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This article aims to realize the brushless operation of a wound rotor vernier machine (WRVM) by a third-harmonic field produced through stator auxiliary winding (X). In the conventional model, a third-harmonic current is generated by connecting a 4-pole armature and 12-pole excitation windings serially with a three-phase diode rectifier to develop a pulsating field in the airgap of a machine. However, in the proposed model, the ABC winding is supplied by a three-phase current source inverter, whereas the auxiliary winding (X) carries no current due to an open circuit. The fundamental MMF component developed in the machine airgap creates a four-pole stator field, while the third-harmonic MMF induces the harmonic current in the specialized rotor harmonic winding. The rotor on the other side contains the harmonic and the field windings connected through a full-bridge rectifier. The electromagnetic interaction of the stator and rotor fields generates torque. Due to the open-circuited winding pattern, the proposed machine results in a low torque ripple. A 2D model is designed using JMAG-Designer, and 2D field element analysis (FEA) is carried out to determine the output torque and machine's efficiency. A comparative performance analysis of both the conventional and proposed topologies is discussed graphically. The quantitative analysis of the proposed topology shows better performance as compared to the recently developed third-harmonic-based brushless WRVM topology in terms of output torque and torque ripples. [ABSTRACT FROM AUTHOR]

This paper suggests a method to improve the performances of the Dual Stator Axial Flux Spoke-type Permanent Magnet (DSAFSPM) machines with phase group concentrated coil (PGCC) windings, by incorporating continuous and discrete step-skewing along with a special winding connection. The purpose of the study is to mitigate the cogging torque and torque ripples while increasing the output torque so it ameliorates the machine performance at minimum cost for various applications such as wind power plants and electric vehicles (EVs). Cogging torque produces noise and vibrations which degrade the machine's performance and reduces its life span. The proposed winding sequence enhances the output torque by improving its distribution factor along with the use of continuous skew and step-skew magnets. This research work improved the cogging torque and torque ripples with the help of skew techniques while output torque is increased by the proposed winding sequence. Further harmonics and ripples are also mitigated by the proposed winding sequence. The overall machine volume is kept constant along with the magnet size and the design parameters for fair performance analysis. Comparative analysis of these machines is performed using three-dimensional (3-D) time-stepped finite element analysis (FEA). Proposed model I and proposed model II reduce the harmonics by 42% and 23%, respectively. By using continuous skew and discrete step-skew magnets, cogging torque is reduced up to 81.5% and 75%, respectively. This reduction in cogging torque reduces the noise and vibration in machines which assists the machines to perform a smooth operation. The reduction in output torque ripples in proposed model I is 60.8% while that of proposed model II is 59.3%. [ABSTRACT FROM AUTHOR]

This paper presents a proposed model of a multi-stack slotted stator axial-flux type permanent magnet synchronous machine (AFPMSM) specifically for reducing torque ripple. The proposed AFPMSM model uses pentagon-shaped permanent magnets (PMs). It has a low value of cogging torque and torque ripples compared to the conventional model with a trapezoidal magnet shape. Additionally, it has increased internal generated voltage (Ef) as compared to the conventional model. To further enhance Ef phases and minimize cogging torque of the proposed model, the proposed AFPMSM model was optimized by varying different sides of PMs using a genetic algorithm (GA). A time-stepped three-dimensional (3D) finite element analysis (FEA) was performed for the comparative analysis of conventional, proposed, and optimized AFPMSM models. From this comparative performance analysis, it is observed that torque ripples and cogging torque of the optimized AFPMSM are significantly decreased, while output average torque is appreciably increased. Ef and output power are also enhanced. [ABSTRACT FROM AUTHOR]

This paper studies the effect of permanent magnet shape on the performance and efficiency of coreless axial flux permanent magnet synchronous generator (AFPMSG) for low-speed applications. The objective of this study was to come up with an optimal magnet shape among the studied cases that will lead to the highest value of induced EMF, eventually leading to the better output power of the machine. According to the obtained results, a coreless AFPMSG with a triangular magnet shape has higher induced EMF as compared to trapezoidal or skewed-shaped magnets. Also, a topology with rounded-triangular magnets is analyzed to investigate the effect of the rounded edges on the performance of the generator. 3D-finite element analysis (FEA) is used to analyze and compare the back-EMF and output power of all the investigated coreless AFPMSG topologies. This analysis is carried out using JMAG-Designer 19. 1. [ABSTRACT FROM AUTHOR]

In this paper, the reluctance torque is utilized for improving the starting and average torques of a conventional brushless wound field synchronous machine (BL-WFSM). The conventional BL-WFSMs have an inherent issue of zero-starting torque. The existing BL topologies use expensive rare-earth permanent magnets (RE-PMs) to improve the starting torque; however, the marker price of RE-PMs fluctuates. Therefore, this paper proposes the use of the reluctance torque for improving the starting and average torques of BL-WFSMs. The winding topology and machine layout are adopted, from recently published work. The suggested approach increases the reluctance effect in BL-WFSM by optimizing the rotor shape. The reluctance effect is optimized, to improve the starting and average torques. The Kriging method and a genetic algorithm are used for the rotor optimization. A two-dimensional finite element analysis confirms the improved starting and average torques based on the increase in the reluctance torque. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]