Halbach阵列板式电涡流阻尼单元参数分析与优化设计

Parametric Analysis and Optimal Design of Planar Eddy Current Damping Element with Halbach Array Magnets

为了提高板式电涡流阻尼单元的耗能效率,在板式电涡流阻尼单元中引入了Halbach永磁阵列,并开展了参数分析和优化设计研究。首先制作了一个Halbach阵列板式电涡流阻尼单元,并通过试验验证了采用三维电磁有限元分析计算其阻尼系数的可靠性。然后基于三维电磁有限元分析方法,研究了永磁体厚度、磁极数、磁极对数、极长比及永磁体背铁对Halbach阵列板式电涡流阻尼单元阻尼系数的影响。最后提出了二维电磁有限元分析与MATLAB遗传算法相结合的板式电涡流阻尼单元永磁阵列参数优化方法,并通过算例分别对有背铁Halbach阵列、无背铁Halbach阵列、垂向极化阵列和纵向极化阵列等4种方案进行了优化设计。研究结果表明:在一定范围内增加永磁体厚度能显著提高Halbach阵列板式电涡流阻尼单元的阻尼系数;在永磁体阵列总长度不变的情况下,阻尼系数随着Halbach阵列磁极数量的增大而增大,但增速逐渐减慢;设置永磁体背铁可提高Halbach阵列板式电涡流阻尼单元的阻尼系数,但永磁体厚度较大或磁极数较多时,其影响逐渐减弱;存在最优极长比使阻尼系数最大,其中有背铁时约为0.65,无背铁时约为0.5。针对优化设计算例,从耗能能力来看,有永磁体背铁的Halbach阵列大于垂向极化永磁体阵列大于无永磁体背铁的Halbach阵列大于纵向极化永磁体阵列;通过参数优化,可大幅提升板式电涡流阻尼单元的耗能能力。

In order to increase the energy dissipation capacity of a planar eddy current damping element(PECDE),the Halbach array magnets are employed,and parametric analysis and optimization are conducted for the planar eddy current damping element with Halbach array(PECDE-HA).Firstly,a PECDE-HA was manufactured and tested,verifying the reliability of the three-dimensional electromagnetic finite element analysis in calculating the damping coefficient.Secondly,based on the three-dimensional electromagnetic finite element analysis,the effects of several main factors,including the thickness of the permanent magnets,magnetic pole number,magnetic pole pair number,pole length ratio,and the back-iron,on the damping coefficient of the PECDE-HA were investigated in detail.Finally,an efficient optimal method,which combines the two-dimensional electromagnetic finite element and the genetic algorithm,was proposed to determine the optimal parameters of the PECDE with four different configurations of permanent magnets,including the Halbach arrays with back iron,Halbach arrays without back iron,vertically magnetized arrays(VA)and longitudinally magnetized arrays(LA).Results show that an increase in the thickness of permanent magnets can significantly increase the damping coefficient of PECDE-HA within a certain range;If the total length of the permanent magnet keeps unchanged,the damping coefficient of the PECDE-HA increases with the increasing magnetic pole number,but the increment decreases gradually;The permanent magnet back iron usually has a positive impact on the performance of PECDE-HA,but the impact attenuates as the thickness or pole number of the permanent magnet grows.An optimal pole length ratio can be obtained for the two-pole Halbach array,which is approximately 0.65 for the case with back-iron and 0.5 for the case without back-iron,respectively.In the optimal design of the PECDE,the optimal parameters and the maximum achievable damping coefficients for the four schemes are obtained,respectively.It can be seen that the Halbach arrays with back-iron performs best in terms of energy dissipation density,which is followed by the Halbach arrays without back-iron,the vertically magnetized arrays and longitudinally magnetized arrays.