Purpose

This paper aims to present a modified MEC algorithm for demagnetization modeling of the PM motor. One of the major issues that the designers of the permanent magnet (PM) motors are faced with is the demagnetization of magnets because of high temperatures and armature reaction. Demagnetization will weaken the magnetic properties of the magnet and lead to a reduction in the performance of the motor. Therefore, it is essential to provide appropriate methods for modeling this phenomenon. One of these methods that has a compromise between accuracy and time consumption is the magnetic equivalent circuit (MEC). In this paper, the MEC method is used for modeling the demagnetization phenomenon for the newly introduced ring winding axial flux PM (RWAFPM) motor. The proposed algorithm can take the demagnetization into account through a time-stepping model and also correct the value of the knee point flux density.

Design/methodology/approach

The modified MEC method is used for demagnetization modeling. The modified algorithm can take into account demagnetization and also renew the knee point at each step to increase the accuracy of the modeling. In addition, the proposed algorithm has a very high and fast execution speed so that the computation time of the MEC algorithm compared to the FEM model is reduced from 3 h to 35 s. In this case, the simulations have been performed on a core i5@ 2.3 GHz/8GB computer. The FEM model is used to verify the validity of the MEC results.

Findings

The obtained results show that at the high temperature, RWAFPM motor is severely vulnerable to demagnetization. At the temperature of 140°C, the demagnetization rate of 35% has occurred. So, it is necessary to use the high-temperature magnet in this motor or modify the motor structure in terms of demagnetization tolerant capability.

Originality/value

The RWAFPM motor is introduced for use in ship propulsion and traction systems. For this reason, an accurate estimation of demagnetization tolerant of this motor in different working conditions can show the strengths and weaknesses of this structure.

中文翻译：

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使用改进的MEC算法对RWAFPM电机进行不可逆退磁分析

目的

本文旨在提出一种改进的MEC算法，用于永磁电动机的去磁建模。永磁（PM）电动机的设计人员面临的主要问题之一是由于高温和电枢反应而使磁体消磁。消磁会削弱磁体的磁性，并导致电动机性能下降。因此，必须提供适当的方法来对此现象进行建模。在精度和时间消耗之间折衷的这些方法之一是磁等效电路（MEC）。本文中，MEC方法用于对新引入的环形绕组轴向磁通PM（RWAFPM）电动机的去磁现象进行建模。

设计/方法/方法

改进的MEC方法用于退磁建模。修改后的算法可以考虑退磁，并且在每个步骤都可以更新拐点以提高建模的准确性。另外，所提出的算法具有非常高且快速的执行速度，因此与有限元模型相比，MEC算法的计算时间从3 h减少到35 s。在这种情况下，仿真是在核心i5 @ 2.3 GHz / 8GB计算机上执行的。FEM模型用于验证MEC结果的有效性。

发现

所得结果表明，RWAFPM电动机在高温下极易退磁。在140℃的温度下，发生了35％的退磁率。因此，有必要在该电动机中使用高温磁铁或根据抗退磁能力修改电动机结构。

创意/价值

RWAFPM电机被引入用于船舶推进和牵引系统。因此，在不同的工作条件下准确估算该电动机的防磁容限可以显示这种结构的优缺点。