Signal Isolation Method for Inductive Displacement Sensors

Inductive displacement sensors are widely used in the non-contact measurement of rotating machinery, the signal transmission of the excitation and vibration modulation is often influenced by high external voltage and electromagnetic noise on the the signal path. In order to improve the reliability and anti-interference ability of the sensor system, we studied the voltage isolation that can isolate the front-end signal transmission path and the back-end signal processing circuit through a transformer. Based on the basic principle of transformer isolation, we studied technical issues such as the selection method of transformer primary and secondary coil parameters, the measures to stabilize the voltage reference point of the front-end signal transmission, the impact of operational amplifier bias on waveform distortion and its elimination. And then we realized the transformer isolation between the displacement sensor conditioning circuit and front-end probe, and the related test results are given.