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An electric machine with permanent magnets on both its rotor and stator is proposed and studied. The key idea is to using the bi-directional flux modulation effect to realize a structure with more rotor poles and less stator poles. Compared with the conventional machines with single-sided permanent magnet excitation, the proposed machine has more flexible pole-slot design when the pole number is large...
A unified theory of general flux-modulated electric machines is presented. Using the proposed theory, the operating principles of the following machines can be easily explained: a basic flux-modulated machine, a vernier permanent-magnet (PM) machine, a doubly-fed reluctance machine, and a dual-excitation PM machine. The performances of different types of the flux-modulated machines are quantitatively...
Electrical Machines are the devices which produce torque by the interaction of the stator and rotor flux linkages. To obtain the maximum torque, the winding current is usually controlled according to the waveforms of back-EMF. However, few papers study about how to design the stator winding and control the winding current according to the excitation flux linkage waveforms. If we focus on the excitation...
Magnetic vector potential (MVP) formulations are widely used in low-frequency computational electromagnetics of finite element method (FEM). How to impose the gauge condition properly to ensure the uniqueness of the MVP is a key problem for researchers. Traditional Coulomb gauged formulation using penalty technique is not feasible for edge elements since the divergence of the edge element basis function...
The traditional method to obtain the response of electromagnetic devices over a wide frequency range is to use a frequency sweeping method. However, this method is very time consuming, especially in time-domain analysis. In order to save the heavy computational time, a novel fast algorithm based on finite-element method (FEM) to obtain the response under different frequencies is therefore proposed...
Disc machines are promising candidates for direct drive in-wheel machines due to the inherent merits such as short axial dimension, high torque density and high efficiency. Currently, most of disc machines have the permanent magnets (PMs) employed on rotor, which can contribute to improved torque but also results in many undesired limitations. Definitely, these structures have large space to install...
The linear sampling method is known to be a simple and computationally efficient approach to retrieve the support of the scatterer using multistatic scattered field data. However, the recovered profile is always misleading, owing to the lack of robust edge detecting. This paper addresses this open issue. Using moving least square approximation, the upper and lower bounds of the profile of scatterers...
The use of Coulomb gauged formulation together with nodal elements, which imposes both tangential and normal continuity, may produce large errors at material interfaces or reentrant corners of problem domains. While traditional Coulomb gauged formulation is not valid for edge elements since the divergence of the edge element basis is zero within each element. In this paper, a novel formulation with...
Magnetic vector potential (MVP) formulations are widely used in eddy-current field computation. How to impose the gauge condition properly to ensure the uniqueness of the MVP is a key problem for researchers. In this paper, a novel MVP formulation with Coulomb Gauge for eddy-current problems using edge elements is proposed. The resultant linear matrix equation is symmetric and well-conditioned, which...
As an artificial material, the metamaterial has great applications in radar, stealth and electronic countermeasure because of its special electromagnetic properties. Considering its negative permittivity and negative permeability, the metamaterial is applied in wireless power transfer system to improve its performance. In this paper, a novel structure of metamaerial is designed. This metamaterial...
A novel structure of dual permanent magnet machine with PMs on both stator and rotor is presented as an effective option for high torque density direct-driven applications. The novel machine has PMs on both sides of rotor and stator. The PMs on the stator are designed as cylinder and can be rotated by an external driven system. Field can be regulated by the rotation of stator PMs. The structure and...
Electromagnetic (EM) inverse problems are usually modeled as simulation-based optimization problems with multimodal and non-differentiable properties. These properties justify the invention of more effective optimization algorithms. Artificial bee colony (ABC) has already been applied to tackle EM inverse problems. This paper applies a tree structure to record all search moves of ABC. A history based...
For three-dimensional (3-D) large-scale problems, iterative solver is preferable due to a huge amount of memories are needed if the direct linear solver is adopted. In this paper, a novel Coulomb-gauged formulation for magnetostatic problems using edge element is first proposed. For the proposed formulation, the resultant linear system is symmetric and well-conditioned. It can be solved by iterative...
How to impose gauge condition properly to ensure the uniqueness of the magnetic vector potential (MVP) formulation is a key problem to investigate. Traditional Coulomb gauged formulation using penalty technique is not valid for edge elements since the divergence of the edge element basis is zero within each element. In this paper, a novel gauged formulation for motional eddy-current problems using...
A novel brushless and gearless power split system is presented in this paper. The proposed system offers an electric solution for continuously variable transmission of the hybrid electrical vehicles (HEV). The key is to use a doubly fed flux bidirectional modulation machine with dual electric port and dual mechanical port to realize the power combination and split in HEV. This electric continuously...
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].
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 proceed to the finite element (FE) computation. Thus...
A method to deal with the effect of the free wheeling diodes in the power electronic converter of brushless d.c. motor when using the time stepping finite element method is described. The circuit equations of the power electronic converter and the finite element equations of magnetic field are directly coupled together and are solved simultaneously. The study reveals that if the effect of the free...
A method to accurately extract the equivalent circuit parameters of eddy-current magnetic field is presented. Based on the solutions of the eddy-current magnetic field and electric circuit coupled model, the lumped parameters of the equivalent circuits are directly computed according to the voltage — current relationships at the terminals of windings and conductors. The merits of the proposed method...
Starting response time is one of the most important parameters of DCT clutch BLDC motor. In this paper, a novel BLDC mathematic model was built based on non-linear flux linkage differential equation method, which inductance derivative can be omitted in the current calculation, and the non-linear magnetic behavior was taken into consideration in the motor inductances, and these nonlinear inductances...
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