Dynamics and Control of Non-Laminated Actuators for Magnetic Levitation

这项拨款为制造业的高性能磁悬浮研究提供资金。需要极高清洁度、高精度定位或非接触式零件处理的制造工艺的增长表明，磁悬浮在生产环境中的作用越来越大。随着电力电子技术、精密位置传感技术、高速数字信号处理技术和控制理论的飞速发展，磁悬浮技术正在迅速发展。磁悬浮在金属输送、金属涂层、硅片输送、薄膜拉伸、光刻等诸多工艺中都有应用。在高性能磁悬浮中，几乎所有的工作都假定执行器可以由层压构造，以便在主动控制引起的快速变化的磁场中最大限度地减少涡流的产生。然而，在许多当前或预期的应用中，层压结构与基本工艺相冲突，或者成本很高。没有层压，在电流施加到电磁铁的线圈的快速变化导致一个缓慢得多的变化，由于在执行器内感应涡流的变化场。这些电流与产生的磁场相互作用，大大复杂化了执行器的动力学。在已知的情况下，可以通过设计良好的控制算法对执行器的动力学进行部分补偿，从而提高刚度和伺服带宽。然而，它们也对悬浮性能施加了基本限制。因此，预测、识别和建模非层压致动器动力学的能力对于实现高刚度/带宽悬浮以及理解无法实现的目标至关重要。本研究工作的理论和实验任务的目标是：(1)确定涡流效应对主动磁悬浮性能的基本限制，(2)开发鲁棒控制策略，为非层压执行器提供非常高的性能水平。如果成功，这项研究工作将使非层压磁性悬浮体能够提供高精度的定位，尽管有干扰力，并快速重新定位悬浮物体。这项工作还将提供一个基本的知识库，将执行器的动态特性与其尺寸、几何形状和组成联系起来。这些知识将允许预测磁悬浮性能限制以及优化定子设计，以最大限度地提高刚度和伺服带宽。最后，预计这项研究将有助于定义高性能磁悬浮制造的新机会。

This grant provides funding for an investigation of high performance magnetic levitation for manufacturing. The growth of manufacturing processes that require extreme cleanliness, very high precision positioning or non-contact part handling suggests an increasing role for magnetic levitation in production environments. As a technology, magnetic levitation is developing rapidly, spurred by dramatic advances in power electronics, precision position sensing, high speed digital signal processing, and control theory. Magnetic levitation has found application in many processes including metal conveyance, metal coating, silicon wafer transport, film stretching, and photolithography. Almost all work in high performance magnetic levitation assumes that the actuator can be constructed from laminations so as to minimize the production of eddy currents in the face of the rapidly varying magnetic fields caused by active control. However, in many current or anticipated applications, laminated construction conflicts with the basic process or would be highly costly. Without laminations, a rapid change in current applied to the electromagnet's coil results in a much slower change in the applied force due to the eddy currents induced within the actuator by the changing field. These currents interact with the produced field and greatly complicate the actuator's dynamics. If known, the actuator dynamics can be partially compensated by a well-designed control algorithm so as to achieve improved stiffness and servo bandwidth. However, they also impose fundamental limits upon levitation performance. Thus, the ability to predict, identify, and model non-laminated actuator dynamics is critical to attaining high stiffness/ bandwidth levitation and to understanding what can not be achieved. The objectives of the theoretical and experimental tasks of this research effort are to (1) determine the fundamental limits that eddy current effects impose upon the performance of active magnetic suspensions, and (2) develop robust control strategies that provide very high levels of performance with non-laminated actuators.If successful, this research effort will enable non-laminated magnetic suspensions that provide highly accurate positioning in spite of disturbance forces and reposition the levitated object quickly. The effort will also provide a fundamental knowledge base that will connect an actuator's dynamic properties to its size, geometry, and composition. This knowledge will allow the prediction of magnetic suspension performance limits as well as the optimization of the stator design to maximize stiffness and servo bandwidth. Finally, it is anticipated that this research will help define new opportunities in manufacturing for high performance magnetic suspension.