Title :
Design of a Linear Variable Differential Transformer With High Rejection to External Interfering Magnetic Field
Author :
Martino, M. ; Danisi, A. ; Losito, R. ; Masi, A. ; Spiezi, G.
Author_Institution :
EN/STI Group, CERN, Geneva, Switzerland
Abstract :
The sensitivity of linear variable differential transformer (LVDT) position sensors to external slowly varying magnetic fields represents a critical issue when these sensors are installed close to high-current cables or electrical motors with significant fringe fields. The resulting position error can reach several hundreds of micrometers against a specified uncertainty normally below a few micrometers. In this paper, the design of a LVDT position sensor with high rejection to external constant or slowly varying magnetic fields is addressed by exploiting the finite element method (FEM) simulator FLUX. A shield, isolated from the sensor´s magnetic circuit, has been considered to reduce the effect of magnetic fields on the secondary voltages of the LVDT. In addition, a dc current is used in order to polarize the magnetic circuit to reduce the sensitivity of the sensor to external interferences.
Keywords :
differential transformers; finite element analysis; interference; magnetic shielding; FLUX simulator; LVDT position sensor; electrical motors; external interfering magnetic field; finite element method; high current cables; linear variable differential transformer; magnetic field rejection; Cables; Circuit simulation; Finite element methods; Magnetic circuits; Magnetic fields; Magnetic sensors; Magnetic shielding; Polarization; Uncertainty; Voltage; Linear Variable Differential Transformer (LVDT); magnetic interference; magnetic shielding;
Journal_Title :
Magnetics, IEEE Transactions on
DOI :
10.1109/TMAG.2009.2033341