Linear-range Extension for Linear Variable Differential Transformer Using Triangular Signal

This paper presents a linear range extension technique for the linear variable differential transformer (LVDT). The technique is based on a signal conditioning circuit using the analog lookup table, which provides very high resolution of resulting signal. The analog table which is obtained by the triangular signal generator, which has the frequency equal to the excitation frequency. Meanwhile, the referenced signal is obtained by the comparison between the excitation signal and the output signal of LVDT. It is used to synchronize with the triangular signal. The proposed technique is simply circuit configuration and it can be implemented using available commercial devices. The experiment shows that the performances of the proposed circuit can be extended from the normal operating range of LVDT to the maximum stroke range. In addition, the response time of the proposed techniques can be approximated as half period of the excitation signal.