Design of Linear Variable Differential Transformer (LVDT) Based Displacement Sensor with Wider Linear Range Characteristics

Abstract

The linear variable differential transformer (LVDT) is widely used in industrial and defence applications for online dimensional measurements.  Its basic structure consists of a primary coil and two secondary coils like an electrical transformer. It works on the principle of variation of mutual inductance between a primary winding and two secondary windings with a movable magnetic core. The core is moved by a nonmagnetic rod connected to a measurement device. When the core is at null position and the primary winding is given an alternating voltage, the voltages induced in the centre of each secondary winding are equal and therefore no output is producted at secondary side. However, while the core moves from its central null position, one of the two induced secondary voltages increases and the other decreases by similar amount. The output voltage of secondary is proportional to the displacement of magnetic core. As LVDT is a physical transducer, therefore, its performance is based on its design and dimensional features. Eash transducer as per its design parameter will have a defined linear range of operation. This paper presents a design model of a solenoid LVDT for simulation on MATLAB and mainly emphasis on achieving an optimum design for increasing the linear range of operation of the LVDT based displacement.