Miklós Kuczmann

Measurement and Simulation of Vector Hysteresis Characteristics

This paper presents a Preisach model of ferromagnetic hysteresis to simulate the vector hysteresis properties of ferromagnetic materials. Vector behavior has been studied using a single sheet tester with a round shaped specimen at low frequency, and the magnetic flux density vector has been controlled by a digital measurement system. Circular magnetic flux density pattern has been measured. An inverse vector Preisach hysteresis model has been developed and identified by applying the measured data. Finally, the inverse model has been inserted into a finite element procedure through the fixed point technique and the reduced magnetic scalar potential formulation. The applicability of the measurement system as well as the developed model has been proven by comparing measured and simulated results.

Using the Newton–Raphson Method in the Polarization Technique to Solve Nonlinear Static Magnetic Field Problems

The paper presents and compares three potential formulations to solve nonlinear static magnetic field problems by applying the fixed point technique and the Newton-Raphson scheme. Nonlinear characteristics are handled by the polarization method in both algorithms. The proposed combination of the Newton-Raphson scheme and the polarization formulation results in a very effective nonlinear solver, because only the derivate of the characteristics, i.e., only the permeability or the reluctivity has to be used. Therefore, this method can be used to solve nonlinear problems with hysteresis, and it is faster than the classical fixed point method.

Comparison of the

We present two eddy-current field potential formulations to solve rotating electrical machine problems by applying the finite-element method (FEM) using the motional A *- A-potential formulation and the motional T, Phi-Phi-potential formulation. We use the single-phase and three-phase solid-rotor induction motors of Problem No. 30a of TEAM Workshops to compare the potential formulations. We have solved both problems in the time domain and the frequency domain.

{\mbi A}^{*}{-}{\mbi A}

Iron parts of electrical machines are made of nonoriented isotropic ferromagnetic materials. The finite element method (FEM) is usually applied in the numerical field analysis and design of this equipment. The scalar Preisach hysteresis model has been implemented for the simulation of static and dynamic magnetic effects inside the ferromagnetic parts of motors. The dynamic model is an extension of the static one; an extra magnetic field intensity term is added to the output of the static inverse model. This is a viscosity-type dynamic model. The fixed point method with stable scheme has been realized to take frequency-dependent anomalous losses into account in FEM. This scheme can be used efficiently in the frame of any potential formulations of Maxwells equations. The comparison between measured and simulated data using a toroidal core shows a good agreement. A modified nonlinear version of T.E.A.M. Problem No. 30.a is also shown to test the hysteresis model in the FEM procedure.

and

Abstract A major problem in switched reluctance motor is torque ripple, which causes undesirable acoustic noise and vibration. This work focuses on reducing the undesirable torque ripple in 6/4-pole three-phase switched reluctance motor by geometry modification and using control technique. The proposed method combined the specially skewed rotor pole shape with instantaneous torque control with sinusoidal torque sharing function. The results of geometry modification are analysed through the three-dimensional finite element simulation to determine the appropriate skewing angle. The drive performances of conventional and modified motor are compared through the simulations. The effectiveness of the proposed method is also demonstrated and verified by the simulations.

{\mbi T}, \Phi{-}\Phi

The paper discusses the standard of the Epstein frame that has been used to measure magnetic characteristics of the core made of material M250-35A supplied by different frequencies between 1-400 Hz...

Formulations for the 2-D Analysis of Solid-Rotor Induction Machines

A comprehensive analysis of the finite element method based lamination modeling has been performed and the results are presented in this paper. The simulations are made in two subsequent steps. In ...

Improvement and Application of the Viscous-Type Frequency-Dependent Preisach Model

This research presents a field-circuit coupled parallel finite element model of a switched reluctance motor embedded in a simple closed loop control system. The parallel numerical model is based on the Schur-complement method coupled with an iterative solver. The used control system is the rotor position based control, which is applied to the FEM model. The results and parallel performance of the voltage driven finite element model are compared with the results from the current driven model. Moreover, the results of the start-up of the loaded motor show why the model accuracy is important in the control loop.

Design and control for torque ripple reduction of a 3-phase switched reluctance motor

This paper presents an axisymmetric formulation of the circuit-coupled finite element method embedded in closed loop control system. The controller checks the current of the coil of the magnetic system after each time step and controls the applied voltage to reach the steady state faster. The results of the voltage driven finite element model are compared with the results from the analytical model. The control parameters for the proportional-integral-derivative controller were estimated using the step response of the system. Furthermore, the results of the closed loop system simulation show why the model accuracy is important in the controller design.

Measuring and simulating magnetic characteristics using epstein frame

The paper deals with high frequency simulations with edge finite element method realized with PETSc functions. The weak formulations of the high frequency simulations are derived from Maxwell’s equations in frequency domain. To reduce the calculation time, the finite element method was implemented in PETSc environment. The realized simulation environments were validated with simple examples, which analytically can be calculated.