Perturbation finite-element method for magnetic circuits

in IET Science, Measurement & Technology (2008), 2(6), 440-446

Accurate magnetic flux distributions are calculated in magnetic circuits via a subproblem finite-element (FE) method based on a perturbation technique. An approximate FE problem considering ideal flux ... [more ▼]

Accurate magnetic flux distributions are calculated in magnetic circuits via a subproblem finite-element (FE) method based on a perturbation technique. An approximate FE problem considering ideal flux tubes is first solved. It gives the source for FE perturbation problems considering the flux tubes with their exterior regions, accounting thus for leakage fluxes, as well as for changes of material properties and shapes. The proposed technique aims to accurately quantify the gain given by each model refinement on both local fields and global quantities and to justify the usefulness of this refinement. It is also well adapted to parameterised analyses on geometrical and material data. [less ▲]

Electromagnetic compatibility analysis of unstructured mains networks for high-speed data transmission: Part 1

in IET Science, Measurement & Technology (2008), 2(3), 146-153

Different approaches for the characterisation of relevant parameters of the low-voltage mains network, used for high-speed data transmission (BPL, broadband over power line) are described. Part 1 of the ... [more ▼]

Different approaches for the characterisation of relevant parameters of the low-voltage mains network, used for high-speed data transmission (BPL, broadband over power line) are described. Part 1 of the paper depicts the disturbance scenario of these BPL devices and the motivation will be given for the development of a new measurement procedure in CISPR for the estimation of the high-frequency characteristics of AC mains network. The improvements of the measurement method is not restricted to BPL applications, but can also be applied to other wire-based telecommunication systems. Part 2 of the paper shows the definitions and comparisons of different symmetry factors. The transfer of the results on the compliance test for BPL devices will be shown. [less ▲]

Perturbation technique for the finite element modelling of differential probes in non-destructive eddy-current testing

in IET Science, Measurement & Technology (2007), 1(1), 25-29

The paper deals with a new finite element scheme for non-destructive eddy-current testing (ECT) problems involving multiply connected test pieces and differential probes. It concerns a perturbation ... [more ▼]

The paper deals with a new finite element scheme for non-destructive eddy-current testing (ECT) problems involving multiply connected test pieces and differential probes. It concerns a perturbation technique applied to the magnetodynamic h - phi formulation. The unperturbed field (in the absence of the flaw) is conventionally computed in the complete domain. The source of the perturbation problem is then determined by the projection of the unperturbed field in a relatively small region around the defect, the optimum size of which depends on the working frequency. The discretisation of this reduced domain is well adapted to the size of the defect and chosen independently of the dimensions of the excitation probe and the specimen under study. At a discrete level, the voltage change is efficiently computed by integration only over the defect and a layer of elements in the reduced domain that touches the defect's boundary. The accuracy of the proposed perturbation model is illustrated by comparison of the results obtained for different dimensions of the reduced domain with those achieved in the conventional way. The considered test case involves a differential probe scanning the outer surface of a metal tube for the detection of through-wall cracks. [less ▲]