Loss Analysis of Magnet Eddy Current in a High-Power Density Machine Using a Field-Circuit Coupled Model

Zhao Hongsen,Yang Jiaqiang 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.5

Magnetic eddy current losses is signifi cant in permanent magnet motors, especially in high-power density permanent magnet motors. It signifi cantly aff ects the magnet’s temperature and properties and may cause irreversible demagnetization. Several methods for reducing magnetic eddy current losses is proposed to address these problems. First, a fi eld-circuit coupled mathematical model was established to calculate the magnetic eddy current losses. Experiments on the phase current and magnetic eddy current losses verify the accuracy of fi eld-circuit coupled mathematical model. Then based on the model, the eff ect of the trigger angle, slot opening width, pole arc coeffi cient, pole arc center off set, and auxiliary slots on the magnetic eddy current losses were assessed. The results showed that the magnetic eddy current loss could be reduced by choosing a suitable leading trigger angle, pole arc coeffi cient, and pole arc center off set. A smaller slot opening width reduced the eddy current losses. A novel auxiliary slot with an optimized size is proposed to reduce eddy current losses. Finally, taking the trigger angle, slot opening width, pole arc coeffi cient, pole arc center off set and the auxiliary groove as the optimization factors and the magnetic eddy current loss as the optimization target, the optimal parameter scheme is obtained by Taguchi method. The simulation results show that the optimized magnetic eddy current losses is reduced by 8.57%.

전류분포가 3본-도체의 임계전류/교류손실 특성에 미치는 영향

류경우,최병주 한국전기전자재료학회 2003 전기전자재료학회논문지 Vol.16 No.5

AC loss is an important issue in the design of high-T$\sub$c/ superconducting power cables which consist of a number of Bi-2223 tapes wound on a former. In the cables, the tapes have different critical currents intrinsically. And they are electrically connected to each other and current leads. These make loss measurements considerably complex, especially for short samples of laboratory size. So special cautions are required in the positioning of voltage leads for measuring the true loss voltage. In this work we have prepared a conductor composed of three Bi-2223 tapes with different critical currents. The critical current and AC loss characteristics in the conductor have experimentally investigated. The results show that for uniform current distributions the conductor's critical current is proportional to the critical current of the Bi-2223 tape to which a voltage lead is attached. However it depends on the current non-uniformity parameter in the conductor rather than the tape's critical currents for nonuniform current distributions. The loss tests indicate that the AC loss is dependent on arrangements of voltage leads but not on their contact positions. The measured losses in the conductor also agree well with the sum of the transport losses measured in each Bi-2223 tape.

인접 교류전류가 Bi-2223테이프의 통전손실에 미치는 영향

류경우,최병주 한국전기전자재료학회 2001 전기전자재료학회논문지 Vol.14 No.3

Bi-2223 tapes have been developed for low-field power applications at liquid nitrogen temperature. When the Bi-2223 tapes are used in an application such as a power transmission cable or a power transformer, they are supplied with an AC transport current simultaneously. AC loss taking into account such real applications is a crucial issue for power applications fo the Bi-2223 tapes to be feasible. In this paper, the transport losses for different AC current levels and arrangements of the neighboring tapes have been measured in a 1./5 m long Bi-2223 tape. The significant increase of the transport losses due to neighboring tape's AC currents is observed. An increase of the transport losses caused by a decrease of the Bi-2223 tape's critical current is a minor effect. The measured trasprot losses could not be explained by a dynamic resistance loss based on DC voltage-current characteristics in combination with the neighboring tape's AC currents.The trasport losses do not depend on the frequency of the neighboring tape's AC currents but is arrangements in the range of small current especially.

전류집전 방법에 따른 원통형 고체산화물 연료전지의 성능 변화 수치해석

유건,박석주,이종원,이승복,임탁형,송락현,신동열,김호영 한국수소및신에너지학회 2011 한국수소 및 신에너지학회논문집 Vol.22 No.2

Performance changes of an anode-supported tubular SOFC including current collectors are analyzed at different current collecting methods using numerical simulation. From the two dimensional numerical model of the solid oxide fuel cell with nickel felts as anodic current collectors and silver wires as cathodic ones,the performance curves and the distributions of temperature, concentration, current density are obtained. Also,the voltage loss of the cell is divided into three parts: activation loss, concentration loss and ohmic loss. The results show that the performance change of the cell is dominantly influenced by the ohmic loss. Although the temperature and concentration distributions are different, the total activation loss and concentration loss are nearly same. And the ohmic loss is divided into each parts of the cell components. The ohmic loss of the anodic current collectorreaches about 60~80% of the cell’s total ohmic loss. Therefore, the reduction of the ohmic loss of the anodic current collector is very important for stack power enhancement. It is also recommended that the load should be connected to the both ends of the anodic current collector.

단층원통형 고온초전도도체의 교류손실 특성

마용호,이주영,류경우,손송호,황시돌,Ma, Yong-Hu,Li, Zhu-Yong,Ryu, Kyung-Woo,Sohn, Song-Ho,Hwang, Si-Dol 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.7

The AC loss is an important issue in the design of the high temperature superconductor (HTS) power cables and fault current limiters. In these applications, a cylindrical HTS conductor is often used. In commercialization of these apparatuses, AC loss is a critical factor but not elucidated completely because of complexities in its measurement, e.g. non-uniform current distribution and phase difference between currents flowing in an individual HTS tape. We have prepared two cylindrical conductors composed of a Bi-2223 tape with different critical current density. In this paper, the AC loss characteristics of the conductors have been experimentally investigated and numerically analyzed. The result show that the measured losses for two conductors are not dependent on both arrangements and contact positions of a voltage lead. This implies that most of loss flux is only in the conductors. The loss for the Bi-2223 conductor with low critical current density is in good agreement with the calculated loss from Monoblock model, whereas the loss measured for the Bi-2223 conductor with high critical current density doesn't coincide with the loss calculated from the Monoblock model. The measured loss is also different from numerically calculated one based on the polygon model especially in low transport current.

자속-자화 전류 곡선과 전압-철손 전류 곡선을 이용한 측정용 철심 변류기의 보상 알고리즘 개발

강용철(Yong-Cheol kang),정태영(Tai-Ying Zheng),강해권(Hae-Gweon Kang),이병은(Byung-Eun Lee),김용균(Yong-Gyun Kim) 대한전기학회 2009 전기학회논문지 Vol.58 No.10

This paper describes the design, evaluation and implementation of a compensating algorithm for an iron-cored measurement current transformer (CT) that removes the effects of the hysteresis characteristics of the iron-core. The exciting current resulting from the hysteresis characteristics of the core causes an error of the CT. The proposed algorithm decomposes the exciting current into the core loss current and the magnetizing current and each of them is estimated. The core loss current is calculated from the secondary voltage and the voltage-core loss current curve. The core flux linkage is calculated and then inserted into the flux-magnetizing current curve to estimate the magnetizing current. The exciting current at every sampling interval is obtained by summing the core loss and magnetizing currents and then added to the measured current to obtain the correct secondary current. The voltage-core loss current curve and flux-magnetizing current curves, which are different from the conventional curves, are derived in this paper. The performance of the proposed algorithm is validated under various conditions using EMTP generated data. The experimental test results of an iron-core type electronic CT, which consists of the iron-core and the compensation board, are also included. The results indicate that the proposed algorithm can improve the accuracy of the measurement CT significantly, and thus reduce the size and the cost of the CT.

마그네틱 기어의 영구자석 부착방법에 따른 영구자석 와전류손실 분석

박의종(Eui-Jong Park),김성진(Sung-Jin Kim),정상용(Sang-Yong Jung),김용재(Yong-Jae Kim) 대한전기학회 2017 전기학회논문지 Vol.66 No.6

Recently, there has been an increasing interest in the non-contact power transmission method of magnetic gears. Since there is no mechanical contact, noise caused by friction can be reduced, and even if a sudden large force is applied, the impact of the gear is close to zero. Further, since the power is transmitted by the magnetic flux, it has high reliability. However, there is a problem that a loss due to a magnetic field due to use of a magnetic flux. The loss caused by the magnetic field of the magnetic gear is a joule loss called eddy current loss. In addition, the eddy current loss in the magnetic gear largely occurs in the permanent magnet, but it is a fatal loss to the permanent magnet which is vulnerable to heat. Particularly, magnetic gears requiring high torque density use NdFeB series permanent magnets, and this permanent magnets have a characteristic in which the magnetic force decreases as temperature increases. Therefore, in this paper, the eddy current loss of the permanent magnet according to the permanent magnet attaching method is analyzed in order to reduce the eddy current loss of the permanent magnet. We have proposed a structure that can reduce the eddy current loss through the analysis and show the effect of reducing the loss of the proposed structure.

A Hybrid PWM Scheme for Stator Loss Reduction of Two Parallel Interleaved Inverter-Fed PMSM Drive with a Minimized Switching Loss

Liu Shengfu,Jin Xiaoliang,Shi Wen,Yang Huan,Zhao Rongxiang 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.1

The modulation’s eff ects on the stator losses have been explored by previous studies. It confi rms that the voltage vector error introduced by the PWM schemes dominants the PWM-related harmonic eddy-current loss and the PWM-related harmonic copper loss. However, the existing PWM schemes of two parallel inverter focus on the ZSCC peak reductions. They do not explore the reductions of the voltage vector error by the optimal vector sequences to suppress the stator loss. This paper aims to reduce the stator loss of the permanent magnet synchronous motor (PMSM) drive systems fed by the two parallel interleaved inverter with an optimal PWM scheme. First, this paper investigates the eff ects of the instantaneous voltage vector error, resulting from a PWM inverter, on the eddy-current loss and stator copper loss and reveals that a reduced voltage error reduces the eddy-current loss and stator copper loss. Then, this paper divides each 60° sector into six subsectors to minimize the voltage vector error, and with the proposed sector division, it further elects the optimal vector sequences for the subsectors, applying the minimum switching times per carrier period. Besides, the proposed optimal vector sequences are implemented through a simplifi ed carrier-based method. The presented analysis confi rms that the proposed PWM scheme can reduce the eddy-current loss, stator copper loss, and switching loss of the existing methods. Finally, the experimental results verify the theoretical analysis and optimal performance of the proposed modulation strategy.

Eddy-Current Loss Analysis of Noncontact Magnetic Device With Permanent Magnets Based on Analytical Field Calculations

Min, Kyoung-Chul,Choi, Jang-Young,Kim, Jeong-Man,Cho, Han-Wook,Jang, Seok-Myoeng IEEE 2015 IEEE transactions on magnetics Vol.51 No.11

<P>This paper reports on the analysis of eddy-current loss of a magnetic coupling (MC) that uses a Halbach array permanent magnet (PM). A MC is a kind of noncontact magnetic device (NCMD). When the conductive materials of NCMDs are exposed to time-varying magnetic fields, eddy currents are induced in the conductive materials, leading to losses. An analysis of the eddy-current loss is therefore required, and for MCs, the analysis of eddy-current loss is particularly more important. We obtain the magnetic field solutions of the Halbach magnetized PM based on the magnetic vector potential and 2-D polar-coordinate system. In addition, using the derived magnetic field solutions, we derive analytical solutions for eddy-current loss using the equivalent electrical resistance that is calculated from the magnet volume and conductivity. A 2-D finite-element analysis is employed to confirm the validity of the analytical results of the eddy-current density and eddy-current loss. Finally, we investigate the influence of the number of Halbach segments on the eddy-current loss induced on the MC.</P>

Reduction of Eddy Current Loss in Metal Sheath of 154 kV Transmission Cable

Sang Hyeon Im,Ki Byung Kim,Gwan Soo Park 한국자기학회 2020 Journal of Magnetics Vol.25 No.2

The power cables in underground transmission lines consist of a conductor, an insulator, and a metallic sheath. The metallic sheath serves to protect the cable from external physical impacts. When a large fault current is applied to the transmission line owing to an accident, the metallic sheath prevents the fault current from penetrating into the transmission-line current and thus enhances the reliability of the transmission line. However, owing to the alternating current flowing through the conductor, an eddy current is generated in the sheath and a loss occurs. Thus, the overall transmission efficiency is reduced. In this paper, an eddy current loss in a metallic sheath was analyzed using an analytical method, and the results thus obtained were verified by comparing them with those obtained using the finite element method. In addition, a design was proposed for reducing the eddy current loss.