3-D adaptive FEA with weighted node density technique

2020 ◽  
Vol 39 (5) ◽  
pp. 1201-1213
Author(s):  
Tadashi Yamaguchi ◽  
Yoshihiro Kawase ◽  
Shota Ishimura
Keyword(s):  
Finite Element ◽  
Magnetic Flux Density ◽  
Error Estimator ◽  
Evaluation Function ◽  
Error Evaluation ◽  
Node Density ◽  
Content Type ◽  
Adaptive Fea ◽  
Delaunay Tetrahedralization ◽  
Finite Element Meshes

Purpose This paper aims to propose a method to create 3-D finite element meshes automatically using the Delaunay tetrahedralization with the weighted node density technique. Using this method, the adaptive finite element analysis (FEA) was carried out for the calculation of the magnetic field of an eddy current verification model to clarify the usefulness of the method. Moreover, the error evaluation function for the adaptive FEA was also discussed. Design/methodology/approach The method to create the 3-D finite element meshes using the Delaunay tetrahedralization is realized by the weighted node density technique, and Zienkiewicz-Zhu’s error estimator is used as the error evaluation function of the adaptive FEA. Findings The magnetic flux density vectors on the node in the error evaluation function for the adaptive FEA should be calculated with the weighted average by the reciprocal of the volume of elements. Originality/value This paper describes the method to create 3-D finite element meshes and the comparison among calculation methods of the magnetic flux density vectors on the node for the error estimator.

Simulation of iron losses in induction machines using an iron loss model for rotating magnetization loci in no electrical steel

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Martin Marco Nell ◽  
Benedikt Schauerte ◽  
Tim Brimmers ◽  
Kay Hameyer
Keyword(s):  
Finite Element ◽  
Flux Density ◽  
Core Loss ◽  
Induction Machine ◽  
Iron Loss ◽  
Magnetic Flux Density ◽  
Loss Model ◽  
Content Type ◽  
Iron Losses ◽  
Loss Models

Purpose Various iron loss models can be used for the simulation of electrical machines. In particular, the effect of rotating magnetic flux density at certain geometric locations in a machine is often neglected by conventional iron loss models. The purpose of this paper is to compare the adapted IEM loss model for rotational magnetization that is developed within the context of this work with other existing models in the framework of a finite element simulation of an exemplary induction machine. Design/methodology/approach In this paper, an adapted IEM loss model for rotational magnetization, developed within the context of the paper, is implemented in a finite element method simulation and used to calculate the iron losses of an exemplary induction machine. The resulting iron losses are compared with the iron losses simulated using three other already existing iron loss models that do not consider the effects of rotational flux densities. The used iron loss models are the modified Bertotti model, the IEM-5 parameter model and a dynamic core loss model. For the analysis, different operating points and different locations within the machine are examined, leading to the analysis of different shapes and amplitudes of the flux density curves. Findings The modified Bertotti model, the IEM-5 parameter model and the dynamic core loss model underestimate the hysteresis and excess losses in locations of rotational magnetizations and low-flux densities, while they overestimate the losses for rotational magnetization and high-flux densities. The error is reduced by the adapted IEM loss model for rotational magnetization. Furthermore, it is shown that the dynamic core loss model results in significant higher hysteresis losses for magnetizations with a high amount of harmonics. Originality/value The simulation results show that the adapted IEM loss model for rotational magnetization provides very similar results to existing iron loss models in the case of unidirectional magnetization. Furthermore, it is able to reproduce the effects of rotational flux densities on iron losses within a machine simulation.

Design and finite element analysis of modular C-Core stator tubular linear oscillating actuator for miniature compressor

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sumeet Khalid ◽  
Faisal Khan ◽  
Zahoor Ahmad ◽  
Basharat Ullah
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Permanent Magnets ◽  
Performance Comparison ◽  
Design Parameters ◽  
Magnetic Flux Density ◽  
Element Analysis ◽  
Content Type ◽  
Static And Dynamic Analysis ◽  
Electromagnetic Performance

Purpose For compactness and ease in assembling, a novel miniature size tubular moving magnet linear oscillating actuator (MT-MMLOA) design for miniature linear compressor application is proposed in this paper. Design/methodology/approach This MT-MMLOA design possesses a modular C-core stator structure having separation at the middle. Axially magnetized tubular permanent magnets are accommodated on the mover. To improve the output parameters of the linear oscillating actuators (LOA), all the design parameters are optimized using a parametric sweep. Finite element analysis of the proposed design is performed to examine the magnetic flux density as well as thrust force under both static and dynamic analysis within the intended stroke range. Findings Compared to conventional LOA for miniature compressors, the motor constant of the proposed LOA is 37 N/A that is 85% greater while keeping the same size of LOA. Permanent magnet volume used in the investigated topology of LOA is 26% reduced. Additionally, the overall volume of the machine is 10.3% decreased. Furthermore, the proposed topology is simple, inexpensive and easy to manufacture. Originality/value Electromagnetic performance comparison with different topologies proposed earlier in literature is carried out to prove the performance superiority of the proposed design.

Parametric model of electric machines based on exponential Fourier approximations of magnetic air gap flux density and inductance

2018 ◽  
Vol 37 (1) ◽  
pp. 520-535 ◽  
Author(s):  
Norman Borchardt ◽  
Roland Kasper
Keyword(s):  
Finite Element ◽  
Magnetic Flux ◽  
Flux Density ◽  
Fourier Coefficients ◽  
Magnetic Circuit ◽  
Parametric Model ◽  
Air Gap ◽  
Magnetic Flux Density ◽  
Electrical Machine ◽  
Content Type

Purpose This study aims to present a parametric model of a novel electrical machine, based on a slotless air gap winding, allowing for fast and precise magnetic circuit calculations. Design/methodology/approach Approximations of Fourier coefficients through an exponential function deliver the required nonlinear air gap flux density and inductance. Accordingly, major machine characteristics, such as back-EMF and torque, can be calculated analytically with high speed and precision. A physical model of the electrical machine with air gap windings is given. It is based on a finite element analysis of the air gap magnetic flux density and inductance. The air gap height and the permanent magnetic height are considered as magnetic circuit parameters. Findings In total, 11 Fourier coefficient matrixes with 65 sampling points each were generated. From each, matrix a two-dimensional surface function was approximated by using exponentials. Optimal parameters were calculated by the least-squares method. Comparison with the finite element model demonstrates a very low error of the analytical approximation for all Fourier coefficients considered. Finally, the dynamics of an electrical machine, modeled using the preceding magnetic flux density approximation, are analyzed in MATLAB Simulink. Required approximations of the phase self-inductance and mutual inductance were given. Accordingly, the effects of the two magnetic circuit parameters on the dynamics of electrical machine current as well as the electrical machine torque are explained. Originality/value The presented model offers high accuracy comparable to FE-models, needing only very limited computational complexity.

Recovery-based error estimator for the natural-convection problem based on penalized finite element method

2019 ◽  
Vol 29 (12) ◽  
pp. 4850-4874
Author(s):  
Lulu Li ◽  
Haiyan Su ◽  
Jianping Zhao ◽  
Xinlong Feng
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Natural Convection ◽  
Posteriori Error ◽  
Optimal Error Estimates ◽  
Error Estimator ◽  
Content Type ◽  
Convection Problem ◽  
Natural Convection Problem ◽  
Element Method

Purpose This paper aims to proposes and analyzes a novel recovery-based posteriori error estimator for the stationary natural-convection problem based on penalized finite element method. Design/methodology/approach The optimal error estimates of the penalty FEM are established by using the lower-order finite element pair P1-P0-P1 which does not satisfy the discrete inf-sup condition. Besides, a new recovery type posteriori estimator in view of the gradient recovery and superconvergent theory to deal with the discontinuity of the gradient of numerical solution. Findings The stability, accuracy and efficiency of the proposed method are confirmed by several numerical investigations. Originality/value The provided reliability and efficiency analysis is shown that the true error can be effectively bounded by the recovery-based error estimator.

Parallel finite-element method using domain decomposition and Parareal for transient motor starting analysis

2019 ◽  
Vol 38 (5) ◽  
pp. 1507-1520 ◽  
Author(s):  
Yasuhito Takahashi ◽  
Koji Fujiwara ◽  
Takeshi Iwashita ◽  
Hiroshi Nakashima
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Parallel Computing ◽  
Domain Decomposition ◽  
Parallel Computation ◽  
Domain Decomposition Method ◽  
Space Time ◽  
Content Type ◽  
Parallel Performance ◽  
Element Method

Purpose This paper aims to propose a parallel-in-space-time finite-element method (FEM) for transient motor starting analyses. Although the domain decomposition method (DDM) is suitable for solving large-scale problems and the parallel-in-time (PinT) integration method such as Parareal and time domain parallel FEM (TDPFEM) is effective for problems with a large number of time steps, their parallel performances get saturated as the number of processes increases. To overcome the difficulty, the hybrid approach in which both the DDM and PinT integration methods are used is investigated in a highly parallel computing environment. Design/methodology/approach First, the parallel performances of the DDM, Parareal and TDPFEM were compared because the scalability of these methods in highly parallel computation has not been deeply discussed. Then, the combination of the DDM and Parareal was investigated as a parallel-in-space-time FEM. The effectiveness of the developed method was demonstrated in transient starting analyses of induction motors. Findings The combination of Parareal with the DDM can improve the parallel performance in the case where the parallel performance of the DDM, TDPFEM or Parareal is saturated in highly parallel computation. In the case where the number of unknowns is large and the number of available processes is limited, the use of DDM is the most effective from the standpoint of computational cost. Originality/value This paper newly develops the parallel-in-space-time FEM and demonstrates its effectiveness in nonlinear magnetoquasistatic field analyses of electric machines. This finding is significantly important because a new direction of parallel computing techniques and great potential for its further development are clarified.

Investigation on the shaft voltage generation of large synchronous turboalternators

2020 ◽  
Vol 39 (5) ◽  
pp. 1145-1156
Author(s):  
Kevin Darques ◽  
Abdelmounaïm Tounzi ◽  
Yvonnick Le-menach ◽  
Karim Beddek
Keyword(s):  
Finite Element ◽  
Design Methodology ◽  
Short Circuit ◽  
Element Model ◽  
Stator Winding ◽  
Content Type ◽  
Voltage Generation ◽  
The Impact ◽  
Investigation Process ◽  
Circulating Currents

Purpose This paper aims to go deeper on the analysis of the shaft voltage of large turbogenerators. The main interest of this study is the investigation process developed. Design/methodology/approach The analysis of the shaft voltage because of several defects is based on a two-dimensional (2D) finite element modeling. This 2D finite element model is used to determine the shaft voltage because of eccentricities or rotor short-circuit. Findings Dynamic eccentricities and rotor short circuit do not have an inherent impact on the shaft voltage. Circulating currents in the stator winding because of defects impact the shaft voltage. Originality/value The original value of this paper is the investigation process developed. This study proposes to quantify the impact of a smooth stator and then to explore the contribution of the real stator winding on the shaft voltage.

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