与同轴式磁力齿轮相比,偏心式谐波磁力齿轮更适用于大传动比领域.在传统磁力齿轮的基础上,外永磁体采用切向充磁且嵌入式安装在定子侧,内永磁体采用60°Halbach阵列.建立有限元分析模型,分析比较了两种磁力齿轮的磁场分布,在静态模型下分析了两种磁力齿轮的磁力线分布,对其气隙磁密、谐波与转矩分别进行对比分析.仿真结果表明,较传统的磁力齿轮结构,改进后的偏心式谐波磁力齿轮具有谐波含量小、转矩大、效率高等优点.

Eccentric magnetic harmonic gears (EMHG) can achieve high speed ratio transmission and large torque output by modulating the air gap length between permanent magnets (PM).The analytical method is based on the boundary perturbation method.The vector magnetic potential perturbation equation in the air gap region is established, and the general solution is obtained using the boundary conditions.According to the superposition principle, the air gap flux density of stator and rotor PMs acting alone is synthesized, and the electromagnetic torque and unbalanced magnetic pull are calculated.Last, we compare magnetic field distributions, electromagnetic torque and unbalanced magnetic pull computed by the analytical method with those obtained from finite-element method (FEM).

An eccentric harmonic magnetic gear (EHMG) with Halbacharray is proposed in this paper. According to the theory of magnetic field modulation and one-side effect, the permanent magnets (PMs) on the inner rotor and outer stator are arranged in a Halbach array. The PMs of inner rotor are divided into three segments per pole, and the PMs on the outer stator are divided into two segments per pole. The proposed EHMG with 15 pole pairs on inner rotor PMs and 16 pole pairs on outer stator PMs is established. The finite element analysis (FEA) is used for simulating the proposed model. The corresponding magnetic field and static torque of the EHMG are calculated. Compared with the conventional EHMG, the results show that the torque density of the proposed EHMG is substantially improved.

In this study, an analytical model is proposed to calculate the magnetic field and electromagnetic torque (including cogging torque) in the surface-mounted permanent-magnet (SMPM) machines with Halbach arrays accounting for semi-closed slots. The analytical model can be used to calculate both no load and load air gap magnetic field of SMPM. The permanent magnets (PMs) on the rotor are arranged Halbach array and each pole is divided into four segments. Additionally, in order to improve the performance of the SMPM, the analytical model is combined with genetic algorithm to optimise some parameters of the motor. The analytical results from the proposed model have been compared with those issued from finite-element method. Finally, the 12-slot/8-pole motor is manufactured and the back-electromotive force, iron loss and load characteristics are validated by experiments.

In order to improve the output torque and transmission stability of coaxial magnetic gear (CMG), a novel CMG with unequal Halbach arrays of the inner rotor and non-uniform air gap is proposed in this paper. According to the principle of magnetic field modulation and "one-sided flux" structures, the unequal Halbach arrays could augment the magnetic field in the inner air gap. Moreover, the permanent magnets (PMs) of the eccentric structure could obtain non-uniform air gap, which is helpful to enhance the flux-modulation effect. The proposed CMG topology with 4 inner and 17 outer pole pairs is established. The topology performance is assessed and calculated by finite element analysis (FEA).

精确计算气隙磁场是分析与设计复合电机的关键,该文运用二维解析法计算Halbach阵列磁力变速永磁无刷电机气隙磁场.根据磁力变速永磁无刷电机的结构特点,分别建立磁力齿轮和永磁无刷电机两部件解析模型;求解场域主要有内中外三层气隙、内外双转子永磁体区域和内外双定子槽区域,每个子区域的求解方程通过边界连续条件建立联系.计算得到各子区域的矢量磁位磁通解析式,计算电机磁场、齿槽转矩、反电动势和电磁转矩;制作样机并搭建控制系统试验平台,进行空载和负载试验测试.解析计算波形和试验样机测试波形对比,结果一致,证明了该方法的正确性和有效性.

Compared with a standard permanent magnet synchronous motor, a line-start permanent magnet synchronous motor (LSPMSM) has additional features that include two-sided slots on its stator and rotor. Thus, due to its complex air gap form, there is no simple method to calculate the cogging torque of this kind of motor at present. This paper presents a new analytical method that models the rotor as an equivalent magnetic motive force (MMF) distribution in the air gap which avoids the influence of rotor slotting in the air gap. Based on the energy method, an analytical method is presented here to analyze the pole-slot match of stator and the influence of number of slots per pole of rotor on the cogging torque. The effect of auxiliary slots on cogging torque of LSPMSM is studied, and by changing the number of auxiliary slots to reduce the cogging torque, the correctness of the above method has been validated by the finite element method.

This paper presents an exact analytical method to compute the air-gap magnetic field of surface-mounted permanent-magnet (SMPM) motors for evaluating slotting effects accurately. Solution field regions are divided into air-gap domain, permanent magnets (PM) domain, and slot domains. The Laplace's equations or Poisson's equations of the sub-domains are contacted by boundary conditions and then solved by exact analytical method. The actual height of slot and distance between slots are taken into account in the computation. Magnetic field distributions and cogging torque computed with the proposed analytical method are compared with those issued from 2-D finite-element method (FEM), and the comparison results are consistent and show the correctness and effectiveness of the proposed analytical method.

In this paper, a new structure for increasing the magnetic gear torque is proposed, which has high torque density and high mechanical properties. The permanent magnets (PMs) of the outer rotor are spoked and magnetized along the tangential direction. The PMs of inner rotor are the surface-mount type and magnetized in the radial direction. The PMs are fixed in the inner and outer rotors' iron yoke that the aim is to keep the PMs from falling off during the rotation. In order to reduce the amount of iron, it is considered to slot on the outer rotor. The two-dimensional finite element method is used for simulating the proposed model. The magnetic field and electromagnetic torque of the magnetic gear are calculated. Compared with the conventional magnetic gear, the results show that the torque transmission capability of the proposed magnetic gear can be substantially improved.

In this paper, an analytical calculation of the magnetic field in a consequent-pole bearingless permanent magnet (PM) type motor with rotor eccentricity is proposed. The analytical method is based on the resolution of Laplace's and Poisson's equations. Due to the presence of consequent-pole, the general solution of the first-order for the vector potential distribution in the air-gap is presented considering the first harmonic. Here, the magnetic field distributions by the analytical method are compared with those obtained from finite element (FE) analyses. Then, the corresponding performances are quantitatively assessed by the finite-element method.