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Dong-Hyeok Kang,Jun-Kyu Park,Seung-Ho Hyun,Jin Hur 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
This paper is analyzed on back electromotive force harmonic characteristic in interior permanent magnet type brushless DC motors according to demagnetization patterns. Demagnetization patterns consist of equality, inequality, and weighted demagnetization. In addition, we used the same pole-slot ratio with different pole-slot numbers models and different pole-slot ratio with different pole-slot numbers model. Furthermore, we performed analysis of flux linkage, back electromotive force, and harmonics of back electromotive force according to demagnetization patterns. In conclusion, we propose detection technique of irreversible demagnetization condition using back electromotive force harmonics characteristic of an interior permanent magnet type brushless DC motors.
Dong-Kyun Woo,Byung Hwan Jeong IEEE 2016 IEEE transactions on magnetics Vol.52 No.4
<P>The overhang structure is an effective solution to increase the performance of a surface- mounted permanent magnet (SPM) motor using a ferrite PM. If a ferrite PM, which can be demagnetized through a large armature reaction, is used for an SPM motor controlled by the field-weakening method, the ferrite PM can suffer from irreversible demagnetization. Moreover, if an SPM from the overhang structure is directly exposed to the armature reaction by the winding of the stator, a ferrite PM of an SPM motor could be partially demagnetized. Because of this, when the field-weakening method is used for the control of the SPM motor with the overhang structure, PMs are disadvantageous to the irreversible demagnetization. To solve these problems, a novel structure is proposed, which can increase the motor performance through the overhang structure without irreversible demagnetization in the overhang part.</P>
Design of Vernier Motor Considering PM Irreversible Demagnetization for Abnormal Operating Condition
Dae-Woo Kim,Jun-Young Song,Do Hyun Kang,Jin-Seok Kim,Yong-Jae Kim,Sang-Yong Jung 한국자기학회 2019 Journal of Magnetics Vol.24 No.1
This study investigates the design of a flux modulation pole (FMP)-type vernier motor considering irreversible demagnetization in a permanent magnet (PM). The FMP-type vernier motor, which has a distinct configuration compared to the conventional vernier motor, is taken into account because the PM placed at its stator is vulnerable to irreversible demagnetization. The demagnetization ratio of the PM is analyzed and compared using two different types of flux barrier, namely the bar- and delta-type barriers with varying design parameters. To guarantee reliability of the motor performance, both normal and abnormal operating conditions are considered for each type of flux barrier. Finally, selected models are compared to the base FMP-type vernier motor model in terms of demagnetization ratio and output torque.
Kim, Hyung-Kyu,Hur, Jin IEEE 2015 IEEE transactions on magnetics Vol.51 No.11
<P>This paper reports on the development of dynamic characteristic analysis algorithm for irreversible demagnetization in brushless dc motors. In general, in static characteristic analysis of irreversible demagnetization, only the <TEX>$d$</TEX>-axis magnetic flux components are considered. As a result, this type of analysis cannot be used to accurately analyze the characteristics of irreversible demagnetization while the motor is actually being driven. Thus, we developed a dynamic characteristic analysis algorithm that we utilize to compare the static and the dynamic characteristic analyses of irreversible demagnetization. Consequently, we propose a maximum current limit for motor designs that reduces the impact of irreversible demagnetization.</P>
Improvement of Demagnetization by Rotor Structure of IPMSM with Dy-free Rare-Earth Magnet
Imamura, Keigo,Sanada, Masayuki,Morimoto, Shigeo,Inoue, Yukinori Journal of International Conference on Electrical 2013 Journal of international Conference on Electrical Vol.2 No.2
Permanent magnet (PM) motors that employ rare-earth magnets containing dysprosium (Dy) are used in electric and hybrid electric vehicles. However, it is desirable to reduce the amount of Dy used since it is expensive. This study investigates the rotor structure of a PM synchronous motor with a Dy-free rare-earth magnet. Flux barrier shapes and PM thicknesses that enhance the irreversible demagnetization are investigated. In addition, a rotor structure that improves the irreversible demagnetization is proposed. We demonstrate that the proposed rotor structure without Dy improves the irreversible demagnetization.
철도차량용 IPMSM의 불가역 감자 강건 설계에 관한 연구
공형식,표현조,정민재,남동우,장익상,김원호 한국철도학회 2019 한국철도학회논문집 Vol.22 No.12
As the technology of induction motor has matured, it has reached a limit to proposed improvements over existing methods. Advances in power electronics have enabled individual control of synchronous motors. As a result, research is being actively conducted to replace conventional induction motors with high efficiency and high torque Interior Permanent Magnet Synchronous Motors (IPMSM). Since IPMSM uses permanent magnets, consideration must be given to the irreversible demagnetization that can occur in railroad cars operating at high temperatures. This paper replaces the existing induction motor with a permanent magnet motor with the same performance and, through performance analysis by rotor type, proposes an IPMSM rotor model that is robust to irreversible demagnetization.
Won-Ho Kim,Hyung-Sik Kong,Kang Been Lee,Hyun-Jo Pyo,Min-Jae Jeong 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.1
Trends of traction motor of railway vehicles have been shifted from induction motors to permanent magnet motors. Recently, studies have been conducted on dysprosium-free permanent magnets. Dysprosium is a heavy rare earth element that has a great impact on performance of motors. However, dysprosium aff ects the coercive force of a permanent magnet and can produce irreversible demagnetization. Conventional studies have focused on improving the performance of motors using permanent magnets without heavy rare earth elements. In this study, a robust rotor design process includes the way to restrain irreversible demagnetization using a dysprosium-free permanent magnet. First, the irreversible magnetization of bar-type and V-type magnets, which are basic models of interior permanent magnet synchronous motors, is analyzed. Next, expected demagnetized parts of the main magnets are used as a submagnets, which make magnetic fi eld bypass both sides of the submagnets, and magnets are added in submagnets regions to compensate gap of performance between target model and double type models. Finally, parameter analysis is performed on the design variables of the main magnet. The proposed the robust design process to restrict irreversible demagnetization proves its validity through fi nite element analysis.
Kim, Hyung-Kyu,Kang, Dong-Hyeok,Hur, Jin IEEE 2015 IEEE transactions on magnetics Vol.51 No.11
<P>This paper proposes a detection technique for irreversible demagnetization using the harmonics characteristics of the back electromotive force (BEMF) in brushless dc motors (BLDCMs). We analyze the harmonics characteristics of the BEMF that are obtained for fault types encountered by interior permanent magnet (PM)-type BLDCMs according to the magnetization pattern of irreversible demagnetization. An irreversible demagnetized PM is represented as an equivalent magnetizing distribution by applying space harmonics analysis using both the finite element method and the space harmonics method. Furthermore, we analyze flux linkage and BEMF waveforms for different demagnetization ratios.</P>
Ferrite 영구자석을 적용한 EV 구동용 IPMSM의 전기적, 기계적 특성 연구
김기오(Ki-O Kim),정영훈(Young-Hoon Jung),박민로(Min-Ro Park),임명섭(Myung-Seop Lim) 한국자동차공학회 2019 한국자동차공학회 학술대회 및 전시회 Vol.2019 No.11
Recently, because of the instability of rare-earth resource supply and demand, research on rare-earth free in various fields is urgent. Accordingly, studies are being actively conducted to apply ferrite permanent magnet to IPMSM (Interior Permanent Magnet Synchronous Motor) used as electrical vehicle (EV) traction motors. Ferrite permanent magnet is cheap and easy to obtain. However, it has lower coercive force values than rare earth permanent magnets, and there is a large armature reaction occurs during EV motor operation, it is necessary to check for irreversible demagnetization. In addition, the limited space of the vehicle requires a high power density of the motor. In order to satisfy the high power density, the motor must be speeded up. Therefore, the problem of mechanical stiffness due to the generation of very large centrifugal force must also be considered. In this paper, the irreversible demagnetization characteristics and mechanical stiffness of IPMSM with ferrite permanent magnet. When determining the rotor shape, the sensitivity of each performance is analyzed through of variance of design factors. Sensitivity analysis is based on the maximum stress of the rotor and irreversible demagnetization characteristics. P-value less than 0.05 can be used as major design factors in motor design by determining sensitivity factors for each performance.
M. S. Mirazimi,A. Kiyoumarsi,S. M. Madani 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.5
A study on the multi-objective optimization of Interior Permanent-Magnet Synchronous Motors (IPMSMs) with 2, 3, 4 and 5 flux barriers per magnetic pole, based on Genetic Algorithm (GA) is presented by considering the aspect of irreversible demagnetization. Applying the 2004 Toyota Prius single-layer IPMSM as the reference machine, the asymmetrical two-, three-, four- and five-layer rotor models with the same amount of Permanent-Magnets (PMs) is presented to improve the torque characteristics, i.e., reducing the torque pulsation and increasing the average torque. A reduction of the torque pulsations is achieved by adopting different and asymmetrical flux barrier geometries in each magnetic pole of the rotor topology. The demagnetization performance in the PMs is considered as well as the motor performance; and analyzed by using finite element method (FEM) for verification of the optimal solutions.