Closed loop frequency tuning of a vibration-based micro-generator

This paper presents a tunable electromagnetic vibration-based micro-generator with closed loop frequency tuning. Frequency tuning is realized by applying an axial tensile force to the micro-generator. A closed-loop frequency tuning system has been developed to control the tuning process so that the generator always operates at the ambient vibration frequency to make the entire process automatic. Experimentally the resonant frequency has been successfully tuned from 67.6 to 98 Hz when various axial tensile forces were applied to the structure. The generator produced a power of 61.6 to 156.6 uW over the tuning range when excited at vibrations of 0.588 m/s2.