基于退磁限制的无轴承永磁同步电机性能参数分析

无轴承永磁同步电机磁场中不仅存在转矩绕组电流产生的磁通,而且存在径向悬浮力绕组电流产生的磁通,这两种磁场会导致永磁体退磁。设计永磁体参数需考虑产生最为有效径向悬浮力、电磁转矩和避免永磁体退磁三者之间的关系。论文分析了转矩绕组电流产生的磁通和径向力绕组电流产生的磁通共同作用下,转子表面永磁体容易引起退磁的关键区域;在电机气隙不变情况下,分析得出了保证产生最为有效的径向力时最佳永磁体厚度;基于永磁体退磁限制,采用有限元分析计算,针对论文中设计的永磁体厚度及气隙长度,得出了无轴承永磁同步电机最大转矩电流、径向悬浮力电流和产生的最大径向悬浮力。

Performance and Parameter Analysis for Bearingless Permanent Magnet Synchronous Motors Considering Demagnetization Limitation

Both fluxes producing by torque winding current and by radial force winding current exist in the motor field. These two fluxes will bring on demagnetization of permanent magnets. The relationship among producing radial force efficiently, outputing electromagnetic torque and permanent magnet demagnetization must be considered when permanent magnet parameters are designed for surface-mounted permanent magnet-type bearingless motors. In the paper, several critical demagnetization parts of permanent magnets affected by fluxes of toque winding and radial force winding currents are analyzed. The optimal permanent magnet thickness is analyzed under the fixed motor gap. Using Finite Element Method, the maximum torque currents, radial force currents and radial forces limited by the demagnetization are obtained. The derived equations are effective in the design of permanent magnet thickness, rated currents and so on.