Effect of Third Harmonic Flux Density on Cogging Torque in Surface-Mounted Permanent Magnet Machines

2019 ◽  
Vol 66 (8) ◽  
pp. 6150-6158
Author(s):  
H. Y. Sun ◽  
K. Wang
Keyword(s):  
Permanent Magnet ◽  
Flux Density ◽  
Permanent Magnet Machines ◽  
Cogging Torque ◽  
Third Harmonic

Cogging Torque Reduction by Means of Pole Segmentation Optimization on the Permanent Magnet Synchronous Machine

2020 ◽  
Author(s):  
Hugo E. Santos ◽  
Khristian M. de Andrade Jr. ◽  
Wellington M. Vilela ◽  
Geyverson T. de Paula
Keyword(s):  
Permanent Magnet ◽  
Flux Density ◽  
Torque Ripple ◽  
Air Gap ◽  
Optimization Techniques ◽  
Machine Construction ◽  
Permanent Magnet Machines ◽  
Element Analysis ◽  
Cogging Torque ◽  
Main Component

One of the main obstacles during the design of permanent magnet machines consists in reducing the developed torque ripple characteristic of this type of machine. The main component of such ripples is a parasitic torque, called cogging torque. A technique present in the literature to reduce this parasitic torque considers the segmentation of the poles. This allows a decrease in the cogging torque, however reducing the air gap flux density too and thus the torque mean. Thus, in order to keep the torque mean reduction in reasonable levels, optimization techniques can be employed with the pole segmentation. The variables to be optimized are the number, distance and width of the segments. The present article proposes two methods to optimize these variables in order to minimize the cogging torque, but also maintain a satisfactory flux density value. Some constraints are added to account for the machine construction feasibility. The proposed methods were validated through a nite element analysis. The results proved the effectiveness of the proposed methods, with a reduction by up to 76% in the cogging torque and keeping, in the best case, about 95% of the reference machine air gap flux density and 78% in the worst one.

A novel analytical calculation of magnetic field in the slotted air gap of spoke-type permanent-magnet machines using conformal mapping

2020 ◽  
pp. 1-15
Author(s):  
Jianqi Li ◽  
Yu Zhou ◽  
Jianying Li
Keyword(s):  
Magnetic Field ◽  
Conformal Mapping ◽  
Permanent Magnet ◽  
Flux Density ◽  
Analytical Method ◽  
Electromotive Force ◽  
Analytical Calculation ◽  
Air Gap ◽  
Permanent Magnet Machines ◽  
Peak Value

This paper presented a novel analytical method for calculating magnetic field in the slotted air gap of spoke-type permanent-magnet machines using conformal mapping. Firstly, flux density without slots and complex relative air-gap permeance of slotted air gap are derived from conformal transformation separately. Secondly, they are combined in order to obtain normalized flux density taking account into the slots effect. The finite element (FE) results confirmed the validity of the analytical method for predicting magnetic field and back electromotive force (BEMF) in the slotted air gap of spoke-type permanent-magnet machines. In comparison with FE result, the analytical solution yields higher peak value of cogging torque.

scholarly journals A Design Method for the Cogging Torque Minimization of Permanent Magnet Machines with a Segmented Stator Core Based on ANN Surrogate Models

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1880
Author(s):  
Elia Brescia ◽  
Donatello Costantino ◽  
Paolo Roberto Massenio ◽  
Vito Giuseppe Monopoli ◽  
Francesco Cupertino ◽  
...  
Keyword(s):  
Finite Element ◽  
Permanent Magnet ◽  
Design Method ◽  
Heuristic Approach ◽  
Topological Optimization ◽  
Permanent Magnet Machines ◽  
Stator Core ◽  
Cogging Torque ◽  
Design Formula ◽  
Harmonic Components

Permanent magnet machines with segmented stator cores are affected by additional harmonic components of the cogging torque which cannot be minimized by conventional methods adopted for one-piece stator machines. In this study, a novel approach is proposed to minimize the cogging torque of such machines. This approach is based on the design of multiple independent shapes of the tooth tips through a topological optimization. Theoretical studies define a design formula that allows to choose the number of independent shapes to be designed, based on the number of stator core segments. Moreover, a computationally-efficient heuristic approach based on genetic algorithms and artificial neural network-based surrogate models solves the topological optimization and finds the optimal tooth tips shapes. Simulation studies with the finite element method validates the design formula and the effectiveness of the proposed method in suppressing the additional harmonic components. Moreover, a comparison with a conventional heuristic approach based on a genetic algorithm directly coupled to finite element analysis assesses the superiority of the proposed approach. Finally, a sensitivity analysis on assembling and manufacturing tolerances proves the robustness of the proposed design method.

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