Modulating Frequency and Responsivity of Pyroelectric Energy Converters by Finite Element Analysis

Abstract

Pyroelectric energy conversion techniques can be used to convert radiated heat, especially in pulsed periodic waveforms, to electric output. Most existing modeling of the response is done through a lumped capacitance heat model which assumes a sufficiently thin sample with adiabatic substrate. A finite element model of a pulsed heat source and the resultant heat distribution is developed to study the optimization of the pyroelectric energy conversion process. The model uses simultaneous analysis of a temperature domain and the attached circuitry for the determination of the voltage responsivity. It is found that the low frequency cutoff of the responses is limited by the thermal time constant of the pyroelectric elements including the sample and the substrate; while the high frequency limit is due to combined effects of the electrical time constant of the material and the trans-impedance of the amplifier. For thin samples the results are consistent with the lumped capacitance model that is effective in predicting the response. For thicker samples however the behavior of the pyroelectric conversion deviates appreciably from that of the lumped model.