Investigations of Vibratory Lines from PWM in Order to Recover Vibratory Energy on an Electric Machine

Vibrational energy harvesting on electric machines can be used to power health monitoring sensors for these machines. This study investigates the energy harvesting from the vibrations of an induction machine, focusing on frequency content. Vibrations of a Pulse Width Modulation (PWM)-fed induction machine are analyzed: the study of the frequency spectrum of the PWM supply allows prediction of frequency content of the surface vibration of the stator. These stator vibrations are converted into voltage by an amplified resonant piezoelectric stack mechanical energy harvester. Furthermore, the resonances of the motor and the harvester are exploited to increase the level of voltage generated on a resistive load. These resonances are excited by vibration lines in frequency spectrum caused by the PWM supply, that we control and explain with the switching frequency.