Calculation Of Two-dimensional Field Research Articles

Electromagnetic design method of linear induction motor considering lateral end effect

Due to the complex end effect, it is difficult for the linear induction motor to design and analyze with the "road" calculation and two-dimensional field calculation. Considering the end effect, skin effect and secondary leakage reactance of the eddy current of the secondary induction plate, a linear induction motor electromagnetic design and calculation program was programmed via VB language. A two-dimensional finite element analysis method was proposed to approximate the lateral end effect on linear induction motor performance by multiplying the two lateral end effect coefficients into secondary induction plate resistivity and air-gap relative permeability. The accuracy for both calculation of end effect coefficients by "road" calculated program and considering lateral end effect in two-dimensional finite element analysis was validated by using the experiment and three-dimensional full model finite element, respectively. This work proposes the calculation method of the lateral end effect, which is faster and more accurate for the electromagnetic design as well as the finite element simulation of linear induction motor.

УДОСКОНАЛЕННЯ ПРИНЦИПУ СУПЕРПОЗИЦії КОНЦЕНТРАЦіі РЕЧОВИН ДЛЯ ВОДОТОКіВ

The paper deals with improving the superposition principle of substance concentration for watercourses. The substance superposition principle in watercourses arises from the linearity of turbulent diffusion equation and its boundary conditions. When using the superposition principle of substance concentration in water courses, usually only point sources of substance are taken into account, neglecting diffuse (distributed along the watercourse) sources and substance-containing effluents. Diffuse sources of substance are formed by the surface and ground waters getting to the watercourse as well as atmospheric precipitation on the water surface. Diffuse effluents are connected with the processes of water filtration through the watercourse bottom. The paper justifies the use of the superposition principle of substance concentration for watercourse with regard to the diffuse sources and substance-containing effluents. The formulas were obtained which reflect the superposition principle of non-conservative substance concentration in watercourse and simplify the calculation of two-dimensional field of substance concentration in view of point and diffuse sources and substance-containing effluents. The formulas allow improving the accuracy of calculations of water quality in watercourses.

A novel structure of multipole field magnets and their applications in uniformizing beam spot at target

A novel structure of multipole field magnets is proposed, and it can provide any order either symmetric or anti-symmetric field distribution within a good-field region in a flat rectangular shape with relative field errors of about 1%. Some of these field distributions cannot be obtained by standard multipole magnets but are quite useful in some applications, thanks to the decoupling of the two halves of the magnets by a pair of shielding plates. In addition, the simplified structure compared with the standard one makes the magnet fabrication easier and cost effective. Two-dimensional magnetic field calculations for anti-symmetric sextupole, octupole, decapole and dodecapole fields show that the new types of multipole magnets have good field quality. Three-dimensional magnetic field calculations have confirmed the validity of the two-dimensional calculations. Symmetric field distributions by the simplified multipole field magnets have also been confirmed by two-dimensional field calculations. Two application examples by using numerical simulations are also given to show the effectiveness of simplified multipole field magnets in producing uniform-like beam spots at two different targets with different beam inputs. It is also shown that combinations of the lower order anti-symmetric field magnets – a merit of this magnet structure – are more advantageous than the traditional combination of octupole and dodecapole magnets in beam spot uniformization, besides with cheaper construction and operation costs. The applications of non-standard field distributions such as anti-symmetric sextupole and symmetric octupole field distributions in synchrotrons are to be exploited in the future.

Improved analytical modeling of conductive losses in gapped high-frequency inductors

An improved method to predict conductive losses in gapped high-frequency inductors is presented and used for parametrization of an equivalent small-signal circuit model. The method is based on the superposition of power losses resulting from the well-known one-dimensional (1-D) field calculation and losses due to eddy currents caused by the fringing field of air gaps determined from novel analytical two-dimensional field calculations. Losses due to reactive currents in the windings caused by self capacitances are also considered. A greatly improved accuracy compared to 1-D analysis is proved by measurements.

Comparison of different methods for calculating the air-gap field of induction motors

In this paper different methods for calculating the air-gap field of induction motors are compared. A “modified one-dimensional field calculation” is proposed, combining the advantages of short computing times and high accuracy of the one- and two-dimensional field calculation, respectively. The different methods are checked against experiments: The total leakage coefficient and the radiated audible noise of induction motors are investigated. Both, the modified one-dimensional and the two-dimensional theory give results which are in good agreement to the measurements.

Optimal design and field measurements of a dipole magnet model for compact electron storage ring (LSI production)

Compact electron storage rings with strongly curved superconducting dipole magnets were developed as the soft X-ray source for the production of LSI (large scale integration). A dipole magnet model with a copper quasi-cos theta winding was manufactured, and the field distributions were measured. An optimal design technique based on the linear programming and two-dimensional field calculations by the finite element method was applied to determine a coil configuration in a 180 degrees sectoral dipole magnet model. Using this model, good agreement between the measured and calculated field uniformities within the order of 10/sup -4/ was obtained. Moreover, a designed good field region of about 50 mm wide was achieved. This result shows the validity of the design techniques.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Factors influencing the need for upwinding in two-dimensional field calculation

Numerical simulations have been conducted in an attempt to clarify some of the findings of previous work on the necessity of upwinding in the finite element analysis of electromagnetic problems that involve relative motion. The results presented demonstrate that, besides the Peclet number, the stability of the finite element solution also depends on the boundary conditions of the problem and the magnetic characteristics of the moving conductor. When the moving conductor is nonferromagnetic and a periodic boundary condition is imposed, a Galerkin method can model the problem successfully. Whenever numerical oscillation is exhibited, the upwind finite element scheme can be used to solve the problem. In a 3-D model where the biconjugate gradient solver is the most economical, and often the only, choice of solver to use, upwinding may be necessary to ensure convergence.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Analytical calculation of the two-dimensional field in the air gap and the slots of electrical machines

As far as the induction machine with squirrel cage rotor is concerned, it has been illustrated how the voltage equations can be arrived at, taking into account the actual two-dimensional field and the multiple armature reaction. Compared with one-dimensional theories, only in the submatrix of the rotor self inductances do additional elements appear due to the inclusion of the stator slots in the analysis. The other elements are modified by introducing the two-dimensional field calculation. The analysis has been derived for the squirrel cage motor without parallel winding branches under steady-state conditions. Correspondingly it is applicable when considering parallel winding branches, for the dynamic behaviour, the slip ring motor and the synchronous machine with turborotor.

Enhanced breakdown voltage in planar metal-overlap laterally diffused (MOLD) Schottky diodes

A novel uniform-avalanche structure is presented consisting of a planar metal-overlap laterally diffused (MOLD) Schottky diode. This structure has been proved to be free of edge breakdown by numerical two-dimensional field calculations. Experimentally obtained aluminum-silicon MOLD Schottky diodes have shown enhanced breakdown voltage in comparison with simultaneously processed standard planar Schottky diodes.