并提取凝聚后转子模型中的激励与响应关系;然后建立电磁轴承激励和加配重激励两种情况下的电磁轴承等效刚度和等效阻尼的识别方程;最后,通过一个电磁轴承-柔性转子系统算例验证了识别方法的有效性。算例分析了由于柔性转子振动相位的变化和增加识别方程主自由度数量对识别精度和效果的影响。

For dynamic analysis of the Active Magnetic Bearing （AMB）-rotor system via the theory and method of the tradition-al rotor dynamics, the equivalent stiffness and the equivalent damping are the important parameters for representing the sup-port characteristic of AMB and must be made certain. The methods for measuring the equivalent stiffness and the equivalent damping of AMB have been proposed in literatures. However, most of them were based on the single degree of freedom （DOF） model or the multi-DOF rigid rotor model. In this study？ a measuring method is proposed by means of parameter iden-tification, which is employed in the AMB-flexible rotor system. By condensation of degrees of freedom （DOF） in the finite ele-ment rotor model, which includes the static force equivalence or the dynamic force equivalence, the whole DOFs can be reduced to some certain DOFs and the quantity of the unknowns in the model is decreased. The relationship between the excitation and the response is extracted from the condensed rotor model. The parameter identification equations are obtained in the conditions of the AMB excitation and the additional weight excitation. By numerical simulation, the equivalent stiffness and the equivalent damping of the AMB support are effectively identified and the possible problems are analyzed.