中文摘要：

为简化三自由度磁轴承结构，缩小其尺寸，降低其制造与运行成本，提出一种新型的交直流三自由度混合磁轴承。该磁轴承轴向单自由度采用直流电控制，径向两自由度采用1个三相逆变器提供控制电流，由1块径向充磁永磁体同时提供轴向与径向偏置磁通。介绍交直流三自由度混合磁轴承结构及悬浮力产生机理，用等效磁路法对该磁轴承的磁路进行了推算，导出了其轴向、径向磁力数学模型，设计了实验样机，并对实验样机的磁路用ANSYS8．1软件进行了有限元分析。理论研究和有限元分析表明：交直流三自由度混合磁轴承结构合理紧凑、承载力大、效率高、成本低。

英文摘要：

To simplify the mechanical structure, decrease the overall system size of the 3 degrees of freedom axial-radial magnetic bearing and reduce the manufacturing costs as well as operating costs, an innovated AC-DC 3 degrees of freedom hybrid magnetic bearing（AC-DC-3DOF-HMB） is proposed, which is driven by a DC amplifier in axial direction and a 3-phase power converter in radial directions respectively, and the axial and radial bias magnetic fluxes are provided with a common radial polarized permanent magnet ring. The structure and principle producing magnetic suspension forces are introduced. The flux path is calculated by using equivalent magnetic circuit; the mathematical models of the magnetic suspension forces are deduced. The experimental prototype of the novel bearing is designed. Lastly, a practical prototype＇s parameters are used in simulation and the magnetic path is analyzed by finite element analysis software ANSYS 8.1. The theory analysis and simulation results have shown that this magnetic bearing incorporates the merits of three-phase AC drive, permanent magnet flux biased and axial-radial combined control. It reduces overall system size and has bigger magnetic suspension force, higher efficiency and lower cost.