This paper presents performance improvement of dual stator axial-flux spoke type permanent magnet vernier machine (DSAFST-PMVM), which has the capability to generate high torque at a lower speed due to magnetic gearing effect. Flux focusing effect is created by means of dual stator single rotor topology with spoke type permanent magnets. It is best suitable for high-performance industrial applications such as servo motors, robot arms, wind power, electric vehicles, and elevator applications. A PM shape is proposed in this paper which has notches in such a way that it produces discrete skew effect which reduces the cogging torque and torque ripples. Optimization of magnet shape is done to make the optimized model more competitive than the proposed and basic models. Main parameters such as back emf, cogging torque, torque ripples, electromagnetic torque, VTHD, airgap flux densities, flux density distribution, power factor, and power of the machine are compared among the basic model, proposed model, and optimized models. The comparative analysis is done by using the time stepped 3D finite element method.INDEX TERMS Axial flux, cogging torque, dual stator axial flux machine, flux focusing effect, magnetic gearing effect, torque ripples, vernier machine, finite element method.

The aim of this paper is to design, analyze and optimize the "Multi-Stack Slotless Axial Flux Switching Permanent Magnet Machine". In the design process, mathematical models are implemented, and the Finite Element Method (FEM) is performed to analyze the machine performances. The paper aims to minimize the occurrence of cogging torque and torque ripple in the multi-stack slotless stator AFPM machine. As a consequence, it reduces the vibrations in the machine and increases its life span. Multi-stack slotless stator AFPM machine with a right-angled trapezoid-shaped PM is proposed and comparison is done with conventional shape AFPM machine. In order to examine the performance of multi-stack slotless stator AFPM machine Finite Element Analysis (FEA) is used. To further enhance the characteristics of the designed machine with the proposed right-angled PM shape, optimization is done by considering inner and outer pole pitch as the design variables. In optimization process, krigging method assigned with Latin Hyper-cube Sampling and a genetic algorithm (GA) is performed due to suitability with non-linear data. Then, finite element analysis by JMAG-Designer is performed to verify the results. It is determined that optimized model has achieved 65% reduction in torque ripples as compared with the conventional design. Hence, this work attempts to optimize the performance of the AFPM machine.INDEX TERMS Axial flux machine, torque ripples, cogging torque, slotless stator, finite element analysis.

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Permanent magnet vernier machines (PMVMs) are becoming increasingly attentive because of their high efficiency and high torque density and can thus be utilized for direct-drive applications such as wind power and electric vehicles etc. This paper presents performance improvement of Multi-Rotor Axial Flux Vernier Permanent Magnet (MR-AFVPM) machine with a proposed two-stage parallelogram shaped PM. The proposed shaped PM reduces the cogging torque and torque ripples due to its skew effect. Furthermore, it also presents a comparative analysis of the conventional and proposed shape PM. Then 3D finite element analysis (FEA) is used for comparative analysis. Genetic Algorithm (GA) associated with krigging method based on LHS is introduced and is used to optimize the proposed shaped PM for further performance improvement in terms of cogging torque, back EMFs, torque ripples, VTHD, output torque, flux density distributions, power factor and output power of the analyzed machines which are validated by 3D-FEA.

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In this paper, a hexagonal magnet shape is proposed to have an arc profile capable of reducing torque ripples resulting from cogging torque in a single-sided axial flux permanent magnet (AFPM) machine. The arc-shaped permanent magnet increases the air-gap length effectively and makes the flux of the air-gap more sinusoidal, which decreases air-gap flux density and hence causes a reduction in cogging torque. Cogging torque is the basic source of vibration, along with the noise in PM machines, since it is the main cause of torque ripples. Cogging torque is independent of the load current and is proportional to the air-gap flux and the reluctance variation. Three-dimensional finite element analysis (FEA) is used in the JMAG-Designer to analyze the performance of the conventional and proposed hexagonal-shaped PM AFPM machines. The proposed shape is designed to reduce cogging torque, and the voltage remains the same as compared to the conventional hexagonal-shaped PM machine. Further, optimization is performed by utilizing an asymmetric overhang. Latin hypercube sampling (LHS) is used to create samples, the kriging method is applied to approximate the model, and a genetic algorithm is applied to obtain the optimum parameters of the machine.