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Electromagnetic Performance Analysis of Variable Flux Memory Machines with Series-magnetic-circuit and Different Rotor Topologies

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CES Transactions on Electrical Machines and Systems 2024年第1期8卷 3-11页

作者： Qiang Wei Z.Q.Zhu Yan Jia Jianghua Feng Shuying Guo Yifeng Li Shouzhi Feng Department of Electronic and Electrical Engineering The University of SheffieldSheffield S13JDU.K. IEEE the CRRC Zhuzhou Institute Company Ltd. Zhuzhou 412001China

In this paper,the electromagnetic performance of variable flux memory(VFM)machines with series-magnetic-circuit is investigated and compared for different rotor topologies.Based on a V-type VFM machine,five topologies with different interior permanent magnet(IPM)arrangements are evolved and optimized under same constrains.Based on two-dimensional(2-D)finite element(FE)method,their electromagnetic performance at magnetization and demagnetization states is evaluated.It reveals that the iron bridge and rotor lamination region between constant PM(CPM)and variable PM(VPM)play an important role in torque density and flux regulation(FR)capabilities.Besides,the global efficiency can be improved in VFM machines by adjusting magnetization state(MS)under different operating conditions.

关键词： Memory machine permanent magnet Rotor topologies Series magnetic circuit Variable flux

Active ferromagnetic shimming of the permanent magnet for magnetic resonance imaging scanner

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Chinese Physics B 2010年第7期19卷 603-610页

作者：唐昕洪礼明俎栋林 Institute of Heavy Ion Physics Beijing Key Laboratory of Medical Physics and EngineeringSchool of PhysicsPeking University

This paper presents an approach of active ferromagnetic shimming for C-type permanent magnetic resonance imaging （MRI） magnet. It is designed to reduce inhomogeneity of magnetostatic field of C-type permanent magnet to meet the stringent requirement for MRI applications. An optimal configuration （locations and thicknesses） of active ferromagnetic pieces is generated through calculation according to the initial field map and the demanded final homo- geneity specifications. This approach uses a minimisation technique which makes the sum of squared magnetic moment minimum to restrict the amount of the active ferromagnetic material used and the maximal thickness of pieces stacked at each hole location in the shimming hoards. Simulation and experimental results verify that the method is valid and efficient.

关键词： magnetic resonance imaging active ferromagnetic shimming permanent magnet NdFeB pieces

Optimal Rotor Poles and Structure for Design of Consequent Pole permanent magnet Flux Switching Machine

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Chinese Journal of Electrical Engineering 2021年第1期7卷 118-127页

作者： Wasiq Ullah Faisal Khan Muhammad Umair Department of Electrical and Computer Engineering COMSATS University Islamabad(Abbottabad Campus)Abbottabad 22040Pakistan

permanent magnet flux switching machines(PMFSM)have attracted significant research interest and are considered as competent candidates when higher torque density is primary requirement.However,conventional PMFSMs uses excessive rare earth PM volumes which ultimately increases machine the machine weight and PM cost.Moreover,the PMs extended at the stator yoke results in stator leakage flux which degrades the performance.To suppress the leakage flux and diminish the PM volume,the consequent pole PMFSM(CPPMFSM)with flux bridges and barriers encompassing partitioned circumferential and radial magnetized PMs is proposed,thereby ensuring an alternate magnetic path for the working harmonics which improves the modulation effect and flux distribution.Moreover,the influence of the rotor pole number on seven different rotor structures namely,curved rotor,trapezoidal rotor,wide rotor tooth tip,wide rotor base width,rectangular segmented and eccentric rotors are investigated based on the electromagnetic performance and stress distribution.Finite element analysis(FEA)reveals that the 12S-13P CPPMFSM with a wider rotor base offers comparatively better electromagnetic performance.Compare to the conventional PMFSM,the proposed CPPMFSM reduces the PM volume which minimizes the overall machine cost and weight,suppresses the torque ripples by 16.49%,diminishes total harmonic distortion(THD)by 35.24%and decreases cogging torque by 32.88%.Furthermore,the torque and power density are enhanced by 7.028%and 7.025%respectively.

关键词： AC Machine consequent pole flux bridge flux switching machine permanent magnet rotor pole number rotor structure stress analysis

Development of the relativistic backward wave oscillator with a permanent magnet

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Chinese Physics C 2012年第8期36卷 753-755页

作者：马乔生刘忠李正红金晓 Institute of Applied Electronics CAEP Laboratory of High Power Microwave Technology

Firstly, an X-band relativistic backward wave oscillator with a low guiding magnetic field is simulated, whose output microwave power is 520 MW. Then, an experiment is carried out on an accelerator to investigate a relativistic backward wave oscillator with a permanent magnetic field whose strength is 0.46 T. When the energy of the electron is 630 keV and the current of the electron beam is 6.7 kA, a 15 ns width pulsed microwave with 510 MW output power at 8.0 GHz microwave frequency is achieved.

关键词： permanent magnet relativistic backward wave oscillator low magnetic field

Parallel-Path Power Flows in magnetic-Geared permanent magnet Machines with Sandwiched Armature Stator

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Chinese Journal of Electrical Engineering 2017年第1期3卷 16-26页

作者： Yujun Shi Jin Wei Linni Jian Department of Electrical and Electronic Engineering Southern University of Science and TechnologyShenzhen518055China Shenzhen Key Laboratory of Electric Direct Drive Technology Shenzhen518055China

Due to the large torque density of magnetic gears(MGs),magnetic-geared permanent magnet machines(MGPMs)have become promising competitors in the family of direct-drive machines.According to the deployment of armature stators,MGPMs can be generally classified into three types,viz.,MGPM with inner armature stator(MGPM-IAS),MGPM with outer armature stator(MGPM-OAS),and MGPM with sandwiched armature stator(MGPM-SAS).Our investigation finds out that the MGPM-SAS can achieve parallel-path power flows better than the MGPM-OAS,while the MGPM-IAS is with serial power flow paths.Therefore,the torque capability of MGPM-IAS is limited by the torque transmission capability of its integrated MG.However,the MGPM-SAS has the possibility to offer even higher output torque than its integrated MG.This paper focuses on the MGPM-SAS.And three typical MGPMs and their power flow paths are introduced;the interaction of electromagnetic fields in MGPM-SAS is analyzed;simulation calculation and experimental verification are conducted to demonstrate the validity of the theoretical analysis.

关键词： Direct drive permanent magnet magnetic gear integrated machines flux modulation power flows

Influence of Inner/Outer Stator Pole Ratio and Relative Position on Electromagnetic Performance of Partitioned Stator Switched Flux permanent magnet Machines

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CES Transactions on Electrical Machines and Systems 2019年第3期3卷 259-268页

作者： J.T.Shi Z.Q.Zhu Department of Electronic and Electrical Engineering The University of Sheffield3 Solly StreetSheffieldS14DEUK

Based on the 6-pole outer stator(armature winding-stator),the influence of inner(permanent magnet-stator)/outer stator pole ratio n(n=NIS/NOS),stator relative positions and rotor pole number combinations on electromagnetic performance of partitioned stator switched flux permanent magnet(PM)machines(PS-SFPMMs)is investigated in this paper.Since the armature windings and PMs are located in two separated stators and PMs are stationary,PS-SFPMMs have high fault tolerance capabilities.To maximize the torque performance,the PM of inner stator pole should be aligned with outer stator pole when n is odd while the iron rib of inner stator pole should be aligned with outer stator pole when n is even.No matter what n is selected,the rotor pole number NR can be any integers except the phase number and its multiples.The analysis results indicate that the optimal NR is closed to(NIS+NOS)/2 and it is odd when n is odd while it is even when n is even.Meanwhile,symmetrical phase back-EMF waveform will be obtained when the ratio of Min(NOS,NIS)to the greatest common divisor of Min(NOS,NIS)and NR is even.Based on the optimal rotor pole numbers for 6-pole outer stator with different n and corresponding optimal relative position together with same rated copper loss,the average torque is improved by 18.4%,25.1%and 25.7%respectively in PS-SFPMMs with n equal to 2,3 and 4 when compared with PS-SFPMM with n equal to 1.The analyses are validated by experiment results of the prototype machine.

关键词： Inner/outer stator partitioned stator permanent magnet pole ratio relative position switched flux.

Linear permanent-magnet Pump and Stirrer for Molten Aluminium

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Journal of Iron and Steel Research(International) 2012年第S1期19卷 528-530页

作者： Beinerts Toms Bojarevics Andris Gelfgat Yurii Bucenieks Imants Institute of Physics University of LatviaSalaspils LV-2169Latvia

A new type of contactless stirrer and/or pump has been developed for Aluminium industry.Large scale synchronously rotating permanent magnet cylinders,which are magnetized orthogonal to the axes,are used to create travelling magnetic field in Aluminium furnace through a thick bottom or wall,which induces stirring in a liquid metal pool similarly to traditional AC three-phase inductors.Flowrate of up to 600 tons per hour can be achieved with negligible energy dissipation even if the total wall thickness of the furnace is 30 cm.The advantage of the permanent magnet inductor is much lower energy consumption-maximum energy consumption of the stirrer to produce sufficiently high mechanical torque does not exceed 20 kW even for 600 ton per hour stirrer.Produced metal flow is quite similar to that,which is achieved by the AC three-phase induction stirrers offered by ABB and other companies.AC three-phase inductors exhibit very high Joule losses in the coils of the machine,but the permanent magnet system working at frequency in the range from 0.5 Hz to 2 Hz produces negligible Joule losses both in liquid Aluminium as well as in stainless steel plate of the furnace bottom enclosure and in the permanent magnet material itself,so relatively weak air cooling is sufficient.The linear permanent magnet stirrer has been experimentally tested on a small scale lab model in a shallow pool of InGaSn eutectic. The tests confirm the predicted flow intensities and flow pattern,and give sufficient results for validation of the large scale flow simulations.Principal schematics of investigated system and the free surface deformation of the liquid metal due to action of the stirrer are shown below.The linear permanent magnet system may be used also as a contactless pump for liquid Aluminium in two-chamber furnaces,for tapping the liquid metal or for transportation and precision dozing.If high flow rate is required simultaneously with considerable elevation of the liquid metal level,the wall thickness of the channel should be lower and frequ

关键词： permanent magnet liquid metal pump aluminium recycling phase shift

Optimization of Added permanent magnet Amount in Synchronous Reluctance Machines for High Performance

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Tsinghua Science and Technology 1998年第3期3卷 87-92页

作者：赵争鸣

An optimizing method of adding permanent magnet into synchronous reluctance machines for high performance is presented. The method enables torque components from reluctance and permanent magnet to reach an optimal combination so as to obtain a maximum efficiency, higher power factor in a wider speed range. Capability curves of synchronous reluctance combined with permanent magnet (SR PM) machines are described for different quantities of permanent magnet. The interacting principle of reluctance and permanent magnet torque is discussed. Simulation results based on an integrated model of the SR PM machine with a controller are presented to demonstrate the interaction of the two kinds of torques. Particularly, efficiency contours over the capability curves are illustrated to show the effect of added permanent magnet amount. An optimizing criterion for added permanent magnet amount in SR PM machine design is developed. Compared to induction, pure synchronous reluctance, and non optimized SR PM machines with same stator, the optimized SR PM machine shows higher efficiency in a wider speed range. 

关键词： synchronous reluctance permanent magnet electric machine optimization

Design Optimization of Axial Flux permanent magnet (AFPM) Synchronous Machine Using 3D FEM Analysis

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Journal of Electromagnetic Analysis and Applications 2016年第11期8卷 247-260页

作者： Joya C. Kappatou Georgios D. Zalokostas Dimitrios A. Spyratos Electrical and Computer Engineering Department University of Patras Patras Greece

This paper deals with the investigation of the behavior of a low speed, dual rotor-single coreless stator, axial flux permanent magnet synchronous machine for small power applications. Firstly, with the use of nonlinear 3D FEM electromagnetic analysis, four models with different magnet topologies are designed, simulated and compared. With criteria such as output power, power factor and torque ripple, the best performing model is selected and a further investigation, regarding the effect of the disk rotor material on the behavior of the machine, is conducted. The simulation results show how the different types of commercially available steel types affect the magnetic field and the performance of the machine.

关键词： Axial Flux permanent magnet magnet Topology Synchronous Generator