Transient Analysis of a Current-Driven Full Wave AC/DC Converter for Indirect Characterization of Piezoelectric Devices during Energy Harvesting

This article provides a new approach to extract piezoelectric energy harvester properties, namely, capacitance and current, from the increase of voltage with time on a storage capacitor after full wave rectification. The work provides a derivation of a more complete expression for the development of the output voltage with time, from which the equilibrium expression used in earlier publications appears as a limiting case. This new formulation enables an accurate estimate of the sinusoidal driving current and the shunt capacitance to be made without recourse to direct measurement. Using the analysis with both simulated and experimental data, a four‐step procedure is proposed that requires only the measurement of the initial slope of the voltage–time profile and the final settling value. This approach allows the much studied method of converting the piezoelectric output into charge stored on a capacitor to provide a unique indirect measurement method of the driving current and device capacitance while the piezoelectric energy harvester operates at a variety of conditions, such as frequency, temperature, stress, and strain.