Design and analysis of a novel electric machine and drive

In many areas of engineering, the improvements in material properties have enabled designers to create sophisticated and previously unrealizable geometries feasible. A new low cost integrated electric machine is designed, analyzed and characterized in this dissertation. The material properties and their effect on motor performance are discussed and examined, the motor design equations are developed and analyzed. The performance test results are compared to analytical expressions previously derived and verified by simulation. Due to the nature by which the machine develops torque, the machine requires an inverter with position feedback which is discussed in detail, additional motor geometries are also presented. In addition, an overview of Maxwell\u27s equations and their applicability to the electromagnetic, magnetostatic and magnetodynamic problem is presented. Finally, a new method of solving the eddy current problem using the control-volume method is explained and numerical results are presented

An investigation of alternating-direction implicit finite-difference time-domain (ADI-FDTD) method in numerical electromagnetics

In this thesis, the alternating-direction implicit method (ADI) is investigated in conjunction with the finite difference time-domain method (FDTD) to allow crossing of the Courant-Friedrich-Levy (CFL) stability criterion while maintaining stability in the FDTD algorithm. The main reason for this is to be able to use a larger numerical time step than that governed by the CFL criterion. The desired effect is a significant reduction in numerical run-times. Although the ADI-FDTD method has been used in the literature, most analysis and application have been performed on simple three-dimensional cavities.This work makes original contribution in two aspects. Firstly, a new modified alternating-direction implicit method for a three-dimensional FDTD algorithm has been successfully developed and implemented in this research. This new method allows correct modelling of a realistic physical structure such as a microstrip patch with the ADI scheme without causing instability even when the CFL criterion is not observed. However, due to the inherent property of this modified ADI-FDTD method, a decreasing reflection coefficient is observed using this scheme.The second and more important contribution this research makes in the field of numerical electromagnetics is the development of a new method of simulating realistic complex structures such as geometries comprising copper patch antennas on a dielectric substrate. With this new method, for the first time, the ADl-FDTD algorithm remains stable while still in violation of the CFL criterion, even when complex structures are being modelled.However, there is a trade-off between accuracy and computational speed in ADI-FDTD and modified ADI-FDTD methods. The larger the numerical time step, the shorter is the simulation run-time but an increase in numerical time step causes a degradation in accuracy of numerical results. Comparison between speed and accuracy is shown in this thesis and it has to be mentioned here that these values are very much dependent on the structure being modelled

Particle simulation of plasmas on the massively parallel processor

Particle simulations, in which collective phenomena in plasmas are studied by following the self consistent motions of many discrete particles, involve several highly repetitive sets of calculations that are readily adaptable to SIMD parallel processing. A fully electromagnetic, relativistic plasma simulation for the massively parallel processor is described. The particle motions are followed in 2 1/2 dimensions on a 128 x 128 grid, with periodic boundary conditions. The two dimensional simulation space is mapped directly onto the processor network; a Fast Fourier Transform is used to solve the field equations. Particle data are stored according to an Eulerian scheme, i.e., the information associated with each particle is moved from one local memory to another as the particle moves across the spatial grid. The method is applied to the study of the nonlinear development of the whistler instability in a magnetospheric plasma model, with an anisotropic electron temperature. The wave distribution function is included as a new diagnostic to allow simulation results to be compared with satellite observations

Hypercube matrix computation task

A major objective of the Hypercube Matrix Computation effort at the Jet Propulsion Laboratory (JPL) is to investigate the applicability of a parallel computing architecture to the solution of large-scale electromagnetic scattering problems. Three scattering analysis codes are being implemented and assessed on a JPL/California Institute of Technology (Caltech) Mark 3 Hypercube. The codes, which utilize different underlying algorithms, give a means of evaluating the general applicability of this parallel architecture. The three analysis codes being implemented are a frequency domain method of moments code, a time domain finite difference code, and a frequency domain finite elements code. These analysis capabilities are being integrated into an electromagnetics interactive analysis workstation which can serve as a design tool for the construction of antennas and other radiating or scattering structures. The first two years of work on the Hypercube Matrix Computation effort is summarized. It includes both new developments and results as well as work previously reported in the Hypercube Matrix Computation Task: Final Report for 1986 to 1987 (JPL Publication 87-18)

Hybrid explicit-implicit FDTD-FEM time-domain solver for electromagnetic problems

The Finite-Difference Time-Domain (FDTD) method and Finite-Element (FEM) method are numerical techniques used for solving Maxwell\u27s electromagnetic equations. FDTD-FEM hybrid methods opt for combining the advantages of both FDTD and FEM. In this dissertation, signal processing techniques were used to analyze the FDTD stability condition. A procedure, which reduces time-sampling error yet preserves the stability of algorithm is proposed. Both explicit and implicit time-stepping schemes were treated in the framework of the developed method. An improved version of the implicit-explicit FEM-FDTD hybrid method was developed. The new method minimizes reflection from the interface between different types of grids. A class of transfer functions with low reflection error for stable hybrid time-stepping was derived. The stability of the method is rigorously proven for a general three-dimensional case

Advances in Time-Domain Electromagnetic Simulation Capabilities Through the Use of Overset Grids and Massively Parallel Computing

A new methodology is presented for conducting numerical simulations of electromagnetic scattering and wave propagation phenomena. Technologies from several scientific disciplines, including computational fluid dynamics, computational electromagnetics, and parallel computing, are uniquely combined to form a simulation capability that is both versatile and practical. In the process of creating this capability, work is accomplished to conduct the first study designed to quantify the effects of domain decomposition on the performance of a class of explicit hyperbolic partial differential equations solvers; to develop a new method of partitioning computational domains comprised of overset grids; and to provide the first detailed assessment of the applicability of overset grids to the field of computational electromagnetics. Furthermore, the first Finite Volume Time Domain (FVTD) algorithm capable of utilizing overset grids on massively parallel computing platforms is developed and implemented. Results are presented for a number of scattering and wave propagation simulations conducted using this algorithm, including two spheres in close proximity and a finned missile

Broadband whole package FDTD simulation

Whole package analysis is becoming more and more important with the rapid expansion of high frequency electronics. The motivation of this thesis is to find and implement a new method for broadband whole package simulation. 3-dimension (3-D) whole package Finite Difference Time Domain (FDTD) simulation result was first reported in detail in this thesis. The FDTD method is a widely used full-wave time-domain simulation method used in the design and analysis for electromagnetic (EM) systems, such as antennas, wave propagating, and microwave circuits. Absorbing boundary condition (ABC), such as the perfect matched layer (PML) method, makes it possible to accurately analyze an EM structure involving complicated wave propagation in three-dimensional domain. Instead of running simulation at each frequency, time-domain solution gives complete frequencydomain response including coupling and dispersion effects. Chapter2 introduces the principle of FDTD and two important boundary condition methods. It also discusses the nonuniform grid numerical error, and gives the FDTD simulation and theoretical result. Flip chip package is one of the most important package types. Chapter 3 presents a wide band approach for characterizing multiple flip chips interconnects by the FDTD method. Detailed analysis for electrical performance for frequencies up to 40 GHz has been performed with variations of interconnect bumps (ball cross section and via cross section). Flip chips of three sizes are studied using FDTD method in detail. The relationship between reflection loss, via pad length, ball crosssection and via cross section is tabulated for future packaging design. Based on the simulation results, some design approaches are proposed for packaging structure operating at near 40 GHz. FDTD whole package simulation method is introduced at the beginning of Chapter 4, followed by discussion how to implement this method to specific packages. The packages used to host circuit in chapter 4 are microstrip line and fiip chip interconnects. The embedded circuits are ideal transmission line and an HP amplifier. Transient effects are observed when an amplifier is hosted in a package. Most of the simulations are processed under three-dimensional environment; twodimensional simulation is used for reference standard. All these results were first reported by the author of this thesis and his collaborators

A hp-like discontinuous Galerkin method for solving the 2D time-domain Maxwell's equations on non-conforming locally refined triangular meshes

This work is concerned with the design of a hp-like discontinuous Galerkin (DG) method for solving the 2D time-domain Maxwell's equations on non-conforming locally refined triangular meshes. The proposed DG method allows non-conforming meshes with arbitrary-level hanging nodes. This method combines a centered approximation for the evaluation of fluxes at the interface between neighboring elements of the mesh, with a leap-frog time integration scheme