基于正负刚度抵消原理的新型磁悬浮重力补偿器的研究

According to the specific requirements of the high-precision fine stage in extreme ultra violet lithography in aspect of vacuum compatible, vibration isolation performance and surface temperature rise, a new magnetic levitation gravity compensator based on the cancellation principle between positive stiffness and negative stiffness is proposed. Compared with the traditional vertical motors, the passive magnetic force in the magnetic levitation gravity compensator can be used to compensate the moving mass of the fine stage and thus the temperature rise of coil is significantly reduced. For the proposed scheme, two magnetic levitation units owning the opposite stiffness characteristics are integrated, and the low stiffness characteristic is obtained by the method of stiffness cancellation. The main research contents are indicated below. The essential error source of the traditional model when applying in low stiffness occasions is analyzed, and the accurate mathematical model for the magnetic levitation gravity compensator is built. The characteristic analysis and performance optimization of the magnetic levitation gravity compensator is researched, and the influences of the main dimensions on the levitation force and stiffness are studied. The methods to increase the levitation force density and to suppress the temperature rise are presented, and the limit force density is explored under the condition of guaranteeing the low stiffness characteristic. Besides, the design method for the magnetic levitation gravity compensator is researched. Finally, the performance evaluation and analysis is achieved based on the prototype test. Through this research, the analysis theory and optimization design criterions for the magnetic levitation gravity compensator can be obtained, which lay the theoretical foundation for its practical application in the related fields.

根据极紫外光刻机对超精密微动台在真空兼容性、隔振性能、表面温升等方面的具体需求，提出一种基于正负刚度抵消原理的新型磁悬浮重力补偿器。与传统的微动台垂向电机相比，磁悬浮重力补偿器利用永磁力对微动台的运动质量进行被动补偿，大大降低线圈发热。本项目提出的结构方案集成两种刚度特性相反的磁悬浮单元，通过刚度抵消的方法获得低刚度特性。本项目拟开展的研究内容如下：探究传统模型在低刚度场合中的误差产生机理，建立磁悬浮重力补偿器的精确数学模型；开展磁悬浮重力补偿器特性分析与性能优化研究，掌握主要参数对悬浮力和刚度的影响规律；研究磁悬浮重力补偿器悬浮力密度的提升方法与表面温升的抑制方法，探索在保证低刚度条件下的悬浮力密度极限；研究该类磁悬浮重力补偿器的设计方法；最终通过样机实验，对其性能进行评估分析。通过上述研究，形成低刚度磁悬浮重力补偿器的理论分析方法与优化设计准则，为其在相关领域的实际应用奠定理论基础。

本项目提出一种面向极紫外光刻机微动工件台的新型磁悬浮重力补偿器，将两种刚度特性相反的被动磁浮单元进行集成，基于正负刚度抵消原理，能够实现较大行程内近乎一致的悬浮力特性，从而满足极紫外光刻机对微动工件台在真空兼容性、表面温升及隔振性能等方面的需求。.本项目主要开展的研究内容如下：探究了传统模型在低刚度场合中的误差产生机理，建立了新型磁悬浮重力补偿器的精确数学模型，解决了传统模型由于忽略永磁体实际工作点而产生误差的问题；分析了新型磁悬浮重力补偿器被动悬浮力、悬浮力刚度及主动悬浮力特性，掌握主要参数对悬浮力和刚度的影响规律；提出了新型磁悬浮重力补偿器的设计方法，确定了以悬浮力和悬浮力刚度为主要设计指标的设计流程；根据所提出的设计方法，对新型磁悬浮重力补偿器进行了电磁设计与优化，确定了电磁参数，并对其机械结构和冷却结构进行了设计，最终研制出一台静态悬浮力为30N、动态悬浮力为6.5N的新型磁悬浮重力补偿器原理样机，并搭建了测试平台。通过测试，在±5mm的轴向位移范围内，新型磁悬浮重力补偿器的静态悬浮力变化仅为0.72N，且在±1mm的径向位移范围内，静态悬浮力基本保持恒定，从而验证了本结构方案的合理性和设计方法的正确性。.低刚度磁悬浮重力补偿器的实现对于磁悬浮隔振领域具有重要意义，通过本基金的开展，为低刚度磁悬浮重力补偿器的实现探索了新的方法与途径，同时也为磁悬浮隔振技术在极紫外光刻机等精密定位及精密测量领域的实际应用做出了重要的基础性工作。