FINITE ELEMENT MODELING OF A TRANSFORMER FEEDING A RECTIFIED LOAD: THE COUPLED POWER ELECTRONICS AND NONLINEAR MAGNETIC FIELD PROBLEM

Abstract-Zedimensional finite elements are used to help directly incorporate models of nonlinear power electronic switching devices into nonlinear transient magnetic finite element analysis. Iko applications are considered: a buck regulator circuit and a transformer feeding a rectified load

Modeling of Transients in Permanent Magnet Generators with Multiple Damping Circuits using the Natural abc Frame of Reference

Abstract: A computer-aided method for modeling the transient performance of permanent magnet generators and determining their parameters is presented. The method is based on the development and use of state models in the natural abc frame of reference, in which the abc machine-winding parameters were determined from combined energy-current perturbation and finite-element magnetic field computation methods. The method is applied to a two-pole, 75 kVA, 208 V, 24000 r/min permanent-magnet generator with multiple damping circuits, to study the effects of various generator faults on generator transient characteristics, starting from no-load and rated-load initial conditions

A Time-stepping Coupled Finite Element-state Space Model for Induction Motor Drives. I. Model Formulation and Machine Parameter Computation (journal article)

A time-stepping coupled finite element-state-space model for induction motor drives is developed. The model utilizes an iterative approach to include the effects of magnetic nonlinearities, and space harmonics due to the machine magnetic circuits\u27 topology and discrete winding layouts. Model formulation and development, which include an improvement in the layout of the cage circuit representation, are given in this paper. This improvement leads to an enhancement of the well-posedness , that is, reduction of ill-conditioning in the overall numerical convergence of the model. Meanwhile, in a companion paper results of induction motor performance simulation are compared with no-load and load tests for sinusoidal and inverter operating conditions. Particular attention is given to comparison between sinusoidal and inverter operating losses obtained from this generalized model

Analysis of the Magnetic Field in Rotating Armature Electronically Commutated DC Machines by Finite Elements

A method for analysis of magnetic fields in rotating armature electronically commutated dc machines is presented. The resulting finite element model is suited for analyzing such machines under any load condition, including no-load. The model is used in the analysis and determination of characteristic parameters of such rotating armature machines of the type designed for use in conjunction with modern brushless excitation systems which supply field currents to large turbine generators. The analysis reveals the effect of various load conditions on the values of machine leakage inductances, and emfs. A considerable influence of the load on leakage inductances is determined. The analysis shows considerable reduction in leakage inductance values at higher saturation. This means that such parameters, contrary to prevailing practices, cannot be treated as constant. Interesting similarities (and differences) between the method of analysis of this type of rotating armature electronically commutated dc machines and that of analyzing ordinary synchronous machines is demonstrated clearly in the model development and results. The model is useful in determination of machine equivalent circuit parameters suited for simulation of armature-diode bridge dynamic performances

Computation of Winding Inductances of Permanent Magnet Brushless DC Motors with Damper Windings by Energy Perturbation

A method for the calculation of motor winding inductances is presented in which damping effects due to metallic retainment sleeves and intentionally introduced damper bar (amortisseur) windings are included. The inductance computation method makes use of the combined energy perturbation concept and finite-element field solutions. These parameters are necessary for the prediction of the dynamic performance of such motors with rotor damping. This modeling approach accounts for all saliency effects, and is entirely carried out in the natural abc frame of reference. Thus, it facilitates the process of integration of the modeling of the motor and its associated power electronics. The approach is most effective in the design of damper bar systems for enhancement of the performance of such motors, as demonstrated in the application of this approach to a 15 hp, 120 V, 6-pole, samarium-cobalt, permanent-magnet brushless DC motor

Shape Optimization of PM Devices using Constrained Gradient Based Inverse Problem Methodology

Permanent magnets (PMs) are widely used in a variety of industrial equipment and devices. In magnet design, the shape of a PM plays an important role and minimization of the leakage flux improves the performance of the device. The shape optimization of PM devices using gradient based inverse problem methodology (GIPM) is presented. The paper describes for the first time the use of analytical sensitivities for shape optimization of PM devices. Furthermore, the adjoint method of the direct differentiation approach is used for the computation of the sensitivities of the object function. Two case studies are presented. The first involves a magnetic circuit with an air gap and PM excitation, the second is that of a PM pole face. In both cases, design optimization is employed to obtain a desired flux density profile in the air gap with a minimum leakage flux and minimum size of the PM material

A Time-stepping Coupled Finite Element-state Space Model for Induction Motor Drives. I. Model Formulation and Machine Parameter Computation (conference proceeding)

A time-stepping coupled finite element-state-space model for induction motor drives is developed. The model utilizes an iterative approach to include the effects of magnetic nonlinearities, and space harmonics due to the machine magnetic circuits\u27 topology and discrete winding layouts. Model formulation and development which include an improvement in the layout of the cage circuit representation, are given in this paper. This improvement leads to an enhancement of the well-posedness that is, reduction of ill-conditioning in the overall numerical convergence of the model. Meanwhile, in a companion paper results of induction motor performance simulation are compared with no-load and load tests for sinusoidal and inverter operating conditions. Particular attention is given to comparison between sinusoidal and inverter operating losses obtained from this generalized model

Computer-aided Modeling of a Rectified DC Load-permanent Magnet Generator System with Multiple Damper Windings in the Natural ABC Frame of Reference

A computer-aided modeling method, used to analyze and predict the dynamic performance of electronically rectified load-permanent magnet generator systems, is presented. These generators include multiple damping circuits. Continuous electronic switching in such systems results in a continuous change in the machine system network topologies. Hence, network modeling of such systems is done on an instantaneous basis. The natural abc frame of reference is used throughout. This is an advantage in that effects of magnetic nonlinearities, space harmonics in the MMFs, and space in the flux density waveforms as well as winding flux linkages on all machine parameters are readily taken into account. This method is applied to a two-pole, 74 kVA, 208 V, 24000 r/min permanent magnet generator, to study the generator-load system performance. Furthermore, the use of the model in studying rotor damping design options and effects of electronic component failure in the associated rectifier bridge on the generator-rectifier load system performance is give