Guilherme Tolentino, Guillaume Parent, Olivier Ninet, Mathieu Rossi, Jean Vianei Leite and Jonathan Blaszkowski
The horizontal rotational single-sheet tester (RSST) suffers from weaknesses such as the reduced size of test samples, measurement disturbances due to magnetic flux leakage and…
Abstract
Purpose
The horizontal rotational single-sheet tester (RSST) suffers from weaknesses such as the reduced size of test samples, measurement disturbances due to magnetic flux leakage and nonhomogeneity of field in the measurement area. Although the vertical RSST allows to overcome the first two aforementioned drawbacks, the heterogeneity of the field in the test sample remains an issue. In addition, there is still a lack of device standardization to ensure test repeatability, as already is well established with the Epstein frame. This paper aims to investigate the influence of several parameters on the field homogeneity in the test sample.
Design/methodology/approach
A fully 3D finite element model of a vertical RSST is developed and used to perform a sensibility study on several geometrical parameters.
Findings
The influence of several parameters on the field homogeneity in the test sample, such as the geometrical dimensions of the yokes, the presence or not of holes drilled inside the test sample for B-coil placement as well as the size of the H-coils and B-coils, is addressed.
Originality/value
It is expected that this study will contribute to the optimization and standardization vertical RSSTs.
Details
Keywords
Gregory Bauw, Bertrand Cassoret, Olivier Ninet and Raphael Romary
The purpose of this paper is to present a design method for induction machines including a three-phase damper winding for noise and vibrations reduction.
Abstract
Purpose
The purpose of this paper is to present a design method for induction machines including a three-phase damper winding for noise and vibrations reduction.
Design/methodology/approach
In the first part, the principle of the damper winding is recalled. The second part presents the iterative design method which is applied on a 4-kW pulse width modulation (PWM)-fed induction machine to study the impact of the additional winding on the geometry. In the third part, the finite-element method is used to validate the designed geometry and highlight the harmonic flux density reduction. Finally, some experimental results are given.
Findings
The study shows that the impact of the additional three-phase winding on the geometry and weight of the machine is low. Moreover, the proposed noise reduction method allows one to reduce the total noise level of a PWM-fed induction machine up to 8.5 dBA.
Originality/value
The originality of the paper concerns the design and characterization of a three-phase damper winding for a noiseless induction machine. The principle of this proposed noise reduction method is new and has been patented.
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Mohamed Omar Younsi, Olivier Ninet, Fabrice Morganti, Jean-Philippe Lecointe, Farid Zidat and Matthieu Buire
This paper aims to study the influence of supply voltage variations on the external magnetic field emitted by grid-powered induction machines (IMs).
Abstract
Purpose
This paper aims to study the influence of supply voltage variations on the external magnetic field emitted by grid-powered induction machines (IMs).
Design/methodology/approach
Two models are developed in the paper to analyse, for different supply voltage values, the influence of the variations of the magnetizing voltage for which there is a link with the tangential component of the external flux. The first is an analytical model based on the IM single-phase-equivalent circuit with variable magnetizing reactance to take into account the saturation of the magnetic circuit. The second is a numerical finite element simulation to model the same phenomenon. Results of both models are analysed with experimental measures of the external flux.
Findings
The study shows that the amplitude of the external field strongly depends on supply voltage values.
Research limitations/implications
The investigation is mainly focused on the tangential component of the external magnetic field which is of high importance concerning the applicability of non-invasive methods of diagnosis, as electromagnetic torque estimation developed by the authors or internal fault determination.
Originality/value
The originality of the paper concerns the characterization of the external flux with the supply voltage for IMs. It is shown that the magnetic circuit radiates external flux differently with the load and with the supply voltage.
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Although the American monetary authorities seemed determined to carry out the normalisation of their policy, the severe downturn of the stock markets at the end of 2018 and the…
Abstract
Although the American monetary authorities seemed determined to carry out the normalisation of their policy, the severe downturn of the stock markets at the end of 2018 and the injunctions of Donald Trump led them to a complete about-face, concretised by reductions in the key rate starting at the end of July 2019. This surrender in front of market blackmail confirms that the unconventional monetary policies implemented after the 2008 crisis have plunged the asset-based economy into a black hole, from which it will not be able to escape without deeply reforming itself.