# Fileset

[REPM2025_O6-2_Kajiwara.pdf](https://mdr.nims.go.jp/filesets/ccd623dc-1c62-4542-a4cc-464f1bd1dc72/download)

## Creator

Jumpei Hinata, Takanori Kajiwara, Takashi Oikawa, Yoshiaki Kano

## Rights

[Creative Commons BY-NC-ND Attribution-NonCommercial-NoDerivs 4.0 International](https://creativecommons.org/licenses/by-nc-nd/4.0/)

## Other metadata

[Design Studies on IPMSM with Radially Oriented Arc-Shaped Metal Magnet for Automotive Traction Drives](https://mdr.nims.go.jp/datasets/107e91a5-8047-4f35-8a04-6da7514498d7)

## Fulltext

Microsoft PowerPoint - ¸»Ç25-048_REPM2025_Design Studies on IPMSM with Radially Oriented Arc-Shaped Metal Magnet for Automotive Traction Drives.pptx28th – 31st July    REPM 20250Design Studies on IPMSM with Radially Oriented Arc-Shaped Metal Magnet for Automotive Traction Drives29th July 11:05~Jumpei Hinata1, *Takanori Kajiwara1, Takashi Oikawa1, Yoshiaki Kano2 1. Corporate R&D center, Daido Steel Co., Ltd. (Japan)2. Dept. of Electrical and Electronics Engineering, Daido University (Japan)1. Demand for permanent magnets in IPMSM1 The increasing demand of xEV presents resource risks of RE elements. Daido has been developing HREE-free hot-deformed magnets for IPMSM.Global market of xEV(×10k)(Source: Fuji Keizai)Distribution of RE production sitesLREHREHREE-freehot-deformed magnetMotor designingfor hot-deformed magnetSource: https://global.honda/en/newsroom/news/2016/4160712eng.htmlToday’s presentation(IPMSM with arc-shaped magnet)2 An arc-shaped multilayer flux barrier enhances reluctance torque, while embedded permanent magnets in the barrier region provide additional magnet torque.2. IPMSM with radially oriented arc-shaped magnetIPMSM to enhance reluctance torque Calculated air gap flux density distribution[1]Multi-layersof flux barriersEmbeddedblock magnetsSource of images: Kondo, IEEJ Transactions on Industry Applications vol.131 No.11 pp.1269-1275 Sinusoidal wave of flux density distribution[2]Arc-shaped magnets2. IPMSM with radially oriented arc-shaped magnet3 3-layer stacking arc-shaped magnets can maximize total & reluctance torque. 4-layer stacking induces magnetic saturation on e-steel area between magnets.1701801902002302402502601 2 3 4Calculated reluctance torque (Nm)Calculated torque (Nm)Number of layersMagnetE-steelAir The amount of magnet remains constant across all conditionsSource: Kano, Industrial Applications Forum Lecture in 20222. IPMSM with radially oriented arc-shaped magnet4・Initial shape・IsotropicMold・Molded shape・AnisotropicDensification&Orientation■OrientationHot deformation process・c-axis is oriented parallel to σ.・σ direction can be changed by the mold design.Nd2Fe14B crystal grainsPunch■ShapeσσVarious mold shapes・Magnet shape is defined by the mold shape.Molten grain boundary phase Hot-deformation process can provide various shape magnets.  Arc-shaped and radially oriented magnets can be producible.Arc-shapeMagnetMoldPrototypeReference (Prius 3rd)Hot-deformed magnet(HREE-free)Br = 1.30T @R. T.HcJ = 1,640kA/m@R. T.Sintered magnet(HREE-contained)Br = 1.30T @R. T.HcJ = 2,070kA/m@R. T.MagnetRotorValueCondition264 mmStator outer diameter50 mmStack length0.8 mmAir gap length48Number of stator slots8Number of rotor poles398 VrmsMax. terminal voltage1200 V0-pWithstand voltage of switching device170 ArmsMax. inverter current26 Arms/mm2Max. current density of armature coil0.46Coil space factor244 NmMax. torque in Ref. motor65.0 kWMax. power(sinusoidal PWM) in Ref. motor13,500 rpmMax. speed in Ref. motor5 The prototype and reference devices underwent performance evaluation tests under identical test bench and power conditions.3. Fabrication & DemonstrationMagnetE-steelArc-shaped magnetE-steelInstalled magnets with each rotorhave the same Br and total weight6 Evaluations using motor testing device confirmed a 30.4% increase in maximum power and a 9.2% increase in maximum torque.3. Fabrication & DemonstrationSource of images: Kano, IEEJ Transactions on Industry Applications vol.140 No.4 pp.255-264 9.2% increase in Max. TorqueTorque vs. speed curvePrototypeReferenceMax power［kw］Speed［r/min］30.4% increase in Max. PowerPower vs. speed curvePrototypeReference020406080100120Torque contribution(%)7 A 9.2% increase in torque in 50-50 motors equates to an 18% Br enhancement, which indicates high potential of arc-shaped magnets in IPMSM.20244. Potential for flexible shape and orientation of magnet202320212018Reluctance torque(50)Magnettorque(50)1.30T-Brmagnet loaded1.54T-Brmagnet loaded+9.2%50-50 motor torque comparison with different Br magnetsMagnetic properties of Daido’s HREE-free magnets+18%1.251.301.351.401.451.501.551.60500 600 700 800 900 1000RT-Br (T) 150degC-HcJ (kA/m)Close to Br limitof NdFeB magnetby new motor design2025~4. Potential for flexible shape and orientation of magnet8 Future efforts will focus on proposing motors utilizing hot-deformed magnets, which could further unlock the potential of motor performance.Orientationc-axis:  FanBread loafLucentArcShapeProduct(Prototype)DesignedrotorEnhancing torque and output Improving efficiency and NV Ripple↓ & Torque↑OngoingEnhancing torque and outputConclusion9 The increasing demand for magnets poses a resource risk, necessitating a reduction in usage through the effective utilization of reluctance torque. The implementation of arc-shaped magnets in an IPM has resulted in a significant performance improvement. - 9.2% increase in maximum torque- 30.4% increase in maximum power Further verification of high-performance motors utilizing hot-deformed magnets will continue, along with proposals to clients, focusing on optimization of shape and orientation.