Modeling of electric energy harvesting using piezoelectric windmill

This letter reports a theoretical model for determination of generated electric power from piezoelectric bimorph transducers in low frequency range far from the piezoelectric resonance. The model is divided into two parts. In the first part the open circuit voltage response of the transducer under the ac stress is computed based on the bending beam theory for bimorph. In the second part, this open circuit voltage acts as the input to the equivalent circuit of the capacitor connected across a pure resistive load. The results of the theoretical model were verified by comparing it with the measured response of a prototype windmill. The prototype piezoelectric windmill consisting of ten piezoelectric bimorph transducers was operated in the wind speed of 1-12 mph. A power of 7.5 mW at the wind speed of 10 mph was measured across a matching load of 6.7 kΩ. The theoretical model was found to give very accurate prediction of the generated power and matching load and an excellent matching was found with the experimental results.