混合叠压圆筒型永磁直线振荡电机电磁特性分析

Electromagnetic Characteristics Analysis of Tubular Permanent Magnet Linear Oscillation Actuator with Hybrid Lamination

圆筒型双定子永磁直线振荡电机因其结构简单、功率密度高而广泛应用于压缩机领域。然而,电机的定子通常采用传统的硅钢片周向叠压方式,导致其叠压系数低、磁路易饱和。因此,该文提出一种新的混合叠压方法。首先,介绍了双定子永磁直线振荡电机的基本拓扑结构和工作原理,给出磁路特有的分布方式;然后,对采用电工纯铁和硅钢片混合叠压方式进行分析,推导了硅钢片数量与电工纯铁之间的占比关系,并对不同硅钢片数量对电机反电动势、电磁推力和损耗的影响进行分析;最后,通过三维有限元分析对采用传统叠压方式和混合叠压方式的双定子永磁直线振荡电机的电磁特性进行了比较和分析。实验结果验证了混合叠压方式在提高电磁推力和简化制作工艺方面的优势。

Tubular permanent magnet linear oscillating actuators(TPMLOA)have widely used in the application field of short-stroke and high frequency linear reciprocating,because of simple mechanical structure,without the rotary-to-linear conversion,low maintenance costs and fast dynamic response.However,the tubular structure and the special distribution of magnetic circuit pose significant challenges to the assembly of silicon steel sheets.The traditional assembly method is to laminate the silicon steel sheets in a circumferential direction,which leads to a low stacking coefficient of the silicon steel sheet of stator and can easily cause magnetic circuit saturation.At present,scholars have proposed some ways to increase the stacking coefficient and improve the performance of the TPMLOA,but these methods also increase the assembly difficulty and processing cost.Therefore,this paper proposes a hybrid lamination method to solve the above problems.The combination of silicon steel sheets and electrical iron materials can effectively reduce the assembly difficulty and increase stacking coefficient.Firstly,the basic structure of a C-core double stator TPMLOA with three permanent magnets is introduced,and the magnetic circuit distribution and the operating principle of the motor at different positions is given.Secondly,the implementation method and related parameter determination of the hybrid lamination scheme proposed in this article is explained and derived,and the upper limit of the number of slots for electrical iron is determined.Thirdly,the influence of different quantities of silicon steel sheets in each slot on the electromagnetic performance of TPMLOA is compared and analyzed,and the optimal number of slots for electrical iron materials is determined.Finally,through three-dimensional finite element analysis(3D-FEA)and prototype experiments,the advantages of using a hybrid lamination TPMLOA in reducing magnetic circuit saturation and improving electromagnetic thrust capacity are verified.By analyzing the impact of different numbers of silicon steel sheets in each slot on the performance of the TPMLOA,it can be concluded that as the number of silicon steel sheets in each slot increases,the amplitude of the back electromotive force(EMF)and electromagnetic thrust of the TPMLOA gradually decreases,while the iron core loss and eddy current loss also increase.Therefore,when the number of silicon steel sheets in each slot is 1,it is more conducive to improving the performance of the motor.The 3D-FEA results show that when the armature current is 20 A,compared to the traditional TPMLOA in a magnetic circuit saturation state,the magnetic field density of the stator in the hybrid lamination TPMLOA is only about 1.6T.Although the electromagnetic thrust of the two lamination methods is the same at the center position,the electromagnetic thrust of the hybrid lamination TPMLOA at the maximum position of 10 mm is 221 N,which is 26%higher than that of traditional TPMLOA.However,the effect of hybrid lamination method on the eddy current loss of the motor cannot be ignored.When the operating frequency is 40 Hz and the armature current is 20 A,the total core loss of the hybrid lamination TPMLOA is 13.8 W,which is greater than the 11.38 W of traditional TPMLOA.The comparison between prototype experiments and the simulation analysis shows that the electromagnetic thrust of the actual prototype is 7%smaller than that of the 3D-FEA,and the amplitude of the actual test back EMF is also smaller than the simulation results.Finally,load test is conducted on the prototype,and the resonance frequency of the surface linear oscillation motor is 52 Hz,and the efficiency of the TPMLOA reaches a maximum of 84.5%.Through comparative analysis,the following conclusions can be drawn:(1)Compared with traditional lamination method,the hybrid lamination method proposed in this paper can effectively improve the saturation of the magnetic circuit and increase the electromagnetic thrust at the maximum position.(2)The hybrid lamination method causes an increase in eddy current loss,which reduces efficiency of the TPMLOA.Therefore,a block-based approach should be adopted to reduce eddy current loss.(3)TPMLOA has the highest efficiency at resonance frequency.