Pub Date : 2015-05-11DOI: 10.1109/INTMAG.2015.7157659
J. Engelen, V. Jonnalagadda, S. Furrer, H. Rothuizen, M. Lantz
A small head-medium spacing is crucial for achieving high linear densities in magnetic tape recording. Traditional contoured (cylindrical) tape heads have been superseded by flat-profile tape heads with sharp skiving edges to remove the natural air bearing that forms between tape and a contoured head, to reduce the head-tape spacing [1]. This means that tape is in contact with the head surface and that the spacing is determined predominantly by the tape surface roughness. To further reduce the head-medium spacing, the tape surface roughness needs to be reduced, which however results in increased head-medium friction. High friction is problematic for tape durability, for reliable operation of the data channel, and for accurate track-follow control. Although friction is lower for smaller tape wrap angles, reducing the wrap angle in a skiving configuration is not desirable because it results in an unacceptable increase in head-medium spacing. Furthermore, recent research has shown that a substantial amount of the friction originates at the skiving edges of the head. In this work, we present a new tape head design which allows dispensing with the skiving edges to reduce friction, while simultaneously maintaining tape-head contact above the read/write transducers.
{"title":"A non-skiving tape head with sub-ambient air pressure cavities","authors":"J. Engelen, V. Jonnalagadda, S. Furrer, H. Rothuizen, M. Lantz","doi":"10.1109/INTMAG.2015.7157659","DOIUrl":"https://doi.org/10.1109/INTMAG.2015.7157659","url":null,"abstract":"A small head-medium spacing is crucial for achieving high linear densities in magnetic tape recording. Traditional contoured (cylindrical) tape heads have been superseded by flat-profile tape heads with sharp skiving edges to remove the natural air bearing that forms between tape and a contoured head, to reduce the head-tape spacing [1]. This means that tape is in contact with the head surface and that the spacing is determined predominantly by the tape surface roughness. To further reduce the head-medium spacing, the tape surface roughness needs to be reduced, which however results in increased head-medium friction. High friction is problematic for tape durability, for reliable operation of the data channel, and for accurate track-follow control. Although friction is lower for smaller tape wrap angles, reducing the wrap angle in a skiving configuration is not desirable because it results in an unacceptable increase in head-medium spacing. Furthermore, recent research has shown that a substantial amount of the friction originates at the skiving edges of the head. In this work, we present a new tape head design which allows dispensing with the skiving edges to reduce friction, while simultaneously maintaining tape-head contact above the read/write transducers.","PeriodicalId":381832,"journal":{"name":"2015 IEEE Magnetics Conference (INTERMAG)","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130669659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-05-11DOI: 10.1109/INTMAG.2015.7157648
C. Romero-Torralva, C. Mayer, V. Franco, A. Conde
In this work, the influence of the rate of change of the applied field to three magnetocaloric samples is studied: a bulk Gd sample used as a reference material, and fully hydrogenated La0.7Ce0.3Fe11.7Si1.3H1.8 and La0.7Ce0.3(Fe0.882Mn0.018Si0.1)13H1.8 alloys, denoted as ERASTEEL-NX and ERASTEEL-11688, respectively . Bulk samples ERASTEEL-NX and ERASTEEL-1688 were prepared from powder batches obtained by gas atomization process as described in [4] . The powder was then sintered at 1150°C for 5 hours in Ar (it has to be noticed that this is not the optimal temperature for maximizing the proportion of NaZn13 type phase), and the obtained blocs were treated at 400°C for 1 hour in hydrogen . The final proportions of NaZn13 type phase is respectively 80 .5% (instead of 92% for optimized heat treatment) and 85% (instead of 92% also for optimized heat treatment) in ERASTEEL-NX and ERASTEEL-1688 . ERASTEEL-NX, with 30% of Ce substituted to La and no substitution on the Fe site shows a very strong 1st order transition, with a wide hysteresis . ERASTEEL-1688 contains some Mn atoms in substitution to Fe . This induces a softening of the 1st order character of the magnetic transition in this sample . The adiabatic temperature change of the samples has been measured using a commercial setup consisting of a set of Halbach cylinders as a variable field source up to 1.78 T, and a thermocouple placed between two pieces of sample, with dimensions of 8 x 4 x 0 .75 mm, which registers the temperature difference between the sample and the sampleholder . The sample is kept in vacuum inside a bath cryostat . The temperature of the sampleholder is stabilized before performing each of the adiabatic measurements . The rate of change of the field ranged from 0 .25 T s-1 to 3 T s-1, which is equivalent to frequencies of a magnetic refrigerator operating between 0 and 1 .78 T ranging from 0 .07 Hz to 0 .84 Hz .
本文研究了外加磁场变化率对三种磁热样品的影响:以体积Gd样品为基准材料，充分氢化的La0.7Ce0.3 fe11.7 si1.3 h1.8和La0.7Ce0.3(fe0.888 mn0.018 si0.1)13H1.8合金，分别记为ERASTEEL-NX和ERASTEEL-11688。用[4]中所述的气雾化工艺获得的粉末批次制备了散装样品ERASTEEL-NX和ERASTEEL-1688。然后将粉末在1150℃的氩气中烧结5小时(需要注意的是，这不是使NaZn13型相比例最大化的最佳温度)，得到的块状物在400℃的氢气中处理1小时。在ERASTEEL-NX和ERASTEEL-1688中，NaZn13型相的最终比例分别为80.5%(优化热处理为92%)和85%(优化热处理为92%)。ERASTEEL-NX中，30%的Ce被La取代，而Fe位点没有被取代，表现出很强的一阶跃迁，具有较宽的滞后。ERASTEEL-1688含有一些取代铁的Mn原子。这引起了该样品中磁跃迁的一阶特性的软化。样品的绝热温度变化使用商业装置进行测量，该装置由一组哈尔巴赫圆柱体作为高达1.78 T的可变场源，以及放置在两块样品之间的热电偶组成，尺寸为8 x 4 x 0.75 mm，其记录了样品和样品支架之间的温差。样品在低温恒温器中真空保存。在进行每次绝热测量之前，样品架的温度是稳定的。磁场的变化率在0.25 T -1到3t -1之间，这相当于一台运行在0到1.78 T之间、0.07 Hz到0.84 Hz的磁制冷机的频率。
{"title":"Dynamic effects in the characterization of the magnetocaloric effect of LaFeSi-type alloys","authors":"C. Romero-Torralva, C. Mayer, V. Franco, A. Conde","doi":"10.1109/INTMAG.2015.7157648","DOIUrl":"https://doi.org/10.1109/INTMAG.2015.7157648","url":null,"abstract":"In this work, the influence of the rate of change of the applied field to three magnetocaloric samples is studied: a bulk Gd sample used as a reference material, and fully hydrogenated La0.7Ce0.3Fe11.7Si1.3H1.8 and La0.7Ce0.3(Fe0.882Mn0.018Si0.1)13H1.8 alloys, denoted as ERASTEEL-NX and ERASTEEL-11688, respectively . Bulk samples ERASTEEL-NX and ERASTEEL-1688 were prepared from powder batches obtained by gas atomization process as described in [4] . The powder was then sintered at 1150°C for 5 hours in Ar (it has to be noticed that this is not the optimal temperature for maximizing the proportion of NaZn13 type phase), and the obtained blocs were treated at 400°C for 1 hour in hydrogen . The final proportions of NaZn13 type phase is respectively 80 .5% (instead of 92% for optimized heat treatment) and 85% (instead of 92% also for optimized heat treatment) in ERASTEEL-NX and ERASTEEL-1688 . ERASTEEL-NX, with 30% of Ce substituted to La and no substitution on the Fe site shows a very strong 1st order transition, with a wide hysteresis . ERASTEEL-1688 contains some Mn atoms in substitution to Fe . This induces a softening of the 1st order character of the magnetic transition in this sample . The adiabatic temperature change of the samples has been measured using a commercial setup consisting of a set of Halbach cylinders as a variable field source up to 1.78 T, and a thermocouple placed between two pieces of sample, with dimensions of 8 x 4 x 0 .75 mm, which registers the temperature difference between the sample and the sampleholder . The sample is kept in vacuum inside a bath cryostat . The temperature of the sampleholder is stabilized before performing each of the adiabatic measurements . The rate of change of the field ranged from 0 .25 T s-1 to 3 T s-1, which is equivalent to frequencies of a magnetic refrigerator operating between 0 and 1 .78 T ranging from 0 .07 Hz to 0 .84 Hz .","PeriodicalId":381832,"journal":{"name":"2015 IEEE Magnetics Conference (INTERMAG)","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123814198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-05-11DOI: 10.1109/INTMAG.2015.7156636
W. Li, W. Hua, M. Cheng, F. Yu, S. Ding
Recently, flux-switching permanent magnet (FSPM) machines, particular for multi-phase topologies have attracted wide interests due to the merits of high power density, strong fault-tolerant capability, and high efficiency, etc. However, the reliability of FSPM machines has never been reported although it is an important issue for electrical machines. Hence, in this paper, a reliability model of a nine-phase FSPM machine is established firstly based on the reliability analysis theory and method. Then, a reliability comparison between a three- and a nine- phase FSPM machine is conducted. Finally, the relationships and consequently, the design principle between the phase number and reliability of the FSPM machines are proposed, which are essentially useful to guide the selection of the phase number for the design of machines further.
{"title":"Reliability analysis of a nine-phase flux-switching PM machine","authors":"W. Li, W. Hua, M. Cheng, F. Yu, S. Ding","doi":"10.1109/INTMAG.2015.7156636","DOIUrl":"https://doi.org/10.1109/INTMAG.2015.7156636","url":null,"abstract":"Recently, flux-switching permanent magnet (FSPM) machines, particular for multi-phase topologies have attracted wide interests due to the merits of high power density, strong fault-tolerant capability, and high efficiency, etc. However, the reliability of FSPM machines has never been reported although it is an important issue for electrical machines. Hence, in this paper, a reliability model of a nine-phase FSPM machine is established firstly based on the reliability analysis theory and method. Then, a reliability comparison between a three- and a nine- phase FSPM machine is conducted. Finally, the relationships and consequently, the design principle between the phase number and reliability of the FSPM machines are proposed, which are essentially useful to guide the selection of the phase number for the design of machines further.","PeriodicalId":381832,"journal":{"name":"2015 IEEE Magnetics Conference (INTERMAG)","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123853982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-05-11DOI: 10.1109/INTMAG.2015.7156691
Y. Cao, L. Yu, H. Jia
Axial-flux permanent-magnet (AFPM) machine with its compact structure, flat shape and high torque-to-weight ratio is increasingly being popularized and applied in various applications, such as wheel motor drives and portable generator sets. The coreless stator design of AFPM machines reduces the weight and eliminates core losses, which can operate at higher efficiency than conventional machines. The coreless AFPM machine has two outer rotor discs and one inner coreless stator disc. The rotor discs play a role both in magnetic circuit and mechanical support. For the coreless AFPM machine, the axial and circumferential electromagnetic force in the rotors will be generated by air-gap magnetic field. The circumferential electromagnetic force leads to electromagnetic torque, which is necessary for the motor rotation. The axial electromagnetic force may cause the rotor's deflection and affect the machine's reliability. Several analysis methods of the axial electromagnetic force and structure deformation for the AFPM machine have been reported. In [1], a simplified two-dimensional (2-D) finite element method (FEM) and three-dimensional (3-D) FEM are used to analyze and design the rotor discs of a high-speed AFPM generators. In [2], the combination method of numerical calculation and FEM is used to study the stiffness of the rotors of an AFPM machine. But there still remain some problems. 3-D FEM is time consuming and 2-D FEM is not accurate enough.
{"title":"Rotor mechanical stress and deformation analysis of coreless stator axial-flux permanentmagnet machines","authors":"Y. Cao, L. Yu, H. Jia","doi":"10.1109/INTMAG.2015.7156691","DOIUrl":"https://doi.org/10.1109/INTMAG.2015.7156691","url":null,"abstract":"Axial-flux permanent-magnet (AFPM) machine with its compact structure, flat shape and high torque-to-weight ratio is increasingly being popularized and applied in various applications, such as wheel motor drives and portable generator sets. The coreless stator design of AFPM machines reduces the weight and eliminates core losses, which can operate at higher efficiency than conventional machines. The coreless AFPM machine has two outer rotor discs and one inner coreless stator disc. The rotor discs play a role both in magnetic circuit and mechanical support. For the coreless AFPM machine, the axial and circumferential electromagnetic force in the rotors will be generated by air-gap magnetic field. The circumferential electromagnetic force leads to electromagnetic torque, which is necessary for the motor rotation. The axial electromagnetic force may cause the rotor's deflection and affect the machine's reliability. Several analysis methods of the axial electromagnetic force and structure deformation for the AFPM machine have been reported. In [1], a simplified two-dimensional (2-D) finite element method (FEM) and three-dimensional (3-D) FEM are used to analyze and design the rotor discs of a high-speed AFPM generators. In [2], the combination method of numerical calculation and FEM is used to study the stiffness of the rotors of an AFPM machine. But there still remain some problems. 3-D FEM is time consuming and 2-D FEM is not accurate enough.","PeriodicalId":381832,"journal":{"name":"2015 IEEE Magnetics Conference (INTERMAG)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123344015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-05-11DOI: 10.1109/INTMAG.2015.7157258
A. Fukushima, K. Yakushiji, H. Kubota, S. Yuasa
Stochastic switching of spin-torque switching in a small-sized magnetic tunnel junction (MTJ) has a unique nature in any kind of solid state devices working at room temperature. The switching probability (Psw) can be controlled by the amplitude of the injected current with good reproducibility. This means that the results of the spin-torque switching events can be used as an ideal physical random number generator which produces completely unpredictable random numbers. Meanwhile, the unpredictable random numbers are required as the key factor for data encryption. For this reason, we have been developing a physical random number generator, called spin dice [1], using the stochastic spin-torque switching.
{"title":"Spin dice (physical random number generator using spin torque switching) and its thermal response","authors":"A. Fukushima, K. Yakushiji, H. Kubota, S. Yuasa","doi":"10.1109/INTMAG.2015.7157258","DOIUrl":"https://doi.org/10.1109/INTMAG.2015.7157258","url":null,"abstract":"Stochastic switching of spin-torque switching in a small-sized magnetic tunnel junction (MTJ) has a unique nature in any kind of solid state devices working at room temperature. The switching probability (Psw) can be controlled by the amplitude of the injected current with good reproducibility. This means that the results of the spin-torque switching events can be used as an ideal physical random number generator which produces completely unpredictable random numbers. Meanwhile, the unpredictable random numbers are required as the key factor for data encryption. For this reason, we have been developing a physical random number generator, called spin dice [1], using the stochastic spin-torque switching.","PeriodicalId":381832,"journal":{"name":"2015 IEEE Magnetics Conference (INTERMAG)","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123501378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-05-11DOI: 10.1109/INTMAG.2015.7157578
K. Kobayashi, T. Murakami, D. Oyama
A wide dynamic range SQUID magnetometer is developed in this study. This magnetometer uses the flux quanta counting method with direct-feedback noise cancellation in order to improve the signal-noise ratio in magnetocardiogram measured without the magnetically shielded room.
{"title":"Wide dynamic range SQUID magnetometer with noise cancellation for magnetocardiogram without magnetically shielded room","authors":"K. Kobayashi, T. Murakami, D. Oyama","doi":"10.1109/INTMAG.2015.7157578","DOIUrl":"https://doi.org/10.1109/INTMAG.2015.7157578","url":null,"abstract":"A wide dynamic range SQUID magnetometer is developed in this study. This magnetometer uses the flux quanta counting method with direct-feedback noise cancellation in order to improve the signal-noise ratio in magnetocardiogram measured without the magnetically shielded room.","PeriodicalId":381832,"journal":{"name":"2015 IEEE Magnetics Conference (INTERMAG)","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123657360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-05-11DOI: 10.1109/INTMAG.2015.7157433
E. Liu, W. Zhang, X. Hu, R. Du, H. Ou, C. Kou, Y. Wang, Y. Zhai, J. Du, Y. Xu, H. Zhai
Half-metallic magnetite with high spin polarization at the Fermi level has always been an ideal candidate for spin dependent transport study, and understanding of the magnetic transportation property of Fe3O4 becomes a critical issue for its future applications in spintronics. Generally the resistance of Fe3O4 decreases (negative MR) when applied in a magnetic field as the conduction in Fe3O4 is attributed to a small polaron hopping mechanism between Fe2+ ions and Fe3+ ions in oxygen ions octahedral sites, and the applied field is suggested to broaden the polaronic band leading to enhanced conduction. Previous studies on magnetic transportation of Fe3O4 film also confirm its negative MR effect, and positive MR effect is only observed in a few specific structures such as TiN/ Fe3O4 superlattices, magnetic tunnel junctions with Fe3O4 electrode, the increase of resistance after application of magnetic field for these system is ascribed to the spin selective quantum confinement effects in the heterostructure, which refer to the extrinsic structures instead of the intrinsic magnetic transportation property of magnetite film. However, in our recent studies, an anomalous positive magnetotransport behavior is demonstrated on high oriented Fe3O4 film grown on Si substrate at high temperature, and the inverse MR effect is believed to be highly correlated to the strong orientation of Fe3O4 film.
{"title":"Inverse magnetoresistance in single layer Fe3O4 film","authors":"E. Liu, W. Zhang, X. Hu, R. Du, H. Ou, C. Kou, Y. Wang, Y. Zhai, J. Du, Y. Xu, H. Zhai","doi":"10.1109/INTMAG.2015.7157433","DOIUrl":"https://doi.org/10.1109/INTMAG.2015.7157433","url":null,"abstract":"Half-metallic magnetite with high spin polarization at the Fermi level has always been an ideal candidate for spin dependent transport study, and understanding of the magnetic transportation property of Fe<sub>3</sub>O<sub>4</sub> becomes a critical issue for its future applications in spintronics. Generally the resistance of Fe<sub>3</sub>O<sub>4</sub> decreases (negative MR) when applied in a magnetic field as the conduction in Fe<sub>3</sub>O<sub>4</sub> is attributed to a small polaron hopping mechanism between Fe<sup>2+</sup> ions and Fe<sup>3+</sup> ions in oxygen ions octahedral sites, and the applied field is suggested to broaden the polaronic band leading to enhanced conduction. Previous studies on magnetic transportation of Fe<sub>3</sub>O<sub>4</sub> film also confirm its negative MR effect, and positive MR effect is only observed in a few specific structures such as TiN/ Fe<sub>3</sub>O<sub>4</sub> superlattices, magnetic tunnel junctions with Fe<sub>3</sub>O<sub>4</sub> electrode, the increase of resistance after application of magnetic field for these system is ascribed to the spin selective quantum confinement effects in the heterostructure, which refer to the extrinsic structures instead of the intrinsic magnetic transportation property of magnetite film. However, in our recent studies, an anomalous positive magnetotransport behavior is demonstrated on high oriented Fe<sub>3</sub>O<sub>4</sub> film grown on Si substrate at high temperature, and the inverse MR effect is believed to be highly correlated to the strong orientation of Fe<sub>3</sub>O<sub>4</sub> film.","PeriodicalId":381832,"journal":{"name":"2015 IEEE Magnetics Conference (INTERMAG)","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121198548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-05-11DOI: 10.1109/INTMAG.2015.7157423
P. Zheng, Zhouhan Lin, Y. Sui
Owing to the advantages of high power density and salient field-weakening performance, interior permanent-magnet (IPM) machines are widely applied in electric vehicles (EVs). However, rare-earth permanent magnets can be demagnetized irreversibly because of large demagnetizing current and high temperature. Hence, this paper proposes a combined pole IPM machine which can improve the demagnetization withstand capability. The combined pole adopts hybrid NdFeB and ferrite magnets to improve the air-gap flux density, further improving the machine performances. Based on finite-element analysis (FEA), the machine performances are evaluated and compared with those of the conventional shaped pole machines.
{"title":"Research on combined pole for interior permanent-magnet machine","authors":"P. Zheng, Zhouhan Lin, Y. Sui","doi":"10.1109/INTMAG.2015.7157423","DOIUrl":"https://doi.org/10.1109/INTMAG.2015.7157423","url":null,"abstract":"Owing to the advantages of high power density and salient field-weakening performance, interior permanent-magnet (IPM) machines are widely applied in electric vehicles (EVs). However, rare-earth permanent magnets can be demagnetized irreversibly because of large demagnetizing current and high temperature. Hence, this paper proposes a combined pole IPM machine which can improve the demagnetization withstand capability. The combined pole adopts hybrid NdFeB and ferrite magnets to improve the air-gap flux density, further improving the machine performances. Based on finite-element analysis (FEA), the machine performances are evaluated and compared with those of the conventional shaped pole machines.","PeriodicalId":381832,"journal":{"name":"2015 IEEE Magnetics Conference (INTERMAG)","volume":"306 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121275282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-05-11DOI: 10.1109/INTMAG.2015.7156547
A. Kohara, K. Hirata, N. Niguchi, Y. Ohno
Electric and hybrid electric vehicles require traction motors that have a high power and efficiency over a wide rotation speed range . In order to satisfy these requirements and reduce the motor cost, variable flux reluctance motors (VFRMs) have been studied . Conventional VMFRMs have DC-field windings and armature windings. However, because there are two kinds of windings, the coil space factor decreases and the wiring becomes complicated . In order to solve these problems, we have developed a motor called the variable flux reluctance motor (CSVFRM) that does not have any DC-field coils, and instead uses current superimposition . In this paper, we propose a modified model whereby permanent magnets are introduced into the stator to increase the efficiency . The structure and operational principle of this machine are described and the N-T characteristics are computed by FEA.
{"title":"Permanent magnet assisted current superimposition variable flux machine","authors":"A. Kohara, K. Hirata, N. Niguchi, Y. Ohno","doi":"10.1109/INTMAG.2015.7156547","DOIUrl":"https://doi.org/10.1109/INTMAG.2015.7156547","url":null,"abstract":"Electric and hybrid electric vehicles require traction motors that have a high power and efficiency over a wide rotation speed range . In order to satisfy these requirements and reduce the motor cost, variable flux reluctance motors (VFRMs) have been studied . Conventional VMFRMs have DC-field windings and armature windings. However, because there are two kinds of windings, the coil space factor decreases and the wiring becomes complicated . In order to solve these problems, we have developed a motor called the variable flux reluctance motor (CSVFRM) that does not have any DC-field coils, and instead uses current superimposition . In this paper, we propose a modified model whereby permanent magnets are introduced into the stator to increase the efficiency . The structure and operational principle of this machine are described and the N-T characteristics are computed by FEA.","PeriodicalId":381832,"journal":{"name":"2015 IEEE Magnetics Conference (INTERMAG)","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121378089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-05-11DOI: 10.1109/INTMAG.2015.7156672
C. Moreau-Luchaire, N. Reyren, C. Moutafis, J. Sampaio, N. Van Horne, C. Vaz, P. Warnicke, K. Garcı́a, M. Weigand, K. Bouzehouane, C. Deranlot, J. George, J. Raabe, V. Cros, A. Fert
Magnetic skyrmions are arguably the smallest stable magnetic configuration in films, and therefore could be the ultimate magnetic storage bit. They have also triggered a wide interest due to the new fundamental phenomena related to their topology. Numerical simulations have shown that the interfacial Dzyaloshinskii-Moriya interaction (DMI) can stabilize such skyrmions in nanoscale disks or tracks for a rather large range of DMI amplitudes for which the skyrmion can either be the ground state or metastable relative to the uniform state. Here, we demonstrate experimentally the presence of skyrmions in metallic multilayers structures engineered to exhibit a strong DMI interaction.
{"title":"Skyrmions at room temperature in magnetic multilayers","authors":"C. Moreau-Luchaire, N. Reyren, C. Moutafis, J. Sampaio, N. Van Horne, C. Vaz, P. Warnicke, K. Garcı́a, M. Weigand, K. Bouzehouane, C. Deranlot, J. George, J. Raabe, V. Cros, A. Fert","doi":"10.1109/INTMAG.2015.7156672","DOIUrl":"https://doi.org/10.1109/INTMAG.2015.7156672","url":null,"abstract":"Magnetic skyrmions are arguably the smallest stable magnetic configuration in films, and therefore could be the ultimate magnetic storage bit. They have also triggered a wide interest due to the new fundamental phenomena related to their topology. Numerical simulations have shown that the interfacial Dzyaloshinskii-Moriya interaction (DMI) can stabilize such skyrmions in nanoscale disks or tracks for a rather large range of DMI amplitudes for which the skyrmion can either be the ground state or metastable relative to the uniform state. Here, we demonstrate experimentally the presence of skyrmions in metallic multilayers structures engineered to exhibit a strong DMI interaction.","PeriodicalId":381832,"journal":{"name":"2015 IEEE Magnetics Conference (INTERMAG)","volume":"80 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114221910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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