International Journal of Engineering

International Journal of Engineering

Demagnetization Study of Permanent Magnets During the Startup of LSPMSM Considering the Effects of Temperature

Document Type : Original Article

Authors
L. Anh Tuan 1
T. Duy Khanh 2
N. Y. Do 3
1 School of Electrical and Electronic Engineering, Hanoi University of Industry, Hanoi, Vietnam
2 Faculty of Electrical Engineering, Saodo University, Haiphong, Viet Nam
3 Faculty of Electro-Mechanics, Hanoi University of Mining and Geology, Hanoi, Vietnam
10.5829/ije.2026.39.10a.21
Abstract
The line-start permanent magnet synchronous motor (LSPMSM) is increasingly being applied due to its high efficiency. However, temperature has a significant effect on the electromagnetic parameters, which in turn affects the operating characteristics of the LSPMSM. Due to the presence of squirrel-cage components in the rotor, LSPMSM can line-start, but the high starting current can lead to localized or complete demagnetization, especially at elevated temperatures. This can result in irreversible demagnetization of the permanent magnets. This paper analyzes the effect of temperature on the electromagnetic parameters of the motor as well as its impact on demagnetization during LSPMSM startup. The theoretical study results indicate the influence of temperature on the electromagnetic parameters of LSPMSM and demonstrate that, under certain temperature conditions, there exists a maximum starting current coefficient to prevent demagnetization. Using FEA simulation for a LSPMSM, 15kW, 2p=2, results show a correlation between theoretical and simulated findings. It is shown that with a high starting current of 337.8A, NdFeB-N38M magnets used in the motor can experience mild demagnetization at 60°C, while visible demagnetization occurs at 120°C. Experimental validation has confirmed the accuracy, as the B-EMF characteristics indicate a close resemblance between experimental and simulated results, with a deviation of less than 7%.

Graphical Abstract

Demagnetization Study of Permanent Magnets During the Startup of LSPMSM Considering the Effects of Temperature
Keywords
Demagnetization
Permanent Magnet
Temperature
Line-start Permanent Magnet Synchornous Motor
Electric Motor

Subjects

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International Journal of Engineering
Volume 39, Issue 10
TRANSACTIONS A: Basics
October 2026
Pages 2617-2629