Finite Element Analysis of the Effects of Process and Material Parameters on the LVDT Output Characteristics

Abstract

Linear variable differential transformer (LVDT) is a displacement sensor and is commonly used owing toits wide measurement range, excellent linearity, high sensitivity, and precision. To improve the outputcharacteristics of LVDT, a few studies have been conducted to analyze the output using a theoretical methodor a finite element method. However, the material properties of the core and the electromagnetic force actingon the core were not considered in the previous studies. In this study, a finite element analysis model wasproposed considering the characteristics of the LVDT composed of coils, core, magnetic shell and electriccircuit, and the core displacement. Using the proposed model, changes in sensitivity and linear region ofLVDT according to changes in process and material parameters were analyzed. The outputs of the LVDTmodel were compared with those of the theoretical analysis, and then, the proposed analysis model wasvalidated. When the electrical conductivity of the core was high and the relative magnetic permeability waslow, the decrease in sensitivity was large. Additionally, an increase in the frequency of the power led tofurther decrease in sensitivity. The electromagnetic force applied on the core increased as the voltageincreased, the frequency decreased, and the core displacement increased.