Design and experimental analysis of low wind speed rotary piezoelectric energy harvester

The Industry 4.0 has focus on connected devices and machines. It needs a number of sensors connected with each other and transfer of the information. Most of the sensors and sensor nodes require low power. In remote areas, where the power is limited, self-powered devices are more useful. Wind is available everywhere but the wind speed varies from place to place. Windmills are being used to generate electric power from the wind, however, is restricted due to large size and high cost. In this paper, it is proposed to develop a magnetic excited rotary harvester to harvest power at low wind speed. This can solve one of the major problems of frequent replacement of the battery in remote devices required for sensor and sensor nodes. To convert the rotation of the windmill to electric power, the rotation energy is converted to vibrating motion of a piezoelectric cantilever beam. The vibrations in the beam are generated with the help of interaction of magnetic field on the stator and blade mounted on the rotating shaft. The vibrations are then converted to electric charge due to the property of the piezoelectric material. An analytical model is developed and the results are compared with experiments. It is observed that at minimum wind speed of 2 m/s the estimated power is 1.06 mW while at a normal wind speed of 5 m/s power is calculated as 2.21 mW from the device.