针对高速磁悬浮飞轮转子的不平衡问题, 提出了一种在力自由不平衡控制下的在线动平衡方法, 用空气环境下低转速的在线动平衡替代真空环境下的高转速在线动平衡, 以实现兼顾高效率和高精度的在线动平衡。通过分析磁悬浮转子系统的不平衡模型和比较各不平衡控制模式下校正质量的求解方法, 得出在力自由控制模式下, 磁轴承的同频控制电流为零, 电磁力在线性化范围内仅是转子位移的线性函数。因此根据转子的同频位移响应可解算动平衡校正质量。通过所设计的磁轴承力自由不平衡控制器使转子绕其惯性主轴旋转, 获得了转子同频位移响应。由于系统参数的理论值与实际值存在一定误差, 通过一次试重对转换系数矩阵进行了校正。实验结果表明, 通过一次试重校正转换系数矩阵, 再经过两次试转后即可实现高精度动平衡。另外, 转子轴心轨迹显著减小、转子两端同频位移响应分别下降了77.29%和94.14%; 在真空环境下, 试验转子升速至500 Hz时, 转子的运行状况与低速状态一致, 进一步验证了本文提出方法的有效性。

A kind of field dynamic balancing method under force free control is proposed aiming at the unbalance of high-speed magnetic suspended flywheel system. It turns out that the low-speed field balancing in the air environment can replace the high-speed field balancing in the vacuum environment with high-efficiency and high-accuracy. By analyzing the unbalance model of the magnetic suspended rotor system and comparing the correction-masses under different unbalance control mode, it is found that under the free control mode, the synchronous component of control current is zero and the electromagnetic force is a linear function of the rotor displacement within linearization range. Therefore, the correction-masses can be calculated from the synchronous displacement response of the rotor in force free mode. The force free controller of magnetic bearing is designed to make the rotor spinning around its principal axis of inertial, and synchronous displacement response of the rotor is extracted to compute the correction-masses. As there exists some deviation between the theoretical and actual value of the system parameters, a trial weight is completed to correct the convention coefficient matrix. The experimental results show that the conversion coefficient matrix can be re-calibrated after a start-up test. And after the second balancing, the high-accuracy field balancing can be achieved. The orbits of rotor shaft centerline reduce significantly and the synchronous displacement response of the rotor decrease by 77.29% and 94.14% respectively. The rotor operating condition with 500Hz rotation speed in vacuum environment is in close proximity to low-speed condition, and it further validates the proposed method.