United States

Magnetic refrigeration (MR), exploiting the adiabatic demagnetization phenomena, is preferable over conventional gas-compression based technology due to its low cost and high efficiency along with environment-friendly method [1-3]. Recently, earth-abundant Mn-based alloy, Mn&lt;sub&gt;5&lt;/sub&gt;Ge&lt;sub&gt;3 &lt;/sub&gt; has emerged as a potential alternative with reasonably high relative cooling power (RCP) which is the centre of the present study [4]. Concerning the technological applications, the role played by the size-reduction (macro to micro-scale) on the engineering of innovative devices is still in its early age. In this context, Mn&lt;sub&gt;5&lt;/sub&gt;Ge&lt;sub&gt;3&lt;/sub&gt; ribbons are synthesized using the melt spinning technique. The temperature and field-dependent dc magnetization are measured with physical properties measurement system (Quantum design, 8T). The M (T) curve at 1 kOe shows a sharp ferromagnetic ordering at T&lt;sub&gt;C&lt;/sub&gt; ~ 304 K. Furthermore, the M (H) hysteresis loop at 5 K reveal the typical soft ferromagnetic behaviour with saturation magnetisation (M&lt;sub&gt;S&lt;/sub&gt;) of 136 emu/g with approximately zero hysteresis loss which is highly preferential for MR technology. From magnetic isotherms, the magneto-caloric effect is studied in the wide temperature range of 250-360 K. Using the Maxwell equation, Isothermal magnetic entropy change (ΔS&lt;sub&gt;M&lt;/sub&gt;) is calculated as 5 J/Kg-K at 5 T applied field [See Fig 1]. From inset of Fig. 1, It is quite apparent that all the normalized entropy curves with various Δ&lt;i&gt;H &lt;/i&gt;values collapse into a single curve, confirms second order magnetic phase transition. Next, we calculate another parameter such as RCP = ΔS&lt;sub&gt;m&lt;/sub&gt;|&lt;sub&gt;max&lt;/sub&gt; × δT&lt;sub&gt;FWHM&lt;/sub&gt;, where δT&lt;sub&gt;FWHM&lt;/sub&gt; is the span for half to maxima of ΔS&lt;sub&gt;m&lt;/sub&gt; (T) curve around a magnetic transition for practical utilization in MR. The RCP value is obtained as 295 (600) J/kg for a field change of 3 (5) T which is significantly larger than 201.3 J/kg (3 T) as observed in an earlier Mn&lt;sub&gt;5&lt;/sub&gt;Ge&lt;sub&gt;3 &lt;/sub&gt;study [5]. Hence, a large RC value makes the Mn&lt;sub&gt;5&lt;/sub&gt;Ge&lt;sub&gt;3&lt;/sub&gt; ribbon highly promising for magnetic refrigeration application near room temperature.

![](https://assets.underline.io/uploads/markdown_image/1/image/b4bb7f645e496a7395e89ca7a488d9ca.jpg)

The temperature dependence of -ΔSm in field range of 0.5 - 3T (ΔH = 0.5 T) and 4 - 8T (ΔH = 1 T). The inset shows normalized -ΔSm as a function of the rescaled temperature (θ).

2022 Joint MMM-INTERMAG

Enhanced refrigerant capacity in Mn5Ge3 melt spun ribbon near room temperature

#### Welcome to the 67th Annual Conference on Magnetism and Magnetic Materials, MMM 2022!

The Conference was held from October 31 to November 4 and offers both in-person and on-demand content.

MMM 2022 is sponsored jointly by AIP Publishing and the IEEE Magnetics Society. Members of the international scientific and engineering communities interested in recent developments in fundamental and applied magnetism are invited to attend and contribute to the technical sessions. The technical program will include invited and contributed papers in oral and poster sessions, invited symposia, a tutorial, and several special sessions. This Conference provides an outstanding opportunity for worldwide participants to meet their colleagues and collaborators and discuss developments in all areas of magnetism research.

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Please register for the MMM 2022 conference to join the event.

MMM 2022

This Conference provides an outstanding opportunity for worldwide participants to meet their colleagues and collaborators and discuss developments in all areas of magnetism research.

Magnetic refrigeration (MR), exploiting the adiabatic demagnetization phenomena, is preferable over conventional gas-compression based technology due to its low cost and high efficiency along with environment-friendly method [1-3]. Recently, earth-abundant Mn-based alloy, Mn5Ge3 has emerged as a potential alternative with reasonably high relative cooling power (RCP) which is the centre of the present study [4]. Concerning the technological applications, the role played by the size-reduction (macro to micro-scale) on the engineering of innovative devices is still in its early age. In this context, Mn5Ge3 ribbons are synthesized using the melt spinning technique. The temperature and field-dependent dc magnetization are measured with physical properties measurement system (Quantum design, 8T). The M (T) curve at 1 kOe shows a sharp ferromagnetic ordering at TC ~ 304 K. Furthermore, the M (H) hysteresis loop at 5 K reveal the typical soft ferromagnetic behaviour with saturation magnetisation (MS) of 136 emu/g with approximately zero hysteresis loss which is highly preferential for MR technology. From magnetic isotherms, the magneto-caloric effect is studied in the wide temperature range of 250-360 K. Using the Maxwell equation, Isothermal magnetic entropy change (ΔSM) is calculated as 5 J/Kg-K at 5 T applied field [See Fig 1]. From inset of Fig. 1, It is quite apparent that all the normalized entropy curves with various ΔH values collapse into a single curve, confirms second order magnetic phase transition. Next, we calculate another parameter such as RCP = ΔSm|max × δTFWHM, where δTFWHM is the span for half to maxima of ΔSm (T) curve around a magnetic transition for practical utilization in MR. The RCP value is obtained as 295 (600) J/kg for a field change of 3 (5) T which is significantly larger than 201.3 J/kg (3 T) as observed in an earlier Mn5Ge3 study [5]. Hence, a large RC value makes the Mn5Ge3 ribbon highly promising for magnetic refrigeration application near room temperature.

![](https://assets.underline.io/uploads/markdown_image/1/image/b4bb7f645e496a7395e89ca7a488d9ca.jpg)

The temperature dependence of -ΔSm in field range of 0.5 - 3T (ΔH = 0.5 T) and 4 - 8T (ΔH = 1 T). The inset shows normalized -ΔSm as a function of the rescaled temperature (θ).

poster

The 15th Joint MMM-INTERMAG Conference (2022 Joint) is sponsored jointly by AIP Publishing and the IEEE Magnetics Society. Members of the international scientific and engineering communities interested in recent developments in fundamental and applied magnetism are invited to attend and contribute to the technical sessions. The technical program will include invited and contributed papers in oral and poster sessions, invited symposia, a plenary session, and an evening session, with about 1500 presentations overall. This Conference provides an outstanding opportunity for worldwide participants to meet their colleagues and collaborators and discuss developments in all areas of magnetism research.

The 2022 Joint Conference will offer both in-person and prerecorded on-demand content.

For tickets to the event, please register at the following link: https://magnetism.org/register

Please register for the Joint MMM-Intermag conference to join the event.

Recently, SmFe11Ti-based compounds with the ThMn12 crystal structure have been widely studied as a candidate for new permanent magnets due to their excellent intrinsic magnetic properties. Although those compounds have a high anisotropy field (12 T), the actual coercivity is less than 10% of their anisotropy field 1. In general, it is well known that fine precipitates corresponding to the size of the domain wall (several nm to several tens of nm) increase the coercivity of hard magnetic materials by acting as the domain wall pinning site. The addition of C to the SmFe11Ti alloy may result in TiC precipitates in the matrix, and subsequent changes in the coercivity can be expected. In this study, SmFe11Ti alloys containing different amount of C atoms were fabricated by the melt-spinning method to investigate the effects of C atoms on the microstructures and magnetic properties. SmFe11Ti1+xCx (x = 0, 0.05, 0.1, 0.2) alloys with the ThMn12 crystal structure was successfully fabricated by the melt-spinning method and subsequent heat treatment. The optimum heat treatment condition was found to be 850°C for 15 minutes, and the coercivity was shown to be about 6.2 kOe regardless of the C content (Fig. 1). In order to understand these results, the microstructural analysis was performed. It was found that the matrix had the ThMn12 crystal structure and the average grain size was about 30 nm in all samples regardless of the C content (Fig. 2). In these samples, coarse TiC grains (&gt;100 nm) instead of TiC nano-precipitates were formed independently from the matrix. This result explains the reason why the coercivity did not change. Thus, the experimental conditions for obtaining the precipitates are under investigation.


![](https://assets.underline.io/uploads/markdown_image/1/image/75746d30b79db84128662e894a5853fe.jpg)


Fig. 1 Coercivity measured at 2.5 T of SmFe11Ti1+xCx (x = 0, 0.5, 0.1, 0.2) alloys heat treated at 850°C for 15 minutes.


![](https://assets.underline.io/uploads/markdown_image/1/image/4b02a146f9f1f24e4dc7ba739af1ff8b.png)

Fig. 2 Microstructures of SmFe11Ti1.2C0.2 sample heat treated at 850°C for 15 minutes. (a)Bright field image using Transmission Electron Microscopy. (b)Dark field image and corresponding EDS mapping image using Scanning Transmission Electron Microscopy. The grains which was shown in dark contrast on the image was region that Ti and C was concentrated.

The effect of C addition on the magnetic properties and microstructures of nanocrystalline SmFe11Ti alloy

Research on rare-earth-free permanent magnet materials have attracted much attention due to the limited supply and high price of the rare-earth metals used in current state-of-the-art permanent magnets. MnBi and MnBi-based magnets have been investigated as prospective rare-earth-free magnets because the magnetic anisotropy of MnBi increases with increasing temperature reaching a maximum value at 590 K. However, segregation of Bi during synthesis of MnBi is one of the issues which reduces the saturation magnetization. We have found that MnBi synthesized in carbon environment substantially reduces the amount of Bi segregation improving its saturation magnetization. We have synthesized Mn55Bi45 and Mn55Bi45C samples using arc melting and high vacuum annealing. The room temperature x-ray diffraction patterns indicate that both Mn55Bi45 and Mn55Bi45C crystallize in the hexagonal NiAs crystal structure (Low temperature phase, LTP). The X-ray diffraction pattern also indicates that the amount of Bi segregation in Mn55Bi45C is less than that in MnBi. As shown in Fig. 1 below, the high field (3T) magnetization measured at room temperature are 61 emu/g and 66 emu/g for Mn55Bi45 and Mn55Bi45C, respectively. There is small increase in the value of anisotropy constant due to carbon doping. In order to find the possibility of carbon occupying the MnBi lattice, we have carried out first principles calculations of MnBi alloy as well. The conclusions of the first principles calculation and experimental data on structural and magnetic properties of Mn55Bi45 and Mn55Bi45C will be presented. This research is supported by South Dakota-NASA EPSCoR Research Initiation Grant no 80NSSC19M0063.

![](https://assets.underline.io/uploads/markdown_image/1/image/e0f6f2e16ebf3f5ccde46e9f75d13c25.jpg)

Fig. 1: Isothermal magnetization curves M(H) for Mn55Bi45 and Mn55Bi45C measured at 300 K. Inset shows the M(H) curve for Mn55Bi45C after aligning in magnetic field.

Modifying magnetic properties of MnBi with Carbon: An experimental and theoretical study

1.Background Rare earth permanent magnets, i.e., Nd2Fe14B and Sm2Co17, have been used in spacecraft motors. However, the direct atomic displacement in the rare earth permanent magnets’ so-called knock-on damage occurs via cosmic rays [1]. If the knock-on atom does not return to a normal lattice position, the empty lattice point becomes atomic vacancy, so-called a point defect. As a result, the rare earth permanent magnets degrade in magnetic properties and demagnetize, and it could also cause cascade damages. We studied Nd2Fe14B with point defects by first-principle calculation to show how the point defect affects its magnetic properties. 2. Calculation method and models Formation energies and magnetic properties were calculated by the first-principles calculations based on density functional theory, which is implemented in the VASP code with GGA + U method (U = 6 eV) [2]. The cut-off energy was 700 eV, k-point mesh was set to and lattice constants were determined based on the experimental values [3]. A point defect of Nd was assumed to be generated when the interatomic bond in the Nd2Fe14B crystal was cut by the collision of radiation particles with Nd atoms (Fig. 1). The generation processes of point defects of B and Fe were assumed to be the same as Nd. Thus the point defect formation energy was defined as the energy difference before and after the collision as shown in Eq. 1. Eform=(Edef+Eiso)-Eperfect (1) where Eper, Edef and Eiso are the total energies of electrons in a perfect crystal, a crystal with a point defect, and an isolated atom, respectively. 3. Results First, we confirmed that the magnetic moments of the calculation for the perfect crystal and experiment were similar (Table I). Subsequrntly, we found that only the crystal with the point defect of B increased the magnetic moment. We also found that the point defect formation energies of Fe were lower than those of B and Nd and the point defect formation energies of B and Nd were similar.

![](https://assets.underline.io/uploads/markdown_image/1/image/aad867ae5234f598c10ca41a8650f875.jpg)

Fig.1 Calculation models for point defect formation energy of Nd in Nd2Fe17B.


![](https://assets.underline.io/uploads/markdown_image/1/image/590f8f080de1faeb3e880ca5a596de16.jpg)

Table I. Magnetic moments and point defect formation energies

First-principles study of rare earth permanent magnets with point defects created by radiation

Recently, more attention has been paid to developing rare earth free permanent magnets. (Fe0.7Co0.3)2B with tetragonal structure shows good intrinsic hard magnetic properties. It has a large saturation magnetization (Js=13 kGs), a high Curie temperature (Tc=940 K), and a moderate uniaxial magneto-crystalline anisotropy (MCA) field (HA= 7.7 kOe) [1-4]. In addition to the good intrinsic properties, the hard magnetic properties such as coercivity are also sensitive to microstructure. In particular, the coercivity reduces sharply upon the existence of the low MCA regions in microstructure, which favors the nucleation of the magnetic domain for the magnetization reversal. There always exist some local structural defects in real magnets, such as chemical composition fluctuation, local strain, and even the second impurity phase. In this work, the sensitivity of MCA to composition fluctuation and structural defects has been studied by a first-principles DFT calculation. The calculated MCA energy (Emca) of (Fe0.7Co0.3)2B with perfect structure is 0.125 meV/f.u. A fluctuation of cobalt content of 10%, or 1% isotropic lattice strain (Fig.1), or 2% tetragonal distortion will cause a reduction of Emca up to 30% in (Fe0.7Co0.3)2B. The spin-resolved MCA analysis indicates that spin-up and spin-down electrons contribute positively to Emca while the spin mixing has a negative contribution (Fig.1). The interplay of these different contributions results in optimized chemical composition or geometrical structure to maximize MCA. Micromagnetic simulation indicates that the coercivity decrease from 2.2 kOe to 1.0 kOe in an isotropic magnet of (Fe0.7Co0.3)2B with an average grain size of 30nm by considering the existence of randomly distributed local reduction of MCA energy up to 30%. This work is supported by the Critical Materials Institute (CMI), an Energy Innovation Hub funded by the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office. Ames Laboratory is operated for the U.S. DOE by Iowa State University under Contract No. DE-AC02-07CH11358.

![](https://assets.underline.io/uploads/markdown_image/1/image/c11d0f0079ff1d8d06c4d6f00a36a5d9.jpg)

Calculated spin-resolved- and total- magnetocrystalline anisotropy energy as a function of lattice strain in (Fe0.7Co0.3)2B.

Robustness of magneto-crystalline anisotropy and its effect on coercivity in (Fe0.7Co0.3)2B

There exist needs for advanced inductors that are (1) power dense, (2) highly efficient, and (3) high temperature stable for a range of power electronics applications which include on-board converters and off-board charging systems for electric vehicles. Nanocrystalline soft magnetic alloys are of great interest for medium frequency and medium to high power applications due to their large saturation flux density relative to ferrites, as well as their improved losses and reduced magnetostriction relative to amorphous alloys. However, state-of-art commercial Fe-based nanocrystalline alloys display inherently large permeabilities and consequently they require gapping for high power inductor applications and suffer from inherent limitations of mechanical brittleness and relatively poor temperature stability (rated at 150C). Recent advances in Co-based nanocrystalline alloys have enabled a new class of highly scalable inductors which overcome the limitations of existing Fe-based nanocrystalline alloys through in-line tension anneal processing to enable a new level of control for large-scale inductor designs not previously possible without the requirement for core gapping. Local permeability control (i.e. permeability engineering) is made possible through real-time controls of applied tension and controlled thermal processing during the in-line processing step, of particular interest for reduced peak temperature rise and highly power dense inductor designs by engineering the distribution of magnetic flux throughout the core. Advanced thermal processing techniques can also be applied during the in-line processing stage to tailor the characteristic spatial length-scale and distribution of the spatially varied permeability profile, and after the in-line processing to tailor domain structure and optimize losses. Temperature stability of magnetic properties are also far superior to traditional Fe-based alloys, with current experiments showing the potential for stability of structure and magnetic properties as high as 400C and even approaching 500C. The presentation will address the latest advances in Co-based nanocrystalline strain annealed gapless inductors for power dense inductor applications. Topics to be addressed will include: 1) Phase identity and magnetic property variation as a function of chemistry in Co-based nanocrystalline alloys; 2) The latest in tension annealing at scale and spatially tuned permeability engineering methods; 3) Demonstrations of engineered permeabilities as well as optimized domain structures for taliored magnetic properties; 4) Development of tailored multi-objective optimization tools specifically for permeability engineered gapless core inductors; 5) Application of advanced lmulti-objective optimization tools for inductor design and benchmarking in both electric vehicle and medium voltage power electronics applications; The presentation will conclude with recent experimental results as well as emerging ideas and future perspectives for highly optimized thermal processing methods and techniques, including spatial optimization of the crystallization process and consequently the magnetic properties through spatially tailored rapid thermal processing with electromagnetic field-assisted methods and techniques.

Power Dense Inductors Based Upon Co-Based Nanocrystalline Alloys

This presentation will focus on the applications of Soft Magnetic Components and Materials for Emerging Power Conversion Applications such as Solid State Transformer [SST] Technology and several power conversion systems at both Medium-Voltage [MV] and Low-Voltage [LV]. The re-evaluation of conventional magnetics solutions has become important and essential due to the emergence and adoption of WBG [Wide-Band Gap] power devices such as SiC and GaN devices. These devices not only enable co-design of MV and higher switching frequency, but also enable higher temperature operations requiring characterization of magnetics for such specifications. This presentation will cover advances in medium frequency magnetics for WBG devices based power converters and especially for high power converters. It will highlight the latest advances in soft magnetic material qualification and characterization under non-sinusoidal waveforms. It will provide an overview of magnetic core loss models and implications for thermal modeling. It will also address novel techniques for understanding leakage inductance and anomalous losses due to leakage flux. The novel concept of strain annealing for permeability engineering and design opportunities for heterogeneously tuned permeability cores in high power converter applications will be addressed.

Solid State Transformer Technology Based on Advanced Materials and Design Concepts

A review of soft magnetic amorphous and nanocrystalline alloys currently used in the market along their primary industrial applications will be discussed. The distribution transformer market continues to be the largest volume application of Fe-based amorphous foil with higher efficiency standards globally helping to drive the growth of amorphous-based transformers. High permeability grades of amorphous foil have largely supplanted the convention grades due to the higher induction levels (1.63T) and increased stacking factor (&gt;90%). Magnetic domain refinement of amorphous foil, further reducing the core losses, is now commercially available. Amorphous foil has long been envisioned for high efficiency electric motors. The emerging trends with electric vehicles have revitalized the efforts to incorporate amorphous and nanocrystalline foils as the motor lamination materials. There are many approaches to fabricate these motor components and we will discuss the methods that have been industrially adopted. FeCo based amorphous alloys further enhance the induction levels (1.8T) and can be viable in these applications. Nanocrystalline alloys of the FeBSiNbCu composition have now become an industry standard for ultra-low loss, high frequency and high permeability applications. Advanced processing methods have produced higher induction nanocrystalline alloys with higher Fe and lower Nb content. There are also new FeCo and FeNi nanocrystalline alloys being developed specifically suited towards gapless inductor and motor applications that will be discussed.

Recent Advances and Remaining Challenges in Manufacturing of Amorphous and Nanocrystalline Alloys

For the regular machines, the pole-pairs of machine stators and rotors are identical, where the torque is produced by the single working harmonic from the rotor and stator magnetic fields. During the last hundred years, numerous studies have been done to enhance the working harmonics and weaken the non-working harmonics, so as to acquire the sinusoidal air-gap magnetic fields and improve the quality of torque. The presentation will provide a view on electrical machines from the third eye –Flux Modulation point of view. As a new type of machine, the flux modulation PM machines, have drawn more and more attention due to their great torque density capability. Compared with regular PM machines, the pole-pairs of armature windings and rotor PMs in flux modulation machines are different, where the torque is generated by multiple working harmonics of PM magnetic fields and armature magnetic fields. Under the same electric and magnetic loadings, the flux modulation machines can acquire nearly double torque density of regular PM machines. This presentation will introduce flux modulation fundamental operation principles, machine main features, and topologies including multiple magnetomotive force harmonic machines, multiple permeance harmonics machines and double-modulation machines. Applications, challenges, and research opportunities will be discussed as well.

Flux Modulation Machines – Innovation & Beyond

Arguably the pinnacle of motorsport are race cars and therefore an excellent showcase for new technologies from the different areas of automotive systems. Racing “should” utilize components that are beyond the state-of-the-art and within the Advanced Electromagnetics Group (www.ae-grp.nl) we are providing powertrains and test systems for the design, testing, and validation of high-tech and innovative race car powertrains for all-electric racing championships. These e-racing championships are not something that is started in the 21st century. No, already in 1899 Belgian driver and engineer Camille Jenatzy drove flat out in his torpedo-shaped ‘La Jamais Contente’ (‘never satisfied’) in a sparsely populated area to the northwest of Paris and became the first person to reach more than 100 km/h in a car [1]. Even though the electric powertrain failed to dominate the car industry in the twentieth century, 115 years later in 2014, Formula E appeared with its first-ever race in Beijing, China. Founded in 2011, this is an all-electric championship that showcases around the world a combination of sustainability claims, entrepreneurial spirit and commercial savviness. In Formula E all cars are aerodynamically similar but have some technological differences. Formula E was helped by the automotive world entering the ‘Dieselgate’ or ‘Emissionsgate’ in 2015. Despite these achievements, Formula E still struggles to showcase the technology to the public. Manufacturers are accumulating ever more know-how on electric cars, where Formula E may even turn out to be a hindrance in terms of innovative solutions. As such, the rulebook has to keep track of what is in it for the OEMs that participate. As an example, the Porsche Taycan model has a peak charging capacity of 270 kW and is one the fastest electric vehicles currently on the market. However, Formula E 2020 vehicles charge at a peak rate of 100 kW. Some motorsport fans have mocked the city based racetracks, and Formula E cars were nicknamed ‘hairdryers’ for not having the classic racing sound. In the beginning drivers had to change vehicles during the race because of the batteries. Especially discussed was the ‘Fanboost’ (an e-voting service providing your favourite driver with extra power in the race). However, what ever is said it is a racing class that is on the move and aim to adapt new technologies. For example, in the FIA Formula E season 3, the VENTURI team used an inverter with insulated-gate bipolar transistors/ Silicon Carbide Schottky Barrier Diode module. It reported a 2 kg weight reduction and 19% size reduction compared season 2 inverter with IGBT module [2]. In the next season a full Silicon Carbide module was used, where the inverter is capable of operating at 150°C junction temperature with a reduced switching losses of 75% compared to the IGBT solution. This opens the path for integrated motor that will use the high power density of SiC devices, and their high efficiency and cooling loop simplification thanks to the high temperature operation capability of SiC devices [3]. These electrical machines and drives not only have to withstand large forces, but also need to be designed to account for many advanced innovations. High-torque densities are a key requirement in traction machines. Using a multiple air gap design can achieve up to 60 percent higher torque density relative to single airgap machine. This talk will provide an overview of advanced powertrain technologies that aided to progress vehicle racing. By a careful choice and sizing of powertrain components coupled with an optimal energy management strategy from the batteries, attractive racing will be here to stay.

Formula E: Electric Machines and Drives Strategy

Reducing the rate of CO2 emissions for hybrid electric vehicles (HEV) and improving the autonomy for full battery electric vehicle (BEV) constitute major challenges for motor manufacturers. That can be done by losses reduction in each part of the electric powertrains. In the electric motors, using high grades magnetic material and optimal design allows reducing iron losses in the important area of the Torque-Speed plane. That is why segmented stator cores mixing grain oriented electrical steel (GOES) and non-oriented electrical steel (NOES) constitute a serious way of improvement. The goal of the paper is to present the existing structures with, for instance GOES teeth and NOES yoke, and to analyze the contribution of the high grade steel in the automotive motor improvement, in terms of efficiency, masse and volume. GOES has strong advantages in terms of iron losses and flux density at saturation, when it is magnetized in the Rolling Direction (RD). GOES has the drawback of being very anisotropic and the performance is not so interesting in the Transverse Direction, compared to NOES, especially in term of iron losses at high induction and high operational frequencies [1]. That implies to adapt the machine geometry to the specificities of this steel [2] [3] [4]. Another disadvantage of GOES is the sensitivity to the manufacturing processes: bending, cutting, compacting… [3]. From a micro-structural point of view, cutting the sheets causes a destruction of the grains close to the cutting border. At a macroscopic scale, that reduces the magnetic performance, depending not only on the cutting technique but also the dimensions of the sheet [5]. First, in the full paper, the authors present the existing magnetic circuit structures and how the constraints linked to the high anisotropy ratio has been taken into account. The electric motor analyzed mixes GOES teeth and NOES yoke, as shown in Fig.1. Second, the question of the modelling is posed. The full analytic simulation of the motor is not really adapted taking into account the complexity of the anisotropy. The Finite Element software applications integrate now both anisotropy and saturation, but not always in 3D. The strong difficulty is that the magnetic characteristics differ as a function of the magnetization angle. As a result, the results are not enough accurate in term of flux density distribution. The loss models, when they are implemented for GOES, are not reliable when the sheet is magnetized in multiple directions. Third, in order to analyse the contribution of the elements constituting the magnetic circuit, the authors propose a device, shown in Fig. 2, for numerical and experimental tests. It is designed in order to reproduce the phenomena occurring in the electrical motors, especially in the region between the teeth and the yoke. To do that, it combines two Epstein frames modified to magnetize different magnetic structures. The goal is to analyse the flux densities in the magnetic circuit and the iron losses, depending on several parameters as different geometries of junctions between the segments. The angle and the depth of insertion of the teeth into the yoke will be analysed. It allows also to evaluate the effect of the flux passing not directly in a teeth, but only the yoke. That happens in fractional slot permanent magnet machines and, in that case, the TD is fully solicited. Then, the nature and the grades of the materials will be tested with 0,20mm GOES and NOES. Effect of manufacturing will also be shown with experimental test made with cut laminations. Fourth, an existing full NO steel reference motor will be numerically compared with an improved machine made with mixed NOES and GOES. The comparison will be made on local quantities (flux density, etc) as well as on integral quantities (Flux, EMF, Electromagnetic torque and losses). The authors will also present simulation results showing the efficiency improved by the use of GOES.

![](https://assets.underline.io/uploads/markdown_image/1/image/aed73ebd63bf37d4e50d037464f03e5c.jpg)

Fig.1

![](https://assets.underline.io/uploads/markdown_image/1/image/548defbb0b245a7f85b58ec80f02f477.jpg)

Fig. 2

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