An electromagnetic energy scavenger from direct airflow

Abstract

Abstract: This paper presents two types of electromagnetic power generators exploiting direct conversion of airflow into mechanical vibration: 1) a windbelt-based vibratory linear micro-generator targeting strong airflows, and 2) a Helmholtz resonator based generator capable of scavenging energy from weaker airflows, i.e. environmental airflows. Both devices consist of two tightly coupled parts: a mechanical resonator, which produces high-frequency mechanical oscillation from quasi-constant airflow; and a permanent magnet/coil system, which generates electrical power from the resonator’s motion. The proposed micro-generators obviate the typically required matching of the resonant frequencies of the scavenger and the ambient energy sources it taps. This enables a device that is simpler, smaller, and higher-frequency than previously reported resonant power generator. The windbelt-based micro-generator demonstrated a peak-to-peak output voltage of 81mV at 0.53kHz, from an input pressure of 50kPa. The Helmholtz-resonator based micro-generator achieved a peak-to-peak output voltage of 4mV at 1.4kHz, from an input pressure of 0.2kPa, which is equivalent to 5m/s (10mph) of wind velocity