Lech Nowak

Simulation of dynamics of electromagnetic driving device for comet ground penetrator

The paper deals with a system designed for the ground penetrator of a comet landing module. A structure with an axisymmetrical electromagnetic actuator energised by discharged pulses of a capacitor has been proposed. The mathematical model of the dynamic phenomena includes: the equation of transient electromagnetic field in a nonlinear conducting and moving medium; the equation of the power converter electric circuit; and the equation of mechanical motion.

The 3D coupled field-circuit simulation of transients in nonlinear systems

An algorithm for simultaneously solving the equations describing the 3D magnetic field and equations describing electric circuits of electromagnetic devices has been elaborated. The nonlinearity and anisotropy of the magnetic core have been taken into account. In order to solve the 3D problem a special iterative procedure, in which the 3D task is substituted with a sequence of 2D problems, has been proposed. For the sake of example, the calculations for an a.c. actuator have been made.

Finite element analysis of saturation effects in a squirrel cage electrical machine

Presents a method for the finite element (FE) analysis of saturation effects in a squirrel‐ cage electrical machine. The proposed mathematical model includes the FE equations of the electromagnetic field, the equations which define the connection of windings, and the mechanical equation. Applies an approach based on a simultaneous solution of these equations, paying special attention to the movement simulation. Applies the time‐stepping method with a fixed grid, independent of the rotar position. In the method the motional effects are simulated by trigonometric interpolation of the results for the previous time step.

Iterative procedure for 3D modelling of electromagnetic actuators

An iterative procedure for calculation of 3D magnetostatic field in nonhomogeneous, nonlinear, and anisotropic regions of electromagnetic actuators has been presented. In the proposed method, the 3D task has been substituted with a sequence of 2D problems, so it was possible to adapt the algorithm worked out to PC 486 computers. The decomposition of the problem consists in: (a) separation of magnetic vector potential components, (b) partition of the considered region with a number of surfaces with 2D discretization. >

Optimization of the permanent magnet brushless DC motor employing finite element method

Purpose – The purpose of this paper is to elaborate the algorithm and computer code for the structure optimization of the outer rotor permanent magnet brushless DC motor and to execute optimization of selected motor structure using the non‐deterministic procedure.Design/methodology/approach – The mathematical model of the device includes the electromagnetic field equations with the nonlinearity of the magnetic core taken into account. The numerical implementation is based on the finite element method and stepping procedure. The genetic algorithm has been applied for the optimization. The computer code has been elaborated.Findings – The elaborated computer software has been applied for the optimization and design of BLDC motors. The elaborated algorithm has been tested and a good convergence has been attained.Originality/value – The presented approach and computer software can be successfully applied to the design and optimization of different structure of BLDC motors.

Calculation of magnetization characteristic of a squirrel cage machine using edge element method

This paper presents the finite element method for the calculation of open‐circuit characteristic of a squirrel cage machine with saturated core. The flux linkage with the stator winding and the winding inductances have been calculated using the edge element method. The calculations show that the equivalent inductance of a balanced three‐phase no‐loaded induction machine with saturated core may be defined like a quadrature‐axis inductance in synchronous machine. The algorithm of this inductance calculation has been proposed. The equivalent inductances have been used in the calculation of electromotive force. The results obtained from numerical calculations have been compared with the measured results.

Optimization of the rotor geometry of the line-start permanent magnet synchronous motor by the use of particle swarm optimization

Purpose – The purpose of this paper is to elaborate the methodology and software for the optimization of rotor structure of the line-start permanent magnet synchronous motor (LSPMSM). To prove usefulness of presented approach the case study problem has been solved. Design/methodology/approach – The modified particle swarm optimization (PSO) algorithm has been employed for the optimization of LSPMSM. The optimization solver has been elaborated in Delphi environment. The software consists of two modules: an optimization solver and a numerical model of LSPMSM. The model of the considered machine has been developed in the ANSYS Maxwell environment. In the optimization procedure the objective function has been based on maximizing efficiency and power factor. Findings – Obtained results show that modified PSO algorithm can be successfully applied for the optimization of the rotor structure of LSPMSM. This software can be used as a design tool to improve the performance of LSPMSM. The results of studied case pro...

Calculation of end‐turn leakage inductances of electrical machines using the edge element method

The end‐turn leakage inductances of the armature winding of the permanent magnet motor have been calculated. In order to describe the magnetic field distribution the edge element method using vector magnetic potential has been applied. First, the formulae that describe the total self‐inductance and total mutual conductance for phase windings are presented. Three‐dimensional and two‐dimensional formulations are considered. The end‐turn leakage inductances have been obtained by comparing the results of these formulations. The symmetrical components transformation has been applied, and the self inductances and mutual inductances have been transformed into the zero‐sequence and positive‐sequence inductances. The calculations have been performed for different dimensions of the coil‐end region. The influence of the position of the boundary surfaces on the results has been investigated.

The 3D coupled field-circuit simulation of transients in converters with conducting solid parts

An algorithm for a simultaneous solving of equations of the 3D electromagnetic field and equations of electric circuits of an electromagnetic device with a solid conducting part has been elaborated. The A-T formulation has been applied, In order to solve the 3D problem a special iterative procedure, in which the 3D task has been substituted with an iterative sequence of 2D problems, has been proposed. The dynamic operation of the electromagnetic device is also considered.

Dynamic operation of an electromagnetic actuator taking nonlinearity and eddy currents into account

The paper deals with a coupled field‐circuit simulation of transient and dynamic states in a non‐linear axisymmetrical electromagnetic device. The mathematical model of the dynamic phenomena includes: an equation of transient electromagnetic field in a non‐linear conducting and moving medium, equations of the converter electric circuits and the equation of mechanical motion. The numerical implementation of the algorithm is based on the finite element method. The Crank‐Nicholson scheme for time discretization has been applied. In order to include nonlinearity, the Newton‐Raphson process has been adopted. The influence of the saturation effect on the dynamic characteristics of the device has been investigated.