A.A. Arkadan

Switched reluctance motor drive systems dynamic performance prediction and experimental verification

In this first of a set of two companion papers on switched reluctance motor drive systems, the results of using a state space model to predict a motor-drive system dynamic performance characteristics under normal operating conditions are presented. Using this approach, the state space model parameters are determined from series of nonlinear magnetic field solutions, thus accounting for magnetic material nonlinearities and space harmonics due to the motor geometry. The method is applied to a 6/4, 0.15 hp, 5000 r/min switched reluctance motor and resulted in the machine inductances, which compared favorably to measured values. Using these parameters in the state space model, the dynamic performance characteristics of the motor drive system are predicted and verified by comparison to experimental data. In addition, the effects of mutual coupling between motor phases on the analysis results are evaluated. >

The coupled problem in switched reluctance motor drive systems during fault conditions

The coupled problem in switched reluctance motor drive systems under fault conditions is considered. The coupling effects are accounted for through the use of an iterative approach for updating the machine parameters. Using this approach, the performance characteristics of the motor drive system are predicted. Experiments verify the results. >

Switched reluctance motor drive systems dynamic performance prediction under internal and external fault conditions

In this second of a set of two companion papers on the dynamic performance of switched reluctance motor drive systems, the results of using an iterative approach to predict the dynamic performance characteristics of a motor drive system during fault conditions are presented. The method is applied to a 6/4, 0.15 hp, 5000 r/min switched reluctance motor drive system to study an external fault due to the failure of a transistor in the converter. The model is also used to study an internal fault due to a partial armature phase short. The analysis resulted in the performance characteristics of the motor drive system which are verified by comparison to experimental data. In addition, the effects of mutual coupling between motor phases on the analysis results are evaluated. >

Genetic algorithms for nondestructive testing in crack identification

A method to identify the nature of a crack on the surface of a region using nondestructive testing (NDT) and inverse problem methodology is presented. A genetic algorithm (GA) based approach, which involves a global search to avoid local minima, is presented and applied to solve the inverse problem of identifying the position, shape and the orientation of a surface crack. A fine tuning algorithm is combined with the GA to reach the optimum solution. >

A time-stepping coupled finite element-state space model for induction motor drives. II. Machine performance computation and verification

In a companion paper, a time-stepping coupled finite element state-space algorithm for modeling of induction motor drives was developed. The model formulation and algorithm allows one to rigorously model the effects of space harmonics caused by magnetic circuit nonlinearities, topology and winding layouts, as well as their interaction with time harmonics caused by the power condition (inverter) operation. In this paper, the model is used in the computation of the parameters and prediction of performance characteristics of a 3-phase, 2 pole, 1.2-hp, 208 V squirrel-cage case-study induction motor. In addition, emphasis is laid on comparison between sinusoidal and inverter operations, with regard to effects on ohmic and core losses, as well as torque ripples. Furthermore, this includes harmonic breakdowns of selected inductance profiles and developed torque profiles. Numerical simulations were verified by comparison to test data with excellent correlation between both sets of results.

Performance prediction of SRM drive systems under normal and fault operating conditions using GA-based ANN method

A method to predict the performance characteristics of switched reluctance motor (SRM) drive systems under normal and fault operating conditions is presented. The method uses a genetic algorithm (GA) based artificial neural networks (ANNs) approach which is applied for its interpolation capabilities for highly nonlinear systems in order to obtain a fast and accurate prediction of the performance of the SRM drive system.

Optimization of a magnetic pole face using linear constraints to avoid jagged contours

Optimum design problems, with an unknown boundary which has to be optimized may not converge to any solution if no regularity constraints are imposed on that boundary. To impose these regularity conditions for finite element analysis the solution region is subdivided into subregions. Then the interior nodes or the subregion which contains the unknown boundary are constructed from the nodes of the unknown boundary using a continuous mapping, even though that boundary is not explicitly known. During the optimization process using gradient techniques the finite element model changes. Maintaining the topological properties of the mesh with the continuously changing finite element model is important to obtain accurate derivatives of the finite element solution with respect to the parameters. In some applications, the use of the above mentioned regularity constraints and topological properties may result in unrealistic solutions and shapes which cannot be practically implemented. In this paper we analyze how the application of some linear constraints on the parametrized nodes of an electromagnet pole face improve the unrealistic shape resulted from the shape optimization of the magnet for a constant flux density in the air gap. >

Finite element modeling of a transformer feeding a rectified load: the coupled power electronics and nonlinear magnetic field problem

A novel method which uses zero-dimensional finite elements to directly analyze the coupled problem of switching power electronics and nonlinear magnetic devices is presented. Zero-dimensional finite elements are used to help directly incorporate models of nonlinear power electronic switching devices into nonlinear transient magnetic finite element analysis. A brief summary of the formulations used in the finite element program MSC/EMAS is presented. The proposed method was used in a nonlinear transient analysis of two systems. In the first example, the method was used to predict the performance of a buck regulator circuit. In the second example, the coupled power electronics and nonlinear magnetic field problem was considered through the analysis of a transformer feeding a rectified load. >

Effects of force fitting on the inductance profile of a switched reluctance motor

The effects of compression on the magnetic properties of a steel alloy used in electromagnetic devices is investigated. The results of a case study on a switched reluctance motor are presented. It is demonstrated that compression affected the winding inductance profiles as well as the performance characteristics of the motor. The simulated performance results are verified by comparison to experimental data. The switched reluctance motor winding inductances were determined from a series of nonlinear magnetic field solutions in conjunction with an energy perturbation approach. A comparison of the inductance values with measured data, as well as the performance characteristics of the machine, revealed that, in cases of high stress conditions due to casing force fitting, the compression effects on the magnetic characteristics of the stator laminations should be taken into account. >

The coupled problem in electromagnetic AC contactors

Two approaches to model the coupled electromechanical behavior of AC contactors are investigated, a coupled three-dimensional magneto-structural finite element analysis (3D-FE) and a coupled state space-finite element analysis (SS-FE). The use of both approaches resulted in the prediction of contactor performance including the drive coil currents and armature force. The computed results were found to be in good agreement with measured data.