Performance Analysis and Comparison for Two Topologies of Flux-Switching Permanent Magnet Machine

Flux-switching permanent magnet(FSPM)machine is a kind of stator-typed permanent magnet machine,which is suitable for driving electric vehicles and hybrid electric vehicles because of their large power/torque density and high efficiency.The axial field flux-switching permanent magnet machine(AFFSPMM)and radial field flux-switching permanent magnet machine(RFFSPMM)with H-typed iron cores are reached and compared in this paper.On the condition of the same outer diameters and total volumes,the electromagnetic performances of the two machines are analyzed and compared by the three-dimensional finite element method,including the air gap flux density,inductance,back electromotive force(EMF),electromagnetic torque and loss.The finite element results show that the copper loss of AFFSPMM is higher than that of RFFSPMM at the rated load,however,the total loss of AFFSPMM is lower than that of the RFFSPMM.Meanwhile,AFFSPMM has greater torque than RFFSPMM in the constant power range.The related experiments are done to validate the finite element results,which are basically consistent with experiment results.

Optimization Design and Analysis of a Hybrid Permanent Magnet Flux-Switching Motor with Compound Rotor Configuration

This paper proposes a type of flux-switching permanent magnet(FSPM)motor,where the design concept of the hybrid permanent magnets(HPM)and the compound rotor are incorporated into the motor design.In such design,the proposed motor can not only realize the significant reduction of NdFeB volume,but also artfully convert external magnetic flux leakage into the air-gap field to achieve competitive torque density and desirable PM usage efficiency.For extensive investigation,two topologies of the HPM are designed and analyzed for the proposed motor,which consist of the parallel-magnetic-hybrid(PMH)mode and serial-magnetic-hybrid(SMH)mode.To fully exploit the potential advantages of the proposed motor,a multi-objective optimization design is conducted,where the response surface method(RSM)and sequential non-linear programming(SNP)method are purposely utilized.After optimization,the electromagnetic performances of the motor with PMH mode and SMH mode are evaluated and compared by using finite element method(FEM),which include the back-EMF,cogging torque,output torque,and so on.Furthermore,the partial demagnetization of the ferrite PM is also investigated in the paper.Finally,the theoretical analysis and simulation study verify the effectiveness of the proposed motor and corresponding optimization design.

Reduction of Cogging Torque in Permanent Magnet Flux-Switching Machines

Permanent magnet flux-switching machine (PMFSM) is a relatively new structure. Available literatures mainly focused on its general design procedure and performance analysis. In this paper, Finite Element Method (FEM) is taken to ana-lyze various design techniques to reduce the cogging torque in a prototype 12/10-pole PMFSM.

Electromagnetic-thermal Coupled Analyses and Joint Optimisation of Electrically-excited Flux-switching Linear Machines

Electrically-excited flux-switching machines are advantageous in simple and reliable structure,good speed control performance,low cost,etc.,so they have arouse wide concerns from new energy field.However,they have much lower torque density/thrust density compared with the same type PM machines.To overcome this challenge,electromagnetic-thermal coupled analysis is carried out with respect to water-cooled electrically-excited flux-switching linear machines(EEFSLM).The simulation results indicate that the conventional fixed copper loss method(FCLM)is no longer suitable for high thrust density design,since it is unable to consider the strong coupling between the electromagnetic and thermal performance.Hence,a multi-step electromagnetic-thermal joint optimisation method is proposed,which first ensures the consistency between the electromagnetic and thermal modelling and then considers the effect of different field/armature coil sizes.By using the proposed joint optimisation method,it is found that the combination of relatively large size of field coil and relatively low field copper loss is favourable for achieving high thrust force for the current EEFSLM design.Moreover,the thrust force is raised by 13-15%compared with using the FCLM.The electromagnetic and thermal performance of the EEFSLM is validated by the prototype test.

Analysis and Optimization of Key Dimensions of Co-Axial Dual-Mechanical-Port Flux-Switching Permanent Magnet Machines for Fuel-Based Extended Range Electric Vehicles

In this paper,key dimensions of a co-axial dual-mechanical-port flux-switching permanent magnet(CADMP-FSPM)machine for fuel-based extended range electric vehicles(ER-EVs),including split ratio,stator/rotor pole arcs,rotor yoke thickness,etc.,are analyzed and optimized.Firstly,the topologies and operation principles of an exampled 3-phase CADMP-FSPM are introduced briefly,in which an inner-rotor FSPM machine with 12-stator-slots/10-rotor-poles for high-speed generation and an outer-rotor FSPM machine with 12-stator-slots/22-rotor-poles for low-speed motoring are assembled co-axially.Then,the relationship between the key dimensions and electromagnetic performance,particularly for electromagnetic torque(power),of the CADMP-FSPM machine is studied by 2D-finite element analysis(FEA).Further,the reasonable matches of split ratio,rotor/stator pole arcs and rotor yoke are determined and the original CADMP-FSPM machine is optimized correspondingly.Finally,the static characteristics,including no-load PM flux-linkage,electro-motive-force(EMF),winding inductances,cogging torques and electromagnetic torques,of the original and optimized machines are compared by 2D-FEA.The results verify that the optimized CADMP-FSPM machine can exhibit improved torque characteristics than the original one,i.e.,the torque ripples of the inner and outer machines can be reduced by 22.7%and 4.7%,respectively,and the average torque of the inner and outer machines can be increased by 0.43Nm and 2Nm,respectively.

Field-Oriented Control and Direct Torque Control for a Five-Phase Fault-Tolerant Flux-Switching Permanent-Magnet Motor

This paper presents a comparative performance analysis of a new five-phase fault-tolerant flux-switching permanent-magnet(FT-FSPM)motor for high-reliability applications under the two most popular control schemes,namely,field-oriented control(FOC)and direct torque control(DTC)based on stator-flux orientation.Firstly,the new motor topology and structural characteristics are briefly presented.Secondly,the d-and q-axis for the FT-FSPM motor are defined,which is crucial to the mathematical model and control scheme,and the mathematical models are derived.Then,two control schemes,i.e.,FOC and DTC,and the main system are proposed.The operational principles of the two control schemes are presented,and space vector pulse width modulation(SVPWM)based on four neighboring vectors is adopted to reduce current harmonics and torque ripples.Finally,the simulated and experimental results are given,and performance analysis of the two control schemes are compared and discussed.The results reveal that FOC scheme has the sinusoidal phase current and low torque ripples,while the DTC scheme has fast dynamic response,verifying the effectiveness of the two proposed control schemes.This paper is a primary investigation for more possible improvements in the control schemes of the five-phase FS-FTPM motor.

Rediscovery of Permanent Magnet Flux-Switching Machines Applied in EV/HEVs:Summary of New Topologies and Control Strategies

Substantial efforts are currently underway around the world to develop environmentally friendly transportation,of which the development of electric vehicles plays a key role.Statorpermanent magnet(PM)machines have attracted wide attention due to the robust rotor structure and comparable performance in terms of normal permanent magnet synchronous machines(PMSM)having magnets in the roto.In particular,the flux-switching machines feature a particular magnetic circuit configuration that favors Dy-free magnets in terms of demagnetization risk,and as a result,the cost of the motor can be reduced considerably.With focus on applications in electric vehicles(EVs)and hybrid electric vehicles(HEVs),this paper reviews the latest developments of PM flux switching machines,with particular emphasis on the novel machine topologies and control strategies.

Comparison of Flux-Switching Machines With and Without Permanent Magnets

In this paper,three advanced flux-switching(FS)machines,namely the radial-field flux-switching permanent-magnet(RF-FSPM)machine,the radial-field flux-switching DC-field(RF-FSDC)machine,and the axial-field FSDC(AF-FSDC)machine are quantitatively compared.Upon the installation of the high-energy-density PM materials,the RF-FSPM machine can definitely provide the superior torque performances as compared to its magnetless counterparts.However,the PM machines suffer from two major fundamental problems,namely the high material costs,and the uncontrollable flux density.By utilizing the concept of axial-field structure,the AF-FSDC machine can offer comparable torque performance as the RF-FSPM machine.Hence,with the consideration of the cost-effectiveness and the control flexibility,the magnetless AF-FSDC machine has exhibited promising potential in various applications.