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This paper deals with the design and analysis of a surface-mounted outer rotor in-wheel motor (IWM) with the aim of reducing cogging torque and torque ripple for electric vehicles. The proposed IWM is equipped with axial sinusoidal surface-mounted permanent magnets (PMs), with the purpose of producing sinusoidal air gap flux density distribution, thus to realize sinusoidal back electromotive force (EMF) and smooth electromagnetic torque. To highlight the advantage of the proposed IWM, the conventional IWM with tile-shaped PMs and the IWM with stepwise-shaped PMs are also studied for comparison. The finite element method in the commercial software package is utilized to analyze the performance of the three motors, including the radial flux density of air gap, back EMF, cogging torque, and electromagnetic torque. Through the quantitative comparison, it is found that the proposed IWM greatly reduces the cogging torque, highly improves the sinusoidality of back EMF, and nearly eliminates the torque ripple. [ABSTRACT FROM AUTHOR]

In this paper, power-sizing equations of rotor-permanent-magnet flux-switching (RPM-FS) machines are proposed and implemented, where the main decisive factors of the electromagnetic torque, namely electric loading and magnetic loading, are deduced, respectively. Although the topologies of RPM-FS machines are evolved from traditional stator-PM flux-switching machines, there are still seriously flux leakages between poles, and it is hard to derive the peak value of the air-gap flux density directly. Hence, a local simplified magnetic equivalent circuit is utilized to calculate the magnetic loading, which is crucial for the power-sizing equation. The influences of the pole-to-pole flux-leakages and harmonics in back-EMF are considered to improve the calculated accuracy of the power-sizing equation. Consequently, the electromagnetic torque can be predicted with acceptable accuracy. The feasibility of the power-sizing equation is verified by the finite element analysis and experimental results. [ABSTRACT FROM AUTHOR]

This paper proposes a novel flux switching claw pole machine (FSCPM) with soft magnetic composite (SMC) cores. The proposed FSCPM holds advantages of the conventional flux switching permanent magnet machine (FSPMM) and claw pole machine (CPM) with SMC cores. As permanent magnets are installed between the stator claw pole teeth, FSCPM has good flux concentrating ability, and the air gap flux density can be significantly improved. The torque coefficient of FSCPM is relatively high due to the applied claw pole teeth and global winding. FSCPM is mechanically robust because there are no windings or PMs on its rotor. Moreover, the core loss of FSCPM is relatively low for the SMC material has lower core loss at high frequency compared with silicon steels. The topology and operational principle of FSCPM are explained first. Several main dimensions of the machine are optimized to achieve better performance, based on 3D finite element method (FEM). Furthermore, the rotor skewing technology is adopted to reduce the cogging torque and torque ripple. [ABSTRACT FROM AUTHOR]

This paper presents a nonlinear iterative magnetic equivalent circuit (MEC) model for a novel counter-rotation dual-rotor axial flux permanent magnet synchronous machine (CRDR-AFPMSM). The proposed machine mainly consists of two rotors with opposite rotation directions, two sets of concentrated windings and a stator core sandwiched in between the two rotors. The model takes into account of the nonlinear characteristics of the saturable permeance in the stator core, and the permeance matrix is updated by an iterative procedure to accurately illustrate its nonlinear feature. The air gap flux density, back electromotive force (EMF) and torque are predicted by the model. Based on the nonlinear model, the thickness of the stator yoke is determined. All of the results obtained by the proposed model match with finite element analysis (FEA) results closely, thus the validity of the proposed MEC model is verified. [ABSTRACT FROM AUTHOR]

This paper examines the influence of pole and slot combinations on the electromagnetic performance of the flux-switching permanent magnet (FSPMs) machine. For this purpose, first the production of air gap flux density in machine analytically discussed. Next, five different pole and slot combination are selected by using the knowledge of air-gap flux density expression. The performances of the different combinations are analyzed and compared using the finite element analysis (FEA), and optimal pole and slot combination is suggested. It is found that the pole and slot combination has a dominant effect on machine performance and needs to be considered during the design stage. [ABSTRACT FROM AUTHOR]

This paper presents a new rotor shape design with optimum reverse 3rd harmonic for wound field synchronous machines to effectively enhance the saliency ratio and reduce the torque ripple in a micro electric vehicle traction system. Due to the enhanced saliency ratio, the reluctance torque is expected to be improved. The air gap flux density distribution is reshaped by the new rotor shape method, which benefits the low torque ripple. By contrast, the reverse 3rd harmonic injection is much more suitable than the general 3rd harmonic injection for increasing the effective air gap length along the q-axis for a high saliency ratio. Subsequently, three amplitudes of the reverse 3rd harmonic are studied and it is found that the optimum reverse 3rd harmonic is 1/6 of the fundamental one. To verify the effectivity of the proposed design, the original model and the ICS model are compared. Finally, all the motor characteristics, such as back electromotive force, cogging torque, and electromagnetic torque, are predicted using a 2-D finite-element method with the aid of JMAG-Designer. [ABSTRACT FROM AUTHOR]

This paper investigates the opportunity to use a proper geometry of Line start permanent-magnet synchronous motor (LSPMSM) that allows the same stator to be used for three different rotor structures, namely, typical, solid rotor and strange rotor. The air-gap flux density, back electromotive force (EMF), cogging torque, efficiency, starting performance and synchronization capability of the three machines are analyzed and compared. It is demonstrated that the typical rotor has the highest air-gap flux density, and the strange rotor has the lowest cogging torque and highest starting torque. In addition, the solid rotor has the lowest total harmonic distortion (THD), the highest efficiency, and the lowest cost. The size of PM and rotor structure are optimized to maximize the starting torque and efficiency of the solid rotor LSPMSM based on response surface method (RSM). Finally, the solid rotor LSPMSM is prototyped to verify the results of the finite element analysis. [ABSTRACT FROM AUTHOR]

In this paper, one kind of U-shape permanent magnet embedded salient pole wind generator is proposed. The permanent magnet is divided into three sections to form a U-shaped structure and inserted into the salient pole in the generator. The size of the PM near the side frame is small, therefore, there is sufficient PM location modification space in the salient pole. Some flux-barriers are set in the upper core of the salient pole, which can reduce the q-axis inductance, and ultimately increases the generator maximum output power. To evaluate the generator's overall performance, some other important electromagnetic parameters such as the air-gap flux density, the output voltage, the cogging torque, the output power, and the demagnetization performance are all calculated and analyzed base on finite element method (FEM). All the above parameters are compared with that of one V-shape permanent magnet embedded salient pole wind generator. The analysis results show that, with the same volume of permanent magnet, the proposed U-shape permanent magnet embedded salient pole wind generator has higher power density than the V-shape permanent magnet embedded salient pole wind generator. [ABSTRACT FROM AUTHOR]

To improve the utilization of wind energy, a new type of deflectable double-stators switched reluctance wind power generator is proposed to solve the unicity of the rotor rotation of existing switched reluctance generator (SRG). The generator adopts inner and outer double-stators structure. The multi-degree-of-freedom deflection of the rotating shaft can adapt to different wind directions and is suitable for the combination of electric fields with unstable energy amplitude, which can improve the working efficiency of the generator. The finite element analysis is used to calculate the rotation of the air gap magnetic flux inside the generator rotor, which lays a foundation for analyzing the vibration displacement of the stator structure. The magnetostriction of stator structure is the main cause of generator vibration. Based on the theory of mechanics, the basic equation of structural mechanics considering magnetostrictive effect is established. Magnetio-solid coupling simulation of internal and external stator and rotor rotation and deflection is carried out using FEA, and the stress distribution and corresponding vibration displacement are obtained. The simulation and analysis results provide a reference for further optimizing the structure of such generators and improving the stability of their operation. [ABSTRACT FROM AUTHOR]

In order to reduce the transverse edge effect of linear induction motors (LIMs) for low-speed Maglev train, this paper proposes a novel single-sided LIMs (SLIMs) with V-shaped ladder-slit secondary. Firstly, the topology of this SLIMs is introduced based on the erected 3-D finite element model. Secondly, for the V-shaped ladder-slit secondary, the effect of slot combination is investigated, and then the secondary is optimized by a single-parameter optimization method, including the width of secondary side-bars, secondary slot width, transverse width of secondary slits and the skew angle of V-shaped slits. Thirdly, the air gap flux density, eddy current, thrust force and normal force of this SLIMs are calculated, respectively. By comparing to those of two SLIMs with available double ladder-slit and cap-solid secondary, the results show the proposed novel SLIMs can improve the performance due to effectively reducing the transverse edge effect. Finally, to the proposed SLIMs, the effect of the middle bar in V-shaped ladder-slit secondary is studied. It is found that adopting middle bar can improve the performance and increase the mechanical strength, which is more suitable for low-speed Maglev train. [ABSTRACT FROM AUTHOR]