软磁复合材料的圆筒形永磁直线电机推力波动与材料铁耗特性研究

Compared with silicon steel, soft magnetic composite (SMC) material has many merits such as magnetic and thermal isotropy, less eddy current losses, direct compression molding and so on. But the hysteresis loss is great obviously. So it is very necessary to study its loss characteristic which is distinct with the silicon steel for the purpose of commercial application. Only when SMC material is applied in the most appropriate working condition can it produce the best possible results. Based on cylindrical permanent magnet linear motor (PMLM) and employing the characteristic of easy molding, this project researches the thrust ripple of the PMLM. The loss characteristic and the law of the SMC material are revealed subsequently. Focused research: (1) SMC material is employed and the preliminary core end shape in PMLM is optimized. Apply the skew slot technique to cylindrical PMLM and investigate the methods of minimizing the detent force. (2) Investigate the loss characteristic of the SMC material in the case of different frequency and different flux density, from which the variable law is derived about the hysteresis loss and eddy current loss. Then the SMC loss characteristic is studied when the multiple frequency fields is exerted commonly. The scientific significance of this project is to manufacturie the cylindrical PMLM through using SMC material. The detent force of the PMLM is minimized through optimization design and the general law is discovered about the SMC’s loss characteristic. This project can lay a good foundation to the further commercial application of the SMC material.

和硅钢片材料不同，软磁复合材料电阻率高，磁、热各向同性，涡流损耗小、可以直接模压成型，但磁滞损耗较大，所以要推广商业应用必须研究SMC材料区别于硅钢片的损耗特性，让它应用在最适合的工况下，才能发挥其优势。本项目利用软磁复合材料易于成型的特点，研究圆筒形直线电机的推力波动，揭示软磁复合材料有别于硅钢片材料的损耗特性和规律。重点研究：（1）应用软磁复合材料，优化直线电机初级铁心端部形状，把斜槽理论应用到圆筒形直线电机中，研究减小直线电机推力波动的方法；（2）研究软磁复合材料在不同频率、不同磁密工作点处的损耗特性，得出软磁复合材料磁滞损耗和涡流损耗的变化规律，并且研究在多频场共同作用下软磁复合材料的损耗特性。本项目的科学意义在于把软磁复合材料引入圆筒形直线电机制造中，通过优化设计减小直线电机的推力波动，同时揭示出软磁复合材料损耗特性的普遍规律，为软磁复合材料的进一步商业化应用奠定了一定的基础。

直线电机由于端部开断有很大的磁阻力，本项目利用SMC 材料易于成型的特点，把斜槽技术应用圆筒形直线电机中，减小直线电机的磁阻力。和硅钢片材料不同，软磁复合材料电阻率高，磁、热各向同性，涡流损耗小、可以直接模压成型，但磁滞损耗较大，所以必须研究SMC材料区别于硅钢片的损耗特性，研究SMC 材料的损耗与频率和磁密的关系特性，揭示SMC 材料铁耗随电机工作频率和磁通密度取值的变化规律。（1）基于环形试样法对SMC材料的磁特性进行测试，得出了SMC材料的磁化曲线和损耗曲线，通过和DW470的对比，发现SMC材料的磁导率比较低；通过测试比损耗，发现400Hz是一个关键频率点，在400Hz以下时，硅钢片材料的损耗比SMC材料的损耗小；当频率高于400Hz时，软磁复合材料的比损耗低于DW470材料。（2）通过样机测试发现，频率低于400Hz时，DW470材料电机效率高，但是随着频率的增加，两种材料制造的样机效率差值越来越小，在400Hz时，两者的频率基本相同，说明了SMC永磁同步电机在中高频时有很好的性能，能够抵消磁导率低和磁滞损耗大的缺点，具有较好的应用前景。（3）在电机加工、装配过程中发现，SMC材料易碎，因此在电机制造时应适当把SMC材料加固，防止“掉渣”。（4）通过磁通函数和虚位移法相结合的方法求解端部力，得出斜端部时磁阻力解析计算公式，得出最佳的斜端部长度为一个极距；将旋转电机斜槽理论推广到直线电机，得到初级斜槽时磁阻力的解析计算公式，并且知道了最佳的初级斜槽槽距为一个槽距。通过样机的实验验证了解析法和有限元仿真的结果，进一步证实了倾斜端部和斜槽可以非常有效的降低电机的磁阻力，全斜槽结构降低磁阻力效果最好，可以降低磁阻力达到50%。.通过本项目的研究进一步认清了SMC材料的应用优势和劣势，指出了SMC材料在制作高频、特殊结构电机上具有很重要的应用价值。利用SMC 材料易于成型的特点，通过斜槽能够解决直线电机磁阻力大的问题具有很强的实际应用价值。.