Design and Development of High Linearity of Trapezoidal Winding LVDT

This work presents a novel linear variable differential transformer (LVDT) design using trapezoidal secondary coils to achieve highly linear displacement sensing over an extended operating range. A new finite element modeling approach is introduced for accurate design and optimization of the tapered coil structure. Simulation results demonstrate exceptional linearity, with a nonlinearity error (NLE) of just 0.05% over a ±13-mm range (46.95% of full stroke). Experimental validation through two prototypes shows measured nonlinearities of 0.34% over ±13 mm (41.19% stroke) and 0.24% over ±9 mm (28.52% stroke), significantly outperforming conventional rectangular coil designs and commercial sensors. The proposed trapezoidal coil structure and modeling approach enable compact LVDT sensors with substantially improved linearity and range for precision industrial applications.