Axial Flux-switching Permanent Magnet Research Articles

SSO-DRSS Axial Flux sensing in Switching Permanent Magnet Motor for cogging torque mitigation

This paper addresses the imperative requirements of high efficiency, power density, and speed in Axial Flux-Switching Permanent Magnet Motors (AxFSPM) for electric vehicles. Recognizing the limitations of conventional motor designs, especially their weight and size, hindering their universal applicability, this study proposes a novel approach. A Double Rotor Single Stator (DRSS) configuration is introduced, and its parameters are systematically optimized using the Shark Smell Optimization (SSO) algorithm. The SSO algorithm refines critical motor parameters, including axial length, turns per phase, and stator and rotor dimensions, resulting in a more compact AxFSPM motor with enhanced torque. Geometrical constraints are similarly optimized with SSO, and magnet skewing angles are employed for cogging torque reduction. The optimization process, implemented in MATLAB and ANSYS Maxwell, yields an average torque below 1.4 N m and cogging torque below 0.8 N m, demonstrating the effectiveness of the proposed approach. Comparative analyses against various motor models underscore the superiority of the SSO-optimized DRSS motor in terms of efficiency and compactness.

Multiple-Mode Current Control for a Hybrid-Excitation Axial Flux Switching Permanent Magnet Motor Considering Driving Cycles

This paper proposes a multiple mode current (MMC) control for hybrid-excitation axial flux switching permanent magnet (HE-AFSPM) motors considering driving cycles. To satisfy the diverse and compound control demands in multiple operating condition of EVs, the model predictive control is adopted, and multiple current vector prediction method including <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> -axis current, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis current, and DC excitation current is proposed to optimize current assignment ratio, enhance the dynamic performance, and improve motor efficiency. An online optimization method considering four operating conditions in two speed domains is demonstrated, where the different current assignment function and constraint is applied in each operating condition, and the optimal assignment currents are obtained effectively by the Lagrange multiplier method online in real time. Finally, to verify the feasibility of the multiple-mode control method, a prototype motor is built and tested. And, the motor performances in the different driving modes are investigated in detail. The experimental results reveal that the proposed control method can offer an effective control for the HE-AFSPM motor, where multi-mode operations are indispensable.

Novel Axial Flux-Switching Permanent Magnet Machine for High-Speed Applications

Conventional high-speed flux-switching machines have either a high fundamental frequency or more even harmonics. This paper proposes a novel six-slot four-pole axial flux-switching permanent magnet machine for high-speed applications. The machine, consisting of two radially distributed stators and one rotor, can effectively eliminate even harmonics in the flux linkage. First, the structural parameters that affect the performance of the motor are determined by the equivalent magnetic circuit method, and the optimal structural parameters of the motor are obtained by simulation optimization. Then, through finite element analysis, the three-dimensional model of the proposed machine is built, and the static electromagnetic characteristics are analyzed, including magnetic field distribution, flux linkage, back-electromotive force, cogging torque, and efficiency. The simulation results show that the total harmonic distortion of the flux linkage and back-electromotive force waveforms of the proposed novel machine is 2.2% and 9.8% respectively. The cogging torque of the optimal model is only 9 N.

Comparative Analysis and Design of Partitioned Stator Hybrid Excitation Axial Flux Switching PM Motors for In-Wheel Traction Applications

A comparative study of new partitioned stator hybrid excitation axial flux switching permanent magnet (HEAFSPM) motors with different partitioned excitation stator topologies for in-wheel traction applications is presented in this paper. The realization approaches of the partitioned stator HEAFSPM motor are discussed, and the motor topology with windings and permanent magnets (PMs) separately setting on different stators is selected in view of the advantageous structure for thermal management. On this basis, two partitioned excitation stator topologies including C-type tooth core and T-type tooth core stator configuration are proposed, and the air-gap flux modulation and flux regulation principle of the motors are analyzed. In addition, the design method of the partitioned stator HEAFSPM motor considering the effect of hybrid excitation sources is provided, and the two motors with different tooth cores are designed respectively. Meanwhile, for a fair comparison, the multiple objectives optimization method coupled with the sensitivity analysis is employed to optimize the two motors. The electromagnetic performances, anti-demagnetization capability, and flux regulation performance of the two motors are all investigated in detail. Finally, two prototype motors are fabricated and tested. Both the theoretical analysis and experimental results verify the effectiveness and reasonability of the motor.

Leakage flux reduction of axial-flux switching PM machine by using HTS-disk

Nowadays, axial flux switching permanent magnet machines are attractive and widely used in direct drive applications because of their unique features. This paper proposes a high temperature superconductor (HTS) disk axial flux switching permanent magnet (AFSPM) machine with spoke type permanent magnets (PMs) and three-phase two layers concentrated windings. The novelty of the proposed machine is using HTS material on the rotor and stator as a disk, insignificant relative permeability of the HTS materials causes magnetic reluctance to become extreme. Because of this feature HTS-Disk in the proposed HTS-AFSPM machine does not allow the flux to enter or exit which causes leakage flux reduces. In order to better investigate and fair comparison, all analyses have done at the same condition using the finite element method (FEM) by Ansys Maxwell. The comparison results show that the proposed HTS-Disk AFSPM machine achieves higher back-EMF, permanent magnet (PM) flux, flux distribution, lower inductance and losses and fewer total harmonics distribution compared to conventional AFSPM machine.

Sizing, Analysis, and Verification of Axial Flux-Switching Permanent Magnet Machine

This paper proposes the analytical design methods of axial flux-switching permanent magnet (AxFSPM) machines. The analytical design methods take the influences of electric and magnetic loadings into account to calculate the specific sizing and scalability of the AxFSPM machine. In addition, the winding functions are implemented to derive the self-, mutual-, d-axis, and q-axis inductances. The results of analytical design methods indicate that the magnetic loading has bigger impact on the stator dimensions of AxFSPM machines than the electrical loading. The d- and q-axis inductances of the all-pole-wound AxFSPM machines are similar under the same number of slots and turns. A prototype is manufactured using analytical design methods. The experimental results show that the prototype machine achieves target specification and the usefulness of the proposed design method is verified.

Influence of Rotor Tooth Shaping on Cogging Torque of Axial Flux-Switching Permanent Magnet Machine

This paper proposes a rotor tooth shaping method to reduce the cogging torque of an axial flux-switching permanent magnet machine. The rotor tooth is shaped in different configurations, including constant, trapezoidal, asymmetrical, extended, and square shapes to evaluate the effects on cogging torque ripple minimization. A three-dimensional (3-D) finite-element analysis (FEA) is performed to compare the proposed shapes of the rotor tooth. Peak-to-peak cogging torque, fundamental flux linkage, loaded torque, and the total weight of teeth are compared using various rotor tooth angles. The simulation results show that overall minimum cogging torque is achieved by the extended shape of the rotor tooth. 3-D FEA results are also verified with experimental results.

Performance Analysis of a Novel Three-phase Axial Flux Switching Permanent Magnet Generator with Overlapping Concentrated Winding

This paper proposes a novel axial flux switching permanent magnet generator for small wind turbine applications. Surface mounted axial flux switching permanent magnet (SMAFSPM) machine is a new type of these machines that is introduced in this paper. One of the most important challenges in optimal designing of this kind of machines, is ease of construction and maintenance. One of the main features of this machine is putting the magnets on the surface, which makes the construction of the machine easier. The overlapped three-phase winding improves the quality of voltages and power of the machine.To reach the optimum dimensions of machine, centeral composite design (CCD) and response surface methodology (RSM) combined with 3D finite element methods have been used.

Dynamic performance of the novel axial flux-switching permanent magnet motor

PurposeThe purpose of this paper is to investigate a novel axial flux-switching motor with sandwiched permanent magnet for direct drive electric vehicles (EVs), in which the torque density is increased and the cogging torque is decreased. For reducing the back-electromotive force (EMF) harmonics and cogging torque, a twisted structure is employed. To improve the dynamic performance of the axial field flux-switching sandwiched permanent magnet (AFFSSPM) motor a space vector modulation-direct torque and flux control scheme is proposed.Design/methodology/approachA multi-objective optimization is performed by means of artificial neural network and non-sorting genetic algorithm II to minimize the cogging torque while preserving the average torque.FindingsA comparative study between two proposed machines and the conventional flux-switching permanent magnet (FSPM) machine is accomplished and the static electromagnetic characteristics are analyzed. It is demonstrated that the proposed model with twisted structure has significantly improved performance over the conventional FSPM machine in back-EMF and efficiency. The proposed controller has a speed loop only and contains neither the current loop nor hysteresis control. The AFFSSPM motor exhibits excellent dynamic performance with this scheme.Originality valueThe axial flux-switching permanent-magnet machine is one of the most efficient machines but the AFFSSPM with sandwiched permanent magnet has not been specially reported to date. Thus in this paper, the authors report on optimal design of an axial flux-switching sandwiched permanent magnet machine for electric vehicles and investigate its dynamic performance.