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Shim coil design for Halbach magnet by equivalent magnetic dipole method 被引量:1
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作者 Jia-Min Wu Zheng Xu +2 位作者 Pan Guo Jin-Feng Qi Yu-Cheng He 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第10期300-307,共8页
Low-field nuclear magnetic resonance magnet(2 MHz) is required for rock core analysis. However, due to its low field strength, it is hard to achieve a high uniform B0 field only by using the passive shimming. Theref... Low-field nuclear magnetic resonance magnet(2 MHz) is required for rock core analysis. However, due to its low field strength, it is hard to achieve a high uniform B0 field only by using the passive shimming. Therefore, active shimming is necessarily used to further improve uniformity for Halbach magnet. In this work, an equivalent magnetic dipole method is presented for designing shim coils. The minimization of the coil power dissipation is considered as an optimal object to minimize coil heating effect, and the deviation from the target field is selected as a penalty function term. The lsqnonlin optimization toolbox of MATLAB is used to solve the optimization problem. Eight shim coils are obtained in accordance with the contour of the stream function. We simulate each shim coil by ANSYS Maxwell software to verify the validity of the designed coils. Measurement results of the field distribution of these coils are consistent with those of the target fields.The uniformity of the B0 field is improved from 114.2 ppm to 26.9 ppm after using these shim coils. 展开更多
关键词 equivalent magnetic dipole method shim coils magnetic resonance halbach magnet
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Optimization Design of Halbach Permanent Magnet Motor Based on Multi-objective Sensitivity 被引量:4
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作者 Shuangshuang Zhang Wei Zhang +2 位作者 Rui Wang Xu Zhang Xiaotong Zhang 《CES Transactions on Electrical Machines and Systems》 CSCD 2020年第1期20-26,共7页
The halbach permanent magnet synchronous motor(HPMSM)combines the advantages of permanent magnet motors and halbach arrays,which make it very suitable to act as a robot joint motor,and it can also be used in other fie... The halbach permanent magnet synchronous motor(HPMSM)combines the advantages of permanent magnet motors and halbach arrays,which make it very suitable to act as a robot joint motor,and it can also be used in other fields,such as electric vehicles,wind power generation,etc.At first,the sizing equation is derived and the initial design dimensions are calculated for the HPMSM with the rated power of 275W,based on which the finite element parametric model of the motor is built up and the key structural parameters that affect the total harmonic distortion of air-gap flux density and output torque are determined by analyzing multi-objective sensitivity.Then the structure parameters are optimized by using the cuckoo search algorithm.Last,in view of the problem of local overheating of the motor,an improved stator slot structure is proposed and researched.Under the condition of the same outer dimensions,the electromagnetic performance of the HPMSM before and after the improvement are analyzed and compared by the finite element method.It is found that the improved HPMSM can obtain better performances. 展开更多
关键词 halbach permanent magnet synchronous motor multi-objective sensitivity cuckoo search algorithm electromagnetic characteristics finite element analysis
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Analysis of the Comprehensive Physical Field for a New Flywheel Energy Storage Motor/Generator on Ships 被引量:1
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作者 Yali Yu Yuanxi Wang +1 位作者 Guosheng Zhang Feng Sun 《Journal of Marine Science and Application》 2012年第1期134-142,共9页
A novel flywheel energy storage (FES) motor/generator (M/G) was proposed for marine systems. The purpose was to improve the power quality of a marine power system (MPS) and strengthen the energy recycle. Two str... A novel flywheel energy storage (FES) motor/generator (M/G) was proposed for marine systems. The purpose was to improve the power quality of a marine power system (MPS) and strengthen the energy recycle. Two structures including the magnetic or non-magnetic inner-rotor were contrasted in the magnetostatic field by using finite element analysis (FEA). By optimally designing the size parameters, the average speed of FEA results of was 17 200 r/m, and the current was controlled between 62 and 68 A in the transient field. The electrical machine electromagnetism design was further optimized by the FEA in the temperature field, to find the local overheating point under the normal operation condition and provide guidance for the cooling system. Finally, it can be concluded from the comprehensive physical field analysis that the novel redundant structure M/G can improve the efficiency of the M/G and maintain the stability of the MPS. 展开更多
关键词 marine power system flywheel energy storage halbach array magnet structure comprehensivephysical field motor/generator finite element analysis
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Preliminary Research of the Propagation of Annular IREBS in Coaxial Permanent Magnet Halbach Circuit 被引量:2
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作者 缪茜茜 刘列 《Chinese Physics C》 SCIE CAS CSCD 北大核心 2008年第z1期313-316,共4页
The magnetic field of coaxial permanent magnet Halbach circuit is calculated first using the finite element method SUPERFISH and the approximate expression of the magnet circuit is obtained.The forces acting on IREB&#... The magnetic field of coaxial permanent magnet Halbach circuit is calculated first using the finite element method SUPERFISH and the approximate expression of the magnet circuit is obtained.The forces acting on IREB's electron in such magnetic field are analyzed by the use of fluid model and the radial force equation in modified Mathieu function form is drawn then.At last a 2.5-D particle in-cell(PIC)simulation code is used to investigate the physical process of the IREB's propagation.In the PIC simulation,the electron beam current,thickness,magnet field amplitude and the beam's initial incident angle related to the stable propagation are mainly discussed.The conclusion is made that several kilo-amperes intense annular electron beam could propagate stably,meanwhile the focusing form of such magnet geometry provides action mechanism for the interaction between beam electrons and microwave in the ubitron. 展开更多
关键词 annular electron beam SUPERFISH coaxial permanent magnet halbach circuit PIC simulation PROPAGATION
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Assembling and Test of a Halbach Array Magnet System for Lorentz Forece Velocimetry in Electrolytes
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作者 Werner Michael Halbedel Bernd 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2012年第S1期145-148,共4页
The paper presents a Halbach array magnet system(HAMS)for the application within a very first Lorentz force velocimetry(LFV)experiment for electrolytic flows.Here the design,assembling procedure and characterization m... The paper presents a Halbach array magnet system(HAMS)for the application within a very first Lorentz force velocimetry(LFV)experiment for electrolytic flows.Here the design,assembling procedure and characterization method are presented under consideration of the strict limited weight of the system.HAMS increase the Lorentz force outcome by a factor of three compared to the currently used simple magnet systems.Furthermore the fluid profile influence on a LFV measurement on electrolytes is investigated numerically-directly on the planned test setup-and presented for the first time.Here the Lorentz forces,generated by the HAMS,decreases by 8%comparing an ideal plug-like profile at the inlet with a semi-parabolic profile arising near the outlet of the experiment. 展开更多
关键词 Lorentz force velocimetry halbach magnet array magnet assemblies magnet system design
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