Selection of Soft Magnetic Core Materials Used on an LVDT Prototype

 

R. Yañez-Valdez¹, R. Alva-Gallegos², A. Caballero-Ruiz*³, L. Ruiz-Huerta⁴

 

^1,3,4 Laboratorio de Micromecánica y Mecatrónica, CCADET-UNAM. Circuito exterior S/N, C.P. 04510. Cd. Universitaria, México, D.F. *ricardo.yanez@ccadet.unam.mx.

² Depto. de Mecatrónica. Universidad Tecnológica del Valle de Toluca. Carretera del departamento del DF. Km 7.5, Ejido de Santa María Atarasquillo, Lerma, Estado de México.

 

Abstract

Traditionally, the use of ferrite as a core of the linear variable differential transformer (LVDT) is suggested in its designs. Nevertheless, problems related to its brittleness and low tensile strength may be considered as important drawbacks for its use as a core material, especially when its geometry is likely to be modified. This work explores other alternatives related to soft magnetic materials, less used in applications of an LVDT core. By means of a decision matrix, from an assortment of different materials, three alternatives were selected. This proposal provides the identification of those materials with higher qualification values to be used as core material. In order to validate the performance of the selected materials, a prototype of LVDT was designed and fabricated. The design was carried out taking into consideration typical performance specifications. Finally, a comparison of the measurements of sensitivity and linearity of the proposed and traditional materials was made.

Keywords: linear variable differential transformer, soft magnetic materials, position measurement, prototype.

 

Resumen

Por tradición, se sugiere el uso de ferrita como núcleo en el diseño de dispositivos LVDT (transformador diferencial variable lineal). Problemas relacionados con la fragilidad de este material hacen poco atractiva su implementación, especialmente cuando su geometría se puede ver modificada. Este trabajo explora otras alternativas en los materiales magnéticamente suaves, menos tradicionales en tal aplicación, con base en requerimientos propuestos. Cada requerimiento está ligado a la implementación y desempeño del LVDT. Esta propuesta provee la identificación de aquellos materiales potencialmente viables para ser usados como núcleos. Para estudiar el comportamiento de los materiales seleccionados, se diseñó y construyó un prototipo de LVDT. El dispositivo LVDT fue diseñado considerando especificaciones de desempeño típicas. Con el prototipo construido, se estudiaron los materiales mejor calificados, identificados con el proceso de selección previo y una matriz de decisión. Finalmente, se realizó una comparación en las mediciones de sensibilidad y linealidad de los materiales seleccionados y el material tradicional.

 

DESCARGAR ARTÍCULO EN FORMATO PDF

 

Acknowledgments

This work was supported by CONACYT grant 60895. Thanks are also due to Dr. José Israel Betancourt-Reyes for providing a piece of Mumetal for preliminary tests.

 

References

[1] D. S. Nyce, Linear Position Sensors: Theory and Application, 2004.         [ Links ]

[2] K. Ma, Ghasemi-Nejhad, N., Smart Composite Systems with Nanopositioning, in Handbook of Nanophysics: Funtional Nanomaterials, K. D. Sattle (Eds.), ed: CRC Press, 2011, pp. 8.1-8.23.         [ Links ]

[3] H. N. Norton, Sensor and Analyzer Handbook, Prentice-Hall, 1982.         [ Links ]

[4] M. Félix, Lizárraga, A., Islas, A., González, A., Analysis of a ferrofluid core LVDT displacement sensor, in IECON 2010 - 36th Annual Conference on IEEE Industrial Electronics Society Glendale, AZ, 2010, pp. 1769-1772.         [ Links ]

[5] J. K. Sykulski, Sysulska, E. Hughes, S. T., Applications of Finite Element Modelling in LVDT Design, COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, 11(1) (1992) pp. 129-134.         [ Links ]

[6] S. Taifour, Al-Sharif, L., Kilani, M., Modelling & Design of a Linear Variable Differential Transformer, in Proc. of the International Conference on Modeling and Simulation (MS'08), Petra, Jordan, 18-20 November, 2008.         [ Links ]

[7] A. Masi, Danisi, A., Losito, R., Martino, M., Spiezia, G., Study of magnetic interference on a LVDT prototype, in Instrumentation and Measurement Technology Conference (I2MTC), 2010 IEEE CERN, Eur. Organ. for Nucl. Res., Geneva, Switzerland 2010, pp. 219-223.         [ Links ]

[8] M. Martino, Danisi, A., Losito, R., Masi, A., Spiezia, G., Design of a Linear Variable Differential Transformer with High Rejection to External Interfering Magnetic Field, Transactions on Magnetics, IEEE, 46(2) (2010) pp. 674-677.         [ Links ]

[9] Ferroxcube, Soft Ferrites Data Handbook 2009 [Online]         [ Links ].

[10] S. Chikazumi, Physics of ferromagnetism: Oxford University Press, 2005.         [ Links ]

[11] B. Williams, W., Soft Magnetic Materials, in Power Electronics: Devices, Drivers, Applications and Passive Components, ed. McGraw Hill, 1992, pp. 618-679.         [ Links ]

[12] K. Hoselitz, Magnetically Soft Materials, in Ferromagnetic properties of Metals and Alloys, ed. Clarendon Press (Oxford), GB: Oxford Univ. Press, 1952, pp. 238-239.         [ Links ]

[13] G. E. Fish, Soft Magnetic Materials, Proceedings of the IEEE, 78 (6) (1990) pp. 947-972.         [ Links ]

[14] P. G. Gogue, Stupak, J. J., A review of steel materials in motion devices, in PCIM 1990 Conference, Philadelphia, PA. December 1990.         [ Links ]

[15] D. W. Callister, Magnetic Properties, in Materials Science and Engineering, An Introduction, 7th Ed. ed. John Willey & Sons, Inc., 2007, pp. 19-56.         [ Links ]

[16] J. Gersten, Smith, F., Magnetic materials, in The physics and chemistry of materials, ed. John Wiley Sons, Inc., 2001, pp. 603-644.         [ Links ]

[17] H. Gavrila, Ionita, V., Crystalline and amorphous soft magnetic materials and their applications - Status of art and challenges, Journal of Optoelectronics and Advanced Materials, 4 (2) (2002) pp. 173-192.         [ Links ]

[18] K. H. J. Buschow, de Boer, F. R., Physics of Magnetism and Magnetic Materials, ed. Kluwer Academic Publisher, New York, 2003.         [ Links ]

[19] Soft Ferrites, A user's guide, ed. Magnetic Materials Producer Association: MMPA Soft Ferrite Division, 1998.         [ Links ]

[20] Soft ferrites A user's guide, in Magnetic Materials Producers Association, 1998.         [ Links ]

[21] Magnetic Cores for Switching Power Supplies, in Magnetics Division of Spang & Company, 2001.         [ Links ]

[22] Soft Magnetic Application Guide, in Group Arnold The Magnetic Products Group of SPS Technologies, 2000.         [ Links ]

[23] C. McLyman, Magnetic Materials and Their Characteristics, in Transformer and Inductor Design Handbook, D. Marcel, Inc. (Eds.) 2004, pp. 85-143.         [ Links ]

[24] D. Benjamin, Metals Handbook: Properties and Selection: stainless steels, tool materials and special purpose metals, 9th Ed. vol. 3, 1980.         [ Links ]

[25] G. W. Elmen, Magnetic Alloys of Iron Nickel, and Cobalt, Transactions of the American Institute of Electrical Engineers, IEEE, 54 (12) (1935) pp. 1292-1299.         [ Links ]

[26] M. Rashid, Power electronics: Circuits, devices and applications, 3th Ed. Prentice Hall, Inc., 2004.         [ Links ]

[27] A. Barua. Lecture Series on Industrial Instrumentation, Department of Electrical Engineering, IIT Kharagpur Available: http://nptel.iitm.ac.in (Accessed: November 2010).         [ Links ]

[28] J. Webster, Mechanical Variables Measurement Solid, Fluid and Thermal, CRC Press. 1999.         [ Links ]