Abstract
In this paper, we propose a new adaptive switch control method to enhance the efficiency of electrical energy harvesting using a piezoelectric transducer. In a previous research, a synchronized switch harvesting on inductor (SSHI) method was proposed. This method controls the switch device on all peaks of the vibration displacement and increases the amount of piezoelectric charge. However, the increased piezoelectric charge generates a vibration-suppression effect that reduces harvested energy when the vibration damping force of the piezoelectric transducer is not negligible. To solve the reduction problem, a switching considering vibration suppression (SCVS) method was proposed. Furthermore, an adaptive SCVS (ASCVS) that was selected the best switch control time was also proposed. ASCVS estimates and predicts the amount of piezoelectric charge. However, piezoelectric parameters can be changed by temperature, which leads a miss of the selection. The appropriate switch time exist in each harvesting system that is constituted by a vibrated structure, a piezoelectric transducer, and an electric circuit. Components of the harvesting system has diversity, as the system is expected to harvest on various vibrated environments, to generate a voltage from various piezoelectric transducers, and to supply the electrical energy to various electrical devices. Thinking of the situation of the harvesting system, modification of each parameters depending on the changing temperature is infeasible. Therefore, a model-free control method instead of ASCVS is needed. Our proposed method selects the appropriate switch control time without a counter and an observer. To realize the model-free controls, we use fuzzy expressions instead of mathematical expression. We present the efficiency in the numerical simulation. The simulation reveals that the proposed method realizes the pausing switch control and recovering vibration amplitude.
