Search

This paper presents an approach utilizing a machine model to achieve an equivalent hardware representation of machines as a computational prototyping tool. The purpose of our study is to find a way to perform hardware experiments of machine control without the actual machine. The proposed approach provides a way to test the control before the machine is fabricated, or in the eases where the controller needs to be experimentally tested before being implemented onto the actual machine. The equivalent hardware of a machine is built using a current controllable load, a controller, and a machine model in a hardware-in-the-loop (HIL) real time simulation environment. The equivalent hardware representation of the machine is achieved by controlling the currents of the controllable load to be the same as the currents of the actual machine under the same operating conditions. The machine model is used to provide the reference signal for the control. In this paper, the introduction of the proposed approach is presented focusing on three issues: the machine model, the procedure to enable the machine model to be compatible with the HIL real time simulation, and performance examination. Finally, the validity of the proposed approach is demonstrated with the voltage and current waveforms and the torque and speed profiles measured at the developed equivalent hardware of the machine. A 2-hp surface mounted permanent magnet (PM) synchronous motor is used as an example machine to present and verify our work. Index Terms--Equivalent hardware representation, hardware-in-the-loop real time simulation, machine model, PM machines.

This paper presents a fast and accurate brushless dc motor (BLDC) phase variable model for drive system simulations. The developed model was built based on nonlinear transient finite-element analysis to obtain the inductances, back electromotive force as well as the cogging torque. The model was implemented in a Simulink environment through the creation of an adjustable inductance component to account for the dependence of inductances on rotor position. Since no dq model for BLDC actually exists, the significance of this work is that it provides an accurate equivalent circuit model of BLDC motors for utilization in simulation environments. Using the developed model, the sensorless control and the torque ripple control issues were investigated and the simulation results show its practical effectiveness. Index Terms--Brushless dc motor (BLDC), finite element analysis (FEA), motor control, phase variable model.

This paper present a system for visually analyzing the electromagnetic fields of electrical machines used in the energy conversion laboratory. The system utilizes the finite element method as well as various modules to achieve a real-time effect in the analysis of electrical machines while hand-on experimentation is in progress. The proposed system is aimed at developing a tool that would help improve the student's understanding of electromagnetic fields inside these machines and its use in calculating performance measures as well as operational concepts pertaining to the practical study of electrical machines. Index Terms - Electric machines, electromagnetic fields analysis, energy conversion, electromagnetic field education.

Genetic Algorithms (GAs) are applied to the design optimization of electromagnetic devices. Techniques used in the practical implementation of the method are discussed in detail. An application example is given highlighting the use of the techniques and indicating the success of the method.

The application of genetic algorithms (GAs) to the design optimization of electromagnetic devices is presented in detail. The method is demonstrated on a magnetizer by optimizing its pole face to obtained the desired magnetic flux density distribution. The shape of the pole face is constructed from the control points by means of uniform nonrational b-splines.

A design sensitivity analysis is extended to cover the nonlinear magnetostatic problems. The formula is derived using material derivative as boundary integrals of the state and adjoint variables over the deformable boundary. A solution scheme for nonlinear state and adjoint equations using boundary element method is also presented to get accurate sensitivity coefficients. And a normalizing scheme for the pointwise sensitivity coefficients are proposed to avoid a zig-zag shapes during optimization.

A 3-D mesh generator for finite element analysis of electromagnetic field problems has been developed. The software is capable of handling complex topologies such as the organs of the human body. The grid is optimized by performing Delaunay correction. The use of digital image processing techniques is suggested to extract topological information from images. This information i used for identifying the regions of the model by placing initial nodes on the surfaces. An application example shows a simplified model of the human thorax created using the grid generator. It should be noticed that this problem includes most of the difficulties encountered in 3-D mesh generation for the finite element method.

An artificial neural network is applied to the inverse electromagnetic fields problem. In the process of the training the network, it is suggested that the simulated annealing algorithm be used to smooth the output errors before the network is trained with the error back-propagation algorithm. And a general way of defining the control parameters of simulated annealing is presented. As a numerical example, the artificial neural network with the suggested training algorithm is applied to the detection of the magnetic body in magnetic field. I is shown, through the numerical test, that the artificial neural network is ver useful for the inverse electromagnetic field problems, especially in real-time system and the artificial neural network trained with the suggested training algorithm gives much less maximum errors than that trained with the error back-propagation algorithm only.

An intelligent system for the design optimization of electromagnetic devices is presented. The system comprises a back-propagation neural network in conjunctio with an optimizing Hopfield Net for performing search and optimization functions. An adaptive algorithm is used to improve the response of the system in a dynamic environment. Data can be input by an experienced designer in addition to a case generator from the finite element (FE) solutions. Optimal designs are obtained quickly once the artificial neural network (ANN) is traine with a variety of topologies. Results of implemented examples are provided to show the effectiveness of the proposed system.

A new technique for the design optimization of electromagnetic devices that adopts the Genetic Algorithms (GAs) as the search method is presented. The method is applied to the optimization of the shape of a pole face in an electric motor. The electromagnetic analysis of the devices implemented is performed using 2-D finite elements. The results show an excellent promise and potential of using GAs as an efficient technique for the optimal design problem.

A new method for the design optimization of electromagnetic devices is presented. Improved Simulated Annealing (SA) is used along with the Hopfield neural network (HN) to optimize a solution obtained from a trained multilayered perception (MLP). This results in an overall increase in the speed of optimization. Results are presented for two examples which show the effectiveness of the proposed method in obtaining a near optimal solution.

A new method for the optimal design of the electromagnetic devices is presented. The method utilizes Artificial Neural Networks (ANNs) in a design environment which encompasses numerical computations and expert's input for generating a variety of ANN training data. Results of two implementation examples are provided. The optimal design is obtained quickly (in a matter of milliseconds) once the ANNs are trained with a variety of geometrical topologies. The procedure explained in this paper can be used to provide good initial designs for use with iterative search techniques (currently used) to reduce searching time. This aspect is highly desirable to increase the effectiveness of the optimal design procedure.

When optimizing designs for practical electromagnetic problems, the number of design constraints and variables is increased drastically. The construction and step-by-step creation of an electrical system, in practice, is a trial and error process. The design may lead to a sub-optimal solution since the success of a design depends on the experience of the designer. Optimization requires that all design goals, of a device, be connected into a single objective function with all independent variables and constraints. In practice, effective pre-processing and post processing of data are necessary in addition to the requirements of high performance computing capabilities. To achieve this process, we propose the utilization of the generalized design optimization environment or the virtual designer described in this paper. Index Terms--Blackboard architectures, design optimization, high performance computing, multi objective optimization, prototyping, virtual designer.

A modified preconditioned conjugate gradient method for solution of large sparse symmetric linear equations is presented. Two controlling parameters are used to reduce the computation time of the incomplete decomposition and each iterative step of the conjugate gradient method. Theoretical analysis and numerical examples show that the method is problem-independent to a certain extent, and could decrease the computation time by 30%~50% than the conventional method. Index Terms--Convergence of conjugate gradient method, eddy current field, finite element analysis, numerical technique.

A new method for solving the 3-D nonlinear transient eddy current problem is presented in this paper. The original finite element governing equations are separated into two parts: algebraic and differential equations. Multi-step algorithm, which is used only for the variables in conducting area, is adopted to analyze the first order differential equations. The investigating results reveal that this method avoids the oscillation occurred in single-step method and has higher precision with less computational effort. Index Terms--Differential equations, eddy currents, numerical analysis, transient equations.

Presents a study which examined a modified preconditioned conjugate gradient approach for solution of large sparse symmetric linear equations. Theoretical background; Numerical methods used; Findings and conclusions.

Provides information on a study which presented the multi-step algorithm method for solving the three-dimensional nonlinear transient eddy current problem. Description of the proposed method; Conclusions.

Information on the 12th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC) 2006 in Miami, Florida is presented. The author discusses that the Institute of Electrical and Electronics Engineer (IEEE) CEFC is one of the most important forums for the computational electromagnetics community. He added that only 614 paper digests were submitted for review to determine their suitability for inclusion in the technical programs.