COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, 2008
PurposeTo study the magnetic shielding of buried high‐voltage (HV) cables by adding conductive me... more PurposeTo study the magnetic shielding of buried high‐voltage (HV) cables by adding conductive metal plates on the ground surface above the cables.Design/methodology/approachThe field is calculated with eight rectangular conductive plates above the cables, positioned with their long edge either parallel to the cables or transversal to the cables. Here, the circuit method is used. In this method, the shield is replaced by a grid of straight filaments in which the unknown currents are searched by solving an electrical circuit.FindingsIt is observed from the calculation results that it is important to have a perfect electrical connection between adjacent plates. In the area above the shield, an “infinite” contact resistance between neighbouring plates results roughly in double field amplitude compared to the situation with contact resistance zero. The positioning of the rectangular plates (parallel or transversal to the cables) has not much influence on the shielding. The shielding eff...
The identification of the magnetic material characteristics for the switched reluctance motor is ... more The identification of the magnetic material characteristics for the switched reluctance motor is presented in this study, by solving an inverse problem. The inverse problem aims at identifying the motor magnetic parameters starting from the measured torque profiles. The computational time of the inverse problem is appreciably reduced by implementing a space mapping-based inverse approach. The space mapping technique combines the computationally intensive finite element model with a much faster magnetic network model. The proposed approach is very helpful for the material identification problem on the electrical machine, and the obtained results reveal the success and the reliability of the proposed scheme.
2008 18th International Conference on Electrical Machines, 2008
Magnetic interaction or cross-saturation affects the accuracy of the position estimator in sensor... more Magnetic interaction or cross-saturation affects the accuracy of the position estimator in sensorless permanent-magnet synchronous drives. To compensate for the estimation error a look-up table or analytic expression can be used. Identifying this estimation error can be done off-line by using a finite-element (FE) model of the machine. Nevertheless, as the FE model has to be simulated with the sensorless controller and for different points of operation, the computation time will be long. Therefore, in this paper, an analytical model is used for which the parameters are obtained from a limited number of FE computations. The estimation error due to magnetic interaction will then be derived from the analytical model directly.
We study a method for nondestructive testing of laminated strips of a nonlinear magnetic material... more We study a method for nondestructive testing of laminated strips of a nonlinear magnetic material. Based on local measurements of the magnetic induction at the surface, we are able to reconstruct the proper position of defects inside the material, by solving an inverse problem. This inverse problem is solved by minimizing a suitable cost function using a gradient-based optimization procedure. Calculation of the gradient is done either by the standard method of small perturbations or by solving the sensitivity equation. The latter method yields a significant reduction of the computational time. The validity of the proposed algorithm is confirmed by experimental results.
In this paper, we discuss the possibilities to improve the magnetic properties of low Si wt% lami... more In this paper, we discuss the possibilities to improve the magnetic properties of low Si wt% laminated electrical steels by introducing a Si-gradient during a diffusion process. It is shown that a numerical model, based on Preisach theory, magnetic field computations and a genetic algorithm, allows us to optimize a Si gradient throughout the thickness of SiFe laminations. The low
ABSTRACT The shielding of buried three-phase high-voltage power lines can be done by placing them... more ABSTRACT The shielding of buried three-phase high-voltage power lines can be done by placing them in conducting ferromagnetic U-shaped gutters covered with plates. In case of a perfect electrical contact between adjacent gutters and between adjacent cover plates, induced currents in the shield efficiently reduce the magnetic field generated by the cables. As however a perfect contact cannot be guaranteed, in practice, it is useful to quantify the effect of a defective electrical contact on the field reduction. From two-dimensional/three-dimensional finite element computations and experiments, the influence of the contact resistance on the shielding efficiency is investigated, as a function of the ratio of axial length to height of the shield elements. Furthermore, the effect of other parameters on the shielding efficiency is studied: the ratio of axial length to height, a parasitic air gap between the gutter and the cover plate and the type of the shield material. It was found that a low contact resistance deteriorates much more the shielding in case of an aluminium shield than in case of a steel shield. As expected, the effect is larger for shield elements with relatively short axial length with regard to the other dimensions. Nevertheless, the effect remains quite significant for aluminium shields with practically convenient dimensions.
COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, 2008
PurposeTo study the magnetic shielding of buried high‐voltage (HV) cables by adding conductive me... more PurposeTo study the magnetic shielding of buried high‐voltage (HV) cables by adding conductive metal plates on the ground surface above the cables.Design/methodology/approachThe field is calculated with eight rectangular conductive plates above the cables, positioned with their long edge either parallel to the cables or transversal to the cables. Here, the circuit method is used. In this method, the shield is replaced by a grid of straight filaments in which the unknown currents are searched by solving an electrical circuit.FindingsIt is observed from the calculation results that it is important to have a perfect electrical connection between adjacent plates. In the area above the shield, an “infinite” contact resistance between neighbouring plates results roughly in double field amplitude compared to the situation with contact resistance zero. The positioning of the rectangular plates (parallel or transversal to the cables) has not much influence on the shielding. The shielding eff...
The identification of the magnetic material characteristics for the switched reluctance motor is ... more The identification of the magnetic material characteristics for the switched reluctance motor is presented in this study, by solving an inverse problem. The inverse problem aims at identifying the motor magnetic parameters starting from the measured torque profiles. The computational time of the inverse problem is appreciably reduced by implementing a space mapping-based inverse approach. The space mapping technique combines the computationally intensive finite element model with a much faster magnetic network model. The proposed approach is very helpful for the material identification problem on the electrical machine, and the obtained results reveal the success and the reliability of the proposed scheme.
2008 18th International Conference on Electrical Machines, 2008
Magnetic interaction or cross-saturation affects the accuracy of the position estimator in sensor... more Magnetic interaction or cross-saturation affects the accuracy of the position estimator in sensorless permanent-magnet synchronous drives. To compensate for the estimation error a look-up table or analytic expression can be used. Identifying this estimation error can be done off-line by using a finite-element (FE) model of the machine. Nevertheless, as the FE model has to be simulated with the sensorless controller and for different points of operation, the computation time will be long. Therefore, in this paper, an analytical model is used for which the parameters are obtained from a limited number of FE computations. The estimation error due to magnetic interaction will then be derived from the analytical model directly.
We study a method for nondestructive testing of laminated strips of a nonlinear magnetic material... more We study a method for nondestructive testing of laminated strips of a nonlinear magnetic material. Based on local measurements of the magnetic induction at the surface, we are able to reconstruct the proper position of defects inside the material, by solving an inverse problem. This inverse problem is solved by minimizing a suitable cost function using a gradient-based optimization procedure. Calculation of the gradient is done either by the standard method of small perturbations or by solving the sensitivity equation. The latter method yields a significant reduction of the computational time. The validity of the proposed algorithm is confirmed by experimental results.
In this paper, we discuss the possibilities to improve the magnetic properties of low Si wt% lami... more In this paper, we discuss the possibilities to improve the magnetic properties of low Si wt% laminated electrical steels by introducing a Si-gradient during a diffusion process. It is shown that a numerical model, based on Preisach theory, magnetic field computations and a genetic algorithm, allows us to optimize a Si gradient throughout the thickness of SiFe laminations. The low
ABSTRACT The shielding of buried three-phase high-voltage power lines can be done by placing them... more ABSTRACT The shielding of buried three-phase high-voltage power lines can be done by placing them in conducting ferromagnetic U-shaped gutters covered with plates. In case of a perfect electrical contact between adjacent gutters and between adjacent cover plates, induced currents in the shield efficiently reduce the magnetic field generated by the cables. As however a perfect contact cannot be guaranteed, in practice, it is useful to quantify the effect of a defective electrical contact on the field reduction. From two-dimensional/three-dimensional finite element computations and experiments, the influence of the contact resistance on the shielding efficiency is investigated, as a function of the ratio of axial length to height of the shield elements. Furthermore, the effect of other parameters on the shielding efficiency is studied: the ratio of axial length to height, a parasitic air gap between the gutter and the cover plate and the type of the shield material. It was found that a low contact resistance deteriorates much more the shielding in case of an aluminium shield than in case of a steel shield. As expected, the effect is larger for shield elements with relatively short axial length with regard to the other dimensions. Nevertheless, the effect remains quite significant for aluminium shields with practically convenient dimensions.
Uploads
Papers by P. Sergeant