磁悬浮电机的高效高精度在线动平衡

Field balancing of magnetically levitated motor in high-efficiency and high-accuracy

提出了一种基于零位移控制的磁悬浮转子在线动平衡方法,用于降低磁悬浮电机的振动并提高悬浮精度。通过在极坐标系中分析磁悬浮转子的静/动不平衡模型,推导出校正质量与磁悬浮系统参数的关系。对各种控制模式下表征校正质量的特点进行分析得出:在零位移模式下,电磁力与不平衡离心力相互抵消,且电磁力是控制电流的线性函数,因此可使用控制电流直接解算校正质量。使用广义选频器控制转子绕其几何轴旋转,获得零位移状态,提取了绕组同频控制电流解算校正质量。最后,针对电流刚度获知误差,在线校正转换系数阵,进行二次高精度平衡。实验结果表明,使用本方法一次启车即可确定校正质量,两次启车校正转换系数阵再次平衡后,转子振动降低98.6%,控制电流降低98.7%,实现了高效高精度动平衡,达到了磁悬浮转子零位移零电流运行状态。

A new balancing method based on zero-displacement control for a Magnetically Levitated Rotor （MLR）was proposed to reduce the vibration and to improve the levitation performance of the magnetically Levitated motor （MLM）. First, the static/dynamic unbalance models of MLR were dis- cussed in polar coordinates, and the relationship between MI.R parameters and correction-masses was derived. After analyzing the characteristics of the above relationships in different control modes, a conclusion was obtained as follows： the correction-masses can be solved from the control current di- rectly in zero-displacement mode, as the electromagnetic force is a linear function of the control cur- rent and can be offset by unbalanced centrifugal force. Then, a general frequency selector was utilized to control the rotor to spin around its geometric axis to achieve the zero-displacement mode and the synchronous control currents were extracted to compute the correction-masses. Finally, based on the current stiffness learning errors, the second balancing was completed in high-accuracy by correcting conversion coefficient matrix on line. The experimental results show that the correction-masses can be obtained through a single start-up, and the rotor vibration and control current have reduced by 98.6 and by 98.7% respectively after the second balancing using the corrected conversion-coefficient-ma- trix. The status of zero-displacement and zero-current are achieved after the field balancing with high- efficiency and high-accuracy.