4. Efficient Energy Harvesting Systems for Vibration and Wireless Sensor Applications

In the first part of the research, we present the design of a vibration-based energy harvesting system. Robotic flexible arm having variable cross-section is investigated to overcome serious problems, e.g. insufficient bandwidth and model inaccuracies. Most of the energy harvesting systems are linear with unimodal characteristics. On the other hand, real vibrations can be modeled as random, multi-modal and time varying systems. Hence, unimodal linear systems can give highly unsatisfactory results under certain circumstances. However, non-linear systems can have multi-modal character with increased performance in real and practical situations. In this work, tapered links are preferred with nonlinear coupling setup to provide sufficient bandwidth and output power requirements for modern applications. Thus, the proposed scheme has been proven by simulated and experimental results successfully. In the second part of the research, we present design and experimental results of an electromagnetic harvester, energy source of which is single-phase household AC power with a nominal voltage of 220 V and a frequency of 50 Hz. In this case, energy harvesting is based on the induced electromotive force (EMF) as a result of the periodic variations of the magnetic field around the AC power cord. In this part, we also discuss basic principles of a wireless sensor network design powered by electromagnetically harvested energy obtained from household alternating current.