Some Experimental Studies on 2DOF Electromagnetic Harvester
An electromagnetic transducer is used for harvesting kinetic energy from ambient vibrations. These are used to power wireless devices, recharge small scale batteries etc. Some of the vibration sources of excitation with low frequency are vibrations of bridges, vehicle suspensions, tall buildings etc. In a vibration based electromagnetic harvester (VEMH), a magnet and coil coupling mechanism is used and under the unidirectional low frequency excitation from vibratory source, a relative movement between coil and magnet causes a variation of magnetic flux density giving rise to an electromotive force through the coil. In a SDOF VEMH, output power is harvested in the vicinity of the resonance. In this paper, for enhancing the harvested power and widening of operational frequency range of SDOF VEMH, a dynamic magnifier system is added to a SDOF VEMH. For this purpose, a 2DOF VEMH is developed. The experimental analysis of the developed 2DOF VEMH is carried out to study the variation of open circuit voltage (E), voltage across resistive load (V), and harvested power (P), with the change in base excitation frequency ω. It is observed that more power can be obtained from a 2DOF VEMH with increase in the bandwidth of excitation frequency. Keywords - 2DOF VEMH, Experimental Setup, Open circuit voltage, Harvested Power.