IEEE Transactions on Industrial Electronics vol:57 issue:12 pages:4170-4177
The behavior of a piezo-electric vibration-driven energy harvester with different power processing circuits is evaluated. Firstly, a general model for vibration-driven harvesters is described. Using this model, an optimal linear resistive load for the harvester is analytically calculated. As the vibration-based harvester provides varying AC power, while electronic loads need a stable DC power supply, the harvester behavior when connected to a AC-DC rectifier is analyzed. Using the same general model, an optimal DC voltage load can be calculated. The difference between the optimal output power flow from the harvester to both load circuits depends on the coupling coefficient of the harvester device. To determine which load leads to the optimal overall efficiency of a harvesting system, two power processing circuits are designed and built, the first emulating a resistive input impedance and the second with a constant input voltage. A buck-boost converter without input filter capacitor is shown to have a resistive input impedance. A buck converter is used to evaluate the rectifier load-case. Simulations and experimental validation show that the efficiency of the overall system increases with a standard buck converter as power processing circuit.