Electromechanical Modeling of the Low-Frequency Zigzag Micro-Energy Harvester

An analytical electromechanical model is proposed to predict the deflection, voltage, and the power output of a proposed low-frequency micro-harvesting structure. The high natural frequencies of the existing designs of micro-scale vibrational energy harvesters are serious drawbacks. A zigzag design is proposed to overcome this limitation. First, the natural frequencies and the mode shapes of the zigzag structure are calculated. The piezoelectric direct and reverse effect equations, together with the electrical equations, are used to relate the voltage output of the structure to the base vibrations magnitude and frequency. The closed-form solution of the continuous electromechanical vibrations gives the power output as a function of base acceleration spectrum. The usefulness of the design is proved by the significant increase of the power output from the same base accelerations, providing a method of designing a micro-scale harvester with low natural frequency. The optimal mechanical and electrical conditions for power generation are investigated through the case studies.