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This paper presents a numerical method to calculate shape of ferrofluid droplet that undergoes three effects: external magnetic field, gravitational force and surface tension. The shape is calculated using an equilibrium energy condition of the coupled system of electromagnetic field and gravitational field and surface tension. The shape of the ferrofluid is traced using level set method, where the...
The performance of a variable speed, direct-drive synchronous generator wind turbine concept is compared for two grades of electric steel applied for the generator stator core lamination. A ring type, radial flux permanent magnet synchronous generator (PMSG) is modelled. For a fixed mechanical power input, the geometry of the PMSG is optimized for each material to maximize the annual energy yield...
To enhance the performance of a Thomson-coil actuator, generalized topology modification method is developed, and applied to the shape optimization of the conducting plate. In the method, shape optimization problem is treated as that of optimal assigning of material to each segment among available materials.
This paper deals with a coupling scheme for open boundary problem. It couples an analytical solution of Fourier series expansion with the standard finite element method. The analytical solution is derived for the magnetic field in the outside of the boundary, and the finite element method is for the magnetic field in the inside with source current and magnetic materials. The main advantage of the...
The magnetic force and body force density distribution in high field magnetic system is an important factor to analyze mechanical deformation, vibration or electro-mechanical coupled phenomenon. Since magnetic apparatuses such as transformer, motor and electromagnet is driven by high magnetic flux density, the resulting magnetic force is so large as to cause mechanical problems. Accurate analysis...
Topology optimization methods suffer from a lack of convexity for the design of electromagnetic actuators. Local minimizers prevent the method from attaining the optimal solution. The optimization result may then vary according to the initial conditions. This paper proposes a convexity-oriented method focusing on the maximization of the forces exerted on ferromagnetic parts. In addition to canceling...
This paper presents the principle of bushing shield size, position and its covering material determination, based on the optimization algorithm. An optimization procedure has been carried out using a differential evolution (DE) algorithm combined with a solver of the software tool EleFAnT, which is used for solving computationally expensive parametrically-written bushing FEM model. The goal of this...
The topological gradient (TG) is derived for Steady state Eddy Current problem using a topological asymptotic expansion for the Maxwell equation of a Time Harmonic problem. TG provides information on where the design is most sensitive to topology changes. An application to eddy current nondestructive testing (NDT) is demonstrated.
Performance of hysteretic magnetostrictive transducers can be affected by a variable applied stress if its magnitude is comparable with the mechanical pre-stress. Aim of this paper is to present the design of a controller with hysteresis compensation able to take into account the applied stress. The controller is implemented and tested in a real-time setup and compared with standard closed loop PID...
The emphasis of this paper is to research the dynamic inductance model of giant magnetostrictive actuator (GMA). First, the relative permeability of giant magnetostrictive material (Terfenol-D) under different pressures and different magnetizations are tested. Then, the inductance parameter of GMA is computed based on the above relative permeability results and the trends of inductance considering...
This paper accomplishes the electromagnetic losses prediction, for instance core losses and rotor eddy current losses, according to the driving method, namely, sine wave drive and square wave drive, of 5kW class high speed PM synchronous motor, using analytical method and finite element method.
This paper presents a generalized continuum design sensitivity formula that is applicable to all cases of the shape optimization of high-frequency devices. Using the proposed approach, it is easy to deal with any shape design problems concerning conducting surfaces as well as dielectric contours. The derived sensitivity formula has been successfully applied to shape optimization of a waveguide T-junction...
This paper presents an efficient approach to determining the corrosion currents distributed on the hull of a naval ship, which offer useful information for underwater electric fields prediction and diagnosis of hull corrosion state. To achieve this, a material sensitivity formula, which gives the first-order gradient information of an objective function with respect to the electric current, is analytically...
A novel transverse-flux PM linear machine is proposed in this paper. Flux leakage analysis and parameter optimization are accomplished by finite-element method (FEM). Thrust characteristics, efficiency and power density are compared between comparable radial, axial, halbach and transverse-flux machines. Simulation results indicate the advantage of the transverse-flux machine in thrust characteristics...
Summary form of only given: This paper proposes a topology optimization method to optimize the material distribution of electrical machines using Genetic Algorithm (GA). In the method, a cluster of material is taken into account to form a group of iron. Moreover, the GA is iterated with the newly increased length of genes. The proposed method is applied to the topology optimization of the stator teeth...
In this paper, wave propagation in two-layered anisotropic media when uniaxially anisotropic medium has its optic axis oriented vertically and tilted around z-axis has been investigated. The Fresnel coefficients are derived for horizontally and vertically polarized incident waves with arbitrary incident angles. The contribution of the cross polarized components of the reflected and transmitted waves...
Magnetic refrigeration (MR) is a cooling technology based on the magnetocaloric effect (MCE). It has the potential to replace conventional refrigeration systems. Recent development in magnetic refrigeration technology has encouraged researchers all over the world to think about some new original systems. This paper aims to describe a new magnetic refrigeration structure based on a rotating bar shaped...
Total electromagnetic force on a body can be predicted by replacing the polarization and magnetization with appropriate equivalent currents and charges. Still, the equivalence of total force does not imply that the integrated densities have physical meaning. The construction of force density directly from dipoles removes the ambiguity caused by partial integration.
The Cell Method, similar to the Finite Integration Technique, is a well-established numerical method for the solution of field problems, however an often raised criticism is that it is limited to constant fields within elements. In this paper we show that for the case of Poisson's equation the cell method can be extended to the second order. Numerical results showing the order of convergence of the...
Ni-Fe-SiC alloy is a promising material in the fabrication of micro actuator. Electrolytic codeposition technique was adopted in the deposition of Ni-Fe-SiC composite coating on stainless steel substrate, using nickel alloyed with iron as the binder phase and SiC as dispersed particles. The morphology analysis indicated that the deposit with SiC nanoparticles is level and compact and the crystal-planes...
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