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Jangho Seo 한국자기학회 2022 Journal of Magnetics Vol.27 No.2
A new winding structure for modular dual 3-phase permanent magnet machine, which makes it possible to reduce mutual coupling between two-winding sets of inverters and interference between phases that belong to the same inverter has been proposed in this study. The modular dual 3-phase system with overlapping winding technique has been widely employed in large-scale machine applications such as wind power production; however, its drawbacks include large torque ripple, long end-winding, and large magnetic mutual interference. To address these problems, a new modular dual 3-phase winding can be achieved by replacing adjacent redundant coils in one of the same phase coils with nonoverlapping winding. For clarity, three dual 3-phase machines are selected to examine their differences. The first is 32-poles/96-slots adopting a conventional overlapping modular winding ("Conv-1"), the second is 32-poles/36-slots based on the conventional nonoverlapping winding ("Conv-2"), and the other is 32-poles/36-slots adopting the proposed modular winding configuration ("Proposed"). The validity of the proposed structure is confirmed from simulation results obtained using finite element analysis.
Jangho Seo 한국자기학회 2013 Journal of Magnetics Vol.18 No.3
This paper shows the characteristics of performance for interior permanent magnet machine (IPM) considering driving conditions such as maximum torque per ampere (MTPA) and flux-weakening control especially in terms of harmonic loss. In particular, based on finite element analysis (FEA), permanent magnet (PM) eddycurrent loss and the harmonic iron loss have been computed where the models have been intentionally designed to identify the effects of pole-slot combinations on the loss while maintaining the required power for electric vehicle. From the analysis results, it was shown that the rotor iron loss and PM eddy-current loss of machine employing fractional slot winding are extremely large at load condition. Furthermore, it was revealed that the harmonic iron loss at high-speed operation is mainly distributed over stator teeth and rotor surface, which may aggravate cooling system of the rotor structure in the vehicle.
Jangho Seo,Jung-Moo Seo 한국자기학회 2016 Journal of Magnetics Vol.21 No.1
This paper shows a new magnetic field analysis of an interior permanent magnet (IPM) machines with an axial overhang structure wherein the rotor axial length exceeds that of the stator. The rotor overhang used to increase torque density of the radial flux machine is difficult to analyze because of extra consideration of axial direction, and thus it is general for machine designer to take 3-D finite element analysis (FEA) capable of considering both radial and axial complicated geometry in the machine. However, it requires too much computing time for preliminary design especially for optimization process. Therefore, in this paper a 2-D analytic method using a lumped magnetic circuit model (LMCM) is proposed to overcome the problem. For the analysis of overhang effect, the magnetic circuit is separated and solved from overhang and non-overhang regions respectively. For the validation of proposed concept, 3-D finite element analysis (FEA) is performed. From the analysis results, it is shown that our new proposed method presents good performance in terms of calculating electromotive force (EMF) and torque within a short time. Therefore, the proposed model can be useful in design of IPM with an overhang structure.
Hybrid Analysis Method Considering Overhang Structures for Surface Permanent-Magnet Machines
Seo Jangho,Kim Rae-Eun,Lee Jae-Gil 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.2
This paper introduces a novel hybrid analysis method based on 2-D fi nite element method (FEM) for analyzing surface permanent-magnet machine (SPM) with an overhang structure which the axial length of rotor exceeds that of the stator. The overhang results the enhanced torque and power density by simply adding extra permanent magnet (PM) in axial direction utilizing the spare length of rotor compared to the stator with end-turn coil. However, it causes the fl ux behavior in axial direction especially around end parts of the motor, with inevitably requiring a time-consuming 3-D FEM for the consideration of the non-uniform aspects. It must be computationally big burden for designers to use the 3-D FEM in whole design process. To deal with the problem, a novel analysis method based on 2-D FEM which utilizes a virtual remanence of PM derived from the magnetic equivalent circuit (MEC) analysis is proposed. This concept introduces the MEC considering the overhang eff ects and combines remanence with a numerical analysis model. The accuracy and usefulness of the proposed method are validated through 3-D FEM and experimental results.
PSO를 이용한 3kW급 ISG용 매입형 영구자석 동기 전동기의 설계에 관한 연구
서장호(Jangho Seo) 한국자동차공학회 2012 한국자동차공학회 지부 학술대회 논문집 Vol.2012 No.10
A new design process of IPMSM for ISG requiring high generating power and starting torque is introduced in this research. Because of its high speed operation and extremely hot room temperature of vehicle, the machine can be demagnetized by heating and the rotor structure can be destroyed by centrifugal force. However, because existing design process needs much calculating time to check many constraints, an optimization algorithm based on PSO was adopted. In addition, in order to deal with mechanical stress in the rotor by centrifugal force at maximum speed we combined mechanical stress analysis with the optimal design process. After optimization, characteristic analysis requiring much time such as iron loss, EMF waveform, and torque-ripple was checked. The validity of our proposed methods was verified by comparing simulation results with experimental data.
매극 매상 슬롯 수에 따른 이중 인버터를 갖는 영구자석형 해상 풍력발전기의 특성 해석
서장호(Jangho Seo) 한국조명·전기설비학회 2016 조명·전기설비학회논문지 Vol.30 No.8
This paper presents several characteristics of performance in dual 3-phase machine for offshore wind power generator according to number of per pole per phase, ‘q’. With the same rotor structure, the number of turn per coil is adjusted to the aim of same electrical loading. By using FEA, self-, mutual- and synchronous inductance are calculated. In addition, magnetic flux density, flux linkage, torque ripple, cogging torque, and demagnetization withstand are investigated. In case of q=1, the model can have large inductance, low mutual coupling between two phase coils, and good demagnetization withstand but it has large torque ripple and cogging. On the contrary, the generator with q=2 can have low torque ripple, cogging and relatively high average torque because of low MMF harmonics but it has high mutual coupling due to low inductance and bad demagnetization withstand.
권선결선 방식에 따른 이중 3상 8극 48슬롯 IPM 전동기 특성 비교 연구
서장호(Jangho Seo) 한국조명·전기설비학회 2021 조명·전기설비학회논문지 Vol.35 No.9
In this paper, characteristic analysis was performed according to the winding connection method of an 8-pole 48-slot IPM motor with a dual inverter system. One 3-phase winding set is connected to a inverter and the other 3-phase winding set is connected to another. With the same rotor structure and same stator, three different types of winding connections for dual 3-phase are proposed. In a winding of type 1 (‘T-1’), the phase coils were placed alternately. In the second type (‘T-2’), the coils of each phase were arranged in half around the circumference. In the the last type (‘T-3’) having 6-phase, phase coils connected to other inverters are placed next to each other so that current angle between two-inverters become 30 degree. For understanding characteristics of IPM with dual 3-phase, the individual torque components are newly presented as equations using the relational expression between flux linkage and torque. By using finite element analysis (FEA), back-elctromotiveforce (EMF), syncrhonous inductance, torque and iron loss were calculated and compared.