Temperature Compensation for a Piezoelectric Fiber-Optic Voltage Sensor

In this paper we demonstrate a temperature compensation technique for the previously developed hybrid voltage sensor that employs a single fiber Bragg grating (FBG) bonded to a piezoelectric stack element. The FBG is used to measure voltage-induced strain within the piezoelectric transducer, and its wavelength readings can be calibrated to recover the instantaneous voltage value. Since only the ac voltage measurement is required in the given application, the local temperature is recovered by way of discriminating between the semi-static temperature signal and the dynamic voltage signal in frequency domain using low-pass filtering. Knowing the thermal behavior of the voltage sensor, voltage readings are readily corrected using the local temperature information. The transducer was thermally cycled between 20 and 100degC, and the proposed method provided compensation of temperature induced errors from 2%/100degC down to the experimental error below 0.5% (full scale output)