Piezoelectric Energy Harvesting Design for Energy Convesion Efficiency
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강종윤 KIST With the advent of the IoT era, the demand for sensors has increased significantly. We note that these sensor systems can communicate with each other over wireless networks in the IoT era. Especially, in particular sites where access to power is difficult, batteries have been installed as power source for wireless sensor systems. However, these batteries have a limited lifetime and require periodic replacement. So, various energy harvesting technologies have received research attention to realize an autonomous wireless sensor network by replacing the batteries. Due to relatively low power generation capability and energy conversion efficiency, however, these harvesting technologies have been applied only to limited applications. In order to address these issues, here, we design and demonstrate a piezoelectric/electromagnetic hybrid energy harvester that can generate significant amount of electricity at vibration environments. Oval-like configuration using two curved piezoelectric energy harvesters based on MFC(Macro-fiber composite) piezoelectric material induces large displacement of a permanent magnet installed at the end of the top surface which allows efficient power generation both piezoelectric and electromagnetic energy harvesters. Also, we provide the resonance frequency tuning guidelines and the optimization strategies of the Oval-shaped hybrid energy harvester. The hybrid energy harvester contains two magnets facing same polarity on both side of Oval-shaped structure which shows improved displacement of the magnet due to magnet induced repulsive force. This force improves the spring constant of Oval-shaped harvester, reducing the damping ratio efficiently. |