Yanpu Zhao

Wuhan University | WHU · School of Electrical Engineering and Automation

While the traditional doubly-fed induction generator (DFIG) currently play a pivotal role in variable speed applications, the brushless doubly-fed generator (BDFG) has emerged as a promising alternative. This study presents a comprehensive literature survey on control strategies aimed at improving power quality in BDFGs. The discussion explores the...

Electronic packaging is an essential branch of electronic engineering that aims to protect electronic, microelectronic, and nanoelectronic systems from environmental conditions. The design of electronic packaging is highly complex and requires the consideration of multi-physics phenomena, such as thermal transport, electromagnetic fields, and mecha...

Accurate calculation of short‐circuit electromagnetic force is crucial for both mechanical strength check and the optimal design of gas‐insulated transmission lines (GIL). Since the full 3D numerical simulation method is highly time‐consuming, a novel lightweight 2D multi‐slice electromagnetic field‐circuit coupled method for computing transient el...

Since the age of the insulation is strongly dependent on the thermal field of transformers, accurate computation of temperature distribution, the hot-spot temperature and reducing the temperature rise are crucial concerns when designing power transformers. With the development of advanced numerical solution techniques, the complicated multiphysical...

本书简明介绍了工程电磁场理论及有限元方法，重点给出了应用开源有限元分析软件FreeFEM进行二维及三维低频电磁场问题自编程计算的方法和技巧，并对约三十个典型问题进行了编程求解。在内容组织编排上，以七大低频电磁场应用场景（包括静电场、交/直流传导电场、瞬态电场、静磁场、涡流场及瞬态磁场）为主线，以典型场景应用案例为牵引，遵循了计算电磁学理论与FreeFEM算法编程并重的原则。在理论方面，给出了七大场景下计算电磁场问题的数学模型（包括控制方程、边界条件、界面连续性条件及激励条件）及相应的有限元弱形式。在FreeFEM编程实践方面，本书所选取的案例来自于经典教材及学术论文且部分为实际工程案例，通过代码语句详细展示了电磁场问题自编程数值计算的全过程。通过将复杂的实际工程计算问题以FreeFEM示例代...

This article proposes an adaptive feedback regulation method for wireless power transfer (WPT) systems, which can be applied to solve the problem of the drop in input voltage from the emergency power supply such as a battery‐based source. The whole WPT system transfers power mainly through the mutual inductance between the transmitter and receiver...

The air gap breakdown voltage is an important physical quantity to consider when designing external insulation. The breakdown voltage is usually determined through extensive experimentation. In this study, we attempted to provide a novel approach for predicting air gap breakdown voltage. Using air gap break-down voltage data from 0.1 m to 1.5 m of...

The coordination of dual extended rectangular coils is an effective way of wireless charging area expansion for unipolar and bipolar receivers (Rxs). However, the cross-coupling field and the leakage field of the dual coils, laid out for multimodal transmission stability, inevitably interfere with system performance and external objects. The paper...

The physical mechanism of leader formation and development is not well understood. In this study, we present experimental and simulation results obtained with a 10 m long air gap discharge. A 10 m outdoor discharge experiment is carried out to obtain the current, voltage, and optical image during the leader discharge process. Four different impulse...

For numerical computation of three-dimensional (3-D) large-scale magnetostatic problems, iterative solver is preferable since a huge amount of memory is needed in case of using sparse direct solvers. In this paper, a recently proposed Coulomb-gauged magnetic vector potential (MVP) formulation for magnetostatic problems is adopted for finite element...

In this article, residual-type a posteriori error estimates developed in our previous work for magnetostatic and eddy-current problems are extended to low-frequency (LF) Maxwell problems using $ {A}/\varphi $ formulation, where both inductive and capacitive effects can be handled simultaneously. Classical low-order finite-element basis (LOFEB)...

In this paper, a novel potential formulation for low-frequency (LF) applications taking into account both inductive and capacitive effects but without considering wave propagation is proposed. Both time-domain and frequency-domain formulations are presented. The resultant fully discrete finite-element matrix is made symmetric by incorporating a gau...

In this paper, a symmetric field-circuit coupled finite element method for low-frequency full-wave Maxwell problems using a magnetic vector potential formulation is proposed. The resultant fully discrete coefficient matrix is made symmetric for the first time by introducing the so-called source electric scalar potential for solid conductors, where...

Dual formulations are accurate in use for computing energy-related global quantities such as inductance and providing upper and lower bounds of the unknown true values of these global parameters, which is not possible if using a single formulation. Since traditional dual formulations result in totally different algebraic matrix equations, people ha...

Calculating the bounds of global energy is an important issue in computational electromagnetism, which can provide guaranteed results when extracting inductance parameters. In this paper, an improved equilibrated type a posteriori error estimate for open boundary magnetostatic problems is proposed. We derive our error estimator based on vector dual...

When using magnetic vector potential (MVP)-based formulations for magnetostatic or eddy-current problems, either gauge conditions specifying the divergence of the MVP or tree gauging by eliminating redundant degrees of freedom of the MVP is usually imposed to ensure uniqueness of solutions. Explicit gauging of the MVP is not always necessary since...

Magnetic vector potential (MVP) formulations are widely used in electromagnetic (EM) field computation. For problems with both inductive and capacitive effects, existing full-wave MVP formulations are mostly non-uniquely solvable and sophisticated preconditioners are indispensable when solving these resultant linear matrix equations. To find a stab...

Magnetic vector potential (MVP) formulations are widely used in low-frequency eddy-current computation. For full-wave Maxwell problems with coupled resistive, inductive and capacitive effects, existing MVP formulations are either ungauged or with too complicated stabilisation procedure or with non-symmetric system matrix. Since sophisticated precon...

Magnetic vector potential (MVP) formulation combined with finite edge elements has gained much application in three-dimensional (3-D) eddy-current field computation. Compared with its magnetic scalar potential (MSP) counterpart, the MVP formulation is much easier to treat multiply connected conductors. With the availability of advanced direct linea...

Accurate computation of motional eddy-currents is essential for the design of electromagnetic (EM) devices such as eddy-current brakes. When the conductors are uniform in the moving direction, it is convenient to formulate and solve the problem within a fixed coordinate system without the need of using two or more coordinate systems and connecting...

A novel magnetic vector potential (MVP) formulation with Coulomb gauge is proposed for solving three-dimensional (3-D) magnetostatic problems. A dummy scalar variable is introduced in the whole computation domain to impose the Coulomb gauge. Unlike traditional Coulomb gauged formulation using penalty technique which works only for nodal elements ap...

Introduction: To improve the performance of electromagnetic (EM) devices in the process of designing new products, geometric sizing or shape optimization is very important in practice. In the optimization process, because there are frequent variations in the design parameters, the computational mesh has to be generated repeatedly before one can pro...

Introduction: Transient magnetic field analysis, which includes arbitrary circuit-coupling and nonlinear material easily in the performance analysis of electromagnetic devices, is very important for designers. However it usually takes a long time to perform the finite element time-stepping before the simulation reaches steady states [1].

The traditional low-frequency eddy-current solvers do not include displacement current effect, while high-frequency solvers do not consider the nonlinearity of material properties. A novel solver for electromagnetic field analysis that addresses both the inductive and capacitive effects is, thus, highly valuable. A stable time-domain magnetic vecto...

The traditional low-frequency electromagnetic field computations do not include stray capacitive effect, while high-frequency solvers do not consider the nonlinear property of materials, and the internal regions of solid conductors as well as external circuit excitations. In this paper, the application of 3-D edge-element finite-element method (FEM...

For transient finite element analysis of eddy-current fields in solid rotors which have invariant material properties, it is convenient to use the Eulerian formulation where only a fixed mesh is needed when modeling motion effect. However, in the Eulerian formulation, a convection-diffusion equation instead of the pure diffusion equation has to be...

Standard Galerkin finite element method (SGFEM) cannot solve eddy-current problems with dominated motional terms accurately and effectively. A numerical method for analyzing eddy-current magnetic field in high-speed rotating solid conductors using operator splitting finite element method (OSFEM) is presented. An artificial example and a benchmark t...

A novel adaptive degrees-of-freedom (DoFs) finite-element method (FEM) for the numerical computation of transient magnetic fields is presented. The proposed adaptive FEM incorporates functions of both mesh refinement and mesh coarsening. The mesh refinement procedure is implemented using the longest edge bisection algorithm, whereas for the coarsen...

A novel adaptive finite element method for the numerical simulation of magnetic fields with nonlinear materials is presented. The proposed method incorporates functions of both mesh refinement and mesh coarsening. Instead of explicitly eliminating unnecessary nodes in the mesh, the proposed mesh coarsening algorithm only needs a single mesh. The pr...

With the advent of electronic technology, researchers are devoting increasing interests to wireless power transfer methods. Generally finite-element method (FEM) is a powerful tool for numerical simulation of such systems. Due to the relatively high operating frequency, the presence of inductance and distributed capacitance in the system as well as...

An algorithm with parameterized mesh generation, refinement and morphing is presented for the optimal design of electromagnetic (EM) devices. The method can do without mesh regeneration when changing design parameters, hence a lot of computation time can be saved in finite element (FE) parameter sweeping analysis. When the design parameters change,...

A novel error estimator for adaptive mesh refinement in finite element analysis (FEA) of magnetic field using quadratic finite elements is presented. The method uses a novel heuristic a posteriori error estimator, which is easy to compute and simple to implement, as an indicator of the numerical errors of the computed solution. The proposed error e...

A parameterized mesh generation and refinement method is presented for parameter sweeping analysis of electromagnetic designs. The advantages of the method are distinct in that the method is remeshing-free, thus it can significantly reduce the numerical simulation time during the finite element analysis (FEA) process. The refinement procedure is ac...

A numerical method for analyzing eddy current magnetic field in high-speed moving conductors using local discontinuous Galerkin (LDG) method is presented. A typical numerical example is chosen to illustrate the accuracy and nonoscillatory nature of the method for a convection dominated case. The simulation results using the proposed algorithm are v...

A numerical method for symmetric cylindrical and spherical waveguide eigenvalue problems is presented using local discontinuous Galerkin (LDG) method based on polar coordinates. The method has the merit of having high accuracy without geometrical triangula-tion errors on the curved boundaries of the solution domain. As an illustration, the formulat...

A parameterized mesh generation is presented for design optimization of electromagnetic devices. The proposed method requires no mesh regeneration, and hence the numerical simulation time can be reduced significantly. When the coordinates of nodes in the refined mesh are changed, the mesh topology will be kept, that is, the node connection relation...

Protein adsorption-dependent electro-kinetic pore flow: Modeling of ion-exchange electrochromatography with an oscillatory transverse electric field Electro-kinetic acceleration of protein mass transfer was studied by dynamic chromato-graphic experiments and computer simulations on IEC with an oscillatory transverse electric field (EF) perpendicula...