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Dan Jiao - One of the best experts on this subject based on the ideXlab platform.

  • an alternative explicit and unconditionally stable time domain finite element method for Electromagnetic Analysis
    IEEE Journal on Multiscale and Multiphysics Computational Techniques, 2018
    Co-Authors: Woochan Lee, Dan Jiao
    Abstract:

    A new method for making an explicit time-domain finite-element method unconditionally stable is developed for general Electromagnetic Analysis, where the dielectrics and conductors can be inhomogeneous, lossless, or lossy. In this method, for a given time step, we find the unstable modes that are the root cause of instability, and deduct them directly from the system matrix resulting from a time-domain finite-element based Analysis. The resultant explicit time-domain simulation is absolutely stable for the given time step no matter how large it is, and irrespective of the space step. The accuracy of the method is also guaranteed when the time step is chosen based on accuracy. In addition to a formulation for lossless problems, formulations for general lossy problems are also presented in detail. Numerical experiments have demonstrated the accuracy, efficiency, and unconditional stability of the proposed new explicit method.

  • direct finite element solver of linear complexity for large scale 3 d Electromagnetic Analysis and circuit extraction
    IEEE Transactions on Microwave Theory and Techniques, 2015
    Co-Authors: Bangda Zhou, Dan Jiao
    Abstract:

    In this paper, we develop a linear-complexity direct finite-element solver for the Electromagnetic Analysis of general 3-D problems containing arbitrarily shaped lossy or lossless conductors in inhomogeneous materials. Both theoretical Analysis and numerical experiments have demonstrated the solver’s linear complexity in CPU time and memory consumption with prescribed accuracy satisfied. The proposed direct solver has successfully analyzed an industry product-level full package involving over 22.8488 million unknowns in approximately 16 h on a single core running at 3 GHz. It has also rapidly solved large-scale antenna arrays of over 73 wavelengths with 3600 antenna elements whose number of unknowns is over 10 million. The proposed direct solver has been compared with the finite-element methods that utilize the most advanced direct sparse solvers and a widely used commercial iterative finite-element solver. Clear advantages of the proposed solver in time and memory complexity, as well as computational efficiency, have been demonstrated.

  • a mass matrix based frequency domain finite element method accelerated by a reduced eigenspace method for circuit modeling
    International Symposium on Electromagnetic Compatibility, 2014
    Co-Authors: Jianfang Zhu, Duo Chen, Dan Jiao
    Abstract:

    The mass matrix resulting from a finite-element-method (FEM) based Electromagnetic Analysis possesses favorable properties that can be exploited to reduce the computational time and memory cost for large-scale circuit modeling. In this paper, a mass-matrix based frequency-domain FEM method is developed for the Analysis of integrated circuits. Its convergence is theoretically proved, and its efficiency is accelerated by a reduced eigenspace method.

  • theoretical study on the rank of integral operators for broadband Electromagnetic modeling from static to electrodynamic frequencies
    IEEE Transactions on Components Packaging and Manufacturing Technology, 2013
    Co-Authors: Wenwen Chai, Dan Jiao
    Abstract:

    To facilitate the broadband modeling of integrated electronic and photonic systems from static to electrodynamic frequencies, we propose an analytical approach to study the rank of the integral operator for Electromagnetic Analysis, which is valid for an arbitrarily shaped object with an arbitrary electric size. With this analytical approach, we theoretically prove that for a prescribed error bound, the minimal rank of the interaction between two separated geometry blocks in an integral operator, asymptotically, is a constant for 1-D distributions of source and observation points, grows very slowly with electric size as square root of the logarithm for 2-D distributions, and scales linearly with the electric size of the block diameter for 3-D distributions. We thus prove the existence of an error-bounded low-rank representation of both surface- and volume-based integral operators for Electromagnetic Analysis, irrespective of electric size and object shape. Numerical experiments validated the proposed analytical approach and the resultant findings on the rank of integral operators. This paper provides a theoretical basis for employing and further developing low-rank matrix algebra for accelerating the integral-equation-based Electromagnetic Analysis from static to electrodynamic frequencies.

  • an explicit and unconditionally stable fdtd method for 3 d Electromagnetic Analysis
    International Microwave Symposium, 2013
    Co-Authors: Dan Jiao
    Abstract:

    In this paper, a fast explicit and unconditionally stable finite-difference time-domain (FDTD) method is developed, which does not require a partial solution of a global eigenvalue problem. In this method, a patch-based single-grid representation of the FDTD algorithm is developed to facilitate both theoretical Analysis and efficient computation. This representation results in a natural decomposition of the curl–curl operator into a series of rank-1 matrices, each of which corresponds to one patch in a single grid. The relationship is then theoretically analyzed between the fine patches and unstable modes, based on which an accurate and fast algorithm is developed to find unstable modes from fine patches with a bounded error. These unstable modes are then upfront eradicated from the numerical system before performing an explicit time marching. The resultant simulation is absolutely stable for the given time step irrespective of how large it is, the accuracy of which is also ensured. In addition, both lossless and general lossy problems are addressed in the proposed method. The advantages of the proposed method are demonstrated over the conventional FDTD and the state-of-the-art explicit and unconditionally stable FDTD methods by numerical experiments.

Nicola Bianchi - One of the best experts on this subject based on the ideXlab platform.

  • a coupled thermal Electromagnetic Analysis for a rapid and accurate prediction of im performance
    IEEE Transactions on Industrial Electronics, 2008
    Co-Authors: Luigi Alberti, Nicola Bianchi
    Abstract:

    The design of electrical machines for extreme operating conditions must include a thermal Analysis coupled with the magnetic Analysis. However, the traditional coupling of the thermal and the magnetic models can result in an unacceptable increase in computation time, particularly if finite elements (FEs) are used for the machine Analysis. This paper proposes a coupled thermal-magnetic Analysis of an induction motor (IM) with the primary goal of achieving a rapid and accurate prediction of the IM performance. Only a minimum set of FE magnetic analyses is carried out so as to determine the parameters of the IM equivalent circuit. These parameters are nonlinear and are adjusted on the basis of the operating point. Then, this equivalent circuit is coupled with a lumped-parameter thermal network to predict the temperature in each part of the IM. Since both the equivalent circuit and thermal network solutions are analytic, the Analysis converges very rapidly. At the same time, the FE Analysis yields a precise estimation of the IM parameters used in the equivalent circuit. Some experimental results are reported, showing the accurate prediction of the proposed methodology.

Eric Michielssen - One of the best experts on this subject based on the ideXlab platform.

  • A fast time-domain finite element-boundary integral method for Electromagnetic Analysis
    IEEE Transactions on Antennas and Propagation, 2001
    Co-Authors: Dan Jiao, Mingyu Lu, Eric Michielssen
    Abstract:

    A time-domain, finite element-boundary integral (FE-BI) method is presented for analyzing Electromagnetic (EM) scattering from two-dimensional (2-D) inhomogeneous objects. The scheme's finite-element component expands transverse fields in terms of a pair of orthogonal vector basis functions and is coupled to its boundary integral component in such a way that the resultant finite element mass matrix is diagonal, and more importantly, the method delivers solutions that are free of spurious modes. The boundary integrals are computed using the multilevel plane-wave time-domain algorithm to enable the simulation of large-scale scattering phenomena. Numerical results demonstrate the capabilities and accuracy of the proposed hybrid scheme.

David G Dorrell - One of the best experts on this subject based on the ideXlab platform.

  • combined thermal and Electromagnetic Analysis of permanent magnet and induction machines to aid calculation
    IEEE Transactions on Industrial Electronics, 2008
    Co-Authors: David G Dorrell
    Abstract:

    This paper reports on methods for the Analysis of electrical machines by combined Electromagnetic and thermal models using commercial software which can be an aid to the design of these machines. Examples using a brushless permanent-magnet motor and an induction motor illustrate the available tools and possible techniques. It reviews the different loss calculations, particularly iron losses, and also the thermal models that can be used, including steady state and transient (where thermal capacitances have to be included). This paper will be useful to an engineer in an industrial design office to illustrate the possibilities that are now possible.

Michel Lecrivain - One of the best experts on this subject based on the ideXlab platform.

  • thermal Electromagnetic Analysis for driving cycles of embedded flux switching permanent magnet motors
    IEEE Transactions on Vehicular Technology, 2012
    Co-Authors: Javier Ojeda, Emmanuel Hoang, M Gabsi, Michel Lecrivain
    Abstract:

    This paper presents a fast and precise Electromagnetic-thermal model of a redundant dual-star flux-switching permanent-magnet (FSPM) motor for embedded applications with driving cycles, e.g., hybrid electrical vehicle (HEV) and aerospace. This model is based on a prior steady characterization by finite-element method (FEM) 2-D of the FSPM motor via calculating the instantaneous torque and the normal and tangential components of the magnetic flux density (Br and Bθ) of each element of the stator and the rotor for different root-mean-square (RMS) current densities and different rotor positions. These results are then used in the analytical copper and iron loss models for calculating the instantaneous copper and rotor and stator iron losses during one driving cycle. The lumped-parameter (LP) and finite-element 2-D transient thermal models are then carried out, in which the previously obtained instantaneous power losses are used as heat sources for calculating the temperatures of different motor parts during driving cycles. In the thermal studies, a transformation of an irregular slot structure into a regular (rectangular) one is applied to simplify the calculation of the winding thermal resistance. The thermal-Electromagnetic Analysis method in this paper can also be extended for all the other applications with driving cycles. The experimental tests are carried out to validate the analytical and numerical results.